JPH069093U - Magnetron drive control circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the size and weight of an inverter power supply that drives a magnetron by selecting the desired magnetron from among multiple magnetrons. [Structure] A series connection of resonance capacitors 7a and 7b is connected to a primary winding 8a of a high voltage transformer 8 and a switching element 5 is connected to a series connection of these resonance capacitors 7a and 7b. The voltage doubler rectifier circuits 9a and 9b are connected between the secondary windings 8b and 8c, and the magnetrons 10 and 11 are connected to the voltage doubler rectifier circuits 9a and 9b, respectively, and the magnetron 10 is further connected to the circuits 9a and 9b. Opening and closing switches 14 and 15 for selectively operating 11 are provided respectively, and a short circuit switch 13 of a resonance capacitor 7b is opened and closed by a driving means 16 in association with the opening and closing switches 14 and 15 described above.
It is provided with a chi.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a magnetron drive control circuit for an electronic range having a plurality of magnetrons for home and business use.

[0002]

[Prior art]

 Conventionally, a microwave oven having a plurality of magnetrons uses a high voltage transformer for each magnetron and has a considerable weight.

After that, in order to improve this, a plurality of switching elements are provided in a power supply formed by one rectifier and a plurality of capacitors to form a high frequency power supply (inverter power supply), and this power supply is used to supply power to a plurality of magnetrons. A high-frequency heating device has been proposed which boosts the applied voltage and controls each switching element with a single pulse generation circuit (inverter power supply control circuit). (See Japanese Patent Publication No. 3-63198) In this high frequency heating device, a plurality of magnetrons 11 and 21 for supplying high frequency radio waves to a heating chamber (not shown) and the same number of these magnetrons 11 and 21 are used. Similar to the conventional inverter power supply, the high voltage transformers 12 and 22 each having one primary winding and one boost secondary winding are wound, and the same number of resonance transformers as the number of these high voltage transformers 12 and 22 are used. Capacitors 17 and 27, a plurality of switching elements 15 and 25 that drive a plurality of resonance circuits formed by the high voltage transformers 12 and 22 and the resonance capacitors 17 and 27, and operation of these switching elements 15 and 25. The inverter power supply consisting of components such as switches 18 and 28 for selecting operation is configured to be controlled by a single pulse generation circuit (inverter power supply control circuit) 30. Lightweight The same number of inverter power supply and the number of the magnetron as described above in which there are been achieved has been mounted.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, in the case of an inverter power supply that controls a plurality of magnetrons, high-voltage transformers, resonance capacitors, and switching elements with a single inverter power supply control circuit, it is true that the magnetron will operate at a commercial frequency. From the perspective of what was driving the motor, the inverter power supply can be operated at 20 to 40 kHz, and the high-voltage transformer can be made smaller and smaller and lighter.

Although this product is certainly smaller and lighter than the case where multiple inverter power supplies are used, it is the most high-voltage transformer operating at 20 to 40 kHz, but it is the best among the inverter power supply units. It is heavy and has a large shape.

Further, the switching element needs a large heat radiation fin, and one heat radiation fin is required for one switching element due to insulation.

Therefore, an inverter power supply unit having a plurality of high-voltage transformers, switching elements and the like still has difficulty in downsizing.

Therefore, in order to further reduce the size of the microwave oven, there is one in which the above-mentioned two high voltage transformers and the primary coil are integrated or integrated. (See Fig. 3 of JP-A-2-186592) In the case where the two high-voltage transformers are integrated and miniaturized, the output of one conventional magnetron is divided and replaced with two magnetrons. Since they are operated in parallel, parts with low ratings can be used as much as they are divided into two magnetrons, and considerable effects are recognized in terms of reliability of parts used and manufacturing costs.

However, this miniaturized microwave oven can be used only with a constant output, and if the output is fixed at 2 Kw, for example, it cannot be used with other electric appliances in a general household with a small contract current. An unexpected situation also occurs.

As a means for avoiding such an unexpected situation, there is one provided with a switch for appropriately disconnecting one of the two magnetrons connected to the secondary side of the high-voltage transformer in accordance with the use state. (See JP-A-2-186592, FIG. 1) However, in the case where the above-mentioned switch is provided, the primary side of the high-voltage transformer necessary for cooking the object to be heated by the "break" and "contact" of the switch. The constant does not match the resonance state of the condenser, and the magnetron cannot be driven to the appropriate state required for cooking.

[0011]

[Means for Solving the Problems]

 In order to solve the above problems, a multiple-stage series-connected resonance capacitor is connected between a single primary winding wound on the primary side of a high-voltage transformer, and a DC power supply is connected to the connection of these capacitors. Connect the switching element to be supplied, wind the same number of secondary windings as the number of magnetrons on the secondary side of the high-voltage transformer, and connect a voltage doubler rectifier circuit to each of these secondary windings. An open / close switch that selectively operates the required number of magnetrons is installed in the appropriate place, and a short-circuit switch that short-circuits the required number of the resonance capacitors described above is provided. It is something that is done.

[0012]

[Action]

 By connecting a magnetron to each of the secondary windings of the high-voltage transformer via a voltage doubler rectifier circuit, it becomes possible to drive all the magnetrons described above by driving the switching elements.

Since an appropriate number of open / close switches of the voltage doubler rectifier circuit and a short-circuit switch for short-circuiting an appropriate number of resonance capacitors are associated with each other to perform open / close driving, it is possible to operate the switch only. It is possible to select the number of magnetrons and also to select the constant of the resonance capacitor that obtains the optimum resonance state according to the number of magnetrons in operation.

[0014]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of a magnetron drive control circuit according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a commercial power supply, which has a full-wave rectifier circuit 2 connected to the output end of the commercial power supply 1 and a rectifying / smoothing capacitor 3 and a choke coil 4 connected to the output end. The full-wave rectifier circuit 2, the rectifying / smoothing capacitor 3 and the choke coil 4 form a DC power supply.

Reference numeral 5 denotes a switching element, and a diode 6 is connected to both ends of this element 5. 7a and 7b are a series connection body composed of a first resonance capacitor and a second resonance capacitor, and a short-circuit switch 13 is connected to both ends of the second resonance capacitor 7b, and the first resonance capacitor 7a and the second resonance capacitor are connected. A series circuit including a capacitor 7b and a switching element 5 is connected in parallel with the capacitor 3.

Reference numeral 8 is a high-voltage transformer, which includes a primary winding 8a, a secondary winding 8b, and a secondary winding 8c, and is composed of the first resonant capacitor 7a and the second resonant capacitor 7b between the primary winding 8a. The series connection body is connected.

Reference numerals 9a and 9b denote voltage doubler rectification circuits each composed of a capacitor and a diode, and are connected to the secondary winding 8b and the secondary winding 8c of the high voltage transformer 8, respectively.

Reference numerals 10 and 11 respectively denote magnetrons, which are connected to the above-mentioned voltage doubler rectifier circuits 9a and 9b, respectively.

A control circuit 12 controls the operation of the switching element 5.

Reference numeral 13 is a short-circuit switch connected in parallel with the second resonance capacitor 7 a. For example, when only one magnetron 10 is used, the second resonance capacitor 7 b is short-circuited by the short-circuit switch 13 to reduce the number of magnetrons 10. Accordingly, only the first resonance capacitor 7a is used as a constant in order to obtain the optimum resonance state.

Numerals 14 and 15 are open / close switches provided in the above-mentioned voltage doubler rectifier circuits 9a and 9b, respectively, for opening and closing the connections to the respective secondary windings 8b and 8c, which are selected from the magnetrons 10 and 11 mentioned above. The opening and closing is controlled when operating a desired magnetron.

A driving means 16 is provided at an appropriate portion of a microwave oven main body (not shown), and one of the opening / closing switches 14 and 15 which is opened / closed in association with the short-circuiting switch 13 is selected. It is driven in order to obtain a resonance state that matches the operating state of the magnetron.

The operation of this embodiment will be described below.

First, it is assumed that the short-circuit switch 13 is in the open state and the open / close switches 14 and 15 are both in the closed state.

First, in FIG. 1, when the switching element 5 is turned on by a command from the inverter control circuit 12, a current flows through the primary winding 8a.

At this time, a voltage is induced in the secondary winding 8b, so that a voltage obtained by adding the induced voltage to the capacitor voltage in the voltage doubler rectifier circuit 9a is applied to the magnetron 10. 10 oscillates.

On the other hand, when the switching element 5 is turned on by a command from the inverter control circuit 12, a current flows through the primary winding 8a and a voltage is similarly generated in the secondary winding 8c as described above. A voltage obtained by adding the capacitor voltage in the voltage doubler rectifier circuit 9b to this induced voltage is applied, and the magnetron 11 oscillates.

Next, a case where only one magnetron 10 is oscillated will be described.

Now, the driving means 16 opens the open / close switch 15 and closes the short-circuit switch 13 so that only the first resonance capacitor 7a is operated in order to obtain a resonance state corresponding to the operating state of the magnetron 10. To select.

When the switching element 5 is turned on by a command from the inverter control circuit 12 in this state, a current flows in the primary winding 8a, a voltage is induced only in the secondary winding 8b, and this induction is caused only in the magnetron 10. A voltage obtained by adding the capacitor voltage in the voltage doubler rectifier circuit 9a to the voltage thus applied is applied, and the magnetron 10 oscillates.

[0033]

[Effect of device]

 By connecting a magnetron to each of the secondary windings of the high-voltage transformer via a voltage doubler rectifier circuit, all of the magnetrons described above are driven by driving the switching elements.Therefore, even if there are multiple magnetrons, Since only one resonance capacitor and switching element (radiation fin) are needed, the size and weight can be reduced and the structure is simpler than before.

Further, an appropriate number of open / close switches are provided in the voltage doubler rectifier circuit, a short-circuit switch for short-circuiting an appropriate number of resonance capacitors is provided, and the open / close and short-circuit switches are associated with each other to open / close drive. By doing so, you can select the number of magnetrons you want to operate, and you can select the constant of the resonance capacitor that obtains the optimum resonance state according to the number of magnetrons in operation. The number can be selected, and the range of practical cooking can be increased.

[Brief description of drawings]

FIG. 1 is a schematic circuit diagram of a magnetron drive control circuit according to an embodiment of the present invention.

[Explanation of symbols]

 2, 3, 4 DC power supply 5 Switching element 7a First resonance capacitor 7b Second resonance capacitor 8 High voltage transformer 8a Primary winding 8b, 8c Secondary winding 9a, 9b Double voltage rectifier circuit 12 Inverter control circuit 13 Short circuit switch 14, 15 Open / close switch 16 Drive means

Claims (1)

[Scope of utility model registration request] 1. A high voltage transformer comprising a DC power supply (2, 3, 4), a single primary winding (8a) and a plurality of secondary windings (8b, 8c).
(8), a first resonance capacitor (7a) and a second resonance capacitor (7b) of a multi-stage series connection type connected between both ends of the primary winding, and the primary winding and the first and second A switching element (5) for intermittently supplying the DC power supply to the connection body of the two-resonance capacitor, an inverter control circuit (12) for driving and controlling the switching element, and a connecting element connected to each of the plurality of secondary windings A voltage rectifier circuit (9a, 9b), a short-circuit switch (13) for short-circuiting an appropriate number of the first and second resonance capacitors, and an appropriate number of the voltage doubler rectifier circuits. And an opening / closing switch (14, 15) provided on each of which opens and closes the connection to the secondary winding, and a driving means (16) for driving the opening and closing by associating the opening and closing switch with the short-circuiting switch. Magnetron drive control circuit characterized by.