Variable frequency drive circuit of induction cooker

Abstract

The utility model provides a frequency conversion drive circuit of an induction cooker, which comprises a power supply circuit, a power supply rectification circuit, a synchronous circuit, a main control part and a motor, the main control part comprises a single chip microcomputer MCU, and the single chip microcomputer MCU is electrically connected with the power supply circuit, the power supply rectification circuit, the synchronous circuit and the motor. The power rectifying circuit rectifies and filters an alternating current power supply of the power supply circuit and then outputs direct current voltage to the synchronous circuit, and the single-chip microcomputer MCU controls voltage output of the synchronous circuit according to the working gear requirement of the induction cooker so as to achieve speed regulation of a motor. Specifically, the variable frequency drive circuit can adjust the rotating speed of the motor in real time and dynamically adjust the rotating speed according to the actual working state of the induction cooker, so that the induction cooker can keep stable operation under different powers, the risk of temperature rise or equipment damage caused by overhigh power is avoided, and the service life of the induction cooker is prolonged. When the power of the induction cooker is increased or decreased, the speed of the motor can be correspondingly adjusted accordingly.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic cookers, in particular to a variable frequency driving circuit of an electromagnetic cooker. Background Art

[0002] There is a serious homogenization phenomenon in the current induction cooker products on the market. The functions are almost the same, the operation noise is loud, the structure is random, and the customer experience is extremely poor. The four-digit monochrome digital display tube is a must for almost every product. The appearance design is even more similar, the size is square and large, and the usage scenarios are too limited.

[0003] Chinese patent document number CN217057622U disclosed an induction cooker core structure in 2022, specifically disclosing a shell, a heating coil connected to the upper side of the shell, a fan module for generating an airflow moving toward the heating coil is provided on the inner side of the bottom of the shell, a mainboard is provided in the shell corresponding to a position adjacent to the fan module, a first heat dissipation fan is provided above the mainboard, the horizontal height of the first heat dissipation fan is greater than the horizontal height of the fan module, the fan module includes a second heat dissipation fan and a third heat dissipation fan arranged side by side, and a fan pressure plate for fixing the second heat dissipation fan and the third heat dissipation fan is connected to the shell. In the above-mentioned disclosed patent documents, the rotation speeds of the first heat dissipation fan, the second heat dissipation fan and the third heat dissipation fan are all fixed, and the heat dissipation fan cannot change the rotation speed as the power increases, resulting in poor heat dissipation of the body, easy damage to the induction cooker components, and large energy loss.

[0004] Therefore, further improvement is needed. Utility Model Content

[0005] Based on this, the purpose of the utility model is to provide a variable frequency drive circuit for an induction cooker to overcome the shortcomings of the prior art. The variable frequency circuit is used to drive two brushless DC fans, so that the speed of the brushless DC fans changes as the power of the induction cooker increases or decreases, thereby reducing the probability of failure of the induction cooker and improving the reliability of the operation of the induction cooker.

[0006] A variable frequency drive circuit for an induction cooker designed for this purpose comprises a power supply circuit, a power rectification circuit, a synchronization circuit, a main control part and a motor. The main control part comprises a single-chip microcomputer MCU. The single-chip microcomputer MCU is electrically connected to the power supply circuit, the power rectification circuit, the synchronization circuit and the motor. The power rectification circuit rectifies and filters the AC power of the power supply circuit and outputs a DC voltage to the synchronization circuit. The single-chip microcomputer MCU controls the voltage output of the synchronization circuit according to the working gear requirements of the induction cooker to achieve speed regulation of the motor.

[0007] The power supply circuit includes a chip U2, a transformer module T1, a capacitor C13, a capacitor C14, a working voltage EC5, a working voltage EC6, a working voltage EC9, a voltage regulator Z1, a diode D4, a diode D5, a diode D6, a triode D7 and a resistor R17, one end of the capacitor C13 is connected to pins 1 and 2 of the chip U2, and the other end of the capacitor C13 and the voltage regulator Z1 are connected to pin 3 of the chip U2;

[0008] The positive electrode of the working voltage EC6 is connected to the pin 3 of the chip U2, and the negative electrode of the working voltage EC6 is grounded;

[0009] The positive electrode of the triode D7 is connected to the 2nd pin of the transformer module T1 and the 5th, 6th, 7th and 8th pins of the chip U2, and the other end of the voltage regulator Z1 is connected to the diode D6;

[0010] Pin 3 of the transformer module T1 is connected to the diode D5 and the working voltage EC9 and grounded, one end of the resistor R17 is grounded, and the resistor R17 is connected to +18V;

[0011] Pin 4 of the transformer module T1 is connected to the diode D4, the positive electrode of the working voltage EC5 and one end of the capacitor C14 and connected to +9V, and the negative electrode of the working voltage EC5 and the other end of the capacitor C14 are grounded;

[0012] Pin 5 of the transformer module T1 is grounded.

[0013] The power supply circuit also includes a resistor R3, a resistor R16, a resistor R26, a capacitor C7 and a working voltage EC1. Pin 2 of the transformer module T1 is connected to the capacitor C7, the resistor R3, the resistor R26 and one end of the resistor R16 and the positive electrode of the working voltage EC1. The other ends of the capacitor C7, the resistor R3 and the resistor R26 are connected to the negative electrode of the triode D7, and the negative electrode of the working voltage EC1 is grounded.

[0014] The power supply circuit also includes a diode D3, a resistor R8, a resistor R20, a resistor R21, a resistor R24, a resistor R36, a capacitor C3, a capacitor C4, a capacitor C10 and a resistor R23. The other end of the resistor R16 is connected to the cathode of the diode D3, one end of the resistor R36 is connected to the capacitor C3, the resistor R23, the capacitor C10, the resistor R21 and one end of the capacitor C4, the other ends of the capacitor C3, the resistor R23 and the capacitor C10 are grounded, the other end of the resistor R21 is connected to pin 4 of the chip U2, the other end of the capacitor C4 is connected to the resistor R24 ​​and the resistor R8, one end of the resistor R20 is connected to one end of the resistor R8, the other end of the resistor R8 is grounded, and the other end of the resistor R20 is connected to +5V.

[0015] The power rectifier circuit includes a fuse FUSE1, a thermistor RZ1, a resistor R3, a resistor R4, a resistor R13, a non-polar capacitor CX1, a diode D1, a diode D2, a metal film resistor RJ1, a metal film resistor RJ2 and a unidirectional bridge rectifier DB1, wherein one end of the thermistor RZ1, the resistor R3, the resistor R4 and the non-polar capacitor CX1 is connected to the positive electrode of the diode D1 and connected to the neutral line, one end of the fuse FUSE1 is connected to the AC live wire, and the other end of the fuse FUSE1 is connected to the thermistor RZ1, the resistor R3, the resistor R4, the other end of the non-polar capacitor CX1, the DC output of the unidirectional bridge rectifier DB1 and the positive electrode of the diode D2;

[0016] The cathodes of the diodes D1 and D2 are connected to the power supply circuit, one end of the resistor R13, the metal film resistor RJ1 and the metal film resistor RJ2 are connected to the AC input of the unidirectional bridge rectifier DB1, the other end of the resistor R13 is connected to pins 15 and 16 of the single-chip microcomputer MCU, the other ends of the metal film resistors RJ1 and the metal film resistors RJ2 are grounded, and the positive DC of the unidirectional bridge rectifier DB1 is connected to the synchronization circuit.

[0017] The synchronization circuit includes an induction coil L1, a non-polar capacitor CX2, a non-polar capacitor CX3, a non-polar capacitor CX4, a non-polar capacitor CX5, an induction coil L2, a resistor R271, a resistor R272, a resistor R273, a resistor R281, a resistor R282, a resistor R283, a resistor R284, a resistor R285, a resistor R286, a resistor R287, a resistor R1, a resistor R2, a resistor R12, a resistor R11, a resistor R22, a capacitor C2, an IGBT1, an IGBT2 and a regulator ZD1.

[0018] One end of the induction coil L1 is connected to the positive DC of the unidirectional bridge rectifier DB1, and one end of the non-polar capacitor CX2 and the non-polar capacitor CX3 are both grounded;

[0019] The resistor R271, the resistor R272, and the resistor R273 are connected in series, one end of which is connected to one end of the resistor R2, and the other end of which is connected to the collectors of the IGBT1 and the IGBT2;

[0020] The resistors R281, R282, R283, R284, R285, R286 and R287 are connected in series and one end of the resistors R281 is connected to one end of the resistor R11, and the other ends of the resistors R281 and R282 are connected to the collectors of the IGBT1 and the IGBT2.

[0021] The capacitor C2, the capacitor C1 and one end of the resistor R12 are connected to the pin 17 of the single-chip microcomputer MCU;

[0022] The other end of the capacitor C2 and one end of the resistor R11 are connected to pin 19 of the single-chip microcomputer MCU;

[0023] The other end of the resistor R11 is grounded, and the capacitor C1 and the resistor R12 are both grounded;

[0024] The non-polar capacitor CX4, the non-polar capacitor CX5 and the induction coil L2 are connected in parallel and connected to the collector of the IGBT1;

[0025] The emitters of the IGBT1 and the IGBT2 are connected and grounded;

[0026] The gate of the IGBT1 is connected to the resistor R2 and connected to the pin 10 of the single-chip microcomputer MCU through the resistor R2;

[0027] The gate of the IGBT2 is connected to the resistor R1, the voltage regulator ZD1 and the resistor R22 and connected to the pin 10 of the single-chip microcomputer MCU;

[0028] The other ends of the voltage regulator ZD1 and the resistor R22 are grounded.

[0029] The variable frequency drive circuit also includes a heat dissipation circuit, the motor includes a first motor and a second motor, the heat dissipation circuit includes a transistor Q3, a transistor Q4, a diode D8, a diode D9, a resistor R9 and a resistor R10, the collector of the transistor Q4 is connected to the negative electrode of the first motor and the positive electrode of the diode D9, the base of the transistor Q4 is connected to the resistor R10, and the transistor Q4 is connected to the 9th pin of the single-chip microcomputer MCU through the resistor R10;

[0030] The collector of the transistor Q3 is connected to the cathode of the second motor and the anode of the diode D8, the base of the transistor Q3 is connected to the resistor R9, and the transistor Q3 is connected to pins 5 and 9 of the single-chip microcomputer MCU through the resistor R9;

[0031] The cathodes of the diode D8 and the diode D9, and the anodes of the first motor and the second motor are all connected to +18V;

[0032] The emitters of the transistor Q3 and the transistor Q4 are both grounded.

[0033] The heat dissipation circuit further includes a buzzer BUZ and a resistor R6, wherein pin 1 of the buzzer BUZ is connected to the resistor R6, the buzzer BUZ is connected to pin 13 of the single-chip computer MCU via the resistor R6, and pin 2 of the buzzer BUZ is connected to +5V.

[0034] The variable frequency drive circuit also includes a temperature measurement circuit, which includes a thermistor RT1, a thermistor RT2, a resistor R14, a resistor R15, a resistor R17 and a capacitor C11. The thermistor RT1, the thermistor RT2, the resistor R15, the resistor R17 and the capacitor C11 are connected in parallel, one end of the thermistor RT1 and the resistor R17 is connected to +5V, one end of the resistor R15, the thermistor RT2 and the capacitor C11 is grounded, one end of the thermistor RT1 and the resistor R15 is connected to the resistor R14 and to pin 2 of the single-chip microcomputer MCU; one end of the resistor R17, the thermistor RT2 and the capacitor C11 is connected to pin 14 of the single-chip microcomputer MCU, and the other ends of the resistor R15, the thermistor RT2 and the capacitor C11 are grounded.

[0035] The single-chip microcomputer MCU also includes a connector CN4, a resistor R4, a resistor R5, a resistor R18 and a resistor R19, wherein pin 1 of the connector CN4 is connected to the resistor R4 and the resistor R18, pin 1 of the connector CN4 is grounded through the resistor R18, and pin 1 of the connector CN4 is connected to pin 1 of the single-chip microcomputer MCU through the resistor R4;

[0036] Pin 2 of the connector CN4 is connected to the resistor R5, and pin 2 of the connector CN4 is connected to pin 20 of the single-chip microcomputer MCU through the resistor R5;

[0037] The 3rd pin of the connector CN4 is grounded;

[0038] Pin 4 of the connector CN4 and one end of the resistor R19 are connected to +5V, and pin 4 of the connector CN4 is connected to pin 2 of CN4 through the resistor R19;

[0039] The single-chip microcomputer MCU also includes a capacitor C5, a resistor R25, a resistor R7 and a capacitor C6. One end of the capacitor C5 and the resistor R25 are connected to the 16th pin of the single-chip microcomputer MCU, and the capacitor C5, the resistor R25, the resistor R7 and the capacitor C6 are connected to the 15th pin of the single-chip microcomputer MCU.

[0040] The variable frequency drive circuit of the induction cooker in the above-mentioned embodiment includes a power supply circuit, a power rectification circuit, a synchronization circuit, a main control part and a motor. The main control part includes a single-chip microcomputer MCU. The single-chip microcomputer MCU is electrically connected to the power supply circuit, the power rectification circuit, the synchronization circuit and the motor. The power rectification circuit rectifies and filters the AC power of the power supply circuit and outputs a DC voltage to the synchronization circuit. The single-chip microcomputer MCU controls the voltage output of the synchronization circuit according to the working gear requirements of the induction cooker to realize the speed regulation of the motor. Specifically, the variable frequency drive circuit can adjust the speed of the motor in real time and make dynamic adjustments according to the actual working state of the induction cooker, which enables the induction cooker to maintain stable operation under different powers and will not cause the risk of temperature increase or equipment damage due to excessive power; secondly, the motor is provided with at least two, and the output shafts of at least two motors are connected to the brushless DC fan. Through the control of the variable frequency circuit, the two brushless DC fans can be precisely controlled. When the power of the induction cooker increases or decreases, the motor can also be adjusted accordingly. This ensures that the induction cooker can be well cooled at every stage of the working process, thereby extending the service life of the induction cooker. It not only solves some pain points of the induction cooker during use, but also greatly improves the user experience of the induction cooker. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and the description thereof are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 The present invention is a circuit diagram of a power supply circuit, a power rectification circuit and a synchronization circuit in one embodiment of the present invention.

[0044] Figure 2It is a schematic diagram of a power supply circuit, a power rectification circuit, a synchronization circuit, a main control part, a heat dissipation circuit and a temperature measurement circuit in one embodiment of the utility model.

[0045] Figure 3 This is a schematic diagram of the main control circuit in one embodiment of the utility model.

[0046] Figure 4 Schematic diagram of a temperature measurement circuit in one embodiment of the present utility model.

[0047] Figure 5 Schematic diagram of a heat dissipation circuit in one embodiment of the utility model. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0049] like Figure 1 and Figure 2 As shown, a variable frequency drive circuit for an induction cooker is provided, including a power supply circuit 1, a power rectification circuit 2, a synchronization circuit 3, a main control part 4 and a motor 5. The main control part 4 includes a single-chip microcomputer MCU, and the single-chip microcomputer MCU is electrically connected to the power supply circuit 1, the power rectification circuit 2, the synchronization circuit 3 and the motor 5. The power rectification circuit 2 rectifies and filters the AC power of the power supply circuit 1 and outputs a DC voltage to the synchronization circuit 3. The single-chip microcomputer MCU controls the voltage output of the synchronization circuit 3 according to the working gear requirement of the induction cooker to realize the speed regulation of the motor 5.

[0050] Specifically, the frequency conversion drive circuit can adjust the rotation speed of the motor 5 in real time and make dynamic adjustments according to the actual working state of the induction cooker, which enables the induction cooker to maintain stable operation under different powers and will not cause the risk of temperature increase or equipment damage due to excessive power; secondly, the motor 5 is provided with at least two, and the output shafts of at least two motors 5 are connected to the brushless DC fans. Through the control of the frequency conversion circuit, the two brushless DC fans can be precisely controlled. When the power of the induction cooker increases or decreases, the motor 5 can also be adjusted accordingly. This ensures that the induction cooker can be well cooled at every stage of the working process, thereby extending the service life of the induction cooker. It not only solves some pain points of the induction cooker during use, but also greatly improves the user experience of the induction cooker.

[0051] Further, the power supply circuit 1 includes a chip U2, a transformer module T1, a capacitor C13, a capacitor C14, a working voltage EC5, a working voltage EC6, a working voltage EC9, a voltage regulator Z1, a diode D4, a diode D5, a diode D6, a triode D7 and a resistor R17, one end of the capacitor C13 is connected to pins 1 and 2 of the chip U2, and the other end of the capacitor C13 is connected to pin 3 of the chip U2 through the voltage regulator Z1;

[0052] The positive electrode of the working voltage EC6 is connected to the 3rd pin of the chip U2, and the negative electrode of the working voltage EC6 is grounded;

[0053] The positive electrode of the triode D7 is connected to the 2nd pin of the transformer module T1 and the 5th, 6th, 7th and 8th pins of the chip U2, and the other end of the voltage regulator Z1 is connected to the diode D6;

[0054] Pin 3 of transformer module T1 is connected to diode D5, working voltage EC9 and grounded, one end of resistor R17 is grounded, and resistor R17 is connected to +18V;

[0055] Pin 4 of the transformer module T1 is connected to the diode D4, the positive electrode of the working voltage EC5 and one end of the capacitor C14 and connected to +9V, and the negative electrode of the working voltage EC5 and the other end of the capacitor C14 are grounded;

[0056] Pin 5 of transformer module T1 is grounded.

[0057] Further, if Figure 2 As shown, the power supply circuit 1 also includes a resistor R3, a resistor R16, a resistor R26, a capacitor C7 and a working voltage EC1. Pin 2 of the transformer module T1 is connected to one end of the capacitor C7, the resistor R3, the resistor R26 and the resistor R16 and the positive electrode of the working voltage EC1. The other ends of the capacitor C7, the resistor R3 and the resistor R26 are connected to the negative electrode of the triode D7, and the negative electrode of the working voltage EC1 is grounded.

[0058] Further, the power supply circuit 1 also includes a diode D3, a resistor R8, a resistor R20, a resistor R21, a resistor R24, a resistor R36, a capacitor C3, a capacitor C4, a capacitor C10 and a resistor R23. The other end of the resistor R16 is connected to the cathode of the diode D3, one end of the resistor R36 is connected to one end of the capacitor C3, the resistor R23, the capacitor C10, the resistor R21 and the capacitor C4, the other ends of the capacitor C3, the resistor R23 and the capacitor C10 are grounded, the other end of the resistor R21 is connected to pin 4 of the chip U2, the other end of the capacitor C4 is connected to the resistor R24 ​​and the resistor R8, one end of the resistor R20 is connected to one end of the resistor R8, the other end of the resistor R8 is grounded, and the other end of the resistor R20 is connected to +5V.

[0059] Further, the power rectifier circuit 2 includes a fuse FUSE1, a thermistor RZ1, a resistor R3, a resistor R4, a resistor R13, a non-polar capacitor CX1, a diode D1, a diode D2, a metal film resistor RJ1, a metal film resistor RJ2 and a unidirectional bridge rectifier DB1, one end of the thermistor RZ1, the resistor R3, the resistor R4 and the non-polar capacitor CX1 is connected to the positive electrode of the diode D1 and connected to the neutral line, one end of the fuse FUSE1 is connected to the AC live wire, and the other end of the fuse FUSE1 is connected to the thermistor RZ1, the resistor R3, the resistor R4, the other end of the non-polar capacitor CX1, the DC output of the unidirectional bridge rectifier DB1 and the positive electrode of the diode D2;

[0060] The cathode of diode D1 and diode D2 is connected to the power supply circuit, one end of resistor R13, metal film resistor RJ1 and metal film resistor RJ2 is connected to the AC input of unidirectional bridge rectifier DB1, the other end of resistor R13 is connected to pins 15 and 16 of the single-chip microcomputer MCU, the other ends of metal film resistor RJ1 and metal film resistor RJ2 are grounded, and the positive DC of unidirectional bridge rectifier DB1 is connected to synchronization circuit 3.

[0061] Specifically, the synchronization circuit 3 includes an induction coil L1, a non-polar capacitor CX2, a non-polar capacitor CX3, a non-polar capacitor CX4, a non-polar capacitor CX5, an induction coil L2, a resistor R271, a resistor R272, a resistor R273, a resistor R281, a resistor R282, a resistor R283, a resistor R284, a resistor R285, a resistor R286, a resistor R287, a resistor R1, a resistor R2, a resistor R12, a resistor R11, a resistor R22, a capacitor C2, an IGBT1, an IGBT2, and a regulator ZD1.

[0062] One end of the induction coil L1 is connected to the positive DC of the unidirectional bridge rectifier DB1, and one end of the non-polarized capacitor CX2 and the non-polarized capacitor CX3 are both grounded;

[0063] Resistors R271, R272 and R273 are connected in series and one end of the resistor is connected to one end of the resistor R2, and the other end is connected to the collectors of IGBT1 and IGBT2;

[0064] Resistor R281, resistor R282, resistor R283, resistor R284, resistor R285, resistor R286 and resistor R287 are connected in series and one end is connected to one end of resistor R11, and the other end is connected to the collectors of IGBT1 and IGBT2;

[0065] Capacitor C2, capacitor C1 and one end of resistor R12 are connected to pin 17 of the microcontroller MCU;

[0066] The other end of capacitor C2 and one end of resistor R11 are connected to pin 19 of the microcontroller MCU;

[0067] The other end of the resistor R11 is grounded, and the capacitor C1 and the resistor R12 are both grounded;

[0068] The non-polarized capacitor CX4, the non-polarized capacitor CX5 and the induction coil L2 are connected in parallel and connected to the collector of the IGBT1;

[0069] The emitters of IGBT1 and IGBT2 are connected and grounded;

[0070] The gate of IGBT1 is connected to resistor R2 and connected to pin 10 of the microcontroller MCU through resistor R2;

[0071] The gate of IGBT2 is connected to resistor R1, voltage regulator ZD1 and resistor R22 and connected to pin 10 of the microcontroller MCU;

[0072] The other end of the voltage regulator ZD1 and the resistor R22 are grounded.

[0073] Specifically, the non-polarized capacitor CX2, the non-polarized capacitor CX3, the non-polarized capacitor CX4, the non-polarized capacitor CX5 and the induction coil L2 are connected in parallel and connected to the collector of the IGBT1. The main purpose is to eliminate the current mutation caused by the load change, thereby reducing the switching frequency of the inverter and reducing the switching loss.

[0074] The emitters of IGBT1 and IGBT2 are connected and grounded to avoid the influence of back electromotive force and ensure the safe and reliable operation of the device;

[0075] The gate of IGBT1 is connected to resistor R2 and connected to pin 10 of the MCU through resistor R2, in order to stabilize the gate voltage within a suitable range, thereby ensuring the safe and reliable operation of the device;

[0076] The gate of IGBT2 is connected to resistor R1, voltage regulator ZD1 and resistor R22 and connected to pin 10 of the microcontroller MCU in order to stabilize the gate voltage within a suitable range to ensure safe and reliable operation of the device;

[0077] The other end of the voltage regulator ZD1 and the resistor R22 are grounded. This part of the design is mainly to ensure the safety and reliability of the entire system.

[0078] Further, if Figure 2 and Figure 4As shown, the variable frequency drive circuit also includes a heat dissipation circuit 6, the motor 5 includes a first motor 501 and a second motor 502, the heat dissipation circuit includes a transistor Q3, a transistor Q4, a diode D8, a diode D9, a resistor R9 and a resistor R10, the collector of the transistor Q4 is connected to the negative electrode of the first motor 501 and the positive electrode of the diode D9, the base of the transistor Q4 is connected to the resistor R10, and the transistor Q4 is connected to the 9th pin of the single-chip microcomputer MCU through the resistor R10;

[0079] The collector of the transistor Q3 is connected to the cathode of the second motor 502 and the anode of the diode D8, the base of the transistor Q3 is connected to the resistor R9, and the transistor Q3 is connected to the pins 5 and 9 of the single-chip microcomputer MCU through the resistor R9;

[0080] The cathodes of diodes D8 and D9, the anodes of the first motor and the second motor are all connected to +18V;

[0081] The emitters of transistor Q3 and transistor Q4 are both grounded.

[0082] Specifically, diode D8 and diode D9 are mounted on the heat dissipation circuit board, and their cathodes are connected to the +18V power supply to prevent them from being damaged by overheating due to excessive current received.

[0083] Further, if Figure 2 and Figure 4 As shown, the heat dissipation circuit 6 also includes a buzzer BUZ and a resistor R6, pin 1 of the buzzer BUZ is connected to the resistor R6, the buzzer BUZ is connected to pin 13 of the microcontroller MCU through the resistor R6, and pin 2 of the buzzer BUZ is connected to +5V.

[0084] Specifically, in the heat dissipation circuit 6, pin 1 of the buzzer BUZ is connected to the resistor R6, which is to provide a stable voltage for the buzzer; pin 2 of the buzzer BUZ is connected to pin 13 of the microcontroller MCU, which is to sound an alarm when the heating coil fails.

[0085] Further, if Figure 2 and Figure 5As shown, the variable frequency drive circuit also includes a temperature measuring circuit 7, which includes a thermistor RT1, a thermistor RT2, a resistor R14, a resistor R15, a resistor R17 and a capacitor C11. The thermistor RT1, thermistor RT2, the resistor R15, the resistor R17 and the capacitor C11 are connected in parallel, one end of the thermistor RT1 and the resistor R17 is connected to +5V, one end of the resistor R15, thermistor RT2 and the capacitor C11 is grounded, one end of the thermistor RT1 and the resistor R15 is connected to the resistor R14 and to the pin 2 of the single-chip microcomputer MCU; one end of the resistor R17, thermistor RT2 and the capacitor C11 is connected to the pin 14 of the single-chip microcomputer MCU, and the other ends of the resistor R15, thermistor RT2 and the capacitor C11 are grounded.

[0086] Further, if Figure 2 and Figure 3 As shown, the single-chip microcomputer MCU also includes a connector CN4, a resistor R4, a resistor R5, a resistor R18 and a resistor R19, a pin 1 of the connector CN4 is connected to the resistor R4 and the resistor R18, a pin 1 of the connector CN4 is grounded through the resistor R18, and a pin 1 of the connector CN4 is connected to a pin 1 of the single-chip microcomputer MCU through the resistor R4;

[0087] Pin 2 of the connector CN4 is connected to the resistor R5, and pin 2 of the connector CN4 is connected to pin 20 of the microcontroller MCU through the resistor R5;

[0088] Pin 3 of connector CN4 is grounded;

[0089] Pin 4 of connector CN4 and one end of resistor R19 are connected to +5V, and pin 4 of connector CN4 is connected to pin 2 of CN4 through resistor R19;

[0090] The single-chip microcomputer MCU also includes a capacitor C5, a resistor R25, a resistor R7 and a capacitor C6. One end of the capacitor C5 and the resistor R25 is connected to the 16th pin of the single-chip microcomputer MCU, and the capacitor C5, the resistor R25, the resistor R7 and the capacitor C6 are connected to the 15th pin of the single-chip microcomputer MCU.

[0091] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0092] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0093] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0094] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0095] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0096] It should also be understood that when explaining the connection relationship or positional relationship of elements, although not explicitly described, the connection relationship and positional relationship are interpreted as including an error range, which should be within the acceptable deviation range of a specific value determined by those skilled in the art. For example, "approximately", "approximately" or "substantially" may mean within one or more standard deviations, which are not limited here.

[0097] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] The above embodiments only express several implementation methods of the utility model, and the descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A variable frequency drive circuit for an induction cooker, characterized in that: The invention comprises a power supply circuit (1), a power rectification circuit (2), a synchronization circuit (3), a main control part (4) and a motor (5). The main control part (4) comprises a single-chip microcomputer (MCU). The single-chip microcomputer (MCU) is electrically connected to the power supply circuit (1), the power rectification circuit (2), the synchronization circuit (3) and the motor (5). The power rectification circuit (2) rectifies and filters the AC power of the power supply circuit (1) and outputs a DC voltage to the synchronization circuit (3). The single-chip microcomputer (MCU) controls the voltage output of the synchronization circuit (3) according to the working gear requirement of the induction cooker to achieve speed regulation of the motor (5).

2. The variable frequency drive circuit of the induction cooker according to claim 1, characterized in that: The power supply circuit (1) comprises a chip U2, a transformer module T1, a capacitor C13, a capacitor C14, a working voltage EC5, a working voltage EC6, a working voltage EC9, a voltage regulator Z1, a diode D4, a diode D5, a diode D6, a triode D7 and a resistor R17, one end of the capacitor C13 is connected to pins 1 and 2 of the chip U2, and the other end of the capacitor C13 and the voltage regulator Z1 are connected to pin 3 of the chip U2; The positive electrode of the working voltage EC6 is connected to the pin 3 of the chip U2, and the negative electrode of the working voltage EC6 is grounded; The positive electrode of the triode D7 is connected to the 2nd pin of the transformer module T1 and the 5th, 6th, 7th and 8th pins of the chip U2, and the other end of the voltage regulator Z1 is connected to the diode D6; Pin 3 of the transformer module T1 is connected to the diode D5 and the working voltage EC9 and grounded, one end of the resistor R17 is grounded, and the resistor R17 is connected to +18V; Pin 4 of the transformer module T1 is connected to the diode D4, the positive electrode of the working voltage EC5 and one end of the capacitor C14 and connected to +9V, and the negative electrode of the working voltage EC5 and the other end of the capacitor C14 are grounded; Pin 5 of the transformer module T1 is grounded.

3. The variable frequency drive circuit of the induction cooker according to claim 2, characterized in that: The power supply circuit (1) further comprises a resistor R3, a resistor R16, a resistor R26, a capacitor C7 and a working voltage EC1; pin 2 of the transformer module T1 is connected to the capacitor C7, the resistor R3, the resistor R26 and one end of the resistor R16 and the positive electrode of the working voltage EC1; the other ends of the capacitor C7, the resistor R3 and the resistor R26 are connected to the negative electrode of the triode D7; and the negative electrode of the working voltage EC1 is grounded.

4. The variable frequency drive circuit of the induction cooker according to claim 3, characterized in that: The power supply circuit (1) further comprises a diode D3, a resistor R8, a resistor R20, a resistor R21, a resistor R24, a resistor R36, a capacitor C3, a capacitor C4, a capacitor C10 and a resistor R23, the other end of the resistor R16 being connected to the cathode of the diode D3, one end of the resistor R36 being connected to the capacitor C3, the resistor R23, the capacitor C10, the resistor R21 and one end of the capacitor C4, the other ends of the capacitor C3, the resistor R23 and the capacitor C10 being grounded, the other end of the resistor R21 being connected to pin 4 of the chip U2, the other end of the capacitor C4 being connected to the resistor R24 ​​and the resistor R8, one end of the resistor R20 being connected to one end of the resistor R8, the other end of the resistor R8 being grounded, and the other end of the resistor R20 being connected to +5V.

5. The variable frequency drive circuit of the induction cooker according to claim 4, characterized in that: The power rectifier circuit (2) comprises a fuse FUSE1, a thermistor RZ1, a resistor R3, a resistor R4, a resistor R13, a non-polar capacitor CX1, a diode D1, a diode D2, a metal film resistor RJ1, a metal film resistor RJ2 and a unidirectional bridge rectifier DB1, wherein one end of the thermistor RZ1, the resistor R3, the resistor R4 and the non-polar capacitor CX1 is connected to the positive electrode of the diode D1 and connected to the neutral line, one end of the fuse FUSE1 is connected to the AC live wire, and the other end of the fuse FUSE1 is connected to the other end of the thermistor RZ1, the resistor R3, the resistor R4, the non-polar capacitor CX1, the DC output of the unidirectional bridge rectifier DB1 and the positive electrode of the diode D2; The cathodes of the diodes D1 and D2 are connected to the power supply circuit; one end of the resistor R13, the metal film resistor RJ1 and the metal film resistor RJ2 is connected to the AC input of the unidirectional bridge rectifier DB1; the other end of the resistor R13 is connected to pins 15 and 16 of the single-chip microcomputer MCU; the other ends of the metal film resistors RJ1 and RJ2 are grounded; and the positive DC of the unidirectional bridge rectifier DB1 is connected to the synchronization circuit (3).

6. The variable frequency drive circuit of the induction cooker according to claim 5, characterized in that: The synchronization circuit (3) comprises an induction coil L1, a non-polar capacitor CX2, a non-polar capacitor CX3, a non-polar capacitor CX4, a non-polar capacitor CX5, an induction coil L2, a resistor R271, a resistor R272, a resistor R273, a resistor R281, a resistor R282, a resistor R283, a resistor R284, a resistor R285, a resistor R286, a resistor R287, a resistor R1, a resistor R2, a resistor R12, a resistor R11, a resistor R22, a capacitor C2, an IGBT1, an IGBT2 and a voltage regulator ZD1, one end of the induction coil L1 is connected to the positive DC of the unidirectional bridge rectifier DB1, and one end of the non-polar capacitor CX2 and the non-polar capacitor CX3 are both grounded; The resistor R271, the resistor R272, and the resistor R273 are connected in series, one end of which is connected to one end of the resistor R2, and the other end of which is connected to the collectors of the IGBT1 and the IGBT2; The resistors R281, R282, R283, R284, R285, R286 and R287 are connected in series and one end of the resistors R281 is connected to one end of the resistor R11, and the other ends of the resistors R281 and R282 are connected to the collectors of the IGBT1 and the IGBT2. The capacitor C2, the capacitor C1 and one end of the resistor R12 are connected to the pin 17 of the single-chip microcomputer MCU; The other end of the capacitor C2 and one end of the resistor R11 are connected to pin 19 of the single-chip microcomputer MCU; The other end of the resistor R11 is grounded, and the capacitor C1 and the resistor R12 are both grounded; The non-polar capacitor CX4, the non-polar capacitor CX5 and the induction coil L2 are connected in parallel and connected to the collector of the IGBT1; The emitters of the IGBT1 and the IGBT2 are connected and grounded; The gate of the IGBT1 is connected to the resistor R2 and connected to the pin 10 of the single-chip microcomputer MCU through the resistor R2; The gate of the IGBT2 is connected to the resistor R1, the voltage regulator ZD1 and the resistor R22 and connected to the pin 10 of the single-chip microcomputer MCU; The other ends of the voltage regulator ZD1 and the resistor R22 are grounded.

7. The variable frequency drive circuit of the induction cooker according to claim 1, characterized in that: The variable frequency drive circuit further comprises a heat dissipation circuit (6); the motor (5) comprises a first motor (501) and a second motor (502); the heat dissipation circuit comprises a transistor Q3, a transistor Q4, a diode D8, a diode D9, a resistor R9 and a resistor R10; the collector of the transistor Q4 is connected to the negative electrode of the first motor (501) and the positive electrode of the diode D9; the base of the transistor Q4 is connected to the resistor R10; and the transistor Q4 is connected to pin 9 of the single-chip microcomputer MCU via the resistor R10; The collector of the transistor Q3 is connected to the cathode of the second motor (502) and the anode of the diode D8, the base of the transistor Q3 is connected to the resistor R9, and the transistor Q3 is connected to pins 5 and 9 of the single-chip microcomputer MCU via the resistor R9; The cathodes of the diode D8 and the diode D9, and the anodes of the first motor and the second motor are all connected to +18V; The emitters of the transistor Q3 and the transistor Q4 are both grounded.

8. The variable frequency drive circuit of the induction cooker according to claim 7, characterized in that: The heat dissipation circuit (6) further comprises a buzzer BUZ and a resistor R6, wherein pin 1 of the buzzer BUZ is connected to the resistor R6, the buzzer BUZ is connected to pin 13 of the single-chip computer MCU via the resistor R6, and pin 2 of the buzzer BUZ is connected to +5V.

9. The variable frequency drive circuit of the induction cooker according to claim 1, characterized in that: The variable frequency drive circuit also includes a temperature measurement circuit (7), which includes a thermistor RT1, a thermistor RT2, a resistor R14, a resistor R15, a resistor R17 and a capacitor C11. The thermistor RT1, the thermistor RT2, the resistor R15, the resistor R17 and the capacitor C11 are connected in parallel, one end of the thermistor RT1 and the resistor R17 is connected to +5V, one end of the resistor R15, the thermistor RT2 and the capacitor C11 is grounded, one end of the thermistor RT1 and the resistor R15 is connected to the resistor R14 and to pin 2 of the single-chip microcomputer MCU; one end of the resistor R17, the thermistor RT2 and the capacitor C11 is connected to pin 14 of the single-chip microcomputer MCU, and the other ends of the resistor R15, the thermistor RT2 and the capacitor C11 are grounded.

10. The variable frequency drive circuit of the induction cooker according to claim 1, characterized in that: The single-chip microcomputer MCU also includes a connector CN4, a resistor R4, a resistor R5, a resistor R18 and a resistor R19, wherein pin 1 of the connector CN4 is connected to the resistor R4 and the resistor R18, pin 1 of the connector CN4 is grounded through the resistor R18, and pin 1 of the connector CN4 is connected to pin 1 of the single-chip microcomputer MCU through the resistor R4; Pin 2 of the connector CN4 is connected to the resistor R5, and pin 2 of the connector CN4 is connected to pin 20 of the single-chip microcomputer MCU through the resistor R5; The 3rd pin of the connector CN4 is grounded; Pin 4 of the connector CN4 and one end of the resistor R19 are connected to +5V, and pin 4 of the connector CN4 is connected to pin 2 of CN4 through the resistor R19; The single-chip microcomputer MCU also includes a capacitor C5, a resistor R25, a resistor R7 and a capacitor C6. One end of the capacitor C5 and the resistor R25 are connected to the 16th pin of the single-chip microcomputer MCU, and the capacitor C5, the resistor R25, the resistor R7 and the capacitor C6 are connected to the 15th pin of the single-chip microcomputer MCU.

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