Electronic transformer for microwave oven

Abstract

The invention relates to an electronic transformer for a microwave oven. The electronic transformer comprises a first rectifying and filtering unit and a power conversion unit connected with the first rectifying and filtering unit, the transformer is connected with the power conversion unit; the second rectifying and filtering unit is connected with the transformer and is used for outputting direct-current high-voltage electricity; the microwave oven magnetron is connected with the second rectifying and filtering unit; the control unit is connected with the power conversion unit; the power adjusting unit is connected with the control unit and used for adjusting the output power of the electronic transformer; and a timer for controlling the output power of the electronic transformer according to preset operation time is arranged in the control unit. The electronic transformer for the microwave oven is provided with the power adjusting unit, the input power can be automatically reduced when the temperature of the anode of the magnetron of the microwave oven is too high, and then the magnetron of the microwave oven can be effectively protected; in addition, a timer is arranged in the control unit, so that the input power can be reduced according to the working duration without arranging an external communication connecting line.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave oven power supplies, and in particular relates to an electronic transformer used in microwave ovens. Background Art

[0002] Traditional microwave ovens are composed of oven cavity, control system, cooling system, lighting system, magnetron, magnetron drive power supply, etc., among which the magnetron drive power supply is a traditional power frequency leakage transformer. With the advancement of technology and the enhancement of people's energy-saving awareness, a new type of switching power supply that can directly replace the traditional power frequency leakage transformer has been widely used, commonly known as electronic transformer. Microwave ovens using electronic transformers have the advantages of energy saving, light weight, good cooking effect, and quietness.

[0003] However, when the existing electronic transformer replaces the traditional power frequency leakage transformer, there are the following problems: 1. The existing electronic transformer has no external communication connection line, so it is impossible to reduce the power according to the working time through external control instructions. 2. After the existing electronic transformer is powered off and then turned on again, it will run at the initial maximum power. The input power will be higher than that of the leakage transformer. At this time, the magnetron itself is still in a hot state and cannot withstand a large power, which can easily cause the magnetron to overheat and be damaged.

[0004] Therefore, the present invention provides an electronic transformer for a microwave oven to solve the above technical problems. Summary of the invention

[0005] In view of the above problems, the object of the present invention is to provide an electronic transformer for a microwave oven, which is provided with a power adjustment unit, which can automatically reduce the input power when the anode temperature of the microwave oven magnetron is too high, thereby effectively protecting the microwave oven magnetron.

[0006] The present invention provides an electronic transformer for a microwave oven, comprising:

[0007] A first rectifying and filtering unit for converting an input AC voltage into a DC voltage;

[0008] A power conversion unit connected to the first rectifying and filtering unit and used for converting the DC voltage into an AC pulse voltage;

[0009] A transformer connected to the power conversion unit and used for performing voltage conversion on the AC pulse voltage;

[0010] A second rectifying and filtering unit connected to the transformer and used to rectify and filter the voltage transformed by the transformer to output DC high voltage electricity;

[0011] A microwave oven magnetron connected to the second rectifying and filtering unit for receiving the DC high voltage electricity and operating;

[0012] A control unit connected to the power conversion unit and used to drive the power conversion unit to convert the DC voltage into the AC pulse voltage;

[0013] a power adjustment unit connected to the control unit and used for adjusting the output power of the electronic transformer according to predetermined conditions;

[0014] The control unit is provided with a timer for controlling the output power of the electronic transformer according to a predetermined operating time.

[0015] Preferably, the power adjustment unit includes an anode voltage sampling unit and a temperature detection unit connected to the control unit, the anode sampling unit is used to reduce the input power when the anode temperature of the microwave oven magnetron is too high, and the temperature detection unit is used to reduce the input power when the temperature of any power device among the first rectifier and filter unit, the power conversion unit, the transformer and the second rectifier and filter unit is too high.

[0016] Preferably, the anode voltage sampling unit includes a first circuit connected to the anode and cathode of the induction cooker magnetron, a filament winding connected to the first circuit for providing filament voltage to the induction cooker magnetron, and a second circuit arranged in parallel with the filament winding and connected to the control unit.

[0017] Preferably, the first circuit includes a high-voltage winding arranged on the high-voltage side of the transformer and a first voltage-doubling rectifier circuit connected to the high-voltage winding, a first end of the first voltage-doubling rectifier circuit is connected to the high-voltage winding, and a second end of the first voltage-doubling rectifier circuit is connected to the anode and cathode of the induction cooker magnetron; the first voltage-doubling rectifier circuit includes a first diode assembly connected to the high-voltage winding, a first capacitor assembly arranged in parallel with the first diode assembly, and a resistor arranged in parallel with the first capacitor assembly, a first output end of the resistor is connected to the anode of the induction cooker magnetron, and a second output end of the resistor is connected to the cathode of the induction cooker magnetron;

[0018] The filament winding is arranged at the high voltage side of the transformer and is connected to the first diode assembly and the first capacitor assembly at the same time;

[0019] The second circuit includes an anode voltage sampling winding arranged on the high-voltage side of the transformer and a second voltage doubling rectifier circuit connected to the anode voltage sampling winding, a first end of the second voltage doubling rectifier circuit is connected to the anode voltage sampling winding, a second end of the second voltage doubling rectifier circuit is connected to the control unit, the second voltage doubling rectifier circuit includes a second diode component connected to the anode voltage sampling winding, a second capacitor component connected to the anode voltage sampling winding and arranged in parallel with the second diode component, and an inductor connected to both the second diode component and the second capacitor component, a first end of the inductor is connected to both the second diode component and the second capacitor component, and a second end of the inductor is connected to the control unit.

[0020] Preferably, the first diode assembly includes a first diode and a second diode arranged in series; the first capacitor assembly includes a first capacitor and a second capacitor arranged in series; the first end of the high-voltage winding is simultaneously connected to the first capacitor, the second capacitor and the positive terminal of the first diode, and the second end of the high-voltage winding is connected to the negative terminal of the second diode; the filament winding is simultaneously connected to the positive terminal of the second diode and the first capacitor;

[0021] The second diode component includes a third diode and a fourth diode arranged in series; the second capacitor component includes a third capacitor and a fourth capacitor arranged in series; the first end of the anode voltage sampling winding is simultaneously connected to the positive terminal of the third diode and the negative terminal of the fourth diode, and the second end of the anode voltage sampling winding is connected to the third capacitor and the fourth capacitor; the first end of the inductor is simultaneously connected to the negative terminal of the third diode, the positive terminal of the fourth diode and the fourth capacitor.

[0022] Compared with the related art, the present invention provides an electronic transformer for a microwave oven, which includes a first rectifying and filtering unit for converting an input AC voltage into a DC voltage; a power conversion unit connected to the first rectifying and filtering unit for converting the DC voltage into an AC pulse voltage; a transformer connected to the power conversion unit for voltage conversion of the AC pulse voltage; a second rectifying and filtering unit connected to the transformer for rectifying and filtering the voltage converted by the transformer to output DC high voltage electricity; a microwave oven magnetron connected to the second rectifying and filtering unit for receiving the DC high voltage electricity and working; a control unit connected to the power conversion unit for driving the power conversion unit to convert the DC voltage into the AC pulse voltage; a power adjustment unit connected to the control unit for adjusting the output power of the electronic transformer according to predetermined conditions; a timer is provided in the control unit for controlling the output power of the electronic transformer according to a predetermined operating time. In the above structure, through the setting of the power adjustment unit, the input power can be automatically reduced when the anode temperature of the microwave oven magnetron is too high or when the temperature of any power device in the rectifier filter unit, power conversion unit, transformer and high-voltage rectifier filter unit is too high, thereby effectively protecting the microwave oven magnetron and power devices; in addition, a timer is provided in the control unit, which can reduce the input power according to the working time without setting an external communication connection line. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a schematic diagram of the circuit structure of an electronic transformer for a microwave oven;

[0024] Figure 2 The figure is a schematic diagram of the circuit structure of the anode voltage sampling unit of the present invention.

[0025] Figure numbers: first rectifying and filtering unit-1; power conversion unit-2; transformer-3; second rectifying and filtering unit-4; microwave oven magnetron-5; control unit-6; power adjustment unit-7; first circuit-10; second circuit-20. DETAILED DESCRIPTION

[0026] The invention provides an electronic transformer for a microwave oven, aiming to solve the problem that a traditional electronic transformer has no external communication connection line, and thus cannot realize power reduction according to working time through external control instructions and a magnetron is easily damaged by overheating.

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Please also refer to the attached Figure 1-2 The present invention provides an electronic transformer for a microwave oven, comprising:

[0029] A first rectifying and filtering unit 1 for converting an input AC voltage into a DC voltage;

[0030] A power conversion unit 2 connected to the first rectifying and filtering unit 1 and used for converting the DC voltage into an AC pulse voltage;

[0031] A transformer 3 connected to the power conversion unit 2 and used for performing voltage conversion on the AC pulse voltage;

[0032] A second rectifying and filtering unit 4 connected to the transformer 3 and used for rectifying and filtering the voltage transformed by the transformer 3 to output a DC high voltage power;

[0033] A microwave oven magnetron 5 connected to the second rectifying and filtering unit 4 for receiving the DC high voltage electricity and operating;

[0034] A control unit 6 connected to the power conversion unit 2 and used to drive the power conversion unit 2 to convert the DC voltage into the AC pulse voltage;

[0035] A power adjustment unit 7 connected to the control unit 6 and used for adjusting the output power of the electronic transformer according to a predetermined condition;

[0036] The control unit 7 is provided with a timer for controlling the output power of the electronic transformer according to a predetermined operating time.

[0037] In the above structure, through the setting of the power adjustment unit 7, the input power can be automatically reduced when the anode temperature of the microwave oven magnetron 5 is too high or when the temperature of any power device in the first rectifier and filter unit 1, the power conversion unit 2, the transformer 3 and the second rectifier and filter unit 4 is too high, thereby effectively protecting the microwave oven magnetron and power devices; in addition, a timer is provided in the control unit 6, which can reduce the input power according to the working time without setting an external communication connection line.

[0038] In this embodiment, the power adjustment unit 7 includes an anode voltage sampling unit 71 and a temperature detection unit 72 connected to the control unit 6, the anode sampling unit 71 is used to reduce the input power when the anode temperature of the microwave oven magnetron 5 is too high, and the temperature detection unit 72 is used to reduce the input power when the temperature of any power device in the first rectifier and filter unit 1, the power conversion unit 2, the transformer 3 and the second rectifier and filter unit 4 is too high.

[0039] Specifically, the anode voltage sampling unit 71 includes a first circuit 10 connected to the anode and cathode of the induction cooker magnetron 5, a filament winding W2 connected to the first circuit 10 for providing a filament voltage to the induction cooker magnetron 5, and a second circuit 20 arranged in parallel with the filament winding W2 and connected to the control unit 6.

[0040] Further, the first circuit 10 includes a high-voltage winding W1 arranged on the high-voltage side of the transformer 3 and a first voltage-doubling rectifier circuit 101 connected to the high-voltage winding, a first end of the first voltage-doubling rectifier circuit 101 is connected to the high-voltage winding W1, and a second end of the first voltage-doubling rectifier circuit 101 is connected to the anode and cathode of the induction cooker magnetron 5; the first voltage-doubling rectifier circuit 101 includes a first diode assembly connected to the high-voltage winding W1, a first capacitor assembly arranged in parallel with the first diode assembly, and a resistor R1 arranged in parallel with the first capacitor assembly, a first output end of the resistor R1 is connected to the anode of the induction cooker magnetron 5, and a second output end of the resistor R1 is connected to the cathode of the induction cooker magnetron 5; the filament winding W2 is arranged on the high-voltage side of the transformer 3 and is simultaneously connected to the first diode assembly and the first capacitor assembly;

[0041] The second circuit 20 includes an anode voltage sampling winding W3 arranged on the high-voltage side of the transformer 3 and a second voltage doubling rectifier circuit 201 connected to the anode voltage sampling winding W3, a first end of the second voltage doubling rectifier circuit 201 is connected to the anode voltage sampling winding W3, a second end of the second voltage doubling rectifier circuit 201 is connected to the control unit 6, the second voltage doubling rectifier circuit 201 includes a second diode component connected to the anode voltage sampling winding W3, a second capacitor component connected to the anode voltage sampling winding W3 and arranged in parallel with the second diode component, and an inductor L connected to both the second diode component and the second capacitor component, a first end of the inductor L is connected to both the second diode component and the second capacitor component, and a second end of the inductor L is connected to the control unit 6.

[0042] Furthermore, the first diode assembly includes a first diode D1 and a second diode D2 arranged in series; the first capacitor assembly includes a first capacitor C1 and a second capacitor C2 arranged in series; the first end of the high-voltage winding W1 is simultaneously connected to the first capacitor C1, the second capacitor C2 and the positive terminal of the first diode D1, and the second end of the high-voltage winding W1 is connected to the negative terminal of the second diode D2; the filament winding W2 is simultaneously connected to the positive terminal of the second diode D2 and the first capacitor C1; the second diode assembly includes a third diode D3 and a fourth diode D4 arranged in series; the second capacitor assembly includes a third capacitor C3 and a fourth capacitor C4 arranged in series; the first end of the anode voltage sampling winding W3 is simultaneously connected to the positive terminal of the third diode D3 and the negative terminal of the fourth diode D4, and the second end of the anode voltage sampling winding W3 is connected to the third capacitor C3 and the fourth capacitor C4; the first end of the inductor L is simultaneously connected to the negative terminal of the third diode D3, the positive terminal of the fourth diode D4 and the fourth capacitor C4.

[0043] In addition, it is worth mentioning that the chip model used in the electronic transformer for a microwave oven provided by the present invention is VT3788.

[0044] Compared with the related art, the present invention provides an electronic transformer for a microwave oven, which includes a first rectifying and filtering unit for converting an input AC voltage into a DC voltage; a power conversion unit connected to the first rectifying and filtering unit for converting the DC voltage into an AC pulse voltage; a transformer connected to the power conversion unit for voltage conversion of the AC pulse voltage; a second rectifying and filtering unit connected to the transformer for rectifying and filtering the voltage converted by the transformer to output DC high voltage electricity; a microwave oven magnetron connected to the second rectifying and filtering unit for receiving the DC high voltage electricity and working; a control unit connected to the power conversion unit for driving the power conversion unit to convert the DC voltage into the AC pulse voltage; a power adjustment unit connected to the control unit for adjusting the output power of the electronic transformer according to predetermined conditions; a timer is provided in the control unit for controlling the output power of the electronic transformer according to a predetermined operating time. In the above structure, through the setting of the power adjustment unit, the input power can be automatically reduced when the anode temperature of the microwave oven magnetron is too high or when the temperature of any power device in the rectifier filter unit, power conversion unit, transformer and high-voltage rectifier filter unit is too high, thereby effectively protecting the microwave oven magnetron and power devices; in addition, a timer is provided in the control unit, which can reduce the input power according to the working time without setting an external communication connection line.

[0045] It should be noted that the above-described embodiments should be understood as illustrative rather than limiting the scope of protection of the present invention, and the scope of protection of the present invention shall be subject to the claims. For those skilled in the art, some non-essential improvements and adjustments made to the present invention still fall within the scope of protection of the present invention without departing from the essence and scope of the present invention.

Claims

1. An electronic transformer for a microwave oven, characterized in that: The electronic transformer comprises: A first rectifying and filtering unit for converting an input AC voltage into a DC voltage; A power conversion unit connected to the first rectifying and filtering unit and used for converting the DC voltage into an AC pulse voltage; A transformer connected to the power conversion unit and used for performing voltage conversion on the AC pulse voltage; A second rectifying and filtering unit connected to the transformer and used to rectify and filter the voltage transformed by the transformer to output DC high voltage electricity; A microwave oven magnetron connected to the second rectifying and filtering unit for receiving the DC high voltage electricity and operating; A control unit connected to the power conversion unit and used to drive the power conversion unit to convert the DC voltage into the AC pulse voltage; a power adjustment unit connected to the control unit and used for adjusting the output power of the electronic transformer according to predetermined conditions; The control unit is provided with a timer for controlling the output power of the electronic transformer according to a predetermined operating time.

2. An electronic transformer for a microwave oven according to claim 1, characterized in that: The power adjustment unit includes an anode voltage sampling unit and a temperature detection unit connected to the control unit. The anode sampling unit is used to reduce the input power when the anode temperature of the microwave oven magnetron is too high. The temperature detection unit is used to reduce the input power when the temperature of any power device among the first rectifying and filtering unit, the power conversion unit, the transformer and the second rectifying and filtering unit is too high.

3. An electronic transformer for a microwave oven according to claim 2, characterized in that: The anode voltage sampling unit includes a first circuit connected to the anode and cathode of the induction cooker magnetron, a filament winding connected to the first circuit for providing filament voltage to the induction cooker magnetron, and a second circuit arranged in parallel with the filament winding and connected to the control unit.

4. An electronic transformer for a microwave oven according to claim 3, characterized in that: The first circuit includes a high-voltage winding arranged on the high-voltage side of the transformer and a first voltage-doubling rectifier circuit connected to the high-voltage winding, a first end of the first voltage-doubling rectifier circuit is connected to the high-voltage winding, and a second end of the first voltage-doubling rectifier circuit is connected to the anode and cathode of the induction cooker magnetron; the first voltage-doubling rectifier circuit includes a first diode assembly connected to the high-voltage winding, a first capacitor assembly arranged in parallel with the first diode assembly, and a resistor arranged in parallel with the first capacitor assembly, a first output end of the resistor is connected to the anode of the induction cooker magnetron, and a second output end of the resistor is connected to the cathode of the induction cooker magnetron; The filament winding is arranged at the high voltage side of the transformer and is connected to the first diode assembly and the first capacitor assembly at the same time; The second circuit includes an anode voltage sampling winding arranged on the high-voltage side of the transformer and a second voltage doubling rectifier circuit connected to the anode voltage sampling winding, a first end of the second voltage doubling rectifier circuit is connected to the anode voltage sampling winding, a second end of the second voltage doubling rectifier circuit is connected to the control unit, the second voltage doubling rectifier circuit includes a second diode component connected to the anode voltage sampling winding, a second capacitor component connected to the anode voltage sampling winding and arranged in parallel with the second diode component, and an inductor connected to both the second diode component and the second capacitor component, a first end of the inductor is connected to both the second diode component and the second capacitor component, and a second end of the inductor is connected to the control unit.

5. An electronic transformer for a microwave oven according to claim 4, characterized in that: The first diode assembly includes a first diode and a second diode connected in series; the first capacitor assembly includes a first capacitor and a second capacitor connected in series; the first end of the high-voltage winding is simultaneously connected to the first capacitor, the second capacitor and the positive terminal of the first diode, and the second end of the high-voltage winding is connected to the negative terminal of the second diode; the filament winding is simultaneously connected to the positive terminal of the second diode and the first capacitor; The second diode component includes a third diode and a fourth diode arranged in series; the second capacitor component includes a third capacitor and a fourth capacitor arranged in series; the first end of the anode voltage sampling winding is simultaneously connected to the positive terminal of the third diode and the negative terminal of the fourth diode, and the second end of the anode voltage sampling winding is connected to the third capacitor and the fourth capacitor; the first end of the inductor is simultaneously connected to the negative terminal of the third diode, the positive terminal of the fourth diode and the fourth capacitor.

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