JP6142283B2 - High frequency heating device - Google Patents

Description

  The present invention proposes that a high-voltage diode used in a high-voltage rectifier circuit is configured at a low cost in a high-frequency heating apparatus that performs dielectric heating by driving a magnetron, such as a microwave oven.

  As a power source used for a high-frequency heating device such as a microwave oven used in a general household, because of its nature (the machine room space in which the power source is built is small so that it can be easily carried and the cooking chamber is enlarged) Small and light ones have been desired. For this reason, switching to a power source has led to a reduction in size and weight and cost, and an inverter power source is becoming mainstream from the viewpoint of energy saving and high efficiency.

  Also, in terms of cooking utensils, oven microwave ovens that enable oven cooking using a heater have become widespread, and the range of use has expanded.

  A high voltage for driving the magnetron is generated by a step-up transformer and converted into a direct current by a high-voltage rectifier circuit. At this time, a high-voltage diode is used. Since high-frequency rectification is performed at a high voltage, the temperature rise of components is large, and a cooling method is a problem. In order to solve this problem, a method of providing a temperature switch inside the component (for example, see Patent Document 1) and a method of devising the arrangement of the component and arranging it in the coldest place (for example, see Patent Document 2) have been proposed. ing. However, there has been a limit in terms of low cost configuration.

  An example of the inverter power supply will be described with reference to a circuit diagram shown in FIG. The commercial power source 1 is rectified by the rectifier 2 and converted into a DC voltage, and power is supplied from the commercial power source 1. The DC voltage is applied to the capacitor 4, the primary winding 13 of the step-up transformer 6, and the inverter resonance circuit 5 of the semiconductor switching element 3 through the filter circuit 11 including the choke coil 9 and the capacitor 10.

  In the inverter resonance circuit 5, the semiconductor switching element 3 switches at a frequency of 20 to 50 kilohertz to create a high frequency alternating current. The high-frequency alternating current generated in the inductor serving as the primary winding 13 of the step-up transformer 6 is boosted to a high voltage by the step-up transformer 6. Further, the high voltage boosted by the step-up transformer 6 (the voltage of the secondary winding 15) is rectified to a DC high voltage by the high-voltage rectifier circuit 7.

  Here, in order to drive the magnetron 8, a diode having a withstand voltage of about 8 KV is required, and the high-voltage diodes 21 and 22 are generally custom-made products having a high withstand voltage. The control circuit unit 14 gives a signal for obtaining a desired high-frequency output to the semiconductor switching element 3 in a form reflecting the input current information obtained from the current transformer 12, and drives it. A command signal for determining a desired output is given from the outside to the control circuit unit 14 by an insulation interface (not shown) such as a photocoupler by a microcomputer 19 to obtain a high frequency output of 1000 W, 800 W, 600 W, etc. Yes.

These electric component parts constitute the inverter power supply 18. The DC high voltage rectified by the high voltage rectifier circuit 7 is applied between the anode portion 17 and the cathode portion (filament portion) 16 of the magnetron 8. The step-up transformer 6 is provided with another heater winding 20, and this heater winding 20 supplies power as a heating current to the cathode portion (filament portion) 16 of the magnetron 8. The magnetron 8 receives current supplied to the cathode part (filament part) 16, oscillates when the cathode temperature rises and a high voltage is applied between the anode part 17 and the cathode part (filament part) 16, and generates microwaves. Occur. Microwaves generated by the magnetron 8 are applied to an object to be heated such as food in a heating chamber to perform dielectric heating cooking.

  FIG. 7 shows the internal structure of the high-voltage diodes 21 and 22 made of custom products. A plurality of chip elements 23 are sealed in a package 24. The chip element 23 is connected by a solder 25 and connected to a lead terminal 26 to realize a high breakdown voltage diode.

JP 2007-280628 A Japanese Patent Laid-Open No. 10-289883

  However, the above configuration has the following problems.

  That is, heat dissipation performance is deteriorated by making a plurality of chip elements into one package, and cooling is difficult. In addition, since it is a custom product, it is expensive and has a problem that it becomes a monopoly state of a specific manufacturer.

  The present invention solves the above-described conventional problems, and an object thereof is to provide a high-frequency heating device in which a high-voltage diode used in a high-voltage rectifier circuit is configured by a general-purpose high-speed diode.

In order to solve the above-described conventional problems, a high-frequency heating device according to the present invention includes an AC power source, a rectifier circuit that full-wave rectifies the AC power source with a rectifier element, at least one semiconductor switching element, and the rectifier element. A heat sink with the semiconductor switching element attached thereto, an inverter unit that converts the voltage from the rectifier circuit into a high-frequency voltage by turning on and off the semiconductor switching element, and a step-up transformer that boosts the output voltage of the inverter unit A high-frequency heating device comprising: a high-voltage rectifier circuit that performs full-wave voltage doubler rectification on the output voltage of the step-up transformer; and a magnetron for radiating the output of the high-voltage rectifier circuit as an electromagnetic wave.
Wherein the high-voltage diode to be used in high-voltage rectifier circuit is constructed on a substrate by a plurality of series in the general-purpose high-speed diode, the plurality of high speed diodes each each of said high-speed diode becomes 1 is a chip configuration the heat dissipating material It has a package and lead terminals connected by lead wires exposed from the respective packages .

According to a first aspect of the present invention, there is provided an AC power source, a rectifier circuit for full-wave rectification of the AC power source with a rectifier element, at least one semiconductor switching element, a heat sink attached with the rectifier element and the semiconductor switching element, An inverter unit that converts the voltage from the rectifier circuit into a high-frequency voltage by turning on and off the semiconductor switching element, a step-up transformer that boosts the output voltage of the inverter unit, and an output voltage of the boost transformer In a high-frequency heating device comprising a high-voltage rectifier circuit for voltage rectification and a magnetron for radiating the output of the high-voltage rectifier circuit as an electromagnetic wave,
Wherein the high-voltage diode to be used in high-voltage rectifier circuit is constructed on a substrate by a plurality of series in the general-purpose high-speed diode, the plurality of high speed diodes each each of said high-speed diode becomes 1 is a chip configuration the heat dissipating material It has a package and lead terminals connected by lead wires exposed from the respective packages .

  The present invention can be constructed at low cost because a plurality of general-purpose high-speed diodes are arranged in series. In addition, since it can be used as a substitute part in several companies' products, it is possible to avoid monopolization of expensive high-voltage diodes as custom products.

Main part circuit diagram which shows high voltage rectifier circuit structure of the high frequency heating apparatus in Embodiment 1 of this invention Main part circuit diagram which shows the high voltage | pressure rectifier circuit structure of the high frequency heating apparatus in Embodiment 2 of this invention Main part circuit diagram which shows the high voltage | pressure rectifier circuit structure of the high frequency heating apparatus in Embodiment 3 of this invention Main part circuit diagram which shows the high voltage | pressure rectifier circuit structure of the high frequency heating apparatus in Embodiment 4 of this invention The principal part top view which shows the high voltage | pressure rectifier circuit structure of the high frequency heating apparatus in Embodiment 5 of this invention Circuit diagram of conventional high-frequency heating device Schematic diagram showing the structure of a conventional high voltage diode

According to a first aspect of the present invention, there is provided an AC power source, a rectifier circuit that full-wave rectifies the AC power source with a rectifier element, at least one semiconductor switching element, a heat sink that has the rectifier element and the semiconductor switching element attached thereto, and the semiconductor An inverter unit that converts the voltage from the rectifier circuit into a high-frequency voltage by turning on and off the switching element, a step-up transformer that boosts the output voltage of the inverter unit, and a full-wave voltage doubler rectification of the output voltage of the boost transformer And a magnetron for radiating the output of the high voltage rectifier circuit as an electromagnetic wave, the high voltage diode used in the high voltage rectifier circuit is a general-purpose high-speed diode in a plurality of series. is configured on the substrate, the high-speed diode package and re each is one-chip configuration and and the heat dissipating material Characterized in that it has been closed and de terminal.

  The second invention is characterized in that, in the first invention, in particular, the output voltage of the step-up transformer is a high-voltage rectifier circuit that performs half-wave rectification.

The third invention is characterized in that, in the first invention, in particular, the resistors are arranged in parallel to the respective high-speed diodes used in the high-voltage rectifier circuit to equalize the applied voltage and are soldered to the substrate. To do.

  The fourth invention is characterized in that, in the third invention, in particular, the output voltage of the step-up transformer is a high-voltage rectifier circuit that performs half-wave rectification.

According to a fifth aspect of the invention, particularly in the first aspect of the invention, the plurality of high-voltage rectifier circuits configured in series with the general-purpose high-speed diodes are attached in a bent arrangement on the side surface of the step-up transformer. It is characterized by.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that this embodiment is merely an exemplification that embodies the present invention, and the present invention includes various modes in which changes are made within the scope of the configurations described in the claims.

(Embodiment 1)
FIG. 1 shows a high-pressure rectifier circuit 28 of the high-frequency heating device according to Embodiment 1 of the present invention.

  In FIG. 1, eight general-purpose high-speed diodes 29 are arranged in series to realize a high breakdown voltage. Assuming that 8 KV is applied during startup, the breakdown voltage of the high-speed diodes 29 is required to be 1 KV or more. Each of the high voltage diodes 21 and 22 shown in FIG. When it is arranged on the substrate, it needs to be wide in terms of space, but it can be constructed at low cost because it is a general-purpose component.

In addition, as a harmful effect of custom-made chip elements in one package, there is a deterioration in cooling performance, but the general-purpose high-speed diode 29 has a single chip configuration and a package and a lead terminal each serving as a heat dissipation material. In addition, the cooling performance is improved by being soldered to the substrate. Here, since the present invention is a high-frequency heating device, in consideration of switching loss, t
A high-speed diode 29 (trr <75 ns) having a fast rr (recovery time (reverse recovery time) in which reverse flow of the diode is possible) is used.

  As described above, in this embodiment, the general-purpose high-speed diodes 29 each have a one-chip configuration and have a package and a lead terminal as a heat dissipation material, and are soldered to the substrate. Cooling performance can be improved.

(Embodiment 2)
FIG. 2 shows a high-pressure rectifier circuit 30 of the high-frequency heating device according to Embodiment 2 of the present invention.

  In FIG. 2, a high-breakdown voltage is realized by arranging eight general-purpose high-speed diodes 29 in series in a half-wave rectifier circuit. Assuming that 8 KV is applied during startup, the breakdown voltage of the high-speed diodes 29 is required to be 1 KV or more. When it is arranged on the substrate, it needs to be wide in terms of space, but it can be constructed at low cost because it is a general-purpose component.

  In addition, as a harmful effect of custom-made chip elements in one package, there is a deterioration in cooling performance, but the general-purpose high-speed diodes 29 each have a one-chip configuration and have a package and a lead terminal as a heat dissipation material. In addition, the cooling performance is improved by being soldered to the substrate.

  As described above, in this embodiment, the general-purpose high-speed diodes 29 each have a one-chip configuration and have a package and a lead terminal as a heat dissipation material, and are soldered to the substrate. Cooling performance can be improved.

(Embodiment 3)
FIG. 3 shows a high-pressure rectifier circuit 31 of the high-frequency heating device according to Embodiment 3 of the present invention.

  In FIG. 3, eight general-purpose high-speed diodes 29 are realized in series as high-voltage diodes, and a resistor 32 is connected in parallel to each high-speed diode 29. The resistance value was 3.9 MΩ. Assuming that 8 KV is applied at the time of startup, each loss is 0.256 W, and a 1/2 W resistor can sufficiently cope with it. The withstand voltage of the resistor 32 is 1 KV or more.

  In the case of the general-purpose high-speed diode 29, the loss ratio of each high-speed diode 29 varies depending on the speed variation of trr. That is, it has a feature that it approaches a breakdown voltage from a diode having a fast trr. Therefore, heat generation is also unbalanced. This phenomenon is because the combined breakdown voltage is a desired high breakdown voltage in order to ensure a necessary breakdown voltage, but the breakdown voltage of each general-purpose high-speed diode 29 is 1/8. It is effective when using.

  As described above, in the present embodiment, the resistors 32 are arranged to equally divide the voltage, and each high-speed diode 29 is applied with an equal voltage without depending on the speed of trr, so that the breakdown voltage is obtained. Never reach the breakdown voltage. Therefore, heat generation is also uniform, and stable operation can be made possible without special consideration for how to apply cooling air.

(Embodiment 4)
FIG. 4 shows a high-pressure rectifier circuit 33 of the high-frequency heating device according to Embodiment 4 of the present invention.

  In FIG. 4, eight general-purpose high-speed diodes 29 are arranged in series in a half-wave rectifier circuit, and a resistor 32 is connected in parallel to each high-speed diode 29 in a state where a high breakdown voltage is realized. In the case of the general-purpose high-speed diode 29, the loss ratio of each high-speed diode 29 varies depending on the speed variation of trr. That is, it has a feature that a breakdown voltage approaches a breakdown voltage from a diode having a fast trr. Therefore, heat generation is also unbalanced.

  This is because the combined breakdown voltage for securing the required breakdown voltage is a desired high breakdown voltage, but the breakdown voltage of each general-purpose high-speed diode 29 is 1/8, and in particular, a high-speed diode with a large trr variation is used. It is effective when doing.

  As described above, in the present embodiment, by arranging the resistors 32 evenly, each high-speed diode 29 is applied with an equal voltage without depending on the speed of trr. The breakdown voltage is not reached, the heat generation becomes uniform, and stable operation can be performed without special consideration for how to apply cooling air.

(Embodiment 5)
FIG. 5 shows the configuration of the high-pressure rectifier circuit 34 of the high-frequency heating device according to Embodiment 5 of the present invention.

  In FIG. 5, the high-voltage rectifier circuit 34 is formed on the side surface of the step-up transformer 6, thereby realizing space saving as a high-frequency heating device. This is realized by constructing a plurality of general-purpose high-speed diodes 29 in series on the daughter board as high-voltage diodes.

  As described above, in the present embodiment, the arrangement of the plurality of high-voltage rectifier circuits 34 configured in series with the general-purpose high-speed diode 29 is attached to the side surface of the step-up transformer 6, so that high-frequency heating is performed. In addition to realizing space saving as a device, by constructing a plurality of general-purpose high-speed diodes 29 in series on a sub-board as a high-voltage diode, inheriting a configuration that is inexpensive and has improved heat dissipation performance, saving Space can be realized.

  As described above, according to the high-frequency heating device of the present invention, a high-voltage diode of a custom product used in a high-voltage rectifier circuit can be realized at low cost by configuring a plurality of general-purpose high-speed diodes in series, and each Since the high-speed diode has a package and a lead terminal, the heat radiation performance can be improved.

DESCRIPTION OF SYMBOLS 1 Commercial power supply 2 Rectifier 8 Magnetron 13 Primary winding 14 Control circuit part 15 Secondary winding 16 Cathode part (filament part)
DESCRIPTION OF SYMBOLS 17 Anode part 18 Inverter power supply 19 Microcomputer 21 High voltage diode 22 High voltage diode 28, 30, 31, 33, 34 High voltage rectifier circuit 29 High speed diode 32 Resistance

Claims (5)

An AC power supply, a rectifier circuit for full-wave rectification of the AC power supply with a rectifier element, at least one semiconductor switching element, a heat sink with the rectifier element and the semiconductor switching element attached thereto, and turning on the semiconductor switching element An inverter unit that converts the voltage from the rectifier circuit to a high-frequency voltage by turning it off, a step-up transformer that boosts the output voltage of the inverter unit, and a high-voltage rectifier circuit that performs full-wave voltage doubler rectification on the output voltage of the boost transformer And a high-frequency heating device comprising a magnetron for radiating the output of the high-voltage rectifier circuit as an electromagnetic wave,
Wherein the high-voltage diode to be used in high-voltage rectifier circuit is constructed on a substrate by a plurality of series in the general-purpose high-speed diode, the plurality of high speed diodes each each of said high-speed diode becomes 1 is a chip configuration the heat dissipating material A high frequency heating apparatus comprising a package and lead terminals connected by lead wires exposed from the respective packages .   The high-frequency heating device according to claim 1, wherein the output voltage of the step-up transformer is a high-voltage rectifier circuit that performs half-wave rectification.   2. The high frequency heating apparatus according to claim 1, wherein resistors are arranged in parallel to the respective high speed diodes used in the high voltage rectifier circuit to equalize the applied voltage and are soldered to the substrate.   The high-frequency heating device according to claim 3, wherein the output voltage of the step-up transformer is a high-voltage rectifier circuit that performs half-wave rectification. 2. The high-frequency heating device according to claim 1, wherein a plurality of high-voltage rectifier circuits configured in series with the general-purpose high-speed diodes are attached in a bent arrangement on a side surface of the step-up transformer.