A multi-frequency induction heating power supply and a control method thereof

Abstract

The application discloses a multi-frequency induction heating power supply and a control method thereof. The multi-frequency induction heating power supply comprises an inverter circuit module for outputting a multi-frequency driving voltage, a bidirectional switch module for controlling a heating mode, and a multi-frequency resonance module for multi-frequency induction heating and power decoupling. The control method corresponds to the multi-frequency induction heating power supply. The application outputs a multi-frequency driving voltage through an inverter module, controls a heating mode through a bidirectional switch module, and realizes multi-frequency heating and power decoupling through a multi-frequency resonance module. The overall structure is simple, and the modules have strong collaboration. The application not only provides a hardware basis for multi-frequency heating, but also can adapt to different workpiece requirements, avoid multi-frequency crosstalk, and improve heating reliability and adaptability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of induction heating devices, in particular to a multi-frequency induction heating power supply and a control method thereof. BACKGROUND

[0002] Induction heating has the advantages of clean safety, high efficiency, environmental protection, controllability, etc., and is widely used in industrial, household cookware and medical fields. In industry, it is commonly used for metal melting, brazing, surface hardening and metal material surface quenching. However, with the development, complex irregular workpieces such as gears have higher demands on the power supply. For example, the skin depth of single-frequency induction heating is single, which is difficult to adapt to the size difference of different parts of the workpiece. For example, uneven heating leads to a large difference in mechanical strength between the root and the top of the gear teeth, so dual-frequency or even multi-frequency induction heating power supply needs to be researched.

[0003] Induction heating devices are divided into low frequency, medium frequency, ultrasonic frequency, high frequency and ultrahigh frequency according to frequency. The difference between the two frequencies is often more than ten times. In the structure of the existing dual-frequency device, the dual-converter type is gradually eliminated due to its large size and high cost. Although the single-converter type has a balanced efficiency and cost, the double-channel superposition is easy to have crosstalk, and the carrier modulation method commonly used by it has risks when facing high switching frequency. Moreover, the dual-frequency induction heating converter matching circuit has defects: the structure is simplified, and the crosstalk is difficult to suppress; the crosstalk suppression effect is good, but there are many passive devices and complex parameter design. Although the double-coil structure has flexible magnetic field, it requires a large number of devices.

[0004] The Chinese invention patent with the authorized announcement number CN114867142B discloses a decoupling adjustment method for synchronizing the output power of a dual-frequency induction heating power supply, but the coil of the invention patent is fixed and still cannot respond to the higher demands of irregular workpieces on the power supply.

[0005] In summary, a new multi-frequency induction heating power supply and its control technology are needed to achieve a good balance between cost and complexity. SUMMARY

[0006] The main purpose of the present application is to provide a multi-frequency induction heating power supply and a control method thereof, which aims to solve the technical problems of imbalance between power supply cost and complexity, low magnetic field flexibility and power coupling in the prior art.

[0007] To achieve the above object, the application provides a multi-frequency induction heating power supply, comprising an inverter circuit module for outputting a multi-frequency driving voltage, a bidirectional switch module for controlling a heating mode, and a multi-frequency resonance module for multi-frequency induction heating and power decoupling; wherein a first input end of the inverter circuit module is connected with a positive pole of a preset output power supply, a second input end of the inverter circuit module is connected with a negative pole of the output power supply, a first output end of the inverter circuit module is connected with a first input end of the multi-frequency resonance module, a second output end of the inverter circuit module is connected with a first end of the bidirectional switch module, a second end of the bidirectional switch module is connected with a second input end of the multi-frequency resonance module, and a third output end of the inverter circuit module is connected with a third input end of the multi-frequency resonance module.

[0008] As a preference, the inverter circuit module comprises a series inverter circuit, which comprises two series-connected half-bridge inverters or two series-connected full-bridge inverters; when the series inverter circuit comprises two series-connected half-bridge inverters, it comprises a first input capacitor, a second input capacitor, a first switch tube, a second switch tube, a third switch tube, and a fourth switch tube; wherein a first end of the first input capacitor and a drain of the first switch tube are connected to form the first input end of the inverter circuit module, a source of the first switch tube and a drain of the second switch tube are connected to form the first output end of the inverter circuit module, a second end of the first input capacitor, a source of the second switch tube, a first end of the second input capacitor, and a drain of the third switch tube are connected to form the second output end of the inverter circuit module, a source of the third switch tube and a drain of the fourth switch tube are connected to form the third output end of the inverter circuit module, and a second end of the second input capacitor and a source of the fourth switch tube are connected to form the second input end of the inverter circuit module.

[0009] As a preference, the multi-frequency resonance module comprises a multi-frequency resonance circuit, which comprises a first resonance circuit and a second resonance circuit, the first resonance circuit comprises a first heating coil and a first resonance compensation circuit, and the second resonance circuit comprises a second heating coil and a second resonance compensation circuit; wherein a first end of the first heating coil and a first end of the second heating coil are connected to form the second input end of the multi-frequency resonance module; a second end of the first heating coil is connected with a first end of the first resonance compensation circuit, and a second end of the first resonance compensation circuit is the first input end of the multi-frequency resonance module; a second end of the second heating coil is connected with a first end of the second resonance compensation circuit, and a second end of the second resonance compensation circuit is the third input end of the multi-frequency resonance module.

[0010] As preferred, the first heating coil is equivalent to a first inductor and a first resistor, a first end of the first inductor is a first end of the first heating coil, a second end of the first inductor is connected with a first end of the first resistor, and a second end of the first resistor is a second end of the first heating coil;

[0011] The second heating coil is equivalent to a second inductor and a second resistor, a first end of the second inductor is a first end of the second heating coil, a second end of the second inductor is connected with a first end of the second resistor, and a second end of the second resistor is a second end of the second heating coil.

[0012] As preferred, the first resonant compensation circuit is any one of LCCL parallel-series-series resonant circuit, LCCCL series-parallel-series resonant circuit, LCCL series-parallel-series resonant circuit, LCCL series-series-parallel resonant circuit, LCCCL series-series-series-parallel resonant circuit and LCCL series-series-parallel resonant circuit;

[0013] When the first resonant compensation circuit is LCCL parallel-series-series resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a third inductor and a first end of a first capacitor connected with each other, a second end of the third inductor and a second end of the first capacitor are both connected with a first end of a second capacitor, and a second end of the second capacitor is connected with a second end of the first heating coil;

[0014] When the first resonant compensation circuit is LCCCL series-parallel-series resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fourth inductor and a first end of a fifth capacitor connected with each other, a second end of the fourth inductor is connected with a first end of a fourth capacitor, a second end of the fourth capacitor and a second end of the fifth capacitor are both connected with a first end of a sixth capacitor, and a second end of the sixth capacitor is connected with a second end of the first heating coil;

[0015] When the first resonant compensation circuit is LCCL series-parallel-series resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fifth inductor and a first end of an eighth capacitor connected with each other, a second end of the fifth inductor is connected with a first end of a seventh capacitor, a second end of the seventh capacitor and a second end of the eighth capacitor are both connected with a second end of the first heating coil;

[0016] When the first resonant compensation circuit is LCCL series-series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a sixth inductor, a second end of the sixth inductor is connected with a first end of a ninth capacitor, a second end of the ninth capacitor and a first end of a tenth capacitor are both connected with a second end of the first heating coil, and a second end of the tenth capacitor is connected with a first end of the first heating coil;

[0017] When the first resonant compensation circuit is an LCCCL series-series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a seventh inductor, a second end of the seventh inductor is connected with a first end of an eleventh capacitor, a second end of the eleventh capacitor and a first end of a twelfth capacitor are both connected with a first end of a thirteenth capacitor, a second end of the thirteenth capacitor is connected with a second end of the first heating coil, and a second end of the twelfth capacitor is connected with a first end of the first heating coil.

[0018] When the first resonant compensation circuit is an LCCL series-series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of an eighth inductor, a second end of the eighth inductor and a first end of a fourteenth capacitor are both connected with a first end of a fifteenth capacitor, a second end of the fifteenth capacitor is connected with a second end of the first heating coil, and a second end of the fourteenth capacitor is connected with a first end of the first heating coil.

[0019] Preferably, the second resonant compensation circuit comprises a third capacitor, a first end of the third capacitor is connected with a second end of the second heating coil, and a second end of the third capacitor is a second end of the second resonant compensation circuit.

[0020] To achieve the above-mentioned purposes, the application further provides a control method of a multi-frequency induction heating power supply, which is suitable for the multi-frequency induction heating power supply described above, and the control method comprises the following steps:

[0021] obtaining a heating mode based on a to-be-heated object, wherein the heating mode comprises a synchronous dual-frequency induction heating mode and an asynchronous dual-frequency induction heating mode;

[0022] obtaining a coil structure based on the heating mode, wherein the coil structure comprises a dual-coil structure and a single-coil structure;

[0023] controlling the multi-frequency induction heating power supply based on the coil structure.

[0024] Preferably, when the multi-frequency induction heating power supply is in the dual-coil structure, the multi-frequency induction heating power supply is in the synchronous dual-frequency induction heating mode; wherein the bidirectional switch module is closed, the first inductor works at a medium frequency, the second inductor works at a high frequency, the first inductor corresponds to a medium-frequency resonant circuit, the second inductor corresponds to a high-frequency resonant circuit, and the power ratio corresponding to the medium frequency and the high frequency is controlled based on the driving pulse density ratio corresponding to the medium frequency and the high frequency.

[0025] Preferably, when in the single-coil structure, the multi-frequency induction heating power supply is in the asynchronous dual-frequency induction heating mode; wherein, the bidirectional switch module is turned on, the first inductor and the second inductor form a single coil, the single coil structure operates in time-division multiplexing at ultra-high frequency and ultra-high frequency, the first resonant circuit and the second resonant circuit are connected in series to form a dual-frequency resonant circuit, and the dual-frequency power ratio is controlled based on the dual-frequency heating time ratio.

[0026] Preferably, the angular frequency design of the first resonant circuit and the second resonant circuit includes:

[0027] The first resonant circuit operates at an angular frequency and angular frequency It exhibits low impedance and operates at angular frequency. It exhibits extremely high impedance; the second resonant circuit operates at an angular frequency. It exhibits low impedance when the frequency deviates from the angular frequency. angular frequency and angular frequency It exhibits high impedance; the first resonant circuit and the second resonant circuit are connected in series to form a dual-frequency resonant circuit, which operates at an angular frequency. and angular frequency It exhibits low impedance and operates at angular frequency. It exhibits extremely high impedance; among which, and angular frequency Corresponding to intermediate frequency and angular frequency Corresponding to ultrasonic and angular frequencies Corresponding to high frequency and angular frequency Corresponding to ultra-high frequency; when in the dual-coil structure, the design is based on the angular frequency of the first resonant circuit and the second resonant circuit: Power decoupling is performed; when in the single-coil structure, power decoupling is performed based on the time-division output of dual-frequency power.

[0028] Beneficial effects: The multi-frequency induction heating power supply and the control method thereof adopt coil multiplexing design, form richer magnetic field distribution through switching of double-coil and single-coil structures, the double-coil structure meets the differentiated heating needs of complex structure workpieces, and the single-coil structure can realize higher frequency induction heating; multiple frequency bands of medium frequency, ultrasonic frequency, high frequency and ultrahigh frequency are covered, different induction eddy current skin depths are utilized to adapt to the heating needs of workpieces of different sizes; double-frequency power decoupling is realized, synchronous double-frequency mode effectively suppresses double-frequency power crosstalk through resonance parameter design, asynchronous double-frequency mode avoids crosstalk from the time dimension through time-sharing output; the double-frequency power ratio adjustment is flexible, the synchronous mode adjusts the medium frequency and high frequency power ratio by changing the driving pulse density, the asynchronous mode adjusts the ultrasonic frequency and ultrahigh frequency power ratio by controlling the double-frequency heating time ratio, and the overall adaptability and controllability are strong; thereby, the technical problems of imbalance between power supply cost and complexity, low magnetic field flexibility and power coupling in the prior art are solved. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0030] Figure 1 A structural block diagram of the multi-frequency induction heating power supply provided by the embodiment of the present application is provided.

[0031] Figure 2 A single-path principle diagram of the multi-frequency induction heating power supply when the series type inversion circuit is composed of two series connected half-bridge inverters is provided for the embodiment of the present application.

[0032] Figure 3 A single-path principle diagram of the multi-frequency induction heating power supply when the series type inversion circuit is composed of two series connected full-bridge inverters is provided for the embodiment of the present application.

[0033] Figure 4 A circuit principle diagram when the first resonance compensation circuit is an LCCL series-parallel series resonance circuit is provided for the embodiment of the present application.

[0034] Figure 5 A circuit principle diagram when the first resonance compensation circuit is an LCCCL series-parallel series resonance circuit is provided for the embodiment of the present application.

[0035] Figure 6 A circuit principle diagram when the first resonance compensation circuit is an LCCL series-parallel series resonance circuit is provided for the embodiment of the present application.

[0036] Figure 7The first resonant compensation circuit provided by the embodiment of the present application is a circuit schematic diagram when LCCL series-parallel resonant circuit is used;

[0037] Figure 8 The first resonant compensation circuit provided by the embodiment of the present application is a circuit schematic diagram when LCCL series-parallel resonant circuit is used;

[0038] Figure 9 The first resonant compensation circuit provided by the embodiment of the present application is a circuit schematic diagram when LCCL series-parallel resonant circuit is used;

[0039] Figure 10 The flow chart of the control method of the multi-frequency induction heating power supply provided by the embodiment of the present application is shown in the figure;

[0040] Figure 11 The equivalent circuit of the multi-frequency induction heating power supply provided by the embodiment of the present application in the synchronous double-frequency induction heating mode is shown in the figure;

[0041] Figure 12 The impedance of the multi-frequency induction heating power supply provided by the embodiment of the present application in different heating modes and different frequencies is shown in the figure;

[0042] Figure 13 The equivalent circuit of the multi-frequency induction heating power supply provided by the embodiment of the present application in the asynchronous double-frequency induction heating mode is shown in the figure;

[0043] Figure 14 The control signal diagram of the synchronous double-frequency induction heating mode provided by the embodiment of the present application is shown in the figure;

[0044] Figure 15 The control signal diagram of the asynchronous double-frequency induction heating mode provided by the embodiment of the present application is shown in the figure.

[0045] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0046] It should be understood that the specific embodiments described herein are intended to explain the present application, but not to limit the present application.

[0047] With the development of induction heating, in the industrial field, the objects to be heated include complex irregular heating workpieces, which puts forward higher requirements for the induction heating power supply. For example, gears, due to the single skin depth of single-frequency induction heating, the size difference between the gear root and the gear top is large, which is easy to cause only one place to meet the heating effect standard, resulting in large mechanical strength difference between the gear root and the gear top. Therefore, it is urgent to study double-frequency or even multi-frequency induction heating power supply.

[0048] In response to the above-mentioned needs, for example, Figure 1As shown, the embodiment discloses a multi-frequency induction heating power supply, which comprises an inverter circuit module for outputting a multi-frequency driving voltage, a bidirectional switch module for controlling a heating mode, and a multi-frequency resonance module for multi-frequency induction heating and power decoupling; wherein the first input end of the inverter circuit module is connected with the positive pole of a preset output power supply, the second input end of the inverter circuit module is connected with the negative pole of the output power supply, the first output end of the inverter circuit module is connected with the first input end of the multi-frequency resonance module, the second output end of the inverter circuit module is connected with the first end of the bidirectional switch module, the second end of the bidirectional switch module is connected with the second input end of the multi-frequency resonance module, and the third output end of the inverter circuit module is connected with the third input end of the multi-frequency resonance module.

[0049] It should be noted that the bidirectional switch module in the embodiment can be but is not limited to using a bidirectional switch to realize bidirectional switching.

[0050] Through the above, the embodiment outputs a multi-frequency driving voltage through an inverter module, controls a heating mode through a bidirectional switch module, and realizes multi-frequency heating and power decoupling through a multi-frequency resonance module; the overall structure is simple and the modules have strong synergy, which not only provides a hardware basis for multi-frequency heating but also can adapt to different workpiece requirements while helping to avoid multi-frequency crosstalk and improve heating reliability and adaptability.

[0051] Based on different induction current frequencies, induction heating devices are divided into low frequency, medium frequency 150Hz-10kHz, ultrasonic frequency 10kHz-100kHz, high frequency 100kHz-1MHz, and ultrahigh frequency 1MHz-5MHz. Due to the influence of the skin depth of induced eddy current, the frequencies of dual-frequency current often differ by more than ten times. The current heating methods of dual-frequency induction heating devices are divided into synchronous dual-frequency induction heating and asynchronous dual-frequency induction heating. Synchronous dual-frequency induction heating can continuously heat workpieces with dual frequencies at the same time, and asynchronous dual-frequency induction heating applies two frequencies to workpieces at different times. Current dual-frequency induction heating devices mostly have the following structures: dual-converter-dual-coil, dual-converter-single-coil, single-converter-dual-coil, and single-converter-single-coil. The dual-converter structure has the problems of large size and high cost due to the existence of two power sources, and has been gradually eliminated. The single-converter structure has obvious advantages in efficiency and cost, and the dual-coil structure can achieve more rich magnetic field distribution, which meets the heating needs of workpieces with complex structures, but compared with the single-coil structure, the design is more complex and the cost is higher. Therefore, we find that the current dual-frequency current generation approaches have various deficiencies, which are as follows:

[0052] The dual-converter structure realizes dual-frequency current output through the superposition principle, which has obvious advantages in effect and dual-frequency power coupling degree, but has high cost and redundant structure.

[0053] The single-converter structure outputs double-frequency current through double-channel superposition, and has a good balance in cost and complexity, but often has the problem of crosstalk between double-frequency channels, which affects the independent control of double-frequency power and the sampling of current zero-crossing point when the crosstalk is serious.

[0054] The carrier modulation method of the single-converter can theoretically realize any form of multi-frequency current waveform, but the high switching frequency of the carrier and the hard switching of the switching tube pose challenges to the design of the converter.

[0055] The inductive heating load needs to be impedance matched to achieve rated power output due to its high quality factor, and the matching circuit and load heating effect of the current double-frequency inductive heating converter often have the following shortcomings:

[0056] When the matching circuit structure is simplified, it is difficult to suppress the crosstalk between double-frequency currents, resulting in high double-frequency power coupling;

[0057] To achieve good crosstalk suppression effect, the matching circuit often has the problem of excessive use of passive devices, which makes the resonant parameter design complex and reduces the circuit operation reliability;

[0058] The magnetic field distribution of the double-coil structure is more flexible than that of the single-coil structure, but the number of matching circuit components is larger.

[0059] To solve the above problems, the embodiment further designs a multi-frequency inductive heating power supply as shown in Figure 1 .

[0060] Specifically, the inverter circuit module includes a series inverter circuit, and the series inverter circuit includes two series-connected half-bridge inverters or two series-connected full-bridge inverters; when the series inverter circuit includes two series-connected half-bridge inverters, it includes a first input capacitor, a second input capacitor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; wherein the first end of the first input capacitor and the drain of the first switch tube are connected to form the first input end of the inverter circuit module, the source of the first switch tube and the drain of the second switch tube are connected to form the first output end of the inverter circuit module, the second end of the first input capacitor, the source of the second switch tube, the first end of the second input capacitor and the drain of the third switch tube are connected to form the second output end of the inverter circuit module, the source of the third switch tube and the drain of the fourth switch tube are connected to form the third output end of the inverter circuit module, and the second end of the second input capacitor and the source of the fourth switch tube are connected to form the second input end of the inverter circuit module.

[0061] Specifically, the multi-frequency resonance module comprises a multi-frequency resonance circuit, the multi-frequency resonance circuit comprises a first resonance circuit and a second resonance circuit, the first resonance circuit comprises a first heating coil and a first resonance compensation circuit, and the second resonance circuit comprises a second heating coil and a second resonance compensation circuit; wherein: a first end of the first heating coil and a first end of the second heating coil are connected to form a second input end of the multi-frequency resonance module; a second end of the first heating coil is connected to a first end of the first resonance compensation circuit, and a second end of the first resonance compensation circuit is a first input end of the multi-frequency resonance module; a second end of the second heating coil is connected to a first end of the second resonance compensation circuit, and a second end of the second resonance compensation circuit is a third input end of the multi-frequency resonance module.

[0062] Specifically, the first heating coil is equivalent to a first inductor and a first resistor, a first end of the first inductor is a first end of the first heating coil, a second end of the first inductor is connected to a first end of the first resistor, and a second end of the first resistor is a second end of the first heating coil.

[0063] The second heating coil is equivalent to a second inductor and a second resistor, a first end of the second inductor is a first end of the second heating coil, a second end of the second inductor is connected to a first end of the second resistor, and a second end of the second resistor is a second end of the second heating coil.

[0064] Specifically, the first resonance compensation circuit is any one of an LCCL parallel-serial-series resonance circuit, an LCCCL parallel-serial-serial resonance circuit, an LCCL parallel-serial-series resonance circuit, an LCCL serial-parallel-series resonance circuit, an LCCCL serial-serial-parallel resonance circuit, and an LCCL serial-serial-parallel resonance circuit.

[0065] When the first resonance compensation circuit is the LCCL parallel-serial-series resonance circuit, the first input end of the multi-frequency resonance module comprises a first end of a third inductor and a first end of a first capacitor connected together, a second end of the third inductor and a second end of the first capacitor are both connected to a first end of a second capacitor, and a second end of the second capacitor is connected to a second end of the first heating coil.

[0066] When the first resonance compensation circuit is the LCCCL parallel-serial-serial resonance circuit, the first input end of the multi-frequency resonance module comprises a first end of a fourth inductor and a first end of a fifth capacitor connected together, a second end of the fourth inductor is connected to a first end of a fourth capacitor, a second end of the fourth capacitor and a second end of the fifth capacitor are both connected to a first end of a sixth capacitor, and a second end of the sixth capacitor is connected to a second end of the first heating coil.

[0067] When the first resonant compensation circuit is an LCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fifth inductor and a first end of an eighth capacitor connected in series, a second end of the fifth inductor is connected with a first end of a seventh capacitor, and a second end of the seventh capacitor and a second end of the eighth capacitor are both connected with a second end of the first heating coil;

[0068] When the first resonant compensation circuit is an LCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fifth inductor and a first end of an eighth capacitor connected in series, a second end of the fifth inductor is connected with a first end of a seventh capacitor, and a second end of the seventh capacitor and a second end of the eighth capacitor are both connected with a second end of the first heating coil;

[0069] When the first resonant compensation circuit is an LCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fifth inductor and a first end of an eighth capacitor connected in series, a second end of the fifth inductor is connected with a first end of a seventh capacitor, and a second end of the seventh capacitor and a second end of the eighth capacitor are both connected with a second end of the first heating coil;

[0070] When the first resonant compensation circuit is an LCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fifth inductor and a first end of an eighth capacitor connected in series, a second end of the fifth inductor is connected with a first end of a seventh capacitor, and a second end of the seventh capacitor and a second end of the eighth capacitor are both connected with a second end of the first heating coil.

[0071] Specifically, the second resonant compensation circuit comprises a third capacitor, a first end of the third capacitor is connected with a second end of the second heating coil, and a second end of the third capacitor is a second end of the second resonant compensation circuit.

[0072] In actual application: when a series type inverter circuit is composed of two series connected half-bridge inverters, the circuit principle diagram of the multi-frequency induction heating power supply of the embodiment is as shown in Figure 2 When a series type inverter circuit is composed of two series connected full-bridge inverters, the circuit principle diagram of the multi-frequency induction heating power supply of the embodiment is as shown in Figure 3 .

[0073] The embodiment takes a series type inverter circuit composed of two series connected half-bridge inverters as an example to explain the specific application of the embodiment.

[0074] As Figure 2As shown, the series type inverter circuit of the embodiment comprises a first input capacitor C in1 , a second input capacitor C in2 , a first switch tube S 1, a second switch tube S 2, a third switch tube S 3 and a fourth switch tube S 4; wherein the first end of the first input capacitor C in1 and the drain of the first switch tube S 1 are connected to form a first input end of the inverter circuit module, the source of the first switch tube S 1 and the drain of the second switch tube S 2 are connected to form a first output end of the inverter circuit module, the second end of the first input capacitor C in1 , the source of the second switch tube S 2, the first end of the second input capacitor C in2 and the drain of the third switch tube S 3 are connected to form a second output end of the inverter circuit module, the source of the third switch tube S 3 and the drain of the fourth switch tube S 4 are connected to form a third output end of the inverter circuit module, and the second end of the second input capacitor C in2 and the source of the fourth switch tube S 4 are connected to form a second input end of the inverter circuit module.

[0075] As shown, the first heating coil is equivalent to a first inductor Figure 2 1 and a first resistor L 1, the first end of the first inductor R 1 is the first end of the first heating coil, the second end of the first inductor L 1 is connected to the first end of the first resistor L 1, and the second end of the first resistor R 1 is the second end of the first heating coil. R

[0076] The second heating coil is equivalent to a second inductor L 2 and a second resistor R 2, the first end of the second inductor L 2 is the first end of the second heating coil, the second end of the second inductor L 2 is connected to the first end of the second resistor R 2, and the second end of the second resistor R 2 is the second end of the second heating coil.

[0077] As​Figure 2 As shown, the second resonance compensation circuit includes a third capacitor C 3, a third capacitor C 3 is connected to the second end of the second heating coil, and the third capacitor C 3 is connected to the second end of the second resonance compensation circuit.

[0078] Figure 4 As shown, the first resonance compensation circuit of the embodiment is an LCCL series-parallel series resonance circuit, and the first input end of the multi-frequency resonance module includes a third inductor L 3 is connected to the first end of the first capacitor C 1, and the third inductor L 3 is connected to the second end of the first capacitor C 1, and the second end of the second capacitor C 2 is connected to the first end of the second capacitor C 2 is connected to the second end of the first heating coil.

[0079] Figure 5 As shown, the first resonance compensation circuit of the embodiment is an LCCL series-parallel series resonance circuit, and the first input end of the multi-frequency resonance module includes a third inductor L 4 is connected to the first end of the fifth capacitor C 5, and the fourth inductor L 4 is connected to the second end of the fourth capacitor C 4 is connected to the first end of the fourth capacitor C 4 is connected to the second end of the fifth capacitor C 5, and the second end of the sixth capacitor C 6 is connected to the first end of the sixth capacitor C 6 is connected to the second end of the first heating coil.

[0080] Figure 6 As shown, the first resonance compensation circuit of the embodiment is an LCCL series-parallel series resonance circuit, and the first input end of the multi-frequency resonance module includes a third inductor L 5 is connected to the first end of the eighth capacitor C 8, and the fifth inductor L 5 is connected to the second end of the seventh capacitor C 7 is connected to the first end of the seventh capacitor C 7 is connected to the second end of the eighth capacitor C 8 is connected to the second end of the first heating coil.

[0081] Figure 7 As shown, the first resonance compensation circuit of the embodiment is an LCCL series-parallel series resonance circuit, and the first input end of the multi-frequency resonance module includes a third inductorL 6, a first end of the sixth inductor L 6, a second end of the sixth inductor is connected with the ninth capacitor C 9, a first end of the ninth capacitor is connected with C 9, a second end of the ninth capacitor is connected with the tenth capacitor C 10 10, a first end of the tenth capacitor is connected with the second end of the first heating coil C 10 10, a second end of the tenth capacitor is connected with the first end of the first heating coil.

[0082] Figure 8 The first resonant compensation circuit of the embodiment is shown in the circuit principle diagram of the LCCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module includes the seventh inductor L 7, a first end of the seventh inductor L 7, a second end of the seventh inductor is connected with the eleventh capacitor C 11 11, a first end of the eleventh capacitor is connected with C 11 11, a second end of the eleventh capacitor is connected with the twelfth capacitor C 12 12, a first end of the twelfth capacitor is connected with the thirteenth capacitor C 13 12, a first end of the thirteenth capacitor is connected with C 13 12, a second end of the thirteenth capacitor is connected with the second end of the first heating coil, the twelfth capacitor C 12 12, a second end of the twelfth capacitor is connected with the first end of the first heating coil.

[0083] Figure 9 The first resonant compensation circuit of the embodiment is shown in the circuit principle diagram of the LCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module includes the eighth inductor L 8, a first end of the eighth inductor L 8, a second end of the eighth inductor is connected with the fourteenth capacitor C 14 14, a first end of the fourteenth capacitor is connected with the fifteenth capacitor C 15 14, a first end of the fifteenth capacitor is connected with C 15 14, a second end of the fifteenth capacitor is connected with the second end of the first heating coil, the fourteenth capacitor C 14 14, a second end of the fourteenth capacitor is connected with the first end of the first heating coil.

[0084] Based on the above circuit design, the embodiment provides a hardware basis for the decoupled multi-frequency induction heating power supply based on coil multiplexing, and the six circuits selected for the first resonant circuit in the embodiment each have two resonant frequency points, one high-frequency high-impedance frequency point, and the same characteristics after being combined with the second resonant circuit, thereby transmitting energy of different frequencies. The multi-frequency induction heating power supply in the embodiment works in a synchronous dual-frequency induction heating mode and an asynchronous dual-frequency induction heating mode, different coil working modes achieve flexible dual-frequency induction heating, the synchronous dual-frequency induction heating mode can meet the heating needs of workpieces of different shapes, the asynchronous dual-frequency induction heating mode can achieve dual-frequency heating of a higher frequency, and the control method of the embodiment can flexibly adjust the dual-frequency power ratio of the two modes.

[0085] To solve the above technical problems, as shown in Figure 10 The embodiment also discloses a control method of a multi-frequency induction heating power supply.

[0086] S1: obtaining a heating mode based on a to-be-heated object, the heating mode including a synchronous dual-frequency induction heating mode and an asynchronous dual-frequency induction heating mode;

[0087] S2: obtaining a coil structure based on the heating mode, the coil structure including a dual-coil structure and a single-coil structure;

[0088] S3: controlling the multi-frequency induction heating power supply based on the coil structure.

[0089] Specifically, when the dual-coil structure is adopted, the multi-frequency induction heating power supply is in the synchronous dual-frequency induction heating mode; wherein the bidirectional switch module is closed, the first inductor works at a medium frequency, the second inductor works at a high frequency, the first inductor corresponds to a medium-frequency resonant circuit, the second inductor corresponds to a high-frequency resonant circuit, and the power ratio corresponding to the medium frequency and the high frequency is controlled based on the driving pulse density ratio corresponding to the medium frequency and the high frequency.

[0090] Specifically, when the single-coil structure is adopted, the multi-frequency induction heating power supply is in the asynchronous dual-frequency induction heating mode; wherein the bidirectional switch module is opened, the first inductor and the second inductor form a single coil, the single coil structure works at an ultrasonic frequency and an ultrahigh frequency in time sharing mode, the first resonant circuit and the second resonant circuit are connected in series to form a dual-frequency resonant circuit, and the dual-frequency power ratio is controlled based on the dual-frequency heating time ratio.

[0091] Specifically, the angular frequency design of the first resonant circuit and the second resonant circuit includes:

[0092] The first resonant circuit works at an angular frequency and an angular frequency , and presents low impedance at an angular frequency presents very high impedance; the second resonant circuit presents low impedance at angular frequency presents low impedance at angular frequency presents high impedance at angular frequency presents high impedance at angular frequency presents low impedance at angular frequency presents low impedance at angular frequency presents very high impedance at angular frequency , and angular frequency corresponds to intermediate frequency, angular frequency corresponds to ultrasonic frequency, angular frequency corresponds to high frequency, angular frequency corresponds to ultrahigh frequency; when in the double-coil structure, angular frequencies of the first resonant circuit and the second resonant circuit are designed based on: power decoupling; when in the single-coil structure, power decoupling is performed based on time-sharing output of double-frequency power.

[0093] Figure 11 The equivalent circuit of the multi-frequency induction heating power supply in the synchronous double-frequency induction heating mode is shown, at this time, the bidirectional switch S is closed, realizing synchronous heating of intermediate frequency and high frequency, V o1 is the inverse output voltage corresponding to the intermediate frequency resonant circuit, V o2 is the inverse output voltage corresponding to the high frequency resonant circuit, I 1 is the current of the intermediate frequency resonant circuit, I 2 is the current of the high frequency resonant circuit. Since there is mutual inductance between the two coils when heating the same object at the same time, M is the mutual inductance between the two coils, j ωΜΙ 1 is the first inductor L 1 controlled voltage source acting on the second inductor L 2, j ωΜΙ 2 is the second inductor L 2 controlled voltage source acting on the first inductor L 1. At this time, the third inductor L 3, the first capacitor C 1, the second capacitor C 2, the first inductor L 1 and the first resistor R 1 form an intermediate frequency resonant circuit, the third capacitor C 3, the second inductor L 2 and the second resistor R 2 form a high frequency resonant circuit. The impedance expression of the intermediate frequency resonant circuit is:​

[0094]

[0095] When the intermediate frequency resonance circuit resonates, the circuit impedance is minimum, and the resonance angular frequency is:

[0096]

[0097]

[0098] Figure 12 The impedance of the multi-frequency induction heating power supply in different heating modes and at different frequencies is shown.

[0099] As shown in Figure 12 (a), the abscissa is the angular frequency , and the ordinate is the impedance of the first resonance circuit, which presents low impedance at the intermediate frequency angular frequency In this embodiment, since the first resonance circuit works as an intermediate frequency resonance circuit when the double-coil structure is used, the is not used. As shown in Figure 12 (b), the abscissa is the angular frequency , and the ordinate is the impedance of the second resonance circuit, which presents low impedance at the high frequency angular frequency , and in combination with Figure 12 (a), , thus realizing decoupling. As shown in Figure 12 (c), the abscissa is the angular frequency , and the ordinate is the impedance of the series connection of the first resonance circuit and the second resonance circuit, which presents low impedance at the ultrasonic frequency angular frequency and the ultrahigh frequency angular frequency .

[0100] When the impedance of the intermediate frequency resonance circuit is maximum, the resonance angular frequency is , and the impedance expression of the high frequency resonance circuit is:

[0101]

[0102] When the high frequency resonance circuit resonates, the resonance angular frequency is , and the current of the intermediate frequency resonance circuit is:

[0103]

[0104] The current of the high frequency resonance circuit is:

[0105]

[0106] The working angular frequency of the intermediate frequency resonance circuit is , and the working angular frequency of the high frequency resonance circuit is , the parameters of the resonance element are designed so that , the intermediate frequency resonance circuit presents a very high impedance to the crosstalk exerted by the high frequency resonance circuit, the current exerted by the high frequency crosstalk in the intermediate frequency resonance circuit is very small, i.e. , and the impedance expression of the high frequency resonance circuit is characterized in that it presents a very high impedance for angular frequencies far from its resonance angular frequency, the current exerted by the intermediate frequency crosstalk in the high frequency resonance circuit is very low, i.e. .

[0107] Thus, the current of the intermediate frequency resonance circuit is:

[0108]

[0109] The current of the high frequency resonance circuit is:

[0110]

[0111] Based on this, the embodiment realizes the mutual decoupling of the intermediate frequency and high frequency powers in the synchronous dual-frequency induction heating mode, and avoids the crosstalk between the intermediate frequency and high frequency currents.

[0112] Figure 13 The equivalent circuit of the multi-frequency induction heating power supply of the embodiment in the asynchronous dual-frequency induction heating mode is shown, at this time the bidirectional switch S is turned on, the first inductor L 1 and the second inductor L 2 are connected in series to work as a coil, realizing asynchronous heating of the ultrasonic frequency and the ultrahigh frequency, V in is the equivalent input voltage of the dual-frequency resonance circuit, I is the output current. The third inductor L 3, the first capacitor C 1, the second capacitor C 2, the first inductor L 1, the first resistor R 1, the third capacitor C 3, the second inductor L 2 and the second resistor R 2 constitute a dual-frequency resonance circuit, and the impedance expression thereof is:

[0113]

[0114] When the dual-frequency resonance circuit resonates, the resonance angular frequency is:

[0115]

[0116]

[0117] The angular frequencies of the equivalent input voltage are and When the inductive heating works at the ultrasonic frequency and the ultrahigh frequency respectively, since the asynchronous dual-frequency inductive heating mode is adopted, the heating at the two frequencies is performed in time division, and there is no coupling between the dual-frequency powers.

[0118] Based on the above design, the angular frequency relationship of the embodiment is , and the angular frequency corresponds to the medium frequency, the angular frequency corresponds to the ultrasonic frequency, the angular frequency corresponds to the high frequency, and the angular frequency corresponds to the ultrahigh frequency.

[0119] In a specific application, Figure 14 The control signal diagram of the synchronous dual-frequency inductive heating mode of the embodiment is shown, the bidirectional switch S is always closed when the driving signal is high, the first switch tube S 1 and the second switch tube S 2 are driven by medium frequency square waves with a duty cycle of 50% and complementarity, the third switch tube S 3 and the fourth switch tube S 4 are driven by high frequency square waves with a duty cycle of 50% and complementarity, V o1 is the inverter output corresponding to the medium frequency resonant circuit, V o2 is the inverter output corresponding to the high frequency resonant circuit, the pulse densities of the medium frequency and high frequency driving are and respectively. By sampling the corresponding voltage values C in1 and C in2 of the first input capacitor and the second input capacitor , the total input current , the current I 1 of the medium frequency channel, we get the total dual-frequency power , so that the power ratio of the medium frequency and the high frequency is:

[0120]

[0121] and the total dual-frequency power is the sum of the medium frequency power and the high frequency power. By adjusting the pulse densities and of the respective driving of the dual frequencies, the input bus voltage values corresponding to the dual frequencies are adjusted, and then the dual-frequency output power ratio is adjusted. It should be noted that the synchronous dual-frequency inductive heating mode of the embodiment does not limit the working time of each coil, which can be on the same time axis or not, Figure 14 an example of being on the same time axis is shown.

[0122] In a specific application, Figure 15 The control signal diagram of the asynchronous dual-frequency induction heating mode of the embodiment is shown, the bidirectional switch S driving signal is low, and the induction heating works in ultrasonic frequency and ultrahigh frequency in time. The driving signals of the first switch tube S1 and the second switch tube S2 are complementary, and the driving signals of the third switch tube S3 and the fourth switch tube S4 are complementary. When working in ultrasonic frequency, the driving signals of the first switch tube S1 and the fourth switch tube S4 are consistent, the driving signals of the second switch tube S2 and the third switch tube S3 are consistent, the driving signals of the two groups of switch tubes are complementary, the duty cycles are both 50%, the frequencies are both ultrasonic frequency, and the high level of the inverter output voltage is Vin and the low level is 0. When working in ultrahigh frequency, the switching frequencies of the four switch tubes are all half of the ultrahigh frequency. Taking the first switch tube S1 as a reference, the first switch tube S1 is driven as a square wave with a duty cycle of 25%, the second switch tube S2 is driven as a square wave with a duty cycle of 75%, the phase lags behind the switching period of the first switch tube S1 by 25%, the third switch tube S3 is driven as a square wave with a duty cycle of 75%, the phase lags behind the switching period of the first switch tube S1 by 75%, the fourth switch tube S4 is driven as a square wave with a duty cycle of 25%, the phase lags behind the switching period of the first switch tube S1 by 50%, and the high level of the inverter output voltage is Vin / 2 and the low level is 0. The ultrasonic frequency mode and the ultrahigh frequency mode work in time, the working time ratio of the ultrasonic frequency is , and are the equivalent resistances of the coils in series under ultrasonic frequency and ultrahigh frequency respectively, and the power ratio of the ultrasonic frequency and the ultrahigh frequency is:

[0123]

[0124] The total power of the dual frequency is the sum of the ultrasonic frequency power and the ultrahigh frequency power, and the dual frequency output power ratio can be adjusted by adjusting the time ratio of the dual frequency heating.

[0125] Based on the above design, the multi-frequency induction heating power supply and the control method thereof of the embodiment at least achieve the following technical effects:

[0126] 1. The heating mode of coil reuse is adopted, the dual-coil structure and the single-coil structure are controlled to realize more abundant magnetic field distribution, the dual-coil structure meets the heating demand of complex structure workpieces, and the single-coil mode realizes higher frequency induction heating;

[0127] 2. The induction heating frequency is rich, covering the induction heating of medium frequency, ultrasonic frequency, high frequency and ultrahigh frequency, and different sizes of workpieces can be heated by using different frequency bands to obtain different skin depths;

[0128] 3. The power decoupling of dual-frequency induction heating is realized, the synchronous dual-frequency induction heating mode is designed through a resonant cavity, the crosstalk of dual-frequency power is well inhibited, and the asynchronous dual-frequency induction heating mode avoids the crosstalk of dual-frequency power in time.

[0129] 4. The flexible adjustment of the dual-frequency power ratio is realized in the control method, the power ratio of the intermediate frequency and the high frequency is adjusted by controlling the driving pulse density in the synchronous dual-frequency induction heating mode, and the power ratio of the ultrasonic frequency and the ultrahigh frequency is adjusted by controlling the dual-frequency heating time ratio in the asynchronous dual-frequency induction heating mode.

[0130] In summary, the multi-frequency induction heating power supply and the control method thereof solve the technical problems of the imbalance between the power supply cost and complexity, low magnetic field flexibility, and power coupling in the prior art.

[0131] It should be understood that the above is only illustrative, and does not constitute any limitation on the technical solutions of the present application. In specific applications, those skilled in the art can set it up according to the needs, and the present application does not limit this.

[0132] It should be noted that the above-described workflow is only illustrative and does not limit the scope of protection of the present application. In actual application, those skilled in the art can select part or all of them to achieve the purpose of the embodiment scheme according to actual needs, which is not limited here.

[0133] It should be noted that in this document, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or system including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or system. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or system including the element.

[0134] From the above description of the embodiments, those skilled in the art can clearly understand that the above embodiment method can be realized by means of software and a general hardware platform as required, and of course it can also be realized by hardware, but in many cases the former is a better embodiment. Based on such understanding, the technical solutions of the present application can be embodied in the form of a software product, which is stored in a storage medium (such as a read-only memory / random access memory, a magnetic disk, an optical disk), and includes a plurality of instructions for making a terminal device (which can be a mobile phone, a computer, a server, an air conditioner, or a network device, etc.) execute the method described in each embodiment of the present application.

[0135] The above merely describes the preferred embodiments of the present application, and is not intended to limit the patent scope of the present application, and any equivalent structure or equivalent process conversion, or direct or indirect application in other related technical fields, which are made by using the content of the present application specification and drawings, are also included in the patent protection scope of the present application.

Claims

1. A multi-frequency induction heating power supply, characterized by, The application relates to a multi-frequency induction heating device, which comprises an inverter circuit module for outputting a multi-frequency driving voltage, a bidirectional switch module for controlling a heating mode and a multi-frequency resonance module for decoupling multi-frequency induction heating and power; wherein a first input end of the inverter circuit module is connected with a positive electrode of a preset output power supply, a second input end of the inverter circuit module is connected with a negative electrode of the output power supply, a first output end of the inverter circuit module is connected with a first input end of the multi-frequency resonance module, a second output end of the inverter circuit module is connected with a first end of the bidirectional switch module, a second end of the bidirectional switch module is connected with a second input end of the multi-frequency resonance module, and a third output end of the inverter circuit module is connected with a third input end of the multi-frequency resonance module. The inverter circuit module comprises a series inverter circuit, and the series inverter circuit comprises two series-connected half-bridge inverters or two series-connected full-bridge inverters; when the series inverter circuit comprises two series-connected half-bridge inverters, the series inverter circuit comprises a first input capacitor, a second input capacitor, a first switch tube, a second switch tube, a third switch tube and a fourth switch tube; wherein a first end of the first input capacitor and a drain of the first switch tube are connected to form the first input end of the inverter circuit module, a source of the first switch tube and a drain of the second switch tube are connected to form the first output end of the inverter circuit module, a second end of the first input capacitor, a source of the second switch tube, a first end of the second input capacitor and a drain of the third switch tube are connected to form the second output end of the inverter circuit module, a source of the third switch tube and a drain of the fourth switch tube are connected to form the third output end of the inverter circuit module, and a second end of the second input capacitor and a source of the fourth switch tube are connected to form the second input end of the inverter circuit module.

2. The multi-frequency induction heating power supply of claim 1, wherein, The multi-frequency resonance module comprises a multi-frequency resonance circuit, and the multi-frequency resonance circuit comprises a first resonance circuit and a second resonance circuit; the first resonance circuit comprises a first heating coil and a first resonance compensation circuit, and the second resonance circuit comprises a second heating coil and a second resonance compensation circuit; wherein a first end of the first heating coil and a first end of the second heating coil are connected to form the second input end of the multi-frequency resonance module; a second end of the first heating coil is connected with a first end of the first resonance compensation circuit, and a second end of the first resonance compensation circuit is the first input end of the multi-frequency resonance module; a second end of the second heating coil is connected with a first end of the second resonance compensation circuit, and a second end of the second resonance compensation circuit is the third input end of the multi-frequency resonance module.

3. The multi-frequency induction heating power supply of claim 2, wherein, The first heating coil is equivalent to a first inductor and a first resistor; a first end of the first inductor is the first end of the first heating coil, a second end of the first inductor is connected with a first end of the first resistor, and a second end of the first resistor is the second end of the first heating coil. The second heating coil is equivalent to a second inductance and a second resistance, a first end of the second inductance is a first end of the second heating coil, a second end of the second inductance is connected with a first end of the second resistance, and a second end of the second resistance is a second end of the second heating coil.

4. The multi-frequency induction heating power supply of claim 3, wherein, The first resonance compensation circuit is any one of an LCCL parallel-series resonant circuit, an LCCCL series-parallel-series resonant circuit, an LCCL series-parallel resonant circuit, an LCCL series-series parallel resonant circuit, an LCCCL series-series-series parallel resonant circuit and an LCCL series-series parallel resonant circuit; When the first resonance compensation circuit is the LCCL parallel-series resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a third inductance and a first end of a first capacitor connected with each other, a second end of the third inductance and a second end of the first capacitor are both connected with a first end of a second capacitor, and a second end of the second capacitor is connected with a second end of the first heating coil; When the first resonance compensation circuit is the LCCCL series-parallel-series resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fourth inductance and a first end of a fifth capacitor connected with each other, a second end of the fourth inductance is connected with a first end of a fourth capacitor, a second end of the fourth capacitor and a second end of the fifth capacitor are both connected with a first end of a sixth capacitor, and a second end of the sixth capacitor is connected with a second end of the first heating coil; When the first resonance compensation circuit is the LCCL series-parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a fifth inductance and a first end of an eighth capacitor connected with each other, a second end of the fifth inductance is connected with a first end of a seventh capacitor, a second end of the seventh capacitor and a second end of the eighth capacitor are both connected with a second end of the first heating coil; When the first resonance compensation circuit is the LCCL series-series parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a sixth inductance, a second end of the sixth inductance is connected with a first end of a ninth capacitor, a second end of the ninth capacitor and a first end of a tenth capacitor are both connected with a second end of the first heating coil, and a second end of the tenth capacitor is connected with a first end of the first heating coil; When the first resonance compensation circuit is the LCCCL series-series-series parallel resonant circuit, the first input end of the multi-frequency resonant module comprises a first end of a seventh inductance, a second end of the seventh inductance is connected with a first end of an eleventh capacitor, a second end of the eleventh capacitor and a first end of a twelfth capacitor are both connected with a first end of a thirteenth capacitor, a second end of the thirteenth capacitor is connected with a second end of the first heating coil, and a second end of the twelfth capacitor is connected with a first end of the first heating coil; When the first resonance compensation circuit is an LCCL series-parallel resonance circuit, the first input end of the multi-frequency resonance module includes a first end of an eighth inductor, a second end of the eighth inductor and a first end of a fourteenth capacitor are connected to a first end of a fifteenth capacitor, a second end of the fifteenth capacitor is connected to a second end of the first heating coil, and a second end of the fourteenth capacitor is connected to a first end of the first heating coil.

5. The multi-frequency induction heating power supply of claim 4, wherein, The second resonance compensation circuit includes a third capacitor, a first end of the third capacitor is connected to a second end of the second heating coil, and a second end of the third capacitor is the second end of the second resonance compensation circuit.

6. A control method of a multi-frequency induction heating power source, the control method being applied to the multi-frequency induction heating power source according to claim 5, characterized by, The control method includes: obtaining a heating mode based on the object to be heated, the heating mode including a synchronous dual-frequency induction heating mode and an asynchronous dual-frequency induction heating mode; obtaining a coil structure based on the heating mode, the coil structure including a double-coil structure and a single-coil structure; controlling the multi-frequency induction heating power supply based on the coil structure.

7. The control method of a multi-frequency induction heating power supply according to claim 6, wherein When in the double-coil structure, the multi-frequency induction heating power supply is in the synchronous dual-frequency induction heating mode; wherein the bidirectional switch module is closed, the first inductor works at a medium frequency, the second inductor works at a high frequency, the first inductor corresponds to the first resonance circuit which is a medium frequency resonance circuit, the second inductor corresponds to the second resonance circuit which is a high frequency resonance circuit, and the power ratio corresponding to the medium frequency and the high frequency is controlled based on the driving pulse density ratio corresponding to the medium frequency and the high frequency.

8. The control method of a multi-frequency induction heating power supply according to claim 6, wherein When in the single-coil structure, the multi-frequency induction heating power supply is in the asynchronous dual-frequency induction heating mode; wherein the bidirectional switch module is opened, the first inductor and the second inductor form a single coil, the single coil structure works at an ultrasonic frequency and an ultrahigh frequency in time sharing mode, the first resonance circuit and the second resonance circuit are connected in series to form a dual-frequency resonance circuit, and the dual-frequency power ratio is controlled based on the dual-frequency heating time ratio.

9. The control method of a multi-frequency induction heating power supply according to any one of claims 7 or 8, characterized by, The angular frequency design of the first resonance circuit and the second resonance circuit includes: The first resonance circuit presents low impedance at angular frequency and presents very high impedance at angular frequency ; the second resonance circuit presents low impedance at angular frequency , presents high impedance at angular frequency deviating from angular frequency , and presents high impedance at angular frequency and angular frequency ; the first resonance circuit and the second resonance circuit are connected in series to form a dual-frequency resonance circuit, which presents low impedance at angular frequency and angular frequency , and presents very high impedance at angular frequency ; wherein, , angular frequency corresponds to medium frequency, angular frequency corresponds to ultrasonic frequency, angular frequency corresponds to high frequency, and angular frequency corresponds to ultrahigh frequency; when in the dual-coil structure, power decoupling is performed based on the angular frequencies of the first resonance circuit and the second resonance circuit; when in the single-coil structure, power decoupling is performed based on the time-sharing output of dual-frequency power.

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