WO2017012338A1 - Microwave oven, and starting control device and method for variable-frequency power supply of microwave oven - Google Patents

Abstract

Disclosed is a starting control device for a variable-frequency power supply of a microwave oven. The starting control device comprises: a variable-frequency power supply; a magnetron anode current detection module, used for detecting an anode current of a magnetron, and generating a current value of the anode current; and a control module, used for controlling the variable-frequency power supply to enter a soft starting stage after the variable-frequency power supply is powered on, controlling the variable-frequency power supply to enter a pre-heating stage after the soft starting stage is completed, determining whether the pre-heating stage is completed according to the anode current of the magnetron, and controlling the variable-frequency power supply to enter a normal operation stage after the pre-heating stage is completed. The device can accurately determine whether pre-heating of the magnetron is completed by means of the detected anode current of the magnetron, so as to control the variable-frequency power supply to enter a normal operation stage. Also disclosed are a microwave oven and a starting control method for a variable-frequency power supply of a microwave oven.

Description

Start control device and method for microwave oven and microwave oven variable frequency power supply Technical field

The invention relates to the technical field of microwave ovens, in particular to a start control device and method for a variable frequency power supply of a microwave oven and a microwave oven.

Background technique

At present, the inverter microwave oven is widely used due to its advantages of light body, low noise and low power consumption.

When the inverter microwave oven is in normal operation, the filament of the magnetron is heated to about 2100K by the 3.3V power supply to start emitting electrons. The emitted electrons move as a wheel under the action of the anode high voltage and magnetic circuit, and generate 2450MHz microwave in the anode cavity. , emitted into the heating cavity of the microwave oven via the energy output device.

However, when the variable frequency power supply in the inverter microwave oven is just powered on, the filament of the magnetron is in a cold state and does not have the ability to emit electrons. If the filament is not sufficiently warmed up, and the anode voltage of the magnetron is too high at this time, the stress of the magnetron is increased, which may cause damage to the magnetron breakdown. At the same time, when the magnetron is instantaneously activated, a large inrush current is generated to destroy the working state of the single-tube LC or the half-bridge resonant circuit of the primary side of the transformer.

In the related art, it is judged whether the preheating of the magnetron is completed by detecting the magnitude of the primary current of the transformer, but since the discreteness of many components between the primary side and the secondary side makes the detected primary current inaccurate, it is difficult Accurately determine whether the magnetron preheating is completed. If the preheating is judged too early, the anode voltage will be too high, which will cause damage to the magnetron and other devices. If the preheating is judged too late, the startup speed will be too slow.

Therefore, how to accurately determine whether the magnetron preheating is completed is an urgent problem to be solved.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the related art to some extent.

To this end, an object of the present invention is to provide a start control device for a microwave oven variable frequency power supply, which can accurately determine whether the magnetron preheating is completed by detecting the anode current of the magnetron.

A second object of the present invention is to provide a microwave oven.

A third object of the present invention is to provide a start control method for a microwave oven variable frequency power supply.

In order to achieve the above object, a start control device for a variable frequency power supply of a microwave oven according to a first aspect of the present invention includes: a variable frequency power supply; a magnetron anode current detecting module for detecting an anode current of the magnetron and generating a current value of the anode current a control module, configured to control the variable frequency power supply to enter a soft start phase after the variable frequency power supply is powered on, and control the variable frequency power supply to enter a warm-up phase after the soft start phase is completed, and according to the magnetron The anode current determines whether the warm-up phase is completed, and controls the variable frequency power supply to enter a normal operation phase after the warm-up phase is completed.

According to an embodiment of the present invention, a startup control device for a variable frequency power supply of a microwave oven detects an anode current of a magnetron through a magnetron anode current detecting module, and the control module controls the variable frequency power source to enter a soft start phase after being powered on the variable frequency power source, and is soft After the startup phase is completed, the variable frequency power supply is controlled to enter the preheating phase, and the preheating phase is judged according to the anode current of the magnetron, and the variable frequency power supply is controlled to enter the normal operation phase after the preheating phase is completed. Therefore, the device can accurately determine whether the magnetron preheating is completed by detecting the anode current of the magnetron after the variable frequency power supply enters the preheating phase, thereby effectively avoiding the magnetron caused by prematurely judging the completion of the preheating phase. And the damage of other devices improves the reliability of the product. At the same time, it effectively avoids the slow start-up speed caused by the late completion of the preheating stage, meets the requirements of rapid heating, and improves the user experience.

In addition, the start control device of the microwave oven variable frequency power supply according to the present invention may further have the following additional technical features:

In an embodiment of the present invention, the method further includes:

The resonant voltage detecting module is configured to detect a resonant voltage of the primary side of the transformer, wherein the control module controls the variable frequency power supply according to the resonant voltage in a warm-up phase.

In an embodiment of the invention, when the anode current of the magnetron is greater than a preset threshold, it is determined that the warm-up phase is completed.

In an embodiment of the invention, the magnetron anode current detecting module specifically includes:

a first resistor, one end of the first resistor is connected to an anode of the magnetron;

a second resistor, one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is grounded, wherein the first resistor and the second resistor have a first node;

And a third resistor, one end of the third resistor is connected to the first node, and the other end of the third resistor is an output end of the magnetron anode current detecting module.

In an embodiment of the present invention, the method further includes:

The upper computer is connected to the magnetron anode current detecting module, and the upper computer sends the anode current of the magnetron to the control module through a communication line.

In an embodiment of the present invention, the method further includes:

An optocoupler coupled between the magnetron anode current detecting module and the control module, the magnetron anode current detecting module transmitting an anode current of the magnetron to the control by the optocoupler Module.

In an embodiment of the invention, the detecting module further includes:

The primary current/primary power detection module is configured to detect a primary current/primary power of the transformer, wherein the control module determines whether the warm-up phase is completed according to the primary current/primary power. And controlling the variable frequency power supply to enter a normal operation phase after the preheating phase is completed.

In an embodiment of the present invention, the method further includes:

a frequency converter, wherein the frequency converter communicates with the upper computer, detects a communication frequency of the upper computer, and determines a rated voltage of the microwave oven according to a communication frequency of the upper computer.

In an embodiment of the invention, the upper computer is further configured to:

A state of the hardware switch is detected, and a communication frequency with the frequency converter is determined according to a state of the hardware switch.

In an embodiment of the invention, the corresponding rated voltage is 100V when the communication frequency is 100Hz, and the corresponding rated voltage is 120V when the communication frequency is 120Hz.

In an embodiment of the invention, the frequency converter is specifically configured to:

The frequency converter detects a width/number of high/low levels of the received signal within a preset time, and detects the communication frequency according to the width/number of times of the high/low level.

In an embodiment of the invention, the control module is further configured to acquire an operating state of the magnetron according to the anode current current value and a pre-stored anode current standard value.

In an embodiment of the invention, the control module is specifically configured to:

If the current value of the anode current is greater than twice the standard value of the anode current, determining that the magnetron is in an anode temperature too high state;

If the current value of the anode current is less than half of the standard value of the anode current, it is judged that the magnetron is in a core rupture state.

In an embodiment of the invention, the control module is further configured to:

After determining that the magnetron is in an anode temperature too high state, further controlling the magnetron to stop working or reducing the output power of the magnetron;

After determining that the magnetron is in the core rupture state, the magnetron is also controlled to stop working.

In order to achieve the above object, a microwave oven according to a second aspect of the present invention includes a start control device for a variable frequency power source of a microwave oven according to an embodiment of the first aspect of the present invention.

According to the microwave oven of the embodiment of the present invention, after the variable frequency power supply is powered on, the variable frequency power supply is controlled to enter the soft start phase, and after the soft start phase is completed, the variable frequency power supply is controlled to enter the warm-up phase, and the preheating is judged according to the anode current of the magnetron. Whether the phase is completed and the variable frequency power supply is controlled to enter the normal operation phase after the warm-up phase is completed. Therefore, after the variable frequency power supply enters the preheating stage, the anode current of the magnetron can be detected to accurately determine whether the magnetron is preheated, thereby effectively avoiding the magnetron and other devices caused by prematurely judging the completion of the preheating phase. The damage improves the reliability, and at the same time, effectively avoids the slow start-up speed caused by the late judgment of the completion of the warm-up phase, meets the requirements of rapid heating, and improves the user experience.

In order to achieve the above object, a method for starting control of a variable frequency power supply of a microwave oven according to a third aspect of the present invention includes: controlling, after powering on the variable frequency power supply, the variable frequency power supply to enter a soft start phase; after the soft start phase is completed, controlling The variable frequency power supply enters a preheating phase, wherein the variable frequency power supply is controlled according to a resonant voltage in a warming up phase; Determining whether the warm-up phase is completed according to an anode current of the magnetron; and after determining that the warm-up phase is completed, controlling the variable frequency power supply to enter a normal operation phase.

In addition, the startup control method of the microwave oven variable frequency power supply according to the present invention may further have the following additional technical features:

In an embodiment of the present invention, the method further includes:

Detecting the resonant voltage of the primary side of the transformer;

The anode current of the magnetron is sensed and the current value of the anode current is generated.

In an embodiment of the invention, when the anode current of the magnetron is greater than a preset threshold, it is determined that the warm-up phase is completed.

In an embodiment of the present invention, the method further includes:

Detecting primary current/primary power of the transformer;

Determining whether the warm-up phase is completed according to the primary current/primary power, and controlling the variable frequency power supply to enter a normal operation phase after the warm-up phase is completed.

In one embodiment of the invention, the anode current of the magnetron is fed back through the host computer.

In one embodiment of the invention, the anode current of the magnetron is fed back through an optocoupler.

In an embodiment of the present invention, the method further includes:

The inverter communicates with the host computer;

The frequency converter detects a communication frequency of the upper computer;

The frequency converter determines a rated voltage of the microwave oven according to a communication frequency of the upper computer.

In an embodiment of the present invention, the method further includes:

The upper computer detects the state of the hardware switch;

A communication frequency with the frequency converter is determined according to a state of the hardware switch.

In an embodiment of the invention, the corresponding rated voltage is 100V when the communication frequency is 100Hz, and the corresponding rated voltage is 120V when the communication frequency is 120Hz.

In an embodiment of the present invention, the detecting, by the frequency converter, the communication frequency of the upper computer includes:

The frequency converter detects a width/number of high/low levels of the received signal within a preset time, and detects the communication frequency according to the width/number of times of the high/low level.

In an embodiment of the present invention, the method further includes:

Obtaining an operating state of the magnetron according to the current value of the anode current and a pre-stored anode current standard value.

In an embodiment of the invention, the obtaining the working state of the magnetron according to the current value of the anode current and the pre-stored anode current standard value includes:

If the current value of the anode current is greater than twice the standard value of the anode current, it is determined that the magnetron is at the anode High temperature state;

If the current value of the anode current is less than half of the standard value of the anode current, it is judged that the magnetron is in a core rupture state.

In an embodiment of the present invention, the method further includes:

After determining that the magnetron is in an anode temperature too high state, further controlling the magnetron to stop working or reducing the output power of the magnetron;

After determining that the magnetron is in the core rupture state, the magnetron is also controlled to stop working.

According to the startup control method of the microwave oven variable frequency power supply according to the embodiment of the present invention, after the variable frequency power supply is powered on, the variable frequency power supply is controlled to enter the soft start phase, and after the soft start phase is completed, the variable frequency power supply is controlled to enter the warm-up phase, and according to the magnetron The anode current is used to judge whether the preheating phase is completed, and the variable frequency power supply is controlled to enter the normal operation phase after the preheating phase is completed. Therefore, the method can accurately determine whether the magnetron is preheated by detecting the anode current of the magnetron after the variable frequency power supply enters the preheating phase, thereby effectively avoiding the magnetron caused by prematurely judging the completion of the preheating phase. And the damage of other devices improves the reliability of the product. At the same time, it effectively avoids the slow start-up speed caused by the late completion of the preheating stage, meets the requirements of rapid heating, and improves the user experience.

The advantages of the additional aspects of the invention will be set forth in part in the description which follows.

DRAWINGS

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a block diagram showing a start control device for a microwave oven variable frequency power supply according to an embodiment of the present invention;

2 is a circuit diagram of a start control device for a microwave oven variable frequency power supply according to an embodiment of the present invention;

3 is a block diagram showing a start control device for a microwave oven variable frequency power supply according to another embodiment of the present invention;

4 is a circuit diagram of a start control device for a microwave oven variable frequency power supply according to another embodiment of the present invention;

5 is a block diagram showing a start control device for a variable frequency power supply of a microwave oven according to still another embodiment of the present invention;

6 is a block diagram showing a start control device for a variable frequency power supply of a microwave oven according to still another embodiment of the present invention;

7 is a circuit diagram of a start control device for a microwave oven variable frequency power supply according to still another embodiment of the present invention;

8 is a block diagram showing a start control device for a microwave oven variable frequency power supply according to still another embodiment of the present invention;

9 is a circuit diagram of a magnetron anode current detection according to another embodiment of the present invention;

10 is a flow chart of a method for starting control of a microwave oven variable frequency power supply according to an embodiment of the present invention;

11 is a flow chart showing a method of starting control of a microwave oven variable frequency power supply according to another embodiment of the present invention;

Figure 12 is a flow chart showing a method of detecting the operating state of a magnetron in a microwave oven in accordance with one embodiment of the present invention.

detailed description

A start control apparatus and method for a microwave oven variable frequency power supply and a microwave oven according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

In order to accurately determine whether the preheating phase of the magnetron is completed, an embodiment of the present invention proposes a start control device for a microwave oven variable frequency power supply.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a block diagram of a start control apparatus for a microwave oven variable frequency power supply in accordance with one embodiment of the present invention. As shown in FIG. 1, the startup control device of the microwave oven variable frequency power supply includes: a magnetron anode current detecting module 100, a control module 200, and a variable frequency power source 300.

Specifically, the magnetron anode current detecting module 100 is configured to detect the anode current of the magnetron and generate a current value of the anode current.

In one embodiment of the present invention, as shown in FIG. 2, the magnetron anode current detecting module 100 may specifically include: a first resistor R1, a second resistor R2, and a third resistor R3, wherein one end of the first resistor R1 Connected to the anode of the magnetron MGT, one end of the second resistor R2 is connected to the other end of the first resistor R1, and the other end of the second resistor R2 is connected to the ground GND, wherein the first resistor R1 and the second resistor R2 have the same One node J1, one end of the third resistor R3 is connected to the first node J1, and the other end of the third resistor R3 is the output terminal IB of the magnetron anode current detecting module 100.

As shown in FIG. 2, a secondary winding of the transformer T is connected to the voltage doubler circuit, and after being double-pressed, one end is connected to the anode of the magnetron MGT, and the other end is connected to one end of the second resistor R2. The resistor R2 is then connected to the magnetron MGT. When the anode voltage (-4000V) supplied to the magnetron MGT passes through the second resistor R2, a certain voltage drop is formed, which is proportional to the magnitude of the current flowing through the anode of the magnetron, and is passed through the third resistor R3. The anode current of the magnetron MGT can be obtained by sampling the voltage drop.

The control module 200 is configured to control the variable frequency power supply 300 to enter a soft start phase after the power supply 300 is powered on, and control the variable frequency power supply 300 to enter a warm-up phase after the soft start phase is completed, and determine whether the warm-up phase is determined according to the anode current of the magnetron. Completed and controls the variable frequency power supply 300 to enter the normal operation phase after the warm-up phase is completed. The soft start phase can be calibrated according to actual conditions. For example, the soft start phase can be a mains cycle.

In one embodiment of the invention, the preheating phase is determined to be complete when the anode current of the magnetron is greater than a predetermined threshold. The preset threshold can be calibrated according to actual conditions.

It can be understood that, since the magnetron of the magnetron is in a cold state when the magnetron is initially powered on, the magnetron is not activated, and the anode current of the magnetron is zero, and the magnetron is preheated. After a period of time, the anode current of the magnetron gradually increases. When the anode current of the magnetron reaches a preset threshold, it is judged that the preheating phase of the magnetron is completed. For example, in the embodiment shown in FIG. 2, when the voltage corresponding to the anode current of the detected magnetron is greater than 0.3 V, it indicates that the anode current of the magnetron detected by the magnetron anode current detecting module 100 is greater than a preset threshold. At this time, it is judged that the warm-up phase is completed

In an embodiment of the present invention, the start control device for the microwave oven variable frequency power supply may further include a host computer, and the upper computer is connected to the magnetron anode current detecting module 100, and the upper computer sends the anode current of the magnetron through the communication line. To the control module 200.

In another embodiment of the present invention, the startup control device for the microwave oven variable frequency power supply may further include: an optocoupler connected between the magnetron anode current detecting module 100 and the control module 200, and a magnetron anode current detecting module. The anode current of the magnetron is sent to the control module 200 through the optocoupler.

That is, after the magnetron anode current detecting module 100 detects the current anode current of the magnetron, it is sent to the control module 200 through the optocoupler, and the control module 200 determines the anode current of the magnetron to obtain the magnetic field. Control the current working state, and control the variable frequency power supply according to the current working state of the magnetron, thereby achieving accurate control of the magnetron, such as reducing the output power of the magnetron or controlling the magnetron to stop working.

Optionally, the embodiment of the invention further provides a detecting device for the working state of the magnetron in the microwave oven, wherein the magnetron anode current detecting module and the control module realize the detection of the working state of the magnetron in the microwave oven, and the specific implementation An example can be as shown in the embodiment of FIG.

In the embodiment of the present invention, both the upper computer and the optocoupler are responsible for transmitting the anode current of the magnetron to the control module 200, so that the control module 200 can accurately determine whether the magnetron preheating is completed, effectively avoiding the cause. Early judgment of the damage of the magnetron and other devices caused by the completion of the preheating stage improves the reliability of the product, and at the same time effectively avoids the problem of slow start-up caused by the late completion of the preheating stage and meets the requirements of rapid heating. , improved user experience.

In another embodiment of the present invention, as shown in FIG. 3, the above-mentioned microwave oven variable frequency power supply startup control device may further include: a resonance voltage detection module 400 for detecting a resonance voltage of a primary side of the transformer, wherein the control module is In the warm-up phase, the variable frequency power supply is controlled according to the resonance voltage.

According to a specific example of the present invention, when the inverter microwave oven is initially powered on, the control module 200 controls the variable frequency power supply 300 to enter a soft start phase, such as controlling the variable frequency power supply 300 to start operating at a fixed frequency, and the switching tube in the variable frequency power supply 300 The duty ratio is less than 10%. After the soft start phase of the variable frequency power supply 300 is completed, the control module 200 controls the variable frequency power supply 300 to enter the warm-up phase. At this time, the control module 200 gradually increases the duty ratio of the switch tube to improve the magnetron. The anode voltage is obtained by the resonant voltage detecting module 400 to obtain the resonant voltage of the primary side of the transformer. When the detected resonant voltage of the primary side of the transformer reaches a limit value, the control module 200 maintains the current duty cycle output. Moreover, when the control module 200 controls the switch tube according to the current duty ratio, if the detected resonant voltage of the primary side of the transformer is greater than the limit value, the control module 200 reduces the duty cycle of the switch tube; if the detected primary side of the transformer The resonant voltage is less than the limit value, and the control module 200 increases the duty cycle of the switching transistor. The problem of inaccurate output caused by calculating the maximum duty ratio of the switch tube according to the primary side supply voltage is effectively solved, thereby ensuring the stability and reliability of the magnetron, and effectively avoiding the possibility that the anode voltage is too high. The magnetron breakdown is damaged, or other devices are damaged, and the problem of slow startup speed due to inaccurate control is effectively avoided.

Optionally, the magnetron anode current detecting module 100 detects the anode current of the magnetron and transmits it through the host computer or the optical coupler. Sent to the control module 200, the control module 200 determines after receiving the anode current of the magnetron. When the anode current of the magnetron is greater than a preset threshold, the control module 200 determines that the filament preheating of the magnetron is completed, and the control module The 200-controlled inverter microwave oven enters the normal power operation phase.

As shown in FIG. 2 or FIG. 4, the resonant voltage detecting module 400 may include a fourth resistor R4, a fifth resistor R5, and a voltage comparator CMP, wherein one end of the fourth resistor R4 is connected to one end of the primary winding of the transformer T, The other end of the fourth resistor R4 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is grounded to GND1, and the other end of the fourth resistor R4 and the one end of the fifth resistor R5 have a second node J2, second The node J2 is connected to the first input end of the voltage comparator CMP, the limit value Vref is connected to the second input end of the voltage comparator CMP, the output end of the voltage comparator CMP is connected to the control module 200, and the control module 200 is based on the voltage comparator CMP. The signal at the output is used to accurately adjust the duty cycle.

It can be understood that the limit value can also be preset in the control module 200, and the control module 200 can adjust the duty ratio by comparing with the resonance voltage detected by the resonance voltage detecting module 400. In addition, in the embodiment of the present invention, the resonant voltage detecting module 100 may also include a resistor, or a capacitor, or a combination of a resistor and a capacitor. Of course, the resonant voltage may also be obtained by detecting the maximum value of the resonant voltage period.

In the embodiment of the present invention, the resonant voltage detection module 400 detects the resonant voltage of the primary side of the transformer, and the control module 200 controls the variable frequency power supply 300 according to the resonant voltage in the warm-up phase of the variable frequency power supply, thereby implementing the anode voltage of the magnetron. The accurate control not only ensures the consistency of the anode voltage at the start of each working voltage, but also ensures that the anode voltage is in a stable ideal state, thus ensuring the stability and reliability of the magnetron, effectively avoiding the anode voltage High possible magnetron breakdown damage, or damage to other devices, and effectively avoids the problem of slow start-up due to inaccurate control, improving the user experience.

In an optional embodiment of the present invention, as shown in FIG. 5, the startup control device of the microwave oven variable frequency power supply may further include: a primary current/primary power detection module 500, and a primary current/primary power detection module 500. The primary current/primary power of the transformer is detected, wherein the control module 200 determines whether the warm-up phase is completed according to the primary current/primary power, and controls the variable frequency power supply 300 to enter a normal operation phase after the warm-up phase is completed.

Specifically, as shown in FIG. 2 or FIG. 4, the primary current of the transformer T is obtained through the sixth resistor R6, and the control module 200 determines whether the preheating phase of the magnetron is completed according to the detected primary current of the transformer T. It can be understood that the primary side power of the transformer T can also be calculated by detecting the primary current of the transformer T, so that whether the preheating phase of the magnetron is completed can be determined according to the primary side power of the transformer T. And after the magnetron preheating phase is completed, the control module 200 controls the variable frequency power supply 300 to enter a normal operation phase.

In the embodiment of the present invention, whether it is the magnetron anode current detecting module 100 or the primary current/primary power detecting module 500, it is responsible for accurately determining whether the warm-up phase is completed, and avoiding prematurely judging that the warm-up phase is completed. The resulting magnetron and other devices are damaged and the startup speed is slow due to the late completion of the preheating phase.

A startup control device for a microwave oven variable frequency power supply according to an embodiment of the present invention is detected by a magnetron anode current detecting module Measuring the anode current of the magnetron, the control module controls the variable frequency power supply to enter the soft start phase after the variable frequency power supply is powered on, and controls the variable frequency power supply to enter the preheating phase after the soft start phase is completed, and judges according to the anode current of the magnetron. Whether the thermal phase is completed and controls the variable frequency power supply to enter the normal operation phase after the warm-up phase is completed. Therefore, the device can accurately determine whether the magnetron preheating is completed by detecting the anode current of the magnetron after the variable frequency power supply enters the preheating phase, thereby effectively avoiding the magnetron caused by prematurely judging the completion of the preheating phase. And the damage of other devices improves the reliability of the product. At the same time, it effectively avoids the slow start-up speed caused by the late completion of the preheating stage, meets the requirements of rapid heating, and improves the user experience. In addition, it effectively avoids the large impulse current generated by the magnetron due to the instantaneous vibration to affect the working state of the resonant circuit.

6 is a block diagram showing the structure of a control device for a frequency converter in a microwave oven according to still another embodiment of the present invention. As shown in FIG. 6, the control device for the inverter in the microwave oven according to the embodiment of the present invention includes: a host computer 10 and a frequency converter 20.

The frequency converter 20 can communicate with the upper computer 10, and can detect the communication frequency of the upper computer 10, and can determine the rated voltage of the microwave oven according to the communication frequency of the upper computer 10.

The upper computer 10 can be built in the microwave oven, communicates with the frequency converter 20 through a communication line, or can be a control device such as a remote controller or a mobile terminal, and communicates with the frequency converter through a Bluetooth, infrared or wireless network.

In an embodiment of the present invention, the host computer 10 can detect the state of the hardware switch and determine the communication frequency with the frequency converter according to the state of the hardware switch. Specifically, the communication frequency corresponding to the hardware switch of the upper computer 10 in the on and off states may be preset. For example, in the state where the hardware switch is on, the communication frequency is 100 Hz, and in the off state, the communication frequency is 120 Hz. Thus, the host computer 10 can determine the communication frequency with the frequency converter through the state of its hardware switch.

After receiving the communication signal from the host computer 10, the frequency converter 20 can detect the width/number of times of the high/low level of the received signal within the preset time, and detect the communication frequency according to the width/number of high/low level. It should be understood that the frequency of the high/low level received by the frequency converter 20 per second, or the reciprocal of the total width of the high/low level of 2 times, is the communication frequency. For example, if 100 low levels are received in 1S, the communication frequency is 100 Hz, and if the high level width is 5 mS, the communication frequency is 100 Hz.

In an embodiment of the invention, the corresponding rated voltage is 100V when the communication frequency is 100Hz, and the corresponding rated voltage is 120V when the communication frequency is 120Hz.

For example, when the power voltage used by the user is 100V, the communication frequency of the host computer 10 and the frequency converter 20 can be controlled to be 100 Hz by adjusting the state of the hardware switch, and the frequency converter 20 determines after receiving the communication frequency of 100 Hz. The rated voltage of the microwave oven is 100V. Thus, during normal use of the microwave oven, the frequency converter 20 can operate at a constant power when the input voltage exceeds 100V, and the frequency converter 20 can operate at a constant current when the input voltage is lower than 100V. This prevents the current from exceeding the standard or causing damage to the circuit due to excessive power.

In an embodiment of the present invention, the frequency converter 20 can also determine the output power of the normal heating phase according to the communication frequency of the upper computer 10. Specifically, the output power of the frequency converter 20 can be set to correspond to the communication frequency of the upper computer 10. E.g, When the communication frequency of the host computer 10 is 1200 Hz, the corresponding inverter 20 has an output power of 1200 W.

Further, in one embodiment of the present invention, in order to save electrical energy and increase the life of the magnetron, the magnetron of the microwave oven may be preheated prior to normal heating. Therefore, in the embodiment of the present invention, the host computer 10 is further configured to: send the anode current of the magnetron to the control module through the communication line, so that the control module determines whether the warm-up phase is completed according to the anode current of the magnetron, and The frequency converter 20 is controlled to enter a normal operation phase after the warm-up phase is completed.

That is, after the magnetron anode current detecting module detects the current anode current of the magnetron, the anode current of the current magnetron is sent to the upper computer 10, and the host computer 10 passes the anode of the current magnetron through the communication line. The current is sent to the control module, and the control module determines the current of the current magnetron to obtain the current working state of the magnetron, and controls the variable frequency power supply according to the current working state of the magnetron, thereby realizing the magnetic control Accurate control of the tube, such as reducing the output power of the magnetron or controlling the magnetron to stop working.

It can be understood that after the host computer 10 receives the anode current of the current magnetron sent by the magnetron anode current detecting module, the host computer 10 can first judge the anode current of the current magnetron to obtain the magnetron. The current working state, and when the magnetron is required to stop working, the control module is controlled to stop the magnetron.

Specifically, when the microwave oven is heated, the preheating phase can be entered first, that is, the frequency converter 20 operates at a lower output power. When the host computer 10 detects that the anode current of the magnetron is greater than a preset value (for example, 15A), it is judged that the warm-up phase is completed and enters the normal heating phase. At this time, the communication frequency of the upper-level machine 10 in the normal heating phase is obtained. The frequency converter 20 is in communication to control the frequency converter 20 to operate at the set output power of the normal heating stage. Wherein, as shown in FIG. 7, the anode current of the magnetron can be detected by a detecting circuit composed of the first resistor R1, the second resistor R2 and the third resistor R3.

It should be understood that the voltage and output power of the frequency converter 20 can be controlled by other means in addition to being controlled by the communication frequency of the upper computer in the above embodiment. For example, the voltage and output power of the frequency converter 20 can be controlled by the total number of pulses. The specific control method should not be construed as limiting the invention.

According to the control device of the frequency converter in the microwave oven according to the embodiment of the invention, the frequency converter can communicate with the upper computer, simultaneously detect the communication frequency of the upper computer, and can determine the rated voltage of the frequency converter according to the communication frequency, thereby, the microwave oven can be The rated voltage is sent to the inverter, so that the inverter can control the output power and working current according to the rated voltage of the microwave oven. While improving safety and reliability, it also improves the versatility of the inverter in the microwave oven, avoiding development and production. In the process, the frequency converter is classified and developed and produced due to different voltage standards, which can effectively reduce the development cycle, expand the production scale, and reduce development and production costs.

Figure 8 is a block diagram showing the structure of a detecting device for a working state of a magnetron in a microwave oven according to still another embodiment of the present invention.

As shown in FIG. 8, the apparatus for detecting the working state of the magnetron in the microwave oven according to the embodiment of the present invention comprises: a magnetron anode current detecting module 10 and a control module 20.

The magnetron anode current detecting module 10 is configured to detect the anode current of the magnetron and generate a current value of the anode current.

According to another embodiment of the present invention, as shown in FIG. 9, the magnetron anode current detecting module 10 specifically includes: a fourth resistor R4 and a fifth resistor R5, wherein one end of the fourth resistor R4 is connected to the anode of the magnetron MGT through the third diode D3, and one end of the fourth resistor R4 and the cathode of the third diode D3 Connected, the other end of the fourth resistor R4 is grounded to GND, one end of the fifth resistor R5 is respectively connected to one end of the fourth resistor R4 and the cathode of the third diode D3, and the other end of the fifth resistor R5 is a magnetron anode current. The output of the module 10 is detected. The circuit can be used in a fixed frequency microwave oven. When the anode voltage (-4000V) supplied to the magnetron MGT is passed through the fourth resistor R4, a voltage drop is formed, which is proportional to the current flowing through the anode of the magnetron. The anode current IB of the magnetron MGT is obtained by sampling the voltage drop through the fifth resistor R5.

The control module 20 is configured to obtain an operating state of the magnetron according to the current value of the anode current and the pre-stored anode current standard value.

It should be understood that in the design and production process of the microwave oven, the standard value of the anode current, that is, the rated anode current value of the magnetron, and the control module 20 of the microwave oven, such as the MCU, may be obtained through theoretical analysis and actual experiments. Micro Control Unit, Micro Control Unit).

After the magnetron anode current detecting module 10 detects the anode current of the magnetron, the anode current can be sent to the control module 20.

Specifically, after the magnetron anode current detecting module 10 detects the current value of the anode current of the magnetron, the current value of the anode current is sent to the upper computer, and the upper computer sends the current value of the anode current to the control module 20 through the communication line. The current value of the anode current is judged by the control module 20 to obtain the current working state of the magnetron, and the magnetron is controlled according to the current working state of the magnetron.

It can be understood that after the host computer receives the current value of the anode current sent by the magnetron anode current detecting module 10, the host computer can first determine the current value of the anode current to obtain the current working state of the magnetron, and When the magnetron is required to stop working, the control transistor 20 or the relay K1 is controlled to stop the magnetron.

In another embodiment of the invention, the anode current of the magnetron can be sent to the control module 20 via an optocoupler, wherein the optocoupler is coupled between the magnetron anode current sensing module 10 and the control module 20. That is, after the magnetron anode current detecting module 10 detects the current value of the anode current, it is sent to the control module 20 through the optocoupler, and the control module 20 determines the current value of the anode current to obtain the current work of the magnetron. State, and control the magnetron according to the current working state of the magnetron.

Of course, the anode current can also be sent to the control module 20 by other means, which are not enumerated here.

After the control module 20 receives the current value of the anode current, the control module 20 can compare it to the anode current standard value. If the current value of the anode current is greater than twice the standard value of the anode current, it is judged that the magnetron is in an anode temperature too high state; if the current value of the anode current is less than half of the anode current standard value, it is judged that the magnetron is in a core rupture state, After determining that the magnetron is in an anode temperature too high state, the magnetron is controlled to stop working or the output power of the magnetron is lowered; and after the magnetron is judged to be in the core rupture state, the magnetron is directly controlled to stop working. . Alternatively, when it is judged that the magnetron is in an anode over temperature state or a core rupture state, the judgment result may be fed back to the user by displaying an error code.

It can be understood that, in the variable frequency microwave oven, the output power of the magnetic control tube can be reduced by the control module 20 adjusting the duty ratio of the variable frequency power supply or the frequency converter; in the fixed frequency microwave oven, the relay of the relay can be adjusted by the control module 20. More than to reduce the output power of the magnetron.

The apparatus for detecting the working state of the magnetron in the microwave oven according to the embodiment of the present invention detects the anode current of the magnetron and obtains the working state of the magnetron according to the anode current of the magnetron and the pre-stored anode current standard value, thereby It can accurately and accurately determine abnormal conditions such as excessive temperature or damage of the magnetron, so that necessary protective measures can be taken in time, such as controlling the microwave oven to stop working, and displaying an error code to remind the user to repair, etc., and the implementation is simple and convenient. The cost is lower.

In order to achieve the above embodiment, the present invention also proposes a microwave oven.

The microwave oven according to the embodiment of the present invention includes the start control device for the variable frequency power supply of the microwave oven according to any of the above embodiments of the present invention.

According to the microwave oven of the embodiment of the present invention, after the variable frequency power supply is powered on, the variable frequency power supply is controlled to enter the soft start phase, and after the soft start phase is completed, the variable frequency power supply is controlled to enter the warm-up phase, and the preheating is judged according to the anode current of the magnetron. Whether the phase is completed and the variable frequency power supply is controlled to enter the normal operation phase after the warm-up phase is completed. Therefore, after the variable frequency power supply enters the preheating stage, the anode current of the magnetron can be detected to accurately determine whether the magnetron preheating is completed, thereby effectively avoiding the magnetron and other devices caused by prematurely judging the completion of the preheating phase. The damage improves the reliability, and at the same time, effectively avoids the slow start-up speed caused by the late judgment of the completion of the warm-up phase, meets the requirements of rapid heating, and improves the user experience. In addition, it effectively avoids the large impulse current generated by the magnetron due to the instantaneous vibration to affect the working state of the resonant circuit.

In order to implement the above embodiments, the present invention also provides a method for starting control of a microwave oven variable frequency power supply.

Figure 10 is a flow chart showing a method of starting control of a microwave oven variable frequency power supply in accordance with the present invention. As shown in FIG. 10, the startup control method of the microwave oven variable frequency power supply includes:

S101, after the variable frequency power supply is powered on, the variable frequency power supply is controlled to enter a soft start phase.

For example, in the soft start phase, the variable frequency power supply can be controlled to start operating at a fixed frequency, and the duty cycle of the switching tube in the variable frequency power supply can be controlled to be less than 10%, wherein the soft start phase can be a mains cycle.

S102, after the soft start phase is completed, controlling the variable frequency power supply to enter a warm-up phase, wherein the variable frequency power supply is controlled according to the resonant voltage in the warm-up phase.

According to a specific example of the present invention, when the inverter microwave oven is initially powered on, the variable frequency power supply is controlled to enter a soft start phase, such as controlling the variable frequency power supply to start operating at a fixed frequency, and the duty cycle of the switching tube in the variable frequency power supply is less than 10%. After the soft start phase of the variable frequency power supply is completed, the variable frequency power supply is controlled to enter the preheating stage. At this time, the duty ratio of the switching tube is gradually increased to increase the anode voltage of the magnetron, and the transformer is obtained by the resonant voltage of the primary side of the transformer. The resonant voltage of the primary side maintains the current duty cycle output when the detected resonant voltage of the primary side of the transformer reaches a limit value. Moreover, when the switching tube is controlled according to the current duty ratio, if the detected resonant voltage of the primary side of the transformer is greater than the limit value, the duty cycle of the switching tube is reduced; if the detected resonant voltage of the primary side of the transformer is less than the limit value , increase the duty cycle of the switch. Effectively solved According to the primary side supply voltage, the output inaccuracy caused by the maximum duty cycle of the switch tube is calculated, thereby ensuring the stability and reliability of the magnetron, and effectively avoiding the magnetic control caused by the excessive anode voltage. Tube breakdown damage, or damage to other devices, while effectively avoiding the problem of slow start-up due to inaccurate control.

Wherein, as shown in FIG. 2 or FIG. 4, the resonant voltage can be detected by the resonant voltage detecting module formed by the fourth resistor R4, the fifth resistor R5 and the voltage comparator CMP, wherein one end of the fourth resistor R4 and the transformer T One end of the primary winding is connected, the other end of the fourth resistor R4 is connected to one end of the fifth resistor R5, the other end of the fifth resistor R5 is grounded to GND1, and the other end of the fourth resistor R4 is connected to the end of the fifth resistor R5. The second node J2 is connected to the first input end of the voltage comparator CMP, the limit value Vref is connected to the second input end of the voltage comparator CMP, and the output end of the voltage comparator CMP is connected to the control module, and the control module is The signal at the output of the voltage comparator CMP is used to accurately adjust the duty cycle.

It can be understood that the limit value can also be preset in the control module, and the control module can adjust the duty ratio by comparing with the detected resonance voltage. In addition, in the embodiment of the present invention, the resonant voltage detecting module may also include a resistor, or a capacitor, or a combination of a resistor and a capacitor. Of course, the resonant voltage may also be obtained by detecting the maximum value of the resonant voltage period.

S103. Determine whether the warm-up phase is completed according to the anode current of the magnetron.

S104, after determining that the warm-up phase is completed, controlling the variable frequency power supply to enter a normal operation phase.

According to a specific example of the present invention, as shown in FIG. 2, a secondary winding of the transformer T is connected to the voltage doubling circuit, and the voltage is doubled, one end is connected to the anode of the magnetron MGT, and the other end is connected to the second resistor. One end of R2 is connected, and is connected to the magnetron MGT via the second resistor R2. When the anode voltage (-4000V) supplied to the magnetron MGT passes through the second resistor R2, a certain voltage drop is formed, which is proportional to the magnitude of the current flowing through the anode of the magnetron, and is passed through the third resistor R3. The anode current of the magnetron MGT can be obtained by sampling the voltage drop. Thereby, it can be accurately judged whether or not the preheating phase of the magnetron is completed.

In one embodiment of the invention, the preheating phase is determined to be complete when the anode current of the magnetron is greater than a predetermined threshold. The preset threshold can be calibrated according to actual conditions.

It can be understood that, since the magnetron of the magnetron is in a cold state when the magnetron is initially powered on, the magnetron is not activated, and the anode current of the magnetron is zero, and the magnetron is preheated. After a period of time, the anode current of the magnetron gradually increases. When the anode current of the magnetron reaches a preset threshold, it is judged that the preheating phase of the magnetron is completed. For example, in the embodiment shown in FIG. 2, when the voltage corresponding to the anode current of the detected magnetron is greater than 0.3 V, it indicates that the anode current of the magnetron is greater than a preset threshold, and it is judged that the warm-up phase is completed.

In one embodiment of the invention, the anode current of the magnetron is fed back through the host computer.

Specifically, the anode current of the magnetron can be detected by the magnetron anode current detecting module shown in FIG. 2, and after detecting the anode current of the current magnetron, the anode current of the current magnetron is sent to the host computer. , the upper computer can pass The signal line sends the anode current of the current magnetron to the control module, and the control module determines the anode current of the current magnetron to obtain the current working state of the magnetron, and converts the frequency according to the current working state of the magnetron. The power supply is controlled to achieve accurate control of the magnetron, such as reducing the output power of the magnetron or controlling the magnetron to stop working.

Optionally, the embodiment of the present invention further provides a method for detecting a working state of a magnetron in a microwave oven, wherein the magnetron anode current detecting module and the control module are used to detect the working state of the magnetron in the microwave oven, and the specific implementation For example, as shown in the embodiment of Fig. 12, Fig. 12 is a flow chart showing a method of detecting the working state of the magnetron in the microwave oven according to an embodiment of the present invention.

It can be understood that after the host computer receives the anode current of the current magnetron sent by the magnetron anode current detecting module, the host computer can first judge the current of the current magnetron to obtain the current state of the magnetron. The working state, and when the magnetron is required to stop working, the control circuit is controlled to stop the magnetron.

In another embodiment of the invention, the anode current of the magnetron is fed back through the optocoupler.

Specifically, after the magnetron anode current detecting module detects the current anode current of the magnetron, it is sent to the control module through the optocoupler, and the control module determines the anode current of the magnetron to obtain the magnetron. The current working state, and the variable frequency power supply is controlled according to the current working state of the magnetron, thereby realizing accurate control of the magnetron, such as reducing the output power of the magnetron or controlling the magnetron to stop working.

In the embodiment of the present invention, both the upper computer and the optocoupler are responsible for transmitting the anode current of the magnetron to the control module, so that the control module can accurately determine whether the magnetron preheating is completed, and effectively avoid premature judgment. The damage of the magnetron and other devices caused by the completion of the preheating stage improves the reliability of the product, and at the same time, effectively avoids the problem of slow start-up caused by the late completion of the preheating stage, and satisfies the requirements of rapid heating and improves The user experience.

In an embodiment of the present invention, the method for starting the control of the variable frequency power supply of the microwave oven may further include: detecting a primary current/primary power of the transformer, and determining whether the warm-up phase is completed according to the primary current/primary power, and After the preheating phase is completed, the variable frequency power supply is controlled to enter the normal operation phase. Specifically, as shown in FIG. 3 or FIG. 5, the primary current of the transformer T is obtained through the sixth resistor R6, and the control module determines whether the preheating phase of the magnetron is completed according to the detected primary current of the transformer T. It can be understood that the primary side power of the transformer T can also be calculated by detecting the primary current of the transformer T, so that whether the preheating phase of the magnetron is completed can be determined according to the primary side power of the transformer T. After the magnetron preheating phase is completed, the control module controls the variable frequency power supply to enter the normal operation phase.

In the embodiment of the present invention, whether it is the magnetron anode current detecting module or the primary current/primary power detecting module, it is responsible for accurately determining whether the warm-up phase is completed or not, thereby avoiding premature judgment of the completion of the warm-up phase. The damage of the magnetron and other devices and the slow start-up caused by the late completion of the preheating phase.

According to a specific example of the present invention, when the inverter microwave oven is initially powered on, the control module controls the variable frequency power supply to enter a soft start phase, such as controlling the variable frequency power supply to start operating at a fixed frequency, and the duty cycle of the switching tube in the variable frequency power supply is less than 10%, after the soft start phase of the variable frequency power supply is completed, the control module controls the variable frequency power supply to enter the warm-up phase. At this time, the control The module gradually increases the duty cycle of the switching tube to increase the anode voltage of the magnetron, and obtains the resonant voltage of the primary side of the transformer through the resonant voltage detecting module. When the detected resonant voltage of the primary side of the transformer reaches a limit value, the control module Maintain the current duty cycle output. Moreover, when the control module controls the switch tube according to the current duty ratio, if the detected resonant voltage of the primary side of the transformer is greater than a limit value, the control module reduces the duty cycle of the switch tube; if the detected primary side resonance of the transformer If the voltage is less than the limit value, the control module increases the duty cycle of the switch. The problem of inaccurate output caused by calculating the maximum duty ratio of the switch tube according to the primary side supply voltage is effectively solved, thereby ensuring the stability and reliability of the magnetron, and effectively avoiding the possibility that the anode voltage is too high. The magnetron breakdown is damaged, or other devices are damaged, and the problem of slow startup speed due to inaccurate control is effectively avoided.

Optionally, the magnetron anode current detecting module detects the anode current of the magnetron and sends it to the control module through the host computer or the optocoupler, and the control module judges after receiving the anode current of the magnetron, when the magnetron When the anode current is greater than the preset threshold, the control module determines that the filament preheating of the magnetron is completed, and the control module controls the inverter microwave oven to enter the normal power operation phase.

According to the startup control method of the microwave oven variable frequency power supply according to the embodiment of the present invention, after the variable frequency power supply is powered on, the variable frequency power supply is controlled to enter the soft start phase, and after the soft start phase is completed, the variable frequency power supply is controlled to enter the warm-up phase, and according to the magnetron The anode current is used to judge whether the preheating phase is completed, and the variable frequency power supply is controlled to enter the normal operation phase after the preheating phase is completed. Therefore, the method can accurately determine whether the magnetron is preheated by detecting the anode current of the magnetron after the variable frequency power supply enters the preheating phase, thereby effectively avoiding the magnetron caused by prematurely judging the completion of the preheating phase. And the damage of other devices improves the reliability of the product. At the same time, it effectively avoids the slow start-up speed caused by the late completion of the preheating stage, meets the requirements of rapid heating, and improves the user experience. In addition, it effectively avoids the large impulse current generated by the magnetron due to the instantaneous vibration to affect the working state of the resonant circuit.

11 is a flow chart showing a method of starting control of a microwave oven variable frequency power supply according to another embodiment of the present invention.

As shown in FIG. 11, after the step S104 in the embodiment shown in FIG. 10, the method for starting the control of the variable frequency power supply of the microwave oven according to the embodiment of the present invention further includes the following steps:

S111, the frequency converter communicates with the upper computer.

Among them, the upper computer can be built in the microwave oven to communicate with the inverter through the communication line; it can also be a control device such as a remote controller or a mobile terminal, and communicates with the frequency converter through a Bluetooth, infrared or wireless network.

S112, the frequency converter detects the communication frequency of the upper computer.

In an embodiment of the invention, the host computer can detect the state of the hardware switch and determine the communication frequency with the frequency converter according to the state of the hardware switch. Specifically, the communication frequency corresponding to the hardware switch of the upper computer in the on and off states may be preset. For example, in the state where the hardware switch is on, the communication frequency is 100 Hz, and in the off state, the communication frequency is 120 Hz. Therefore, the host computer can determine the communication frequency with the inverter through the state of its hardware switch.

Figure 7 is a circuit diagram of a variable frequency microwave oven in accordance with one embodiment of the present invention. Specifically, as shown in FIG. 7, the upper computer can The communication signal is sent to the MCU (Micro Control Unit) of the inverter. After receiving the communication signal from the host computer, the inverter can detect the width/number of high/low level of the received signal within the preset time, and detect the communication frequency according to the width/number of high/low level. It should be understood that the frequency of the high/low level received by the frequency converter per second, or the reciprocal of the total width of the high/low level of 2 times, is the communication frequency. For example, if 100 low levels are received in 1S, the communication frequency is 100 Hz, and if the high level width is 5 mS, the communication frequency is 100 Hz.

S113, the frequency converter determines the rated voltage of the microwave oven according to the communication frequency of the upper computer.

In an embodiment of the invention, the corresponding rated voltage is 100V when the communication frequency is 100Hz, and the corresponding rated voltage is 120V when the communication frequency is 120Hz.

For example, when the power voltage used by the user is 100V, the communication frequency of the host computer and the inverter can be controlled to be 100 Hz by adjusting the state of the hardware switch. After receiving the communication frequency of 100 Hz, the inverter determines the microwave oven. The rated voltage is 100V. Thus, during normal use of the microwave oven, the inverter can operate at a constant power when the input voltage exceeds 100V, and the inverter can operate at a constant current when the input voltage is lower than 100V. This prevents the current from exceeding the standard or causing damage to the circuit due to excessive power.

In an embodiment of the invention, the frequency converter can also determine the output power of the normal heating phase according to the communication frequency of the upper computer. Specifically, the output power of the frequency converter can be set to correspond to the communication frequency of the upper computer. For example, when the communication frequency of the host computer is 1200 Hz, the output power of the corresponding inverter is 1200 W.

It should be understood that, for the inverter voltage and the output power, in addition to being controlled by the communication frequency of the upper computer in the above embodiment, the control may be performed by other means. For example, the voltage and output power of the frequency converter can be controlled by the total number of pulses. The specific control method should not be construed as limiting the invention.

According to the control method of the frequency converter in the microwave oven according to the embodiment of the invention, the frequency converter can communicate with the upper computer, simultaneously detect the communication frequency of the upper computer, and can determine the rated voltage of the frequency converter according to the communication frequency, thereby, the microwave oven can be The rated voltage is sent to the inverter, so that the inverter can control the output power and working current according to the rated voltage of the microwave oven. While improving safety and reliability, it also improves the versatility of the inverter in the microwave oven, avoiding development and production. In the process, the frequency converter is classified and developed and produced due to different voltage standards, which can effectively reduce the development cycle, expand the production scale, and reduce development and production costs.

Figure 12 is a flow chart showing a method of detecting the operating state of a magnetron in a microwave oven in accordance with one embodiment of the present invention.

As shown in FIG. 12, a method for detecting a working state of a magnetron in a microwave oven according to an embodiment of the present invention includes the following steps:

S121, detecting an anode current of the magnetron and generating a current value of the anode current.

According to an embodiment of the invention, the anode current of the magnetron can be detected by the circuit shown in FIG. Wherein, one end of the first resistor R1 is connected to the anode of the magnetron MGT, one end of the second resistor R2 is connected to the other end of the first resistor R1, and the other end of the second resistor R2 is grounded to GND, wherein the first resistor R1 and The second resistor R3 has a first node J1, one end of the third resistor R3 is connected to the first node J1, and the other end of the third resistor R3 is a magnetron anode current test. Test the output of the module. This circuit can be used in inverter microwave ovens.

As can be seen from Fig. 2, a secondary winding of the transformer T is connected to the voltage doubling circuit, and the doubled voltage is connected to the anode of the magnetron MGT at one end, and the other end is connected to one end of the second resistor R2 via the second resistor. After R2, it is connected to the magnetron MGT. When the anode voltage (-4000V) supplied to the magnetron MGT passes through the second resistor R2, a certain voltage drop is formed, and the magnitude of the voltage drop is proportional to the magnitude of the current flowing through the anode of the magnetron through the third resistor R3. The voltage drop is sampled to obtain the anode current IB of the magnetron MGT.

According to another embodiment of the present invention, the anode current of the magnetron can be detected by the circuit shown in FIG. Wherein, one end of the fourth resistor R4 is connected to the anode of the magnetron MGT through the third diode D3, and one end of the fourth resistor R4 is connected to the cathode of the third diode D3, and the other end of the fourth resistor R4 The grounding GND, one end of the fifth resistor R5 is respectively connected to one end of the fourth resistor R4 and the cathode of the third diode D3, and the other end of the fifth resistor R5 is an output end of the magnetron anode current detecting module. The circuit can be used in a fixed frequency microwave oven. When the anode voltage (-4000V) supplied to the magnetron MGT is passed through the fourth resistor R4, a voltage drop is formed, which is proportional to the current flowing through the anode of the magnetron. The anode current IB of the magnetron MGT is obtained by sampling the voltage drop through the fifth resistor R5.

S122. Acquire an operating state of the magnetron according to a current value of the anode current and a pre-stored standard value of the anode current.

It should be understood that in the design and production process of the microwave oven, the standard value of the anode current, that is, the rated anode current value of the magnetron, needs to be obtained through theoretical analysis and actual experiment, and can be pre-stored in the MCU of the microwave oven.

After the anode current of the magnetron is detected, the anode current can be sent to the MCU. In an embodiment of the present invention, the anode current of the magnetron can be fed back through the host computer. For example, a host computer is disposed in the microwave oven, and the host computer transmits the anode current of the magnetron through the communication line.

Specifically, after detecting the current value of the anode current of the magnetron, the current value of the anode current is sent to the upper computer, and the upper computer sends the current value of the anode current to the control module through the communication line, and the current value of the anode current is controlled by the control module. A judgment is made to obtain the current working state of the magnetron, and the magnetron is controlled according to the current working state of the magnetron.

It can be understood that after the host computer receives the current value of the anode current sent by the magnetron anode current detecting module, the host computer can first judge the current value of the anode current to obtain the current working state of the magnetron, and when needed When the magnetron stops working, the magnetron is stopped by controlling the control module or relay.

In another embodiment of the invention, the anode current of the magnetron can be fed back through the optocoupler. That is to say, after detecting the current value of the anode current, it is sent to the control module through the optocoupler, and the control module determines the current working state of the magnetron by determining the current value of the anode current, and according to the current work of the magnetron. The state controls the magnetron.

Of course, the anode current can also be fed back by other means, which are not enumerated here.

After receiving the current value of the anode current, it can be compared to the anode current standard value. If the current value of the anode current is greater than twice the standard value of the anode current, it is judged that the magnetron is in an anode temperature too high state; if the current value of the anode current is less than half of the anode current standard value, it is judged that the magnetron is in a core rupture state, And can judge the magnetron at the anode temperature After the state is too high, the magnetron is controlled to stop working or the output power of the magnetron is lowered; and after the magnetron is judged to be in the state of the core rupture, the magnetron is directly controlled to stop working. Alternatively, when it is judged that the magnetron is in an anode over temperature state or a core rupture state, the judgment result may be fed back to the user by displaying an error code.

It can be understood that in the variable frequency microwave oven, the output power of the magnetron can be reduced by adjusting the duty ratio of the variable frequency power supply or the frequency converter; in the fixed frequency microwave oven, the magnetron can be lowered by adjusting the on/off ratio of the relay. Output power.

According to the method for detecting the working state of the magnetron in the microwave oven according to the embodiment of the present invention, the anode current of the magnetron is detected, and the working state of the magnetron is obtained according to the anode current of the magnetron and the pre-stored anode current standard value, thereby It can accurately and accurately determine abnormal conditions such as excessive temperature or damage of the magnetron, so that necessary protective measures can be taken in time, such as controlling the microwave oven to stop working, and displaying an error code to remind the user to repair, etc., and the implementation is simple and convenient. The cost is lower.

One of ordinary skill in the art can understand that all or part of the steps carried by the method of implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium. When executed, one or a combination of the steps of the method embodiments is included.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing module, or each unit may exist physically separately, or two or more units may be integrated into one module. The above integrated modules can be implemented in the form of hardware or in the form of software functional modules. The integrated modules, if implemented in the form of software functional modules and sold or used as stand-alone products, may also be stored in a computer readable storage medium.

The above mentioned storage medium may be a read only memory, a magnetic disk or an optical disk or the like.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Claims (28)

A start control device for a microwave oven variable frequency power supply, comprising: Frequency Power; a magnetron anode current detecting module for detecting an anode current of the magnetron and generating a current value of the anode current; a control module, configured to control the variable frequency power supply to enter a soft start phase after the variable frequency power supply is powered on, and control the variable frequency power supply to enter a warm-up phase after the soft start phase is completed, and according to the magnetron The anode current determines whether the warm-up phase is completed, and controls the variable frequency power supply to enter a normal operation phase after the warm-up phase is completed. The device of claim 1 , wherein the method further comprises: The resonant voltage detecting module is configured to detect a resonant voltage of the primary side of the transformer, wherein the control module controls the variable frequency power supply according to the resonant voltage in a warm-up phase. The starting control device for a variable frequency power supply of a microwave oven according to claim 1, wherein when the anode current of the magnetron is greater than a preset threshold, it is determined that the warm-up phase is completed. The starting control device for the variable frequency power supply of the microwave oven according to claim 2, wherein the magnetron anode current detecting module comprises: a first resistor, one end of the first resistor is connected to an anode of the magnetron; a second resistor, one end of the second resistor is connected to the other end of the first resistor, and the other end of the second resistor is grounded, wherein the first resistor and the second resistor have a first node; And a third resistor, one end of the third resistor is connected to the first node, and the other end of the third resistor is an output end of the magnetron anode current detecting module. The device of claim 2, wherein the method further comprises: The upper computer is connected to the magnetron anode current detecting module, and the upper computer sends the anode current of the magnetron to the control module through a communication line. The device of claim 2, wherein the method further comprises: An optocoupler coupled between the magnetron anode current detecting module and the control module, the magnetron anode current detecting module transmitting an anode current of the magnetron to the control by the optocoupler Module. The device of claim 1 , wherein the detecting module further comprises: The primary current/primary power detection module is configured to detect a primary current/primary power of the transformer, wherein the control module determines whether the warm-up phase is completed according to the primary current/primary power. And controlling the variable frequency power supply to enter a normal operation phase after the preheating phase is completed. The device of claim 5, wherein the method further comprises: a frequency converter, the frequency converter communicates with the upper computer, and detects a communication frequency of the upper computer, and according to the The communication frequency of the upper computer determines the rated voltage of the microwave oven. The starter control device for a variable frequency power supply of a microwave oven according to claim 5, wherein the upper computer is further configured to: A state of the hardware switch is detected, and a communication frequency with the frequency converter is determined according to a state of the hardware switch. The starting control device for a variable frequency power supply of a microwave oven according to claim 8, wherein the corresponding rated voltage is 100V when the communication frequency is 100 Hz, and the corresponding rated voltage is 120V when the communication frequency is 120 Hz. The control device for a frequency converter in a microwave oven according to claim 8, wherein the frequency converter is specifically configured to: The frequency converter detects a width/number of high/low levels of the received signal within a preset time, and detects the communication frequency according to the width/number of times of the high/low level. The control device for a frequency converter in a microwave oven according to claim 1, wherein the control module is further configured to acquire an operating state of the magnetron according to the current value of the anode current and a pre-stored standard value of the anode current. The control device for a frequency converter in a microwave oven according to claim 12, wherein the control module is specifically configured to: If the current value of the anode current is greater than twice the standard value of the anode current, determining that the magnetron is in an anode temperature too high state; If the current value of the anode current is less than half of the standard value of the anode current, it is judged that the magnetron is in a core rupture state. The control device for a frequency converter in a microwave oven according to claim 13, wherein the control module is further configured to: After determining that the magnetron is in an anode temperature too high state, further controlling the magnetron to stop working or reducing the output power of the magnetron; After determining that the magnetron is in the core rupture state, the magnetron is also controlled to stop working. A microwave oven comprising the startup control device for a variable frequency power supply of a microwave oven according to any one of claims 1-14. A startup control method for a microwave oven variable frequency power supply, characterized in that it comprises: After the variable frequency power supply is powered on, the variable frequency power supply is controlled to enter a soft start phase; After the soft start phase is completed, the variable frequency power supply is controlled to enter a warm-up phase, wherein the variable frequency power supply is controlled according to a resonant voltage in the warm-up phase; Determining whether the warm-up phase is completed according to an anode current of the magnetron; After determining that the warm-up phase is completed, the variable frequency power supply is controlled to enter a normal operation phase. The method for controlling the startup of a variable frequency power supply for a microwave oven according to claim 16, further comprising: Detecting the resonant voltage of the primary side of the transformer; The anode current of the magnetron is sensed and the current value of the anode current is generated. The method for controlling the startup of a variable frequency power supply of a microwave oven according to claim 17, wherein when the anode current of the magnetron is greater than a preset threshold, it is determined that the warm-up phase is completed. The method for controlling the startup of a variable frequency power supply for a microwave oven according to claim 16, further comprising: Detecting primary current/primary power of the transformer; Determining whether the warm-up phase is completed according to the primary current/primary power, and controlling the variable frequency power supply to enter a normal operation phase after the warm-up phase is completed. The method for controlling the startup of a variable frequency power supply of a microwave oven according to claim 17, wherein the anode current of the magnetron is fed back by the upper computer. The method for starting control of a variable frequency power supply of a microwave oven according to claim 17, wherein the anode current of the magnetron is fed back through an optocoupler. The method for controlling the startup of a variable frequency power supply for a microwave oven according to claim 16, further comprising: The inverter communicates with the host computer; The frequency converter detects a communication frequency of the upper computer; The frequency converter determines a rated voltage of the microwave oven according to a communication frequency of the upper computer. The method for controlling the startup of a variable frequency power supply of a microwave oven according to claim 22, further comprising: The upper computer detects the state of the hardware switch; A communication frequency with the frequency converter is determined according to a state of the hardware switch. The method for controlling the startup of a variable frequency power supply for a microwave oven according to claim 22, wherein the corresponding rated voltage is 100V when the communication frequency is 100 Hz, and the corresponding rated voltage is 120V when the communication frequency is 120 Hz. The method for controlling the frequency conversion power supply of the microwave oven according to claim 22, wherein the detecting the communication frequency of the upper computer by the frequency converter specifically comprises: The frequency converter detects a width/number of high/low levels of the received signal within a preset time, and detects the communication frequency according to the width/number of times of the high/low level. The method for controlling the startup of a variable frequency power supply of a microwave oven according to claim 17, further comprising: Obtaining an operating state of the magnetron according to the current value of the anode current and a pre-stored anode current standard value. The method for controlling the startup of a variable frequency power supply of a microwave oven according to claim 26, wherein the obtaining the operating state of the magnetron according to the current value of the anode current and the pre-stored anode current standard value comprises: If the current value of the anode current is greater than twice the standard value of the anode current, determining that the magnetron is in an anode temperature too high state; If the current value of the anode current is less than half of the standard value of the anode current, it is determined that the magnetron is in the magnetic core Rupture state. The method for controlling the startup of a variable frequency power supply of a microwave oven according to claim 27, further comprising: After determining that the magnetron is in an anode temperature too high state, further controlling the magnetron to stop working or reducing the output power of the magnetron; After determining that the magnetron is in the core rupture state, the magnetron is also controlled to stop working.

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