A dual-frequency induction heating power supply and control method thereof

Abstract

The present disclosure relates to a dual-frequency induction heating power supply and a control method thereof, comprising: a controller, a zero-crossing detection circuit, a three-phase full-bridge rectifier circuit, a single-phase full-bridge inverter circuit, a resonant capacitor, and a heating coil. The single-phase full-bridge inverter circuit comprises a first thyristor, a second thyristor, a third thyristor, and a fourth thyristor. The first thyristor and the fourth thyristor form a pair of tubes, and the second thyristor and the third thyristor form a pair of tubes. The controller is connected to the control ends of the first thyristor, the second thyristor, the third thyristor, and the fourth thyristor and to the zero-crossing detection circuit. When the controller controls a pair of tubes to be turned on, and after determining that the zero-crossing detection circuit detects that the voltage of the alternating current output by the pair of tubes is turned on for a certain number of times, the controller triggers another pair of tubes to be turned on. In this way, the single-phase full-bridge inverter circuit can output alternating current including super-frequency resonance current and intermediate-frequency resonance current components, thereby realizing dual-frequency induction heating of thyristors to meet the needs of high-power heating application scenarios.

Description

Technical Field

[0001] The present disclosure relates to the technical field of heating power supplies, and in particular, to a dual-frequency induction heating power supply and a control method thereof. Background Art

[0002] In the field of high-power induction heating, thyristor induction heating power supply is the preferred solution for various manufacturers due to its advantages of high single-unit power, strong overload capacity, stable and reliable operation, low cost, etc. With the technological innovation of the steel industry, more and more high-power online heating requires high-power induction heating to achieve, especially in the heating field of thin plates, which requires dual-frequency induction heating of supersonic induction heating and medium-frequency induction heating to meet the requirements of heating efficiency, temperature uniformity, heating speed and other index parameters.

[0003] However, the thyristor induction heating power supply in the prior art has only one frequency output, and when equipped with ordinary fast thyristors, the stable operating frequency of the induction power supply generally does not exceed 2500Hz, and when equipped with high-frequency thyristors, the stable operating frequency of the induction power supply will not exceed 6000Hz, and the power of a single machine is small, and it cannot be used in the field of high-power induction heating, especially in the case of super-audio (about 10kHz) induction heating, the thyristor induction heating power supply in the prior art cannot be used. Summary of the invention

[0004] The purpose of the present disclosure is to provide a dual-frequency induction heating power supply and a control method thereof.

[0005] In order to achieve the above-mentioned purpose, according to the first aspect of the embodiment of the present disclosure, a dual-frequency induction heating power supply is provided, including: a three-phase full-bridge rectifier circuit, a smoothing reactor, a single-phase full-bridge inverter circuit, a resonant capacitor and a heating coil, the single-phase full-bridge inverter circuit includes a first inverter bridge arm and a second inverter bridge arm connected in parallel, the first inverter bridge arm includes a first thyristor located in the upper arm and a second thyristor located in the lower arm, the second inverter bridge arm includes a third thyristor located in the upper arm and a fourth thyristor located in the lower arm, wherein the first thyristor and the fourth thyristor are connected in parallel. The three-phase full-bridge rectifier circuit is a pair of tubes, the second thyristor and the third thyristor are a pair of tubes, the output positive end of the three-phase full-bridge rectifier circuit is connected to the smoothing reactor, the anode of the first thyristor and the anode of the third thyristor, the cathode of the second thyristor and the cathode of the fourth thyristor are connected to the output negative end of the three-phase full-bridge rectifier circuit; the resonant capacitor and the heating coil are connected in parallel to the connection point between the first thyristor and the second thyristor, and the connection point between the third thyristor and the fourth thyristor, and also includes: a controller and a zero-crossing detection circuit,

[0006] The controller is respectively connected to the control ends of the first thyristor, the second thyristor, the third thyristor, the fourth thyristor and the zero-crossing detection circuit, the zero-crossing detection circuit is connected in parallel with the resonant capacitor, and the controller is used to control a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and determine that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit has crossed zero points for a certain number of times, triggering another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and the single-phase full-bridge inverter circuit outputs alternating current including super-frequency resonance current and intermediate frequency resonance current components.

[0007] Optionally, the controller is used to control a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and determine that the zero-crossing detection circuit detects that the alternating current output by the single-phase full-bridge inverter circuit crosses zero points for a certain number of times, and trigger another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, including:

[0008] The controller is used to trigger another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to turn on when it is determined that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit is after the second zero-crossing point and before the third zero-crossing point.

[0009] Optionally, a transformer is also included, wherein one input terminal of the primary of the transformer is connected to the connection point of the first thyristor and the second thyristor, the other input terminal of the primary of the transformer is connected to the connection point of the third thyristor and the fourth thyristor, and the secondary output terminal of the transformer is connected in parallel with the zero-crossing detection circuit, the resonant capacitor and the heating coil.

[0010] Optionally, a first commutation inductor and a second commutation inductor are connected in series between the first thyristor and the second thyristor, a third commutation inductor and a fourth commutation inductor are connected in series between the third thyristor and the fourth thyristor, a connection point between the first commutation inductor and the second commutation inductor is connected to one incoming line terminal of the primary of the transformer, and a connection point between the third commutation inductor and the fourth commutation inductor is connected to another incoming line terminal of the primary of the transformer.

[0011] According to a second aspect of an embodiment of the present disclosure, a control method for a dual-frequency induction heating power supply is provided, which is applied to a dual-frequency induction heating power supply, wherein the induction heating power supply includes a controller, a three-phase full-bridge rectifier circuit, a smoothing reactor, a single-phase full-bridge inverter circuit, a zero-crossing detection circuit, a resonant capacitor, and a heating coil; the single-phase full-bridge inverter circuit includes a first inverter bridge arm and a second inverter bridge arm connected in parallel, the first inverter bridge arm includes a first thyristor located in an upper arm and a second thyristor located in a lower arm, the second inverter bridge arm includes a third thyristor located in an upper arm and a fourth thyristor located in a lower arm, the output positive terminal of the three-phase full-bridge rectifier circuit is connected to the smoothing reactor, the first thyristor located in a lower arm, and the output positive terminal of the three-phase full-bridge rectifier circuit is connected to the first thyristor located in an upper arm and the second thyristor located in a lower arm. The anode of the first thyristor and the anode of the third thyristor are connected, and the cathode of the second thyristor and the cathode of the fourth thyristor are connected to the negative output terminal of the three-phase full-bridge rectifier circuit; wherein the first thyristor and the fourth thyristor are a pair of tubes, and the second thyristor and the third thyristor are a pair of tubes; the resonant capacitor and the heating coil are connected in parallel to the connection point of the first thyristor and the second thyristor, and the connection point of the third thyristor and the fourth thyristor, and the controller is respectively connected to the control end of the first thyristor, the second thyristor, the third thyristor, the fourth thyristor and the zero-crossing detection circuit, and the method comprises:

[0012] Controlling a pair of transistors in the first inverter bridge arm and the second inverter bridge arm to be turned on;

[0013] Determine that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit is after the second zero-crossing point and before the third zero-crossing point, triggering another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and the single-phase full-bridge inverter circuit outputs alternating current including super-frequency resonant current and intermediate frequency resonant current components.

[0014] Through the above technical solution, the dual-frequency induction heating power supply includes a controller, a zero-crossing detection circuit, a three-phase full-bridge rectifier circuit, a smoothing reactor, a single-phase full-bridge inverter circuit, a resonant capacitor, and a heating coil. The single-phase full-bridge inverter circuit includes a first inverter bridge arm and a second inverter bridge arm connected in parallel. The first inverter bridge arm includes a first thyristor on the upper tube and a second thyristor on the lower tube. The second inverter bridge arm includes a third thyristor on the upper tube and a fourth thyristor on the lower tube. The first thyristor and the fourth thyristor are a pair of tubes, the second thyristor and the third thyristor are a pair of tubes, and the controller is connected to the first thyristor, the second thyristor, and the third thyristor. The control ends of the thyristor, the third thyristor and the fourth thyristor are connected to the zero-crossing detection circuit. When the controller controls a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and after determining that the zero-crossing detection circuit detects that the voltage of the alternating current output by the pair of tubes has crossed zero several times, the controller triggers another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on. In this way, the single-phase full-bridge inverter circuit can output alternating current including ultrasonic resonant current and intermediate frequency resonant current components, realize thyristor dual-frequency induction heating, and meet the needs of high-power heating application scenarios.

[0015] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0017] Figure 1 It is a schematic diagram of a thyristor induction heating power supply in the prior art;

[0018] Figure 2 is a schematic diagram of a dual-frequency induction heating power supply according to an exemplary embodiment;

[0019] Figure 3 is a waveform diagram of related parameters of a dual-frequency induction heating power supply according to an exemplary embodiment;

[0020] Figure 4 is a schematic diagram of another dual-frequency induction heating power supply according to an exemplary embodiment. DETAILED DESCRIPTION

[0021] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0022] Before describing the contents of the present disclosure in detail, the application scenarios of the present disclosure are first described.

[0023] The schematic diagram of the thyristor induction heating power supply in the prior art is as follows Figure 1 As shown, it mainly includes a three-phase full-bridge rectifier circuit 1, a smoothing reactor 2, a single-phase full-bridge inverter circuit 3, a resonant capacitor 4 and a heating coil 5. The three-phase full-bridge rectifier circuit 1 includes 6 thyristors KP1 to KP6, and the single-phase full-bridge inverter circuit 3 includes 4 thyristors KK1 to KK4. Figure 1 (a) is a thyristor induction heating power supply composed of a resonant capacitor 4 and a heating coil 5 connected in series, Figure 1 (b) is a thyristor induction heating power supply composed of a resonant capacitor 4 and a heating coil 5 connected in parallel. Figure 1 The thyristor induction heating power supply shown in (a) and (b) has only one heating frequency, and Figure 1 The heating frequency of (a) is slightly lower than the resonant frequency of the heating power supply. If the heating frequency is close to the resonant frequency, the thyristor of the single-phase full-bridge inverter circuit will not be able to turn off and the circuit will be short-circuited. Figure 1 The operating frequency of the thyristor induction heating power supply of (b) is slightly higher than the resonant frequency of the heating power supply. If the heating frequency is close to the resonant frequency, the thyristor of the single-phase full-bridge inverter circuit will not be able to turn off and the circuit will be short-circuited.

[0024] also, Figure 1 The thyristor induction heating power supply shown, when equipped with ordinary fast thyristors, the stable operating frequency of the induction heating power supply generally does not exceed 2500Hz, and when equipped with high-frequency thyristors, the stable operating frequency of the induction heating power supply will not exceed 6000Hz, and the power of a single machine is small, and it cannot be used in the field of high-power induction heating, especially in situations where super-audio frequency (about 10kHz) induction heating is required, the thyristor induction heating power supply in the prior art cannot be used.

[0025] In order to solve the problem in the prior art that the traditional thyristor induction heating power supply can only output one heating frequency and cannot meet the application of high-power dual-frequency induction heating, the present disclosure proposes a dual-frequency induction heating power supply and a control method thereof, wherein the dual-frequency induction heating power supply comprises a controller, a zero-crossing detection circuit, a three-phase full-bridge rectifier circuit, a smoothing reactor, a single-phase full-bridge inverter circuit, a resonant capacitor, and a heating coil, wherein the single-phase full-bridge inverter circuit comprises a first inverter bridge arm and a second inverter bridge arm connected in parallel, wherein the first inverter bridge arm comprises a first thyristor of an upper tube and a second thyristor of a lower tube, and the second inverter bridge arm comprises a third thyristor of an upper tube and a fourth thyristor of a lower tube, wherein the first thyristor and the fourth thyristor are A pair of tubes, the second thyristor and the third thyristor are a pair of tubes, the controller is connected to the control ends of the first thyristor, the second thyristor, the third thyristor and the fourth thyristor and to the zero-crossing detection circuit. When the controller controls a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to turn on, and after determining that the zero-crossing detection circuit detects that the voltage of the alternating current output by the pair of tubes has crossed zero several times, the controller triggers another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to turn on. In this way, the single-phase full-bridge inverter circuit can output alternating current including supersonic frequency resonant current and intermediate frequency resonant current components, realize thyristor dual-frequency induction heating, and meet the needs of high-power heating application scenarios.

[0026] The contents of the present disclosure are described in detail below.

[0027] Figure 2 is a schematic diagram of a dual-frequency induction heating power supply according to an exemplary embodiment, such as Figure 2 As shown, the dual-frequency induction heating power supply includes a three-phase full-bridge rectifier circuit 21, a smoothing reactor 22, a single-phase full-bridge inverter circuit 23, a resonant capacitor 24 and a heating coil 25. The single-phase full-bridge inverter circuit 23 includes a first inverter bridge arm and a second inverter bridge arm connected in parallel. The first inverter bridge arm includes a first thyristor K1 located in the upper arm and a second thyristor K2 located in the lower arm. The second inverter bridge arm includes a third thyristor K3 located in the upper arm and a fourth thyristor K4 located in the lower arm. The three-phase full-bridge rectifier circuit 21 The output positive end is connected to the anode of the smoothing reactor 22, the first thyristor K1 and the third thyristor K3, and the cathode of the second thyristor K2 and the cathode of the fourth thyristor K4 are connected to the output negative end of the three-phase full-bridge rectifier circuit 21; the resonant capacitor 24 and the heating coil 25 are connected in parallel to the connection point of the first thyristor K1 and the second thyristor K2, and the connection point of the third thyristor K3 and the fourth thyristor K4. The dual-frequency induction heating power supply also includes: a controller 26 and a zero-crossing detection circuit 27;

[0028] The controller 26 is respectively connected to the control ends of the first thyristor K1, the second thyristor K2, the third thyristor K3, the fourth thyristor K4 and the zero-crossing detection circuit 27. The zero-crossing detection circuit 27 is connected in parallel with the resonant capacitor 24. The controller 26 is used to control a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and to determine that the zero-crossing detection circuit 27 detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit 23 crosses zero for a certain number of times, and then triggers another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, so that the single-phase full-bridge inverter circuit 23 outputs an alternating current including an ultrasonic resonant current and an intermediate frequency resonant current component.

[0029] The first thyristor K1 and the fourth thyristor K4 form a pair of tubes, and the second thyristor K2 and the third thyristor K3 form a pair of tubes.

[0030] In this embodiment, when the controller controls a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, such as the first thyristor K1 and the fourth thyristor K4, the pair of tubes is turned on, and the output is an alternating current that oscillates around zero through the first thyristor K1 and the fourth thyristor K4, and the alternating current will continue to oscillate and the amplitude will gradually increase. The zero-crossing detection circuit can detect whether the voltage of the alternating current passes through the zero point. Before the voltage of the alternating current passes through the zero point for the first time, the controller does not control the other pair of tubes (the second thyristor K2 and the third thyristor K3) to be turned on, and the alternating current output by the single-phase full-bridge inverter circuit will continue to maintain an oscillating state. After the controller determines that the voltage of the alternating current output by the single-phase full-bridge inverter circuit has passed through the zero point for a certain number of times, another pair of tubes (the second thyristor K2 and the third thyristor K3) is triggered to be turned on.

[0031] After the controller controls the second thyristor K2 and the third thyristor K3 to be turned on, the controller also outputs an alternating current that oscillates around the zero point through the second thyristor K2 and the third thyristor K3, and the alternating current will continue to oscillate and the amplitude will gradually increase. After the controller determines that the zero-crossing detection circuit detects that the voltage of the alternating current output through the second thyristor K2 and the third thyristor K3 has also passed the zero point for the same number of times, it controls the first thyristor K1 and the fourth thyristor K4 to be turned on. In this alternating cycle, the single-phase full-bridge inverter circuit can output an alternating current including super-audio resonance current and intermediate frequency resonance current components. In this way, the alternating current flowing through the heating coil is an alternating current with dual-frequency components of super-audio resonance current and intermediate frequency resonance current, which can realize dual-frequency induction heating of high-power devices.

[0032] like Figure 2 As shown, the three-phase full-bridge rectifier circuit 21 includes 6 thyristors T1~T6. The connection and control method of the 6 thyristors can refer to the existing technology. The input AC power is converted into DC power through the three-phase full-bridge rectifier circuit 21 and output to the single-phase full-bridge inverter circuit 23.

[0033] Optionally, the controller can trigger another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to turn on when it is determined that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit is after the second zero-crossing point and before the third zero-crossing point. Figure 3 : is an output waveform of the relevant parameters of the dual-frequency induction heating power supply shown in an exemplary embodiment. Figure 3 (a) is a waveform diagram of the alternating current output by the dual-frequency induction heating power supply, which contains dual-frequency components of super-frequency resonance current and intermediate-frequency resonance current. It can be seen from the figure that the frequency of the super-frequency resonance current contained in the current waveform is around 10kHz. Figure 3 (b) is the voltage waveform of the dual-frequency alternating current output by the dual-frequency induction heating power supply, which contains the super-frequency resonant current and the intermediate frequency resonant current. Figure 3 (c) is the signal waveform triggered by two pairs of thyristors (the first thyristor and the fourth thyristor, the second thyristor and the third thyristor) in the single-phase full-bridge inverter circuit. Figure 3 (b) and Figure 3 (c) It can be seen that the trigger frequency of the two pairs of tubes is much lower than the resonant frequency of the dual-frequency induction heating power supply, and the resonant frequency of the dual-frequency induction heating power supply is about 2 to 3 times the trigger frequency of the two pairs of tubes. In this way, on the one hand, it is possible to output alternating current containing two frequency components, the supersonic resonant current and the intermediate frequency resonant current, without the need for high-frequency thyristors. On the other hand, it can avoid the problem of short circuit failure caused by the first thyristor and the second thyristor being turned on at the same time, and the third thyristor and the fourth thyristor being turned on at the same time.

[0034] like Figure 4 As shown, the dual-frequency induction heating power supply also includes a transformer 28, one input terminal of the primary of the transformer 28 is connected to the connection point of the first thyristor K1 and the second thyristor K2, the other input terminal of the primary of the transformer 28 is connected to the connection point of the third thyristor K3 and the fourth thyristor K4, and the secondary output terminal of the transformer 28 is connected in parallel with the zero-crossing detection circuit 27, the resonant capacitor 24 and the heating coil 25.

[0035] Among them, the transformer can ensure the electrical isolation between the load side and the single-phase full-bridge inverter circuit side, ensuring the circuit safety of the dual-frequency induction heating power supply.

[0036] Reference Figure 4The first commutation inductor L1 and the second commutation inductor L2 are connected in series between the first thyristor K1 and the second thyristor K2, the third commutation inductor L3 and the fourth commutation inductor L4 are connected in series between the third thyristor K3 and the fourth thyristor K4, the connection point of the first commutation inductor L1 and the second commutation inductor L2 is connected to one incoming line terminal of the primary of the transformer 28, and the connection point of the third commutation inductor L3 and the fourth commutation inductor L4 is connected to the other incoming line terminal of the primary of the transformer 28.

[0037] The first commutation inductor, the second commutation inductor, the third commutation inductor and the fourth commutation inductor can suppress the alternating conduction of the first thyristor and the fourth thyristor in the single-phase full-bridge inverter circuit and the other pair of second thyristors and third thyristors, thereby avoiding a sudden change in the peak value of the AC power output by the dual-frequency induction heating power supply and preventing damage to the first thyristor, the second thyristor, the third thyristor and the fourth thyristor.

[0038] The present disclosure also provides a control method for a dual-frequency induction heating power supply, which is applied to Figures 2 to 4 The dual-frequency induction heating power supply shown in any one of the items, wherein the control method of the dual-frequency induction heating power supply comprises:

[0039] Controlling a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on;

[0040] Determine that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit is after the second zero-crossing point and before the third zero-crossing point, triggering another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and the single-phase full-bridge inverter circuit outputs alternating current including supersonic frequency resonant current and intermediate frequency resonant current components.

[0041] In this embodiment, when a pair of tubes in the first inverter bridge arm and the second inverter bridge arm are controlled to be turned on, such as the first thyristor and the fourth thyristor, the first thyristor and the fourth thyristor are output as an alternating current that oscillates around zero, and the alternating current will continue to oscillate and the amplitude will gradually increase. The zero-crossing detection circuit can detect whether the voltage of the alternating current passes through the zero point. Before the voltage of the alternating current passes through the zero point for the first time, the other pair of tubes (the second thyristor and the third thyristor) is not controlled to be turned on, and the alternating current output by the single-phase full-bridge inverter circuit will continue to maintain an oscillating state. After determining that the voltage of the alternating current output by the single-phase full-bridge inverter circuit has passed through the zero point for a certain number of times, another pair of tubes (the second thyristor and the third thyristor) is triggered to be turned on.

[0042] After the second thyristor and the third thyristor are controlled to be turned on, the second thyristor and the third thyristor also output an alternating current that oscillates above and below the zero point, and the alternating current will continue to oscillate and the amplitude will gradually increase. After determining that the zero-crossing detection circuit detects that the voltage of the alternating current output by the second thyristor and the third thyristor has also passed the zero point for the same number of times, the first thyristor and the fourth thyristor are controlled to be turned on. In such an alternating cycle, the single-phase full-bridge inverter circuit can output an alternating current including supersonic frequency resonance current and intermediate frequency resonance current components. In this way, the alternating current flowing through the heating coil is an alternating current with dual-frequency components of supersonic frequency resonance current and intermediate frequency resonance current, which can realize dual-frequency induction heating of high-power devices.

[0043] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0044] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0045] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A dual-frequency induction heating power supply, comprising: A three-phase full-bridge rectifier circuit, a smoothing reactor, a single-phase full-bridge inverter circuit, a resonant capacitor and a heating coil, wherein the single-phase full-bridge inverter circuit comprises a first inverter bridge arm and a second inverter bridge arm connected in parallel, wherein the first inverter bridge arm comprises a first thyristor located at an upper arm and a second thyristor located at a lower arm, and the second inverter bridge arm comprises a third thyristor located at an upper arm and a fourth thyristor located at a lower arm, wherein the first thyristor and the fourth thyristor are a pair of tubes, and the second thyristor and the third thyristor are a pair of tubes, the output positive end of the three-phase full-bridge rectifier circuit is connected to the smoothing reactor, the anode of the first thyristor and the anode of the third thyristor, and the cathode of the second thyristor and the cathode of the fourth thyristor are connected to the output negative end of the three-phase full-bridge rectifier circuit; the resonant capacitor and the heating coil are connected in parallel to the connection point between the first thyristor and the second thyristor, and the connection point between the third thyristor and the fourth thyristor, and characterized in that it also includes: a controller and a zero-crossing detection circuit, The controller is respectively connected to the control ends of the first thyristor, the second thyristor, the third thyristor, the fourth thyristor and the zero-crossing detection circuit, the zero-crossing detection circuit is connected in parallel with the resonant capacitor, and the controller is used to control a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and determine that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit has crossed zero points for a certain number of times, triggering another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and the single-phase full-bridge inverter circuit outputs alternating current including super-frequency resonance current and intermediate frequency resonance current components.

2. The dual-frequency induction heating power supply according to claim 1, characterized in that: The controller is used to control a pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and determine that the zero-crossing detection circuit detects that the alternating current output by the single-phase full-bridge inverter circuit has crossed zero points for a certain number of times, and trigger another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, including: The controller is used to trigger another pair of tubes in the first inverter bridge arm and the second inverter bridge arm to turn on when it is determined that the zero-crossing detection circuit detects that the voltage of the alternating current output by the single-phase full-bridge inverter circuit is after the second zero-crossing point and before the third zero-crossing point.

3. The dual-frequency induction heating power supply according to claim 2, characterized in that: It also includes a transformer, wherein one input terminal of the primary of the transformer is connected to the connection point of the first thyristor and the second thyristor, the other input terminal of the primary of the transformer is connected to the connection point of the third thyristor and the fourth thyristor, and the secondary output terminal of the transformer is connected in parallel with the zero-crossing detection circuit, the resonant capacitor and the heating coil.

4. The dual-frequency induction heating power supply according to claim 3, characterized in that: A first commutation inductor and a second commutation inductor are connected in series between the first thyristor and the second thyristor, a third commutation inductor and a fourth commutation inductor are connected in series between the third thyristor and the fourth thyristor, a connection point between the first commutation inductor and the second commutation inductor is connected to one incoming line terminal of the primary of the transformer, and a connection point between the third commutation inductor and the fourth commutation inductor is connected to the other incoming line terminal of the primary of the transformer.

5. A control method for a dual-frequency induction heating power supply, applied to a dual-frequency induction heating power supply, the induction heating power supply comprising a controller, a three-phase full-bridge rectifier circuit, a smoothing reactor, a single-phase full-bridge inverter circuit, a zero-crossing detection circuit, a resonant capacitor and a heating coil; the single-phase full-bridge inverter circuit comprises a first inverter bridge arm and a second inverter bridge arm connected in parallel, the first inverter bridge arm comprises a first thyristor located in an upper arm and a second thyristor located in a lower arm, the second inverter bridge arm comprises a third thyristor located in an upper arm and a fourth thyristor located in a lower arm, the output positive terminal of the three-phase full-bridge rectifier circuit is connected to the smoothing reactor, the anode of the first thyristor and the anode of the third thyristor, the cathode of the second thyristor and the cathode of the fourth thyristor are connected to the output negative terminal of the three-phase full-bridge rectifier circuit; wherein, The first thyristor and the fourth thyristor are a pair of tubes, and the second thyristor and the third thyristor are a pair of tubes; the resonant capacitor and the heating coil are connected in parallel to the connection point between the first thyristor and the second thyristor, and the connection point between the third thyristor and the fourth thyristor, and the controller is respectively connected to the control ends of the first thyristor, the second thyristor, the third thyristor, and the fourth thyristor and the zero-crossing detection circuit, characterized in that the method comprises: Controlling a pair of transistors in the first inverter bridge arm and the second inverter bridge arm to be turned on; Determine that the voltage of the alternating current output by the single-phase full-bridge inverter circuit detected by the zero-crossing detection circuit is after the second zero-crossing point and before the third zero-crossing point, trigger the other pair of tubes in the first inverter bridge arm and the second inverter bridge arm to be turned on, and the single-phase full-bridge inverter circuit outputs alternating current including super-frequency resonance current and intermediate frequency resonance current components; The zero-crossing detection circuit is connected in parallel with the resonant capacitor.

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