Microwave oven circuit and microwave oven

Abstract

The utility model discloses a microwave oven circuit and a microwave oven. The microwave oven circuit comprises a variable-frequency power supply, a heating tube and a magnetron, two input ends of the variable-frequency power supply are respectively connected to a live wire and a zero wire of a mains supply, and an output end of the variable-frequency power supply is respectively connected with the heating tube and the magnetron; two ends of the heating tube are respectively connected to a first output end and a second output end of the variable-frequency power supply; and two ends of the magnetron are respectively connected to a third output end and a fourth output end of the variable-frequency power supply. According to the microwave oven circuit, the variable-frequency power supply is adopted to control the working power of the heating tube by adjusting the voltage or current output to the heating tube, and the power of the heating tube can be adjusted. In addition, the variable-frequency power supply is adopted to control the heating tube, electromagnetic pollution can be reduced, electric devices do not need to be added due to the electromagnetic compatibility problem, the drive control module of the microwave oven is small in size, and the manufacturing cost of the microwave oven is low. In addition, a variable-frequency power supply is adopted to control the graphene heating tube, so that the flicker phenomenon of the graphene heating tube can be eliminated.

Description

Technical Field

[0001] The utility model relates to the technical field of cooking appliances, in particular to a microwave oven circuit and a microwave oven. Background Art

[0002] At present, microwave ovens integrate the functions of variable-frequency microwave and baking, and are developing towards the direction of multi-function. Among them, the variable-frequency microwave function of the microwave oven is mainly realized by an inverter circuit board. The baking function of the microwave oven is mainly realized by heating with a metal heating tube, a quartz heating tube or a graphene heating tube, and the heating tube is mainly driven and controlled by a relay or a thyristor circuit in a computer board or a main control board.

[0003] In the related art, when using a relay to control the heating tube, the state of the heating tube is full-power operation (fully opening the relay) or not working at all (closing the relay). Since there is no intermediate state, the power of the heating tube cannot be adjusted, so the temperature cannot be accurately controlled, and the baking effect of the microwave oven is affected. When using a thyristor to control the heating tube, although the power adjustment of the heating tube can be realized, it will generate great electromagnetic pollution, and the electromagnetic compatibility (EMC) problem is serious. A filter needs to be added, which will make the volume of the drive control module of the microwave oven large and the manufacturing cost of the microwave oven high. In addition, when using a thyristor to control a graphene heating tube, due to the characteristics of the thyristor itself and the graphene heating tube, when the thyristor and the graphene heating tube are used in combination, if the compatibility and matching between the two are not good, the graphene heating tube will have a flashing phenomenon. The flashing phenomenon will not only affect the baking effect, but also cause damage to the heating tube itself. Summary of the Utility Model

[0004] In view of this, the utility model aims to solve at least one of the problems in the related art to some extent. For this reason, the purpose of the utility model is to provide a microwave oven circuit and a microwave oven.

[0005] The present application provides a microwave oven circuit. The microwave oven circuit includes a variable-frequency power supply, a heating tube and a magnetron. Two input ends of the variable-frequency power supply are respectively connected to the live wire and the neutral wire of the commercial power, and the output end of the variable-frequency power supply is respectively connected to the heating tube and the magnetron; both ends of the heating tube are respectively connected to the first output end and the second output end of the variable-frequency power supply; both ends of the magnetron are respectively connected to the third output end and the fourth output end of the variable-frequency power supply.

[0006] In some embodiments, the variable-frequency power supply includes a variable-frequency control circuit, and the variable-frequency control circuit includes a heating tube control circuit and a main controller. The heating tube control circuit includes a first insulated gate bipolar transistor and a first current detection resistor. The first end of the first insulated gate bipolar transistor is connected to the heating tube, and the second end of the first insulated gate bipolar transistor is connected to the first end of the first current detection resistor; the second end of the first current detection resistor is connected to the current detection module of the main controller, and the third end of the first current detection resistor is grounded.

[0007] In some embodiments, the variable-frequency control circuit includes a magnetron control circuit, and the magnetron control circuit includes a resonant transformer, a first capacitor, a second insulated gate bipolar transistor, and a second current detection resistor. The first end of the resonant transformer is connected to the magnetron, and the second end of the resonant transformer is connected to the first end of the second insulated gate bipolar transistor; the first capacitor is connected in parallel with the inductance coil of the resonant transformer to form a resonant circuit; the first end of the second insulated gate bipolar transistor is connected in series with the second end of the inductance coil of the resonant transformer, and the second end of the second insulated gate bipolar transistor is connected in series with the first end of the second current detection resistor; the second end of the second current detection resistor is connected to the current detection module of the main controller, and the third end of the second current detection resistor is grounded.

[0008] In some embodiments, the variable-frequency control circuit further includes a first filter circuit. The first filter circuit is connected to the heating tube control circuit, and the first filter circuit includes a first inductor and a second capacitor. The first inductor is connected in parallel with the second capacitor; the first end of the second capacitor is connected to the heating tube, and the second end of the second capacitor is connected to the third end of the second current detection resistor.

[0009] In some embodiments, the variable-frequency control circuit further includes a rectifier and a second filter circuit. The rectifier converts alternating current into direct current; the input end of the rectifier is connected to the second filter circuit, and the output end of the rectifier is connected to the first filter circuit.

[0010] In some embodiments, the rectifier includes a rectifier bridge stack. The second filter circuit includes a third capacitor, and both ends of the third capacitor are respectively connected to two input ends of the rectifier bridge stack; the first output end of the rectifier bridge stack is connected to the first inductor, and the second output end of the rectifier bridge stack is connected to the second end of the second capacitor.

[0011] In some embodiments, the variable-frequency control circuit further includes the power supply circuit, which includes a voltage-drop circuit, a linear voltage-regulating circuit, and an auxiliary winding circuit connected in series. One end of the voltage-drop circuit is connected between the first filter circuit and the rectifier, and one end of the auxiliary winding circuit is connected to the inductance coil of the resonance transformer of the magnetron control circuit.

[0012] In some embodiments, the variable-frequency control circuit further includes a voltage-doubling rectifier circuit. The first end of the voltage-doubling rectifier circuit is connected to the inductance coil of the resonance transformer, and the second end of the voltage-doubling rectifier circuit is connected to the magnetron.

[0013] In some embodiments, the variable-frequency control circuit further includes a magnetron anode current sampling circuit, which is connected in series with the voltage-doubling rectifier circuit.

[0014] This application also provides a microwave oven, which includes the heat preservation structure described in any one of the above embodiments.

[0015] Thus, the microwave oven circuit of this application uses a variable-frequency power supply to control the working power of the heating tube by adjusting the voltage or current output to the heating tube, and the heating tube can achieve power adjustment. In addition, using a variable-frequency power supply to control the heating tube can reduce electromagnetic pollution, eliminate the need to add electrical components due to electromagnetic compatibility problems, the driving control module of the microwave oven is smaller in size, and the manufacturing cost of the microwave oven is lower. Moreover, using a variable-frequency power supply to control the graphene heating tube can eliminate the flashing phenomenon of the graphene heating tube.

[0016] Additional aspects and advantages of the present utility model will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present utility model will become apparent and be readily understood from the following description of the embodiments in conjunction with the drawings, where:

[0018] Figure 1 is a schematic structural diagram of the microwave oven circuit according to the embodiment of this application;

[0019] Figure 2 is a schematic structural diagram of the variable-frequency control circuit according to the embodiment of this application.

[0020] Main reference numerals of the components:

[0021] Microwave oven circuit 100;

[0022] Variable-frequency power supply 10; Heating tube 20; Magnetron 30;

[0023] The first input terminal 11 of the variable-frequency power supply, the second input terminal 12 of the variable-frequency power supply, the first output terminal 13 of the variable-frequency power supply, the second output terminal 14 of the variable-frequency power supply, the third output terminal 15 of the variable-frequency power supply, the fourth output terminal 16 of the variable-frequency power supply;

[0024] The variable-frequency control circuit 17;

[0025] The heating tube control circuit 171, the magnetron control circuit 172, the first filter circuit 173, the rectifier 174, the second filter circuit 175, the power supply circuit 176, the voltage drop circuit 1761, the linear voltage regulator circuit 1762, the auxiliary winding circuit 1763, the voltage doubler rectifier circuit 177, the magnetron anode current sampling circuit 178, the main controller MCU;

[0026] The first insulated gate bipolar transistor Q2, the first end 21 of the first insulated gate bipolar transistor, the second end 22 of the first insulated gate bipolar transistor; The first current detection resistor RS2, the first end 23 of the first current detection resistor, the second end 24 of the first current detection resistor, the third end 25 of the first current detection resistor;

[0027] The resonance transformer TR1, the first end 31 of the resonance transformer, the second end 32 of the resonance transformer; The second insulated gate bipolar transistor Q1, the first end 33 of the second insulated gate bipolar transistor, the second end 34 of the second insulated gate bipolar transistor Q1; The second current detection resistor RS1, the first end 35 of the second current detection resistor, the second end 36 of the second current detection resistor, the third end 37 of the second current detection resistor;

[0028] The second capacitor C1, the first end 41 of the second capacitor C1, the second end 42 of the second capacitor C1;

[0029] The input end 51 of the rectifier, the output end 52 of the rectifier, the rectifier bridge stack B1, the first input end 53 of the rectifier bridge stack, the second input end 54 of the rectifier bridge stack, the first output end 55 of the rectifier bridge stack, the second output end 56 of the rectifier bridge stack B1;

[0030] The power resistor Rst1, the voltage stabilizing diode Z1, the capacitor EC1, the power supply chip 7805, the resistor R8, the capacitor EC2, the capacitor C3, the rectifier diode D3, the resistor R7, one end 61 of the voltage drop circuit, one end 62 of the auxiliary winding circuit;

[0031] The first end 71 of the voltage doubler rectifier circuit, the second end 72 of the voltage doubler rectifier circuit. Detailed implementation manner

[0032] The embodiments of the present utility model will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present utility model and should not be construed as limiting the present utility model.

[0033] In the description of the present utility model, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present utility model, "a plurality of" means two or more unless otherwise specifically defined.

[0034] In the description of the present utility model, it should be noted that unless otherwise clearly specified and defined, the terms "installation" and "connection" should be understood in a broad sense. It may refer to fixed connection, detachable connection, or integral connection; it may be mechanical connection, electrical connection, or communication with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0035] The following disclosure provides many different embodiments or examples for implementing different structures of the present utility model. To simplify the disclosure of the present utility model, the components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present utility model. In addition, the present utility model may repeat reference numerals and / or reference letters in different examples. This repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0036] The embodiments of the present utility model will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present utility model and should not be construed as limiting the present utility model.

[0037] Please refer to Figure 1 , an embodiment of the present application discloses a microwave oven circuit 100. The microwave oven circuit 100 includes a variable frequency power supply 10, a heating tube 20, and a magnetron 30. The microwave oven circuit 100 can not only drive and control the magnetron 30 for microwave frequency conversion, but also control the heating tube 20 for baking, integrating the functions of variable frequency microwave and baking.

[0038] The input terminals 11 and 12 of the variable-frequency power supply 10 are respectively connected to the live wire L and the neutral wire N of the mains power supply. The variable-frequency power supply 10 can convert the mains power supply (alternating current) into direct current for the microwave oven circuit 100.

[0039] At present, most of the heating tubes are driven and controlled through relays or thyristor circuits in the main control board, and the variable-frequency microwave function is mostly realized by a variable-frequency drive circuit board. The related microwave oven circuit technology realizes the microwave frequency conversion function of the magnetron and the heating function of the heating tube through two circuit boards. The current heating tube control board using the relay control scheme can only realize the on-off function and cannot adjust the power, resulting in poor baking effect; using the thyristor control scheme can realize power adjustment, but it will generate great electromagnetic pollution, and the EMC problem is serious. It is necessary to increase the volume of the filter, which is large in size and high in cost; when using the thyristor to control the graphene heating tube, the graphene heating tube will have a flashing phenomenon.

[0040] In view of this, in the microwave oven circuit 100 of the embodiment of the present application, the four output terminals of the variable-frequency power supply 10 are respectively connected to the heating tube 20 and the magnetron 30. Both ends of the heating tube 20 are respectively connected to the first output terminal 13 and the second output terminal 14 of the variable-frequency power supply 10. Both ends of the magnetron 30 are respectively connected to the third output terminal 15 and the fourth output terminal 16 of the variable-frequency power supply 10. That is to say, the heating tube 20 and the magnetron 30 of the embodiment of the present application share a variable-frequency power supply 10, which can reduce electromagnetic pollution without increasing the volume of the power supply module of the microwave oven circuit 100, and there is no need to increase electrical components due to electromagnetic compatibility problems. The driving control module of the microwave oven is small in volume, and the manufacturing cost of the microwave oven is low. The heating tube 20 used for microwave oven baking adopts variable-frequency drive control, which can realize stepless power adjustment of the heating tube 20 and no flashing.

[0041] In this way, the microwave oven circuit 100 of the present application uses the variable-frequency power supply 10 to control the working power of the heating tube 20 by adjusting the voltage or current output to the heating tube 20, and the heating tube 20 can realize power adjustment. In addition, using the variable-frequency power supply 10 to control the heating tube 20 can reduce electromagnetic pollution, and there is no need to increase electrical components due to electromagnetic compatibility problems. The driving control module of the microwave oven is small in volume, and the manufacturing cost of the microwave oven is low. In addition, the heating tube 20 can be a graphene heating tube. Using the variable-frequency power supply 10 to control the heating tube 20, due to the advantages of the variable-frequency power supply 10 such as accurately controlling the current and voltage, real-time monitoring and adjustment, optimizing the power waveform, and strong adaptability, the flashing phenomenon of the heating tube 20 can be eliminated.

[0042] Please refer to Figure 2, the variable-frequency power supply 10 includes a variable-frequency control circuit 17. The microwave oven circuit 100 uses the variable-frequency control circuit 17 of the variable-frequency power supply 10 to perform variable-frequency drive control on the heating tube 20 and the magnetron 30, so as to realize the power adjustment of the heating tube 20 and the magnetron 30.

[0043] Specifically, the variable-frequency control circuit 17 includes a variable-frequency control circuit 171 and a main controller MCU. The variable-frequency control circuit 171 is used for variable-frequency drive control of the heating tube 20. The variable-frequency control circuit 171 includes a first insulated gate bipolar transistor Q2 and a first current detection resistor RS2. The first end 21 of the first insulated gate bipolar transistor Q2 is connected to the heating tube 20, and the second end 22 of the first insulated gate bipolar transistor Q2 is connected to the first end 23 of the first current detection resistor RS2; the second end 24 of the first current detection resistor RS2 is connected to the current detection module of the main controller MCU, and the third end 25 of the first current detection resistor RS2 is grounded.

[0044] Specifically, an insulated gate bipolar transistor (Insulate-Gate Bipolar Transistor, IGBT) is a composite fully controlled - voltage driven - power semiconductor device, which is composed of a bipolar junction transistor and an insulated gate field effect transistor. The IGBT can perform high-frequency switching control and is suitable for high-efficiency power control devices such as frequency converters. The first insulated gate bipolar transistor Q2 realizes the on and off states by controlling the gate voltage, thereby regulating the current and voltage.

[0045] In some embodiments, the first insulated gate bipolar transistor Q2 of the variable-frequency control circuit 17, the heating tube 20, and the first current detection resistor RS2 are connected in series. In this way, the variable-frequency control circuit 17 uses IGBT to control the heating tube 20, and the heating tube 20 can realize power adjustment. In addition, using IGBT to control the heating tube 20 can reduce electromagnetic pollution, can reduce the volume of electrical components for suppressing EMC, and reduce costs. Using IGBT to control the graphene heating tube 20 can also eliminate the flashing phenomenon of the graphene heating tube 20.

[0046] The main controller MCU has five modules: voltage detection, surge detection, current detection, synchronization detection, and IGBT overvoltage protection, which are respectively connected to different circuits and resistors to perform function control and detection on the microwave oven circuit 100. The second end 32 of the first current detection resistor RS2 is connected to the current detection module of the main controller MCU, and the third end 25 of the first current detection resistor RS2 is grounded. The MCU can real-time monitor the current situation in the microwave oven variable-frequency control circuit 171, and can prevent the circuit from overloading and protect the microwave oven from damage.

[0047] Such as Figure 2As shown, in some embodiments, the variable frequency control circuit 17 includes a variable frequency control circuit 172. The variable frequency control circuit 172 is used for variable frequency drive control of the magnetron 30. The variable frequency control circuit 172 includes a resonant transformer TR1, a first capacitor C2, a second insulated gate bipolar transistor Q1, and a second current detection resistor RS1. The first end 31 of the resonant transformer TR1 is connected to the magnetron 30, and the second end 32 of the resonant transformer TR1 is connected to the first end 33 of the second insulated gate bipolar transistor Q1; the first capacitor C2 is connected in parallel with the inductance coil of the resonant transformer TR1 to form a resonant circuit; the first end 33 of the second insulated gate bipolar transistor Q1 is connected in series with the second end 32 of the inductance coil of the resonant transformer TR1, and the second end 34 of the second insulated gate bipolar transistor Q1 is connected in series to the first end 35 of the second current detection resistor RS1; the second end 36 of the second current detection resistor RS1 is connected to the current detection module of the main controller MCU, and the third end 37 of the second current detection resistor RS1 is grounded.

[0048] Specifically, the magnetron 30 is an electro-vacuum device used to generate microwave energy, and its working principle requires high voltage and large current for driving. The resonant transformer TR1 forms a resonant circuit by connecting the inductance coil in parallel with the first capacitor C2, and large current and high voltage can be generated by using the principle of parallel resonance. In the application of the magnetron 30, this large current and high voltage can ensure the normal operation of the magnetron 30 and generate the required microwave energy.

[0049] The second insulated gate bipolar transistor Q1 is a key component in the microwave oven variable frequency control circuit 172. The first end 33 of the second insulated gate bipolar transistor Q1 is connected in series with the second end 32 of the inductance coil of the resonant transformer TR1, and its current state directly reflects the working condition of the magnetron 30. The current detection module of the microwave oven main controller MCU detects the current of the second insulated gate bipolar transistor Q1 by measuring the voltage drop across the resistor connected in series with the second insulated gate bipolar transistor Q1 or by using a dedicated current sensor. The main controller MCU processes and calculates the received signal and compares it with a preset threshold value to determine whether the working state of the magnetron 30 is normal.

[0050] The variable frequency control circuit 17 further includes a first filter circuit 173. In one embodiment, as Figure 2 shown, the first filter circuit 173 is connected to the variable frequency control circuit 171. The first filter circuit 173 includes a first inductor L1 and a second capacitor C1. The first inductor L1 is connected in parallel with the second capacitor C1; the first end 41 of the second capacitor C1 is connected to the heating tube 20, and the second end 42 of the second capacitor C1 is connected to the third end 37 of the second current detection resistor RS1.

[0051] Specifically, the first filter circuit 173 consists of a first inductor L1 and a second capacitor C1 to form a DC-side LC filter circuit. The power supply enters the circuit through the first inductor L1, and then returns to the ground wire through the second capacitor C1. In this connection method, the impedance of the first inductor L1 is small at low frequencies, and the impedance of the second capacitor C1 is large, allowing low-frequency signals to pass through; at high frequencies, the impedance of the first inductor L1 is large, and the impedance of the second capacitor C1 is small, blocking high-frequency signals from passing through. Therefore, the connection between the variable-frequency control circuit 171 and the first filter circuit 173 can be used to screen signals within a specific frequency range.

[0052] In addition, please refer to Figure 2 , the variable-frequency control circuit 17 further includes a rectifier 174 and a second filter circuit 175. The rectifier 174 converts alternating current into direct current; the input terminal 51 of the rectifier 174 is connected to the second filter circuit 175, and the output terminal 52 of the rectifier 174 is connected to the first filter circuit 173.

[0053] Specifically, after the commercial power is filtered by the AC-side filter circuit of the second filter circuit 175, it enters the input terminal 51 of the rectifier 174. The rectifier 174 is responsible for converting the commercial power (alternating current) into direct current in the variable-frequency control circuit 17 to provide a stable DC power supply for the subsequent circuits. The connection between the first filter circuit 173 and the output terminal 52 of the rectifier 174 is responsible for eliminating the pulsation and noise interference in the direct current output by the rectifier 174, further ensuring the stability of the DC power supply, and avoiding self-interference problems during the operation of the circuit.

[0054] In the above embodiment, the rectifier 174 includes a rectifier bridge stack B1. The second filter circuit 175 includes a third capacitor CX1, and both ends of the third capacitor CX1 are respectively connected to the two input terminals 53 and 54 of the rectifier bridge stack B1; the first output terminal 55 of the rectifier bridge stack B1 is connected to the first inductor L1, and the second output terminal 56 of the rectifier bridge stack B1 is connected to the second end 42 of the second capacitor C1.

[0055] Specifically, the rectifier bridge stack B1 is internally composed of four diodes connected in a bridge configuration, with 4 ports, respectively responsible for the input of alternating current and the output of direct current. The input terminals 53 and 54 of the rectifier bridge stack B1 are AC input terminals, and the output terminals 55 and 56 are DC output terminals. The CX1 safety capacitor in the second filter circuit 175 is used as a filtering element, and both ends are respectively connected to the first input terminal 53 and the second input terminal 54 of the rectifier bridge stack B1, in parallel with the rectifier bridge stack B1, mainly used to filter out the high-frequency noise and pulse interference signals of the commercial power input to the rectifier bridge stack B1. After the rectifier 174 converts the input alternating current into pulsating direct current, the two output terminals 55 and 56 are connected to the first filter circuit 173 for DC-side filtering.

[0056] As Figure 2As shown, in one embodiment, the variable frequency control circuit 17 further includes a power supply circuit 176. The power supply circuit 176 includes a voltage drop circuit 1761, a linear voltage regulator circuit 1762, and an auxiliary winding circuit 1763 connected in series. The power supply circuit 176 is used to provide a stable voltage with a specific amplitude. One end 61 of the voltage drop circuit is connected between the first filter circuit 173 and the rectifier 174, and one end 62 of the auxiliary winding circuit is connected to the inductor coil of the resonance transformer TR1 of the variable frequency control circuit 172.

[0057] Specifically, the voltage drop circuit 1761 is composed of a power resistor Rst1, a zener diode Z1, and a capacitor EC1 connected in series. The overall function is to achieve voltage stabilization and reduction. Rst1 and Z1 work together to limit and stabilize the voltage in the circuit, while EC1 is used for filtering to reduce voltage fluctuations and noise.

[0058] The linear voltage regulator circuit 1762 is composed of a power supply chip 7805, a resistor R8, a capacitor EC2, and a capacitor C3. It is a commonly used linear voltage regulator that can stabilize the input voltage to an output voltage of 5V. The 7805 chip is the core of this circuit. When the input voltage varies within a certain range (for example, it can be from 7V to 35V), the 7805 chip can automatically adjust the internal circuit to maintain the stability of the output voltage.

[0059] The auxiliary winding circuit 1763 is composed of a rectifier diode D3 and a resistor R7, and can provide a stable power supply for the magnetron 30. Through the rectifier diode D3, the auxiliary winding circuit 1763 can convert alternating current into direct current to provide the required DC power supply for the magnetron 30. At the same time, combined with components such as the resistor R7, the voltage and current of the circuit can be adjusted to meet the requirements under different working conditions. This increases the flexibility and reliability of the power supply, ensuring that the magnetron 30 can work stably.

[0060] In some embodiments, the variable frequency control circuit 17 further includes a voltage multiplier rectifier circuit 177. The first end 71 of the voltage multiplier rectifier circuit 177 is connected to the inductor coil of the resonance transformer TR1, and the second end 72 of the voltage multiplier rectifier circuit is connected to the magnetron 30. The voltage multiplier rectifier circuit 177 can receive electrical energy from the resonance transformer TR1, perform voltage multiplication, and stabilize the output voltage to provide the required high DC voltage for the magnetron 30.

[0061] The resonance transformer TR1 can adjust the input voltage to a voltage level suitable for the voltage multiplier rectifier circuit 177 to process, transmit electrical energy through its inductor coil, and provide the necessary energy for the voltage multiplier rectifier circuit 177. In this way, the coordinated operation of the resonance transformer TR1 and the voltage multiplier rectifier circuit 177 can optimize the energy transmission efficiency and circuit performance, thereby improving the efficiency of the entire variable frequency control circuit 172.

[0062] In some embodiments, the variable frequency control circuit 17 further includes a magnetron anode current sampling circuit 178, and the magnetron anode current sampling circuit 178 is connected in series with the voltage multiplier rectification circuit 177.

[0063] The magnetron anode current sampling circuit 178 is used to obtain the current information of the anode of the magnetron 30. This can be achieved by connecting a sampling resistor with a small resistance value in series with the anode. The resistor converts the anode current into a voltage signal. After the voltage signal is processed (such as amplified by an operational amplifier), it can be input into a single-chip microcomputer or other control systems for A / D conversion, so as to realize the real-time monitoring of the anode current. By real-time monitoring the anode current, the magnetron anode current sampling circuit 178 can ensure that the magnetron 30 operates within a safe current range and prevent damage caused by overcurrent. In this way, the magnetron anode current sampling circuit 178 monitors and samples the current of the anode of the magnetron 30 by being connected in series with the voltage multiplier rectification circuit 177.

[0064] This application also provides a microwave oven, which includes the circuit structure described in any of the above embodiments. Specifically, the structure of the microwave oven circuit 100 is as described above and will not be elaborated here.

[0065] In this way, this application integrates the baking function drive circuit and the microwave variable frequency power supply, saves electrical components, reduces costs, reduces the volume of the power supply module, and realizes the miniaturization of the microwave oven.

[0066] The above embodiments only represent several implementation manners of the present utility model. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several deformations and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the patent of the present utility model shall be subject to the appended claims.

Claims

1. A microwave oven circuit, characterized in that: The microwave oven circuit comprises a variable frequency power supply, a heating tube and a magnetron, wherein two input ends of the variable frequency power supply are respectively connected to the live wire and the neutral wire of the mains, and the output end of the variable frequency power supply is respectively connected to the heating tube and the magnetron; two ends of the heating tube are respectively connected to the first output end and the second output end of the variable frequency power supply; and two ends of the magnetron are respectively connected to the third output end and the fourth output end of the variable frequency power supply.

2. The microwave oven circuit according to claim 1, characterized in that: The variable frequency power supply includes a variable frequency control circuit, the variable frequency control circuit includes a heating tube control circuit and a main controller, the heating tube control circuit includes a first insulated gate bipolar transistor and a first current detection resistor; A first end of the first insulated gate bipolar transistor is connected to the heating tube, and a second end of the first insulated gate bipolar transistor is connected to a first end of the first current detection resistor; The second end of the first current detection resistor is connected to the current detection module of the main controller, and the third end of the first current detection resistor is grounded.

3. The microwave oven circuit according to claim 2, characterized in that: The frequency conversion control circuit includes a magnetron control circuit, and the magnetron control circuit includes a resonant transformer, a first capacitor, a second insulated gate bipolar transistor, and a second current detection resistor; The first end of the resonant transformer is connected to the magnetron, and the second end of the resonant transformer is connected to the first end of the second insulated gate bipolar transistor; The first capacitor is connected in parallel with the inductor of the resonant transformer to form a resonant circuit; The first end of the second insulated gate bipolar transistor is connected in series to the second end of the inductor of the resonant transformer, and the second end of the second insulated gate bipolar transistor is connected in series to the first end of the second current detection resistor; The second end of the second current detection resistor is connected to the current detection module of the main controller, and the third end of the second current detection resistor is grounded.

4. The microwave oven circuit according to claim 3, characterized in that: The frequency conversion control circuit further includes a first filter circuit, the first filter circuit is connected to the heating tube control circuit, and the first filter circuit includes a first inductor and a second capacitor; The first inductor and the second capacitor are connected in parallel; A first end of the second capacitor is connected to the heating tube, and a second end of the second capacitor is connected to a third end of the second current detection resistor.

5. The microwave oven circuit according to claim 4, characterized in that: The frequency conversion control circuit also includes a rectifier and a second filter circuit, wherein the rectifier converts the alternating current into direct current; The input end of the rectifier is connected to the second filter circuit, and the output end of the rectifier is connected to the first filter circuit.

6. The microwave oven circuit according to claim 5, characterized in that: The rectifier includes a rectifier bridge stack; the second filter circuit includes a third capacitor, and the two ends of the third capacitor are respectively connected to the two input ends of the rectifier bridge stack; The first output end of the rectifier bridge stack is connected to the first inductor, and the second output end of the rectifier bridge stack is connected to the second end of the second capacitor.

7. The microwave oven circuit according to claim 6, characterized in that: The frequency conversion control circuit also includes the power supply circuit, which includes a voltage drop circuit, a linear voltage stabilization circuit and an auxiliary winding circuit connected in series; One end of the voltage drop circuit is connected between the first filter circuit and the rectifier, and one end of the auxiliary winding circuit is connected to the inductor of the resonant transformer of the magnetron control circuit.

8. The microwave oven circuit according to claim 3, characterized in that: The frequency conversion control circuit also includes a voltage doubler rectifier circuit, a first end of the voltage doubler rectifier circuit is connected to the inductor of the resonant transformer, and a second end of the voltage doubler rectifier circuit is connected to the magnetron.

9. The microwave oven circuit according to claim 8, characterized in that: The frequency conversion control circuit also includes a magnetron anode current sampling circuit, and the magnetron anode current sampling circuit is connected in series with the voltage doubler rectification circuit.

10. A microwave oven, characterized in that: The microwave oven comprises the microwave oven circuit according to any one of claims 1 to 9.

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