Microwave oven magnetron driving circuit and microwave oven

Abstract

The utility model relates to a microwave oven magnetron driving circuit and a microwave oven. The microwave oven magnetron driving circuit comprises a driving unit used for receiving a driving signal to drive a magnetron to work; the current detection unit is connected with the driving unit and is used for measuring the anode current of the magnetron and outputting a current sampling signal; the adjusting unit is connected with the driving unit and is used for receiving the adjusting signal and adjusting the working current of the magnetron filament; and the main control unit is connected with the driving unit, the current detection unit and the adjusting unit, and is used for receiving the current sampling signal and outputting the adjusting signal and the driving signal. According to the utility model, the output power of the magnetron can be accurately controlled, and the user experience is improved.

Description

Technical Field

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

[0002] The magnetron is usually driven by a switching power supply, and the secondary side of the transformer in the switching power supply is used to drive the magnetron. In the related art, the output power of the switching power supply is usually collected from the primary side of the transformer, and the magnetron is controlled to work stably according to the collected signal. However, due to the differences in the parameters of the magnetron, transformer and other components (such as the resistance of the magnetron filament and the inductance of the transformer), this scheme of taking the primary side signal for control is low in cost, but because the power of the magnetron is not directly collected, there will be differences in the heating power between different microwave ovens. In addition, as the microwave oven is used, the magnetron will gradually age, which will aggravate the inaccuracy of the microwave oven output power and affect the user experience. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a microwave oven magnetron driving circuit and a microwave oven.

[0004] The technical solution adopted by the utility model to solve the technical problem is: construct a microwave oven magnetron drive circuit, including:

[0005] A driving unit for receiving a driving signal to drive the magnetron to work;

[0006] A current detection unit connected to the driving unit and used to measure the anode current of the magnetron and output a current sampling signal;

[0007] an adjusting unit connected to the driving unit and configured to receive an adjusting signal and adjust an operating current of the magnetron filament; and

[0008] A main control unit connected to the driving unit, the current detection unit and the regulating unit, and configured to receive the current sampling signal and output the regulating signal and the driving signal.

[0009] Preferably, the adjustment unit comprises:

[0010] A shunt unit connected to the filament driving winding of the driving unit, configured to receive a first shunt control signal and a second shunt control signal and shunt the current input to the filament;

[0011] a first shunt control unit connected to the shunt unit and configured to receive the adjustment signal and output the first shunt control signal; and

[0012] A second shunt control unit is connected to the shunt unit and is used to receive the adjustment signal and output the second shunt control signal.

[0013] Preferably, the shunting unit includes a second NPN transistor Q2, a third NPN transistor Q3, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4;

[0014] The collector of the second NPN transistor Q2 and the emitter of the third NPN transistor Q3 are simultaneously connected to the first end of the filament driving winding of the driving unit. After the emitter of the second NPN transistor Q2 and the collector of the third NPN transistor Q3 are connected, one path is connected to the second end of the filament driving winding of the driving unit via the first resistor R1 and the third resistor R3, and the other path is connected to the second end of the filament driving winding of the driving unit via the second resistor R2 and the fourth resistor R4. The base of the second NPN transistor Q2 is connected to the first shunt control unit to receive the first shunt control signal, and the base of the third NPN transistor Q3 is connected to the second shunt control unit to receive the second shunt control signal.

[0015] Preferably, the first current shunting control unit includes a first optical coupler U1, a fifteenth resistor R15, a fifth resistor R5, a second diode D2, a seventh resistor R7 and a third capacitor C3;

[0016] The anode of the first optical coupler U1 is connected to the main control unit to receive the adjustment signal, the cathode of the first optical coupler U1 is connected to the ground via the fifteenth resistor R15, the collector of the first optical coupler U1 is connected to the second end of the fifth resistor R5, the first end of the fifth resistor R5 is simultaneously connected to the cathode of the second diode D2, the second end of the seventh resistor R7 and the second end of the third capacitor C3, the anode of the second diode D2 is connected to the first end of the filament driving winding of the driving unit, the first end of the seventh resistor R7 and the first end of the third capacitor C3 are simultaneously connected to the second end of the filament driving winding of the driving unit, and the emitter of the first optical coupler U1 outputs the first shunt control signal;

[0017] The second current shunt control unit includes a second optical coupler U3, a sixteenth resistor R16, a sixth resistor R6, a third diode D3, an eighth resistor R8 and a fourth capacitor C4;

[0018] The anode of the second optocoupler U3 is connected to the main control unit to receive the adjustment signal, the cathode of the second optocoupler U3 is connected to the ground via the sixteenth resistor R16, the collector of the second optocoupler U3 is connected to the second end of the sixth resistor R6, the first end of the sixth resistor R6 is simultaneously connected to the cathode of the third diode D3, the second end of the eighth resistor R8 and the second end of the fourth capacitor C4, the anode of the third diode D3 is connected to the second end of the filament drive winding of the drive unit, the first end of the eighth resistor R8 and the first end of the fourth capacitor C4 are simultaneously connected to the first end of the filament drive winding of the drive unit, and the emitter of the second optocoupler U3 outputs the second shunt control signal.

[0019] Preferably, the current detection unit comprises:

[0020] A sampling unit for measuring the anode current of the magnetron and outputting an AC sampling signal;

[0021] a first rectifying unit connected to the sampling unit and used for rectifying the AC sampling signal; and

[0022] An amplifying unit connected to the first rectifying unit and configured to amplify the rectified AC sampling signal and output the current sampling signal.

[0023] Preferably, the sampling unit includes a current transformer CT1 and an eleventh resistor R11; the primary side of the current transformer CT1 is coupled to the power supply line of the magnetron anode to collect the magnetron anode current, the secondary side of the current transformer CT1 is connected in parallel with the eleventh resistor R11, and the eleventh resistor R11 is also connected to the first rectifier unit to input the AC sampling signal thereto.

[0024] Preferably, the first rectifying unit includes a sixth diode D6 and a seventh capacitor C7; the anode of the sixth diode D6 is connected to the first signal output end of the sampling unit, the cathode of the sixth diode D6 is connected to the second signal output end of the sampling unit via the seventh capacitor C7, and the seventh capacitor C7 is also connected to the amplifying unit to input the rectified AC sampling signal thereto.

[0025] Preferably, the amplifying unit comprises an operational amplifier U2, a thirteenth resistor R13, a twelfth resistor R12 and a fourteenth resistor R14;

[0026] The positive phase input terminal of the operational amplifier U2 is connected to the positive terminal of the first rectifier unit and is connected to the negative terminal of the first rectifier unit via the twelfth resistor R12. The negative phase input terminal of the operational amplifier U2 is connected to the negative terminal of the first rectifier unit via the thirteenth resistor R13 in one path and is connected to the output terminal of the operational amplifier U2 via the fourteenth resistor R14 in another path. The output terminal of the operational amplifier U2 outputs the current sampling signal.

[0027] Preferably, the driving unit comprises:

[0028] A second rectifying unit for receiving an AC voltage and outputting a first DC voltage;

[0029] A transformer T1, whose primary winding is connected to the second rectifier unit, and whose filament drive winding is connected to the regulating unit and can be connected to the magnetron filament;

[0030] A voltage doubling unit connected to the secondary winding of the transformer T1 and capable of being connected to the anode of the magnetron;

[0031] A resonant capacitor connected in parallel with the primary winding of the transformer T1 and used to form a resonant circuit with the primary winding of the transformer T1;

[0032] A power switch connected to the primary winding of the transformer T1 and used to control the energy storage or energy release of the primary winding of the transformer T1; and

[0033] A switch control unit connected to the main control unit and the power switch tube, used to receive the drive signal and control the power switch tube to be turned on or off.

[0034] The utility model also constructs a microwave oven, which comprises the microwave oven magnetron drive circuit mentioned above.

[0035] The implementation of the utility model has the following beneficial effects: the anode current of the magnetron is measured at the secondary winding through the current detection unit, and the working current of the magnetron filament is adjusted through the adjustment unit, so as to accurately control the output power of the magnetron and improve the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0037] Figure 1 It is a circuit structure block diagram of a microwave oven magnetron drive circuit in some embodiments of the utility model;

[0038] Figure 2 is a circuit schematic diagram of a drive unit in some embodiments of the utility model;

[0039] Figure 3 is a circuit schematic diagram of a switch control unit in some embodiments of the utility model;

[0040] Figure 4 is a circuit schematic diagram of a current detection unit in some embodiments of the utility model;

[0041] Figure 5 is a circuit schematic diagram of a shunt unit in some embodiments of the utility model;

[0042] Figure 6 is a circuit schematic diagram of a first shunt control unit and a second shunt control unit in some embodiments of the utility model;

[0043] Figure 7 It is a circuit schematic diagram of the main control unit in some embodiments of the utility model. DETAILED DESCRIPTION

[0044] In order to have a clearer understanding of the technical features, purposes and effects of the present utility model, the specific implementation methods of the present utility model are now described in detail with reference to the accompanying drawings.

[0045] Figure 1 This is a circuit structure block diagram of a microwave oven magnetron drive circuit in some embodiments of the utility model. The drive circuit can accurately control the output power of the magnetron. Figure 1 The microwave oven magnetron driving circuit includes a driving unit 1, a current detection unit 2, a regulating unit 3 and a main control unit 4.

[0046] The driving unit 1 is used to receive a driving signal to drive the magnetron to work. Specifically, the driving unit 1 is used to supply power to the magnetron and control its output power according to the driving signal, thereby controlling the working power of the magnetron.

[0047] In some embodiments, Figure 2 As shown, the driving unit 1 includes a second rectifying unit 11 , a transformer T1 , a voltage doubling unit 12 , a resonant capacitor 13 , a power switch tube 14 and a switch control unit 15 .

[0048] The second rectifying unit 11 is used to receive the AC voltage and output the first DC voltage. Specifically, the second rectifying unit 11 is used to rectify and filter the AC voltage to obtain a stable first DC voltage.

[0049] In some embodiments, Figure 2 As shown, the second rectifier unit 11 includes a fuse F1, a rectifier bridge D1 and a first capacitor C1. One end of the fuse F1 can be connected to the live wire, and the other end is connected to the first AC input end of the rectifier bridge D1. The second AC input end of the rectifier bridge D1 can be connected to the neutral wire. The two DC output ends of the rectifier bridge D1 are connected in parallel with the first capacitor C1 and output a first DC voltage.

[0050] The primary winding of the transformer T1 is connected to the second rectifier unit 11, and the filament drive winding of the transformer T1 is connected to the adjustment unit 3 and can be connected to the magnetron filament. Specifically, the transformer T1 is used to store and release energy using the first DC voltage, so as to transfer energy to its secondary winding and the filament drive winding by electromagnetic coupling, thereby using the secondary winding and the filament drive winding to power the magnetron.

[0051] The voltage doubling unit 12 is connected to the secondary winding of the transformer T1 and can be connected to the anode of the magnetron. Specifically, the voltage doubling unit 12 doubles the output voltage of the secondary winding to supply power to the anode and cathode of the magnetron using the doubled voltage.

[0052] In some embodiments, Figure 2 As shown, the voltage doubling unit 12 includes a fourth diode D4, a fifth diode D5, a fifth capacitor C5 and a sixth capacitor C6. The anode of the fourth diode D4 is connected to the second end of the filament driving winding of the transformer T1 and can be connected to the first end of the filament of the magnetron, the anode of the fourth diode D4 is also connected to the cathode of the fifth diode D5 via the fifth capacitor C5 and the sixth capacitor C6, the cathode of the fourth diode D4 is connected to the first end of the secondary winding and the anode of the fifth diode D5, the second end of the secondary winding is connected to the connection point between the fifth capacitor C5 and the sixth capacitor C6, and the cathode of the fifth diode D5 can be connected to the anode of the magnetron.

[0053] The resonant capacitor 13 is connected in parallel with the primary winding of the transformer T1. The resonant capacitor 13 is used to form a resonant circuit with the primary winding of the transformer T1 so that the primary winding generates a resonant signal during energy storage and release to supply power to the secondary winding and the filament drive winding.

[0054] The power switch tube 14 is connected to the primary winding of the transformer T1, and the power switch tube 14 is used to control the primary winding of the transformer T1 to store or release energy. Specifically, the power switch tube 14 can be an existing field effect tube, as long as it can control the primary winding to be connected or disconnected with the first DC voltage, thereby realizing the primary winding energy storage or energy release, and no specific limitation is made here.

[0055] The switch control unit 15 is connected to the main control unit 4 and the power switch tube 14, and is used to receive the drive signal and control the power switch tube 14 to turn on or off. Specifically, the switch control unit 15 outputs a switch signal with a corresponding duty cycle to the control end of the power switch tube 14 based on the drive signal to control the on and off of the power switch tube 14, thereby controlling the energy storage or release of the primary winding, and can control the output power of the magnetron by adjusting the duty cycle.

[0056] In some embodiments, Figure 3As shown, the switch control unit 15 includes a gate driver U4, a twelfth capacitor C12 and an eleventh capacitor C11. The model of the gate driver U4 may be MCP1402. The input end of the gate driver U4 is connected to the main control unit 4 to receive a drive signal, the output end of the gate driver U4 outputs a switch signal, the power supply end of the main control unit 4 is connected to a second DC voltage and connected to the ground via the twelfth capacitor C12, and the eleventh capacitor C11 and the twelfth capacitor C12 are connected in parallel. The second DC voltage may be provided by an existing switching power supply or a DC voltage regulator, which is not limited here.

[0057] The current detection unit 2 is connected to the driving unit 1, and the current detection unit 2 is used to measure the anode current of the magnetron and output a current sampling signal. Specifically, by directly measuring the anode current of the magnetron through the current detection unit 2, the real working current of the magnetron can be accurately determined, and the current sampling signal that can characterize the magnitude of the anode current of the magnetron is input to the main control unit 4, so that the main control unit 4 can control the adjustment signal based on the current sampling signal.

[0058] In some embodiments, Figure 4 As shown, the current detection unit 2 includes a sampling unit 21 , a first rectifying unit 22 and an amplifying unit 23 .

[0059] The sampling unit 21 is used to measure the anode current of the magnetron and output an AC sampling signal.

[0060] In some embodiments, Figure 4 As shown, the sampling unit 21 includes a current transformer CT1 and an eleventh resistor R11. The primary side of the current transformer CT1 is coupled to the power supply line of the magnetron anode to collect the magnetron anode current, the secondary side of the current transformer CT1 is connected in parallel with the eleventh resistor R11, and the eleventh resistor R11 is also connected to the first rectifier unit 22 to input an AC sampling signal to the first rectifier unit 22. In this embodiment, the function of the eleventh resistor R11 is to convert the induced current output from the secondary side of the current transformer CT1 into a voltage signal so that it can be rectified and amplified in subsequent steps.

[0061] The first rectifying unit 22 is connected to the sampling unit 21 , and is used for rectifying the AC sampling signal.

[0062] In some embodiments, Figure 4As shown, the first rectifying unit 22 includes a sixth diode D6 and a seventh capacitor C7. The anode of the sixth diode D6 is connected to the first signal output end of the sampling unit 21 (i.e., the first end of the eleventh resistor R11), and the cathode of the sixth diode D6 is connected to the second signal output end of the sampling unit 21 (i.e., the second end of the eleventh resistor R11) via the seventh capacitor C7. The seventh capacitor C7 is also connected to the amplifying unit 23 to input the rectified AC sampling signal to the amplifying unit 23. In this embodiment, the function of the first rectifying unit 22 is to perform half-wave rectification and filtering on the AC signal output by the sampling unit 21 to output a DC voltage signal that can characterize the magnitude of the anode current of the magnetron.

[0063] The amplifying unit 23 is connected to the first rectifying unit 22 , and is used to amplify the rectified AC sampling signal and output a current sampling signal.

[0064] In some embodiments, Figure 4 As shown, the amplification unit 23 includes an operational amplifier U2, a thirteenth resistor R13, a twelfth resistor R12, an eighth capacitor C8, a fourteenth resistor R14 and a ninth capacitor C9. The positive phase input terminal of the operational amplifier U2 is connected to the positive end of the first rectifier unit 22 (i.e., the first end of the seventh capacitor C7), and is connected to the negative end of the first rectifier unit 22 (i.e., the second end of the seventh capacitor C7) through the twelfth resistor R12, the positive phase input terminal of the operational amplifier U2 is also connected to the negative phase input terminal of the operational amplifier U2 through the eighth capacitor C8, the negative phase input terminal of the operational amplifier U2 is connected to the negative end of the first rectifier unit 22 through the thirteenth resistor R13, and is connected to the output terminal of the operational amplifier U2 through the fourteenth resistor R14, the ninth capacitor C9 is connected in parallel with the fourteenth resistor R14, and the output terminal of the operational amplifier U2 outputs a current sampling signal. In this embodiment, the operational amplifier U2, the thirteenth resistor R13, the twelfth resistor R12 and the fourteenth resistor R14 form an amplifier circuit, which can amplify the rectified AC sampling signal to obtain a current sampling signal; and the eighth capacitor C8 and the ninth capacitor C9 play a filtering role, which helps to improve the stability of the amplifier circuit.

[0065] The adjustment unit 3 is connected to the driving unit 1, and is used to receive the adjustment signal and adjust the working current of the magnetron filament. Specifically, the adjustment unit 3 is used to shunt the current input to the magnetron filament, and can control the magnitude of the shunt current based on the adjustment signal, thereby fine-tuning the working current input to the magnetron filament to control the power of the magnetron filament, and further control the power of the magnetron.

[0066] In some embodiments, Figure 5 and Figure 6 As shown, the regulating unit 3 includes a diversion unit 31 , a first diversion control unit 32 and a second diversion control unit 33 .

[0067] The shunt unit 31 is connected to the filament driving winding of the driving unit 1 , and is used to receive the first shunt control signal and the second shunt control signal and shunt the current input to the filament.

[0068] In some embodiments, Figure 5 As shown, the shunt unit 31 includes a second NPN transistor Q2, a third NPN transistor Q3, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4. The collector of the second NPN transistor Q2 and the emitter of the third NPN transistor Q3 are simultaneously connected to the first end of the filament drive winding of the driving unit 1, the emitter of the second NPN transistor Q2 and the collector of the third NPN transistor Q3 are connected to the second end of the filament drive winding of the driving unit 1 through the first resistor R1 and the third resistor R3, and the other end of the filament drive winding of the driving unit 1 through the second resistor R2 and the fourth resistor R4, the base of the second NPN transistor Q2 is connected to the first shunt control unit 32 to receive the first shunt control signal, and the base of the third NPN transistor Q3 is connected to the second shunt control unit 33 to receive the second shunt control signal.

[0069] In this embodiment, both the second NPN transistor Q2 and the third NPN transistor Q3 can work in the amplification region. Since the filament driving winding outputs an AC voltage, when the voltage at the first end of the filament driving winding is greater than the voltage at the second end, the first shunt control signal controls the second NPN transistor Q2 to turn on, and the current flowing through the second NPN transistor Q2 is determined by the current magnitude of the first shunt control signal and the amplification factor of the second NPN transistor Q2 itself. Since the amplification factor is determined, the shunt current magnitude can be controlled by controlling the current magnitude of the first shunt control signal, which is equivalent to controlling the shunt current magnitude of the filament. When the voltage at the first end of the filament driving winding is less than the voltage at the second end, the second shunt control signal controls the third NPN transistor Q3 to turn on, and the shunt current magnitude is controlled by the circuit magnitude of the second shunt control signal. Therefore, by controlling the current magnitudes of the first shunt control signal and the second shunt control signal, the shunt current magnitude when the shunt unit 31 shunts the filament driving winding can be controlled, thereby fine-tuning the working current of the filament.

[0070] The first shunt control unit 32 is connected to the shunt unit 31 , and is used to receive the adjustment signal and output a first shunt control signal.

[0071] In some embodiments, Figure 6As shown, the first shunt control unit 32 includes a first optical coupler U1, a fifteenth resistor R15, a fifth resistor R5, a second diode D2, a seventh resistor R7 and a third capacitor C3. The anode of the first optical coupler U1 is connected to the main control unit 4 to receive the adjustment signal, the cathode of the first optical coupler U1 is connected to the ground via the fifteenth resistor R15, the collector of the first optical coupler U1 is connected to the second end of the fifth resistor R5, the first end of the fifth resistor R5 is simultaneously connected to the cathode of the second diode D2, the second end of the seventh resistor R7 and the second end of the third capacitor C3, the anode of the second diode D2 is connected to the first end of the filament driving winding of the driving unit 1, the first end of the seventh resistor R7 and the first end of the third capacitor C3 are simultaneously connected to the second end of the filament driving winding of the driving unit 1, and the emitter of the first optical coupler U1 outputs the first shunt control signal.

[0072] In this embodiment, the adjustment signal is an analog voltage signal. When the first optocoupler U1 works in the amplification region, the voltage of the adjustment signal can control the output current of the reflector of the first optocoupler U1 (i.e., control the first shunt control signal). Furthermore, when the voltage at the first end of the filament drive winding is less than the voltage at the second end, the second diode D2 and the third capacitor C3 will rectify and filter the output voltage of the filament drive winding, and the first shunt control signal output from the emitter of the first optocoupler U1 is controlled by the voltage of the adjustment signal. Therefore, the main control unit 4 can control the current of the first shunt control signal by controlling the voltage of the adjustment signal.

[0073] The second shunt control unit 33 is connected to the shunt unit 31 , and is used to receive the adjustment signal and output a second shunt control signal.

[0074] In some embodiments, Figure 6 As shown, the second current shunt control unit 33 includes a second optical coupler U3, a sixteenth resistor R16, a sixth resistor R6, a third diode D3, an eighth resistor R8 and a fourth capacitor C4.

[0075] The anode of the second optocoupler U3 is connected to the main control unit 4 to receive the adjustment signal, the cathode of the second optocoupler U3 is connected to the ground via the sixteenth resistor R16, the collector of the second optocoupler U3 is connected to the second end of the sixth resistor R6, the first end of the sixth resistor R6 is simultaneously connected to the cathode of the third diode D3, the second end of the eighth resistor R8 and the second end of the fourth capacitor C4, the anode of the third diode D3 is connected to the second end of the filament driving winding of the driving unit 1, the first end of the eighth resistor R8 and the first end of the fourth capacitor C4 are simultaneously connected to the first end of the filament driving winding of the driving unit 1, and the emitter of the second optocoupler U3 outputs a second shunt control signal.

[0076] In this embodiment, the principle of the second shunt control unit 33 generating the second shunt control signal is similar to the principle of the first shunt control unit 32 generating the first shunt control signal, and they can refer to each other, so they are not described in detail.

[0077] The main control unit 4 is connected to the driving unit 1, the current detection unit 2 and the adjustment unit 3, and the main control unit 4 is used to receive the current sampling signal and output the adjustment signal and the driving signal. Specifically, the main control unit 4 can obtain the working current of the magnetron anode by receiving the current sampling signal, so as to accurately determine the actual power of the magnetron, and then analyze whether the power of the magnetron is accurate based on the actual power and the set power. If it is inaccurate, the shunt current of the adjustment unit 3 can be controlled by adjusting the voltage of the adjustment signal, so as to control the power of the magnetron filament, and then fine-tune the power of the magnetron to make its power closer to the set power, thereby improving the accuracy of the magnetron power and improving the user experience.

[0078] In some embodiments, Figure 7 As shown, the main control unit 4 includes a single-chip microcomputer MCU1. The connection relationship between the single-chip microcomputer MCU1 and each unit can be referred to Figures 2 to 7 Of course, the main control unit 4 may also include peripheral circuits (such as crystal oscillator circuits, etc.) related to the operation of the single-chip microcomputer MCU1.

[0079] In some embodiments, Figure 2 As shown, the microwave oven magnetron driving circuit also includes a power feedback unit 5. The power feedback unit 5 is connected to the second rectifier unit 11 and the main control unit 4. The power feedback unit 5 measures the working voltage and charging current of the primary winding of the transformer T1, so as to input the voltage feedback signal VFB that can characterize the working voltage of the primary winding and the current feedback signal CS that can characterize the charging current of the primary winding to the main control unit 4. The main control unit 4 can generate a driving signal based on the current feedback signal CS and the voltage feedback signal VFB through an existing algorithm, so as to control the power of the magnetron to be basically close to the set power, and then combine the current sampling signal to control the voltage of the adjustment signal, fine-tune the power of the magnetron, and thus accurately control the power of the magnetron.

[0080] The utility model also provides a microwave oven, comprising the microwave oven magnetron driving circuit in the embodiment of the utility model.

[0081] It can be understood that the above embodiments only express the preferred implementation methods of the utility model, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the utility model. It should be pointed out that, for ordinary technicians in this field, without departing from the concept of the utility model, the above-mentioned technical features can be freely combined, and several deformations and improvements can be made, which all belong to the protection scope of the utility model. Therefore, all equivalent changes and modifications made to the scope of the claims of the utility model should belong to the scope covered by the claims of the utility model.

Claims

1. A microwave oven magnetron drive circuit, characterized in that: include: A driving unit (1) for receiving a driving signal to drive the magnetron to work; A current detection unit (2) connected to the driving unit (1) and used to measure the anode current of the magnetron and output a current sampling signal; An adjustment unit (3) connected to the driving unit (1) and used for receiving an adjustment signal and adjusting the operating current of the magnetron filament; as well as A main control unit (4) connected to the driving unit (1), the current detection unit (2) and the regulating unit (3), and used for receiving the current sampling signal and outputting the regulating signal and the driving signal.

2. The microwave oven magnetron driving circuit according to claim 1, characterized in that: The regulating unit (3) comprises: A shunt unit (31) connected to the filament driving winding of the driving unit (1), used for receiving a first shunt control signal and a second shunt control signal and shunt current input to the filament; a first shunt control unit (32) connected to the shunt unit (31) and configured to receive the adjustment signal and output the first shunt control signal; and A second shunt control unit (33) connected to the shunt unit (31) and configured to receive the adjustment signal and output the second shunt control signal.

3. The microwave oven magnetron driving circuit according to claim 2, characterized in that: The shunting unit (31) comprises a second NPN transistor Q2, a third NPN transistor Q3, a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4; The collector of the second NPN transistor Q2 and the emitter of the third NPN transistor Q3 are simultaneously connected to the first end of the filament drive winding of the drive unit (1); after the emitter of the second NPN transistor Q2 and the collector of the third NPN transistor Q3 are connected, one path is connected to the second end of the filament drive winding of the drive unit (1) via the first resistor R1 and the third resistor R3, and the other path is connected to the second end of the filament drive winding of the drive unit (1) via the second resistor R2 and the fourth resistor R4; the base of the second NPN transistor Q2 is connected to the first shunt control unit (32) to receive the first shunt control signal, and the base of the third NPN transistor Q3 is connected to the second shunt control unit (33) to receive the second shunt control signal.

4. The microwave oven magnetron driving circuit according to claim 2, characterized in that: The first current shunting control unit (32) comprises a first optical coupler U1, a fifteenth resistor R15, a fifth resistor R5, a second diode D2, a seventh resistor R7 and a third capacitor C3; The anode of the first optical coupler U1 is connected to the main control unit (4) to receive the adjustment signal, the cathode of the first optical coupler U1 is connected to the ground via the fifteenth resistor R15, the collector of the first optical coupler U1 is connected to the second end of the fifth resistor R5, the first end of the fifth resistor R5 is simultaneously connected to the cathode of the second diode D2, the second end of the seventh resistor R7 and the second end of the third capacitor C3, the anode of the second diode D2 is connected to the first end of the filament driving winding of the driving unit (1), the first end of the seventh resistor R7 and the first end of the third capacitor C3 are simultaneously connected to the second end of the filament driving winding of the driving unit (1), and the emitter of the first optical coupler U1 outputs the first shunt control signal; The second current shunting control unit (33) comprises a second optical coupler U3, a sixteenth resistor R16, a sixth resistor R6, a third diode D3, an eighth resistor R8 and a fourth capacitor C4; The anode of the second optical coupler U3 is connected to the main control unit (4) to receive the adjustment signal, the cathode of the second optical coupler U3 is connected to the ground via the sixteenth resistor R16, the collector of the second optical coupler U3 is connected to the second end of the sixth resistor R6, the first end of the sixth resistor R6 is simultaneously connected to the cathode of the third diode D3, the second end of the eighth resistor R8 and the second end of the fourth capacitor C4, the anode of the third diode D3 is connected to the second end of the filament driving winding of the driving unit (1), the first end of the eighth resistor R8 and the first end of the fourth capacitor C4 are simultaneously connected to the first end of the filament driving winding of the driving unit (1), and the emitter of the second optical coupler U3 outputs the second shunt control signal.

5. The microwave oven magnetron driving circuit according to claim 1, characterized in that: The current detection unit (2) comprises: A sampling unit (21) for measuring the anode current of a magnetron and outputting an AC sampling signal; a first rectifying unit (22) connected to the sampling unit (21) and used for rectifying the AC sampling signal; and An amplifying unit (23) connected to the first rectifying unit (22) and used for amplifying the rectified AC sampling signal and outputting the current sampling signal.

6. The microwave oven magnetron driving circuit according to claim 5, characterized in that: The sampling unit (21) comprises a current transformer CT1 and an eleventh resistor R11; the primary side of the current transformer CT1 is coupled to a power supply line of a magnetron anode to collect the magnetron anode current, the secondary side of the current transformer CT1 is connected in parallel to the eleventh resistor R11, and the eleventh resistor R11 is also connected to the first rectifier unit (22) to input the AC sampling signal thereto.

7. The microwave oven magnetron driving circuit according to claim 5, characterized in that: The first rectifying unit (22) comprises a sixth diode D6 and a seventh capacitor C7; the anode of the sixth diode D6 is connected to the first signal output end of the sampling unit (21), the cathode of the sixth diode D6 is connected to the second signal output end of the sampling unit (21) via the seventh capacitor C7, and the seventh capacitor C7 is also connected to the amplifying unit (23) to input the rectified AC sampling signal thereto.

8. The microwave oven magnetron driving circuit according to claim 5, characterized in that: The amplification unit (23) comprises an operational amplifier U2, a thirteenth resistor R13, a twelfth resistor R12 and a fourteenth resistor R14; The positive phase input terminal of the operational amplifier U2 is connected to the positive terminal of the first rectifier unit (22) and is connected to the negative terminal of the first rectifier unit (22) via the twelfth resistor R12; the negative phase input terminal of the operational amplifier U2 is connected to the negative terminal of the first rectifier unit (22) via the thirteenth resistor R13 and is connected to the output terminal of the operational amplifier U2 via the fourteenth resistor R14; the output terminal of the operational amplifier U2 outputs the current sampling signal.

9. The microwave oven magnetron driving circuit according to claim 1, characterized in that: The driving unit (1) comprises: A second rectifying unit (11) for receiving an AC voltage and outputting a first DC voltage; A transformer T1, whose primary winding is connected to the second rectifier unit (11), whose filament drive winding is connected to the regulating unit (3) and can be connected to the magnetron filament; A voltage doubling unit (12) connected to the secondary winding of the transformer T1 and capable of being connected to the anode of the magnetron; A resonant capacitor (13) connected in parallel with the primary winding of the transformer T1 and used to form a resonant circuit with the primary winding of the transformer T1; A power switch tube (14) connected to the primary winding of the transformer T1 and used to control energy storage or energy release of the primary winding of the transformer T1; and A switch control unit (15) connected to the main control unit (4) and the power switch tube (14) and used for receiving the drive signal and controlling the power switch tube (14) to turn on or off.

10. A microwave oven, characterized in that: The invention comprises a microwave oven magnetron driving circuit as claimed in any one of claims 1 to 9.

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