CN210725392U - IGBT protection circuit and cooking utensil - Google Patents

Abstract

The embodiment of the utility model provides an IGBT protection circuit and cooking utensil. The IGBT protection circuit includes: resonance circuit, IGBT drive circuit and control circuit, and control circuit includes: m control sub-circuits and a control signal generator. The first input ends of the M control sub-circuits are connected with one end of the resonance circuit, the second input ends of the M control sub-circuits respectively input reference voltages with different voltage values, the control sub-circuits send first control signals to the control signal generator according to the voltage of the IGBT and the reference voltages input through the second input ends to control the duration of second control signals output by the control signal generator, and therefore the control signal generator controls the duration of the IGBT which is in a conducting state next time through controlling the duration of the IGBT driving circuit to be conducted. The switching-on duration of the IGBT at the next time is adjusted according to the voltage of the IGBT, the efficiency of reducing the voltage of the IGBT is improved, and the problem that the IGBT is damaged due to the fact that the c-pole voltage is continuously too high when the IGBT is switched off is avoided.

Description

IGBT protection circuit and cooking utensil

Technical Field

The embodiment of the utility model provides a relate to domestic appliance technical field, especially relate to an IGBT protection circuit and cooking utensil.

Background

Insulated Gate Bipolar Transistors (IGBTs) are used in electrical circuits such as induction cookers. The voltage of the IGBT exceeds a set value due to circuit aging or user operation and the like, so that the IGBT is in an overvoltage working state, the IGBT is damaged, and a fire disaster can be caused in serious cases.

In the prior art, when it is detected that the voltage of the IGBT exceeds a set value, a width circuit of a pulse signal (PPG) sent by a Pulse Program Generator (PPG) is triggered and interrupted by software or reduced by hardware, so that the turn-on time of the IGBT is reduced, thereby reducing the voltage of the IGBT. As shown in fig. 1, a comparator is usually disposed in a control chip of the induction cooker, and by comparing the voltage of the IGBT with a reference voltage, when the comparison result shows that the voltage of the IGBT exceeds a set value, the PPG width is automatically decreased by a preset fixed value, so as to decrease the turn-on time of the IGBT.

However, in the prior art, when the voltage of the IGBT exceeds the set value, the PPG width is decreased by a preset fixed value, regardless of how much the voltage of the IGBT exceeds the set value. This results in that when the voltage of the IGBT exceeds the set value, the voltage of the IGBT still exceeds the set value after the PPG width is reduced, and thus the PPG width needs to be reduced again until the voltage of the IGBT is less than or equal to the predetermined value, so that the efficiency of reducing the voltage of the IGBT is low, and the IGBT is damaged.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides an IGBT protection circuit and cooking utensil for it is long when IGBT switches on next time to adjust according to the size of the voltage of the c utmost point of IGBT, has improved the efficiency that reduces IGBT's voltage, protects IGBT.

In a first aspect, an embodiment of the present invention provides an IGBT protection circuit, include: resonance circuit, IGBT drive circuit and control circuit, resonance circuit respectively with IGBT, control circuit connects, control circuit with IGBT drive circuit connects, IGBT drive circuit with IGBT connects, wherein, control circuit includes: m control subcircuits and control signal generators, M is an integer greater than or equal to 2;

first input ends of the M control sub-circuits are connected with one end of the resonant circuit, wherein the one end of the resonant circuit is connected with the IGBT, second input ends of the M control sub-circuits (310) are respectively input with reference voltages with different voltage values, output ends of the M control sub-circuits are connected with the control signal generator, and the control signal generator is further connected with the IGBT driving circuit;

the control sub-circuit is configured to send a first control signal to the control signal generator according to the voltage of the IGBT input by the first input end and the reference voltage input by the second input end, where the first control signal is used to control a duration of a second control signal output by the control signal generator, and the duration of the second control signal is used to control a duration of a next on-state of the IGBT by controlling a duration of the on-state of the IGBT driving circuit;

the control signal generator is used for receiving first control signals output by the N control sub-circuits and outputting second control signals according to the N first control signals, wherein N is an integer which is greater than or equal to 1 and less than or equal to M.

In some embodiments, each control sub-circuit comprises: a comparator and a controller corresponding to the comparator;

a first input end of the comparator is connected with one end of the resonance circuit, a second input end of the comparator inputs a reference voltage corresponding to the comparator, and the controller is connected between an output end of the comparator and the control signal generator;

the comparator is used for comparing the voltage of the IGBT with a reference voltage input into the comparator, and when the comparison result meets the comparison result corresponding to the comparator, a third control signal is sent to the controller and is used for indicating the controller to send the first control signal;

the controller is configured to receive the third control signal and send the first control signal to the control signal generator according to the third control signal.

In some embodiments, the first input of the comparator is a positive input, and the second input of the comparator is a negative input; or,

the first input end of the comparator is a reverse input end, and the second input end of the comparator is a forward input end.

In some embodiments, the controller in any one of the M control sub-circuits is a shutdown controller, the shutdown controller is configured to send the first control signal to the control signal generator after receiving a third control signal, and the first control signal is configured to instruct the control signal generator not to output a second control signal.

In some embodiments, the reference voltage input to the second input terminal of the comparator connected to the shutdown controller is the largest.

In some embodiments, the difference between any two of the reference voltages of adjacent magnitudes is equal.

In some embodiments, the control signal generator is a pulse program generator PPG.

In some embodiments, the controller is a register.

In some embodiments, the one end of the resonant circuit connected to the IGBT is also connected to ground through at least one resistor.

In a second aspect, embodiments of the present invention provide a cooking appliance, including an IGBT protection circuit and an IGBT as described in any of the embodiments of the first aspect;

the IGBT protection circuit is used for detecting the voltage of the IGBT and protecting the IGBT according to the voltage of the IGBT.

The embodiment of the utility model provides a IGBT protection circuit and cooking utensil, IGBT protection circuit, include: resonance circuit, IGBT drive circuit and control circuit to make control circuit include: m control sub-circuits and a control signal generator. The first input ends of the M control sub-circuits are connected with one end of the resonant circuit, wherein one end of the resonant circuit is connected with the IGBT, the second input ends of the M control sub-circuits are respectively input with reference voltages with different voltage values, the output ends of the M control sub-circuits are connected with the control signal generator, so that the control sub-circuits send first control signals to the control signal generator according to the voltage of the IGBT and the reference voltage input through the second input ends to control the duration of second control signals output by the control signal generator, and the control signal generator is further connected with the IGBT driving circuit, so that the control signal generator controls the duration of the IGBT which is in a conducting state next time through controlling the duration of the IGBT driving circuit to be conducted. The IGBT switching-on time length is adjusted according to the voltage of the c pole of the IGBT, so that the switching-on time length of the IGBT at the next time can be reduced through one-time adjustment when the c pole voltage is too high, the efficiency of reducing the voltage of the IGBT is improved, and the problem that the IGBT is damaged due to the fact that the c pole voltage is continuously too high when the IGBT is cut off is avoided.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

FIG. 1 is a schematic structural diagram of an IGBT protection circuit in the prior art;

fig. 2 is a schematic structural diagram of an IGBT protection circuit according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of an IGBT protection circuit according to another embodiment of the present invention;

fig. 4 is a schematic structural diagram of a cooking appliance according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

The terms "first," "second," "third," "fourth," and the like in the description and in the claims of the present application and in the drawings described above, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order.

In addition, in the present invention, unless otherwise explicitly specified or limited, the terms "connected" and the like are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection; the term "connected" refers to a direct connection or an indirect connection through an intermediate medium, and refers to a connection between two elements or an interaction relationship between two elements, unless otherwise specifically defined, and the specific meaning of the terms in the present invention is understood by those skilled in the art according to specific situations.

Fig. 2 is a schematic structural diagram of an IGBT protection circuit according to an embodiment of the present invention. As shown in fig. 2, the present embodiment provides an IGBT protection circuit including: the IGBT driving circuit comprises a resonant circuit 100, an IGBT driving circuit 200 and a control circuit 300, wherein the resonant circuit 100 is respectively connected with an IGBT and the control circuit 300, the control circuit 300 is connected with the IGBT driving circuit 200, and the IGBT driving circuit 200 is connected with the IGBT. Wherein, the control circuit 300 includes: m control sub-circuits 310 and a control signal generator 320, M being an integer greater than or equal to 2. Wherein, in some embodiments, the control signal generator 320 is a pulse program generator PPG.

First input ends of the M control sub-circuits 310 are connected to one end of the resonant circuit 100, wherein one end of the resonant circuit 100 is connected to the IGBT, second input ends of the M control sub-circuits 310 respectively input reference voltages with different voltage values, output ends of the M control sub-circuits 310 are connected to the control signal generator 320, and the control signal generator 320 is further connected to the IGBT driving circuit 200.

The control sub-circuit 310 is configured to send a first control signal to the control signal generator 320 according to the voltage of the IGBT input by the first input terminal and the reference voltage input by the second input terminal, where the first control signal is used to control a duration of a second control signal output by the control signal generator 320, and the duration of the second control signal is used to control a duration of a next on-state of the IGBT by controlling a duration of the on-state of the IGBT driving circuit 200.

The control signal generator 320 is configured to receive the first control signals output by the N control sub-circuits 310, and output a second control signal according to the N first control signals, where N is an integer greater than or equal to 1 and less than or equal to M.

As shown in fig. 1, the IGBT protection circuit includes a resonance circuit 100, an IGBT drive circuit 200, and a control circuit 300. The resonant circuit 100 is powered by a main power supply of the cooking appliance, the inductor L1 in the resonant circuit 100 is connected in parallel with the capacitor C1, and one end (hereinafter referred to as point a) of the resonant circuit 100 is connected to a collector (i.e., a pole C) of the IGBT, and since the pole C of the IGBT at the point a is connected, in some embodiments, the point a is grounded through at least one resistor, thereby preventing the pole C of the IGBT from being directly grounded and protecting the IGBT. The first input terminal of the control circuit 300 is connected between the point a and the resistor connected to ground, so that the control circuit 300 can obtain the voltage of the point a (i.e. the voltage of the c-pole in the IGBT), and the second input terminal is connected to the reference voltage. The other end of the control circuit 300 is connected to the IGBT drive circuit 200, and the IGBT drive circuit 200 is connected to the base (i.e., the b-pole) of the IGBT.

The working principle of the IGBT protection circuit is as follows: when the IGBT is turned on, the inductor L1 is charged, when the IGBT is turned off, the inductor L1 is grounded through the point a, and when the electric energy of the inductor L1 is gradually released to reverse the voltage of the first input terminal and the voltage of the second input terminal of the control circuit 300 (for example, when the voltage of the first input terminal is greater than the voltage of the second input terminal, the voltage of the second input terminal is changed into the voltage of the second input terminal is greater than the voltage of the first input terminal), the control circuit 300 controls the IGBT driving circuit 200 to be turned on by outputting a control signal (i.e., a second control signal), and when the output of the second control signal is stopped, the IGBT driving circuit 200 is turned off until the control circuit 300 outputs the second control signal again. The longer the IGBT on-time is, the more the inductor L1 stores energy, and when the IGBT is turned off, the more the IGBT releases energy, and since the resonant circuit 100 is connected to the c-pole of the IGBT through the a-point, if the inductor L1 releases too much energy, the voltage at the a-point becomes too high (even if the voltage of the IGBT exceeds a set value), and the IGBT will be damaged. Therefore, it is necessary to compare the voltage of the first input terminal and the voltage of the second input terminal of the control circuit 300, and control the duration of the second control signal output by the control circuit 300 according to the comparison result to control the duration of the turn-on of the IGBT driving circuit 200, so as to control the duration of the next turn-on state of the IGBT.

In the IGBT protection circuit shown in fig. 1, the duration of the output second control signal is decreased by a preset fixed value no matter how much the voltage of the IGBT exceeds the set value, and if the voltage of the IGBT exceeds the set value, the duration of the output second control signal needs to be decreased by a preset fixed value again until the voltage of the IGBT does not exceed the set value any more. The efficiency is low when the voltage of the IGBT is reduced, and the IGBT is damaged, so that the purpose of protecting the IGBT cannot be achieved.

As shown in fig. 2, in the present embodiment, the control circuit 300 includes M control sub-circuits 310 and a control signal generator 320. First input terminals (i.e., input terminals having the same characteristic) of the M control sub-circuits 310 are all connected between the point a and the resistor connected to ground, and second input terminals respectively input reference voltages having different voltage values, for example, the reference voltage connected to the second input terminal of the first control sub-circuit 310 is V1, the reference voltage connected to the second input terminal of the second control sub-circuit 310 is V2, …, and the reference voltage connected to the second input terminal of the mth control sub-circuit 310 is Vm. The output terminals of the M control sub-circuits 310 are all connected to a first terminal of the control signal generator 320, and a second terminal of the control signal generator 320 is connected to the IGBT driving circuit 200.

Since the first input terminals of the M control sub-circuits 310 are all connected between the point a and the resistor connected to ground, the input voltages of the first input terminals of the M control sub-circuits 310 are the same, and the second input terminals of the M control sub-circuits 310 respectively input the reference voltages with different voltage values. Accordingly, voltages of the first and second input terminals of each of the M control sub-circuits 310 are compared to send a first control signal to the control signal generator 320 according to the comparison result. For example, the comparison result is the ratio of the voltage of the first input terminal and the voltage of the second input terminal, when the ratio of the control sub-circuit 310 is greater than the preset ratio corresponding to the control sub-circuit 310, the control sub-circuit 310 is enabled to output the first control signal, and when the ratios of a plurality of control sub-circuits 310 are greater than the preset ratios corresponding to the control sub-circuits 310, each control sub-circuit 310 may be enabled to output the first control signal, or the control sub-circuit 310 accessing the maximum reference voltage may be enabled to output the first control signal. For another example, the comparison result is a difference between the voltage of the first input terminal and the voltage of the second input terminal, and when the difference is greater than a preset difference corresponding to the control sub-circuit 310, for example, the control sub-circuit 310 with the difference greater than the preset difference may output the first control signal, and when the differences of a plurality of control sub-circuits 310 are greater than the preset differences corresponding thereto, each control sub-circuit 310 may output the first control signal, or the control sub-circuit 310 with the maximum reference voltage may output the first control signal.

When the plurality of control sub-circuits 310 output the first control signal, the first control signal output by each control sub-circuit 310 is used to indicate the time length for which the next output second control signal is to be reduced, and therefore the time length for which the next output second control signal is to be reduced is the sum of the time lengths for which all the first control signals indicate to be reduced. When the IGBT is turned off, the higher the voltage of the c-pole of the IGBT is, the more the number of the control sub-circuits 310 whose difference/ratio is greater than the preset difference/preset ratio is, so that the more the time length for which the second control signal to be output next time is to be reduced is, and therefore, the time length for turning on the IGBT next time can be reduced. It should be noted that, the time duration for the next time of decreasing the second control signal outputted by the second control sub-circuit 310 indicated by the first control signal outputted by each control sub-circuit 310 may be equal or unequal. In some embodiments, a time period for which the second control signal to be output next time is decreased, which is indicated by the first control signal, is positively correlated with the magnitude of the reference voltage.

When only the control sub-circuit 310 with the difference larger than the preset difference and the maximum reference voltage outputs the first control signal, or only the control sub-circuit 310 with the ratio larger than the preset ratio and the maximum reference voltage outputs the first control signal, the first control signal is used for indicating the time length of the second control signal output next time. Since the larger the reference voltage is, the shorter the time duration of the second control signal outputted next time indicated by the first control signal outputted by the corresponding control sub-circuit 310 is, the time duration of the next IGBT on can be reduced. The preset difference value/preset ratio value is related to the voltage set value of the c pole of the IGBT and the corresponding reference voltage.

The control signal generator 320 receives the first control signals output by the N control sub-circuits 310, where N is 1 when the control sub-circuits 310 having the difference larger than the preset difference all output the first control signals, N is the number of the control sub-circuits 310 having the difference larger than the preset difference, and when the control sub-circuit 310 having the difference larger than the preset difference and the reference voltage is the largest outputs the first control signal. The control signal generator 320 controls a time period for outputting the second control signal next time according to the first control signal.

In some embodiments, the difference between any two of the reference voltages of adjacent magnitudes is equal. In this embodiment, a difference between the voltage of the first input terminal and the voltage of the second input terminal is taken as an example of the comparison result.

For example, when M is 5, the reference voltages are 1.0V, 1.5V, 2.0V, 2.5V, and 3V in order from small to large, and the difference between two reference voltages of arbitrary adjacent magnitudes is 0.5V. At this time, for example, the preset difference corresponding to each reference voltage may be equal, the set value of the c-electrode voltage of the IGBT is 10V, since the difference between any two adjacent reference voltages is equal, the preset difference is determined to be 9V according to the minimum reference voltage and the set value, it should be noted that the present invention does not limit the size of the determined preset difference, and may also be 8V, 8.5V, and so on. When the IGBT is turned off, if the c-voltage exceeds 10V, for example, 11V, the difference between the voltage of the first input terminal in the control sub-circuit 310 corresponding to the reference voltage 1.0V and the reference voltage in the control sub-circuit 310 corresponding to the reference voltage 1.5V is greater than the preset difference 9V, at this time, for example, both the two control sub-circuits 310 output the first control signal and simultaneously control the time length of the second control signal to be output next time, or the control sub-circuit 310 corresponding to the reference voltage 1.5V outputs the first control signal and controls the time length of the second control signal to be output next time. In this embodiment, the difference between any two reference voltages of adjacent magnitudes in the reference voltages is equal, and the preset difference of each comparator can be preset to be the same value, so that the hardware design can be simplified, and the comparison results of all the comparators are more regular and accurate in difference, so that the duration of the second control signal output by the control signal generator 320 for outputting the first control signal can be more accurately controlled, and the duration of the next turn-on of the IGBT can be more accurately controlled.

In this embodiment, the IGBT protection circuit includes: resonance circuit, IGBT drive circuit and control circuit to make control circuit include: m control sub-circuits and a control signal generator. The first input ends of the M control sub-circuits are connected with one end of the resonant circuit, one end of the resonant circuit is connected with the IGBT, the second input ends of the M control sub-circuits are respectively input with reference voltages with different voltage values, the output ends of the M control sub-circuits are connected with the control signal generator, so that the control sub-circuits send first control signals to the control signal generator according to the voltage of the IGBT and the reference voltages input through the second input ends to control the duration of second control signals output by the control signal generator, and the control signal generator is further connected with the IGBT driving circuit, so that the duration of the IGBT which is in a conducting state next time is controlled by the duration of the control signal generator through controlling the turn-on of the IGBT driving circuit. The IGBT switching-on time length is adjusted according to the voltage of the c pole of the IGBT, so that the switching-on time length of the IGBT at the next time can be reduced through one-time adjustment when the c pole voltage is too high, the efficiency of reducing the voltage of the IGBT is improved, and the problem that the IGBT is damaged due to the fact that the c pole voltage is continuously too high when the IGBT is cut off is avoided.

Fig. 3 is a schematic structural diagram of an IGBT protection circuit according to another embodiment of the present invention. As shown in fig. 3, on the basis of the embodiment shown in fig. 2, each control sub-circuit 310 includes: a comparator 311 and a controller 312 corresponding to the comparator 311. Wherein, in some embodiments, the controller 312 is a register.

A first input terminal of the comparator 311 is connected to one end of the resonant circuit 100, a second input terminal thereof inputs a reference voltage corresponding to the comparator 311, and the controller 312 is connected between an output terminal of the comparator 311 and the control signal generator 320;

a comparator 311 for comparing the voltage of the IGBT with a reference voltage input to the comparator 311, and when the comparison result satisfies a comparison result corresponding to the comparator, transmitting a third control signal to the controller 312, the third control signal being used to instruct the controller 312 to transmit the first control signal;

the controller 312 is configured to receive the third control signal and send the first control signal to the control signal generator 320 according to the third control signal.

In this embodiment, taking M as 5 as an example, each control sub-circuit 310 includes a comparator 311 and a controller 312 corresponding to the comparator 311, wherein a first input terminal of any one of the comparators 311 is connected between the point a of the resonant circuit 100 and the ground resistor, so that the voltage of the c pole can be obtained when the IGBT is turned off, and the second input terminal is connected to the reference voltage, so that the comparator 311 can compare the voltage of the c pole with the reference voltage when the IGBT is turned off. The reference voltages correspond to the comparators 311 one to one. The controller 312 corresponding to the comparator 311 is connected between the output terminal of the comparator 311 and the control signal generator 320.

In some embodiments, the first input of the comparator 311 is a positive input, and the second input of the comparator 311 is a negative input; alternatively, the first input terminal of the comparator 311 is an inverting input terminal, and the second input terminal of the comparator 311 is a positive input terminal. Fig. 2 shows a case where the first input terminal of the comparator 311 is an inverting input terminal, and the second input terminal of the comparator 311 is a positive input terminal.

The comparator 311 compares the voltage of the c-pole with the reference voltage when the IGBT is turned off, and when the comparison result satisfies the comparison result corresponding to the comparator 311, sends a third control signal to the controller 312 corresponding to the comparator 311, where the third control signal is used to enable the controller 312 corresponding to the comparator 311 to send out a first control signal so as to control the time length of a second control signal output by the control signal generator 320 next time.

For example: the reference voltages are 1.0V, 1.4V, 2.0V, 2.8V and 4V from small to large in sequence, the preset difference corresponding to each reference voltage can be equal, the set value of the c-pole voltage of the IGBT is 10V, and the preset difference is 9V, 10V, 10.5V, 11V and 12V in sequence. When the IGBT is turned off, if the c-voltage exceeds 10V, for example, 12V, the comparison result between the voltage of the first input terminal of the comparator 311 corresponding to the reference voltage 1.0V and the comparison result between the voltage of the first input terminal of the comparator 311 corresponding to the reference voltage 1.4V and the reference voltage satisfies the comparison result corresponding to the comparator 311, that is, the difference is greater than the preset difference, at this time, for example, both the comparators 311 output the third control signal, the controller 312 corresponding to both the comparators 311 output the first control signal, or the comparator 311 corresponding to the reference voltage 1.4V outputs the third control signal, and the controller 312 corresponding to the comparator 311 outputs the first control signal.

In this embodiment, each control sub-circuit is provided with a comparator and a controller corresponding to the comparator, such that the first input terminal of the comparator is connected to one end of the resonant circuit, the second input terminal of the comparator inputs the reference voltage corresponding to the comparator, and the controller is connected between the output terminal of the comparator and the control signal generator. And when the comparison result of the voltage of the IGBT and the reference voltage input into the comparator is compared by the comparator to meet the comparison result corresponding to the comparator, sending a third control signal to the controller, so that the controller sends a first control signal to control the time length of a second control signal output by the control signal generator next time. Therefore, the time length for switching on the IGBT at the next time can be adjusted according to the voltage of the c pole of the IGBT, the efficiency of reducing the voltage of the IGBT is improved, and the IGBT is protected.

In some embodiments, the controller 312 of any of the M control sub-circuits 310 is a shutdown controller 312a, and the shutdown controller 312a is configured to send a first control signal to the control signal generator after receiving the third control signal, where the first control signal is configured to instruct the control signal generator not to output the second control signal.

In this embodiment, when the comparison result of the comparator 311 corresponding to the shutdown controller 312a satisfies the comparison result corresponding to the comparator 311, the comparator 311 outputs a third control signal to the shutdown controller 312a, and the shutdown controller 312a outputs a first control signal to the control signal generator 320 according to the third control signal, at this time, the first control signal is used to instruct the control signal generator 320 not to output the second control signal next time, so that the IGBT driving circuit 200 is not turned on, and the IGBT is not turned on. At this time, in order to turn on the IGBT again, the control signal generator 320 may be caused to output the second control signal after a predetermined period of time.

In this embodiment, by providing a shutdown controller in one of the control sub-circuits 310, when the shutdown controller receives a third control signal, it indicates that the comparison result of the comparator corresponding to the shutdown controller satisfies the comparison result corresponding to the comparator, and at this time, the shutdown controller directly sends a control signal generator to enable the control signal generator not to output a second control signal next time, so that the efficiency of reducing the c-voltage of the IGBT can be quickly improved, and the IGBT is protected.

In some embodiments, the reference voltage input to the second input terminal of the comparator 311 connected to the shutdown controller 312a is the largest. In this embodiment, when the IGBT is turned off, the larger the c-voltage is, the larger the number of comparators 311 whose comparison results satisfy the comparison results corresponding to the comparators 311 becomes. Therefore, when the comparison result of the comparator 311 corresponding to the maximum reference voltage satisfies the comparison result corresponding to the comparator 311, it means that the c-voltage is very large and the IGBT is easily broken. Therefore, the shutdown controller 312a is connected to the output terminal of the comparator 311 corresponding to the maximum reference voltage.

For example, the reference voltages are 1.0V, 1.4V, 2.0V, 2.8V, and 4V in sequence from small to large, the preset difference corresponding to each reference voltage may be equal, the set value of the c-voltage of the IGBT is 10V, and the preset differences are 9V, 10V, 10.5V, 11V, and 12V in sequence. When the IGBT is turned off and the c-voltage is 12V, the comparison result between the voltage of the first input terminal and the reference voltage in the comparator 311 corresponding to the reference voltage 1.0V and the comparator 311 corresponding to the reference voltage 1.4V satisfies the comparison result corresponding to the comparator 311; when the voltage of the c-electrode is 18V, the comparison result of the voltage of the first input terminal of each comparator 311 and the reference voltage satisfies the comparison result corresponding to the comparator 311, and at this time, it indicates that the voltage of the c-electrode far exceeds the preset value, so that the comparator 311 with the accessed reference voltage of 4V directly sends a third control signal to the closing controller 312a, and the closing controller 312a sends a first control signal to the control signal generator 320 for instructing the control signal generator 320 not to output a second control signal next time.

In this embodiment, the shutdown controller is connected to the output end of the comparator 311 corresponding to the maximum reference voltage, and when the shutdown controller receives the third control signal, it indicates that the voltage of the c pole far exceeds the preset value, the IGBT needs to be turned off when turned on next time, and the voltage of the c pole when the IGBT is turned off from on next time is reduced. Therefore, when the turn-off controller receives the third control signal, the first control signal for instructing the control signal generator not to output the second control signal next time is sent to the control signal generator, so that the IGBT is not conducted when conducting next time. Therefore, when the voltage of the c pole far exceeds the preset value when the IGBT is cut off, the IGBT is directly not conducted when the IGBT is conducted next time, the voltage of the c pole is still higher than the preset value when the IGBT is switched from conduction to cut off next time, and the IGBT is protected from being damaged.

Fig. 4 is a schematic structural diagram of a cooking appliance according to an embodiment of the present invention. As shown in fig. 4, the cooking appliance includes the IGBT protection circuit 400 and the IGBT shown in any of the embodiments described above. Wherein,

the IGBT protection circuit 400 may detect the voltage of the IGBT and protect the IGBT according to the voltage of the IGBT, and the specific implementation manner thereof may refer to the above embodiments, and will not be described herein again.

It should be noted that the cooking appliance shown in fig. 4 includes other components, not shown in fig. 4, in addition to the IGBT protection circuit 400 and the IGBT shown in any of the above embodiments.

Those of ordinary skill in the art will understand that: all or a portion of the steps of implementing the above-described method embodiments may be performed by hardware associated with program instructions. The program may be stored in a computer-readable storage medium. When executed, the program performs steps comprising the method embodiments described above; and the aforementioned storage medium includes: various media that can store program codes, such as ROM, RAM, magnetic or optical disks.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims (10)

1. An IGBT protection circuit comprising: resonance circuit (100), IGBT drive circuit (200) and control circuit (300), resonance circuit (100) respectively with the IGBT, control circuit (300) are connected, control circuit (300) with IGBT drive circuit (200) are connected, IGBT drive circuit (200) with the IGBT is connected, characterized in that, control circuit (300) include: m control sub-circuits (310) and control signal generators (320), M being an integer greater than or equal to 2;

first input ends of the M control sub-circuits (310) are connected with one end of the resonant circuit (100), wherein the one end of the resonant circuit (100) is connected with the IGBT, second input ends of the M control sub-circuits (310) are respectively input with reference voltages with different voltage values, output ends of the M control sub-circuits (310) are connected with the control signal generator (320), and the control signal generator (320) is further connected with the IGBT driving circuit (200);

the control sub-circuit (310) is configured to send a first control signal to the control signal generator (320) according to the voltage of the IGBT input by the first input end and the reference voltage input by the second input end, where the first control signal is used to control a duration of a second control signal output by the control signal generator (320), and the duration of the second control signal is used to control a duration of a next on-state of the IGBT by controlling a duration of an on-state of the IGBT driving circuit (200);

the control signal generator (320) is configured to receive the first control signals output by the N control sub-circuits (310) and output second control signals according to the N first control signals, where N is an integer greater than or equal to 1 and less than or equal to M.

2. The circuit according to claim 1, wherein each control sub-circuit (310) comprises: a comparator (311) and a controller (312) corresponding to the comparator (311);

a first input terminal of the comparator (311) is connected to the one end of the resonance circuit (100), a second input terminal thereof inputs a reference voltage corresponding to the comparator (311), and the controller (312) is connected between an output terminal of the comparator (311) and the control signal generator (320);

the comparator (311) is used for comparing the voltage of the IGBT with a reference voltage input into the comparator (311), and when the comparison result meets the comparison result corresponding to the comparator (311), a third control signal is sent to the controller (312), and the third control signal is used for instructing the controller (312) to send out the first control signal;

the controller (312) is configured to receive the third control signal and send the first control signal to the control signal generator (320) according to the third control signal.

3. A circuit according to claim 2, characterized in that the first input of the comparator (311) is a positive input and the second input of the comparator (311) is a negative input; or,

the first input end of the comparator (311) is an inverting input end, and the second input end of the comparator (311) is a positive input end.

4. The circuit of claim 2, wherein the controller (312) in any one of the M control sub-circuits (310) is a shutdown controller (312), the shutdown controller (312) being configured to send the first control signal to the control signal generator (320) after receiving a third control signal, the first control signal being configured to instruct the control signal generator (320) not to output a second control signal.

5. The circuit according to claim 4, characterized in that the reference voltage input to the second input of the comparator (311) connected to the shutdown controller (312) is the largest.

6. The circuit of claim 1, wherein the difference between any two of the reference voltages of adjacent magnitudes is equal.

7. A circuit according to claim 1 or 2, characterized in that the control signal generator (320) is a pulse program generator PPG.

8. The circuit of claim 2, wherein the controller (312) is a register.

9. A circuit according to any of claims 1-6, characterized in that the end of the resonance circuit (100) connected to the IGBT is also connected to ground via at least one resistor.

10. A cooking appliance, characterized by comprising an IGBT protection circuit (400) according to any one of claims 1-9 and an IGBT;

the IGBT protection circuit (400) is used for detecting the voltage of the IGBT and protecting the IGBT according to the voltage of the IGBT.

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