Multi-channel induction heating power supply

Abstract

The utility model belongs to the technical field of induction coating power supplies, and particularly relates to a multi-channel induction heating power supply, which comprises an input circuit, a common direct-current bus, a multi-channel IGBT (Insulated Gate Bipolar Translator) inverter bridge and an output circuit, a three-phase power supply enters a circuit breaker, is connected to a rectifier bridge through a fuse wire, is connected to a common DC bus through a buffer circuit and an electric reactor, and is connected to an IGBT inverter bridge of each channel; the output of the IGBT inverter bridge of each channel is respectively connected to the primary of the isolation transformer through the blocking capacitor bank; and the secondary of the isolation transformer, the resonant capacitor bank and the load of each channel form a series resonant circuit. According to the utility model, through the design of the whole circuit structure, the induction heating power supply with eight channels operating independently and the IGBT inverter bridges with the eight channels share the same input circuit, the common direct-current bus and other components, so that the power supply cost is saved, the coupling induction current from the inductor can be prevented from flowing backwards, and the reliability of the induction heating power supply is improved. And overvoltage of a power supply DC bus and even burnout of components may be caused.

Description

Technical Field

[0001] The utility model relates to the technical field of induction coating power supply, in particular to a multi-channel induction heating power supply, more specifically a multi-channel digital induction heating power supply designed for induction evaporation coating process, which is used for induction evaporation coating and other occasions requiring multiple channel induction heating. Background Art

[0002] There are three types of traditional induction coating power supplies:

[0003] The earliest power supply used a medium frequency generator, which was then divided into various channels. The system had only one frequency, and each channel had an independent resonant capacitor group. Each channel was tuned through an adjustable reactor to adjust the output current and power. This system is not static, has a high failure rate, low efficiency, complex adjustment system, and high cost, and has been basically eliminated.

[0004] The second type is a multi-power single-frequency operation system, where multiple power supplies independently operate at the same output frequency. Each channel is equipped with a power supply and has an independent intermediate frequency transformer and resonant capacitor group, and uses pulse width modulation PWM to adjust the output current and power. The biggest problem with this system is poor stability and reliability. The magnetic field of the induction coil is easily coupled to the adjacent coil, interfering with its control system, and the coupling current is likely to cause overvoltage or even damage to the power supply.

[0005] The third type is a dual-frequency integrated multi-channel power supply system, where multiple independent output channels are integrated into one and share a DC bus, thus preventing overvoltage caused by electromagnetic coupling induction. The system has two frequency bands, which can reduce the electromagnetic induction intensity of two adjacent channels and use frequency modulation and power modulation to adjust the output current and power. However, this system has a defect: in the multi-channel induction coil structure with two rows of staggered distribution, one induction coil has four adjacent coils, so the dual-frequency band cannot avoid the problem of same-frequency coupling resonance, which will cause problems such as unstable oscillation of the control system, power fluctuations, and coating splashing.

[0006] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Utility Model Content

[0007] The purpose of the utility model is to solve the technical problems existing in the background technology, and for this purpose, a multi-channel induction heating power supply is provided.

[0008] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0009] A multi-channel induction heating power supply comprises an input circuit, a common DC bus, an IGBT inverter bridge of multiple channels and an output circuit;

[0010] The input circuit includes a circuit breaker, a fuse, a rectifier bridge, a buffer circuit and a reactor; the three-phase power supply enters the circuit breaker, is connected to the rectifier bridge through the fuse, and is then connected to the common DC bus after passing through the buffer circuit and the reactor, and the output end of the common DC bus is connected to the IGBT inverter bridge of each channel, thereby supplying power to the IGBT inverter bridge of each channel;

[0011] The output circuit includes a DC-isolating capacitor group, an isolation transformer and a resonant capacitor group; the output of the IGBT inverter bridge of each channel is connected to the primary of the isolation transformer via the DC-isolating capacitor group, and the secondary of the isolation transformer, the resonant capacitor group and the load of each channel form a series resonant circuit.

[0012] The following is a technical solution further defined by the present invention: a plurality of the channels are independently arranged, the plurality of channels are sequentially distributed in a wave-like pattern and three adjacent channels are distributed in a triangular pattern.

[0013] The following is a technical solution further defined by the present utility model: there are three circuit breakers, and the three circuit breakers are respectively connected to each phase of the three-phase power supply; the rectifier bridge is a three-phase rectifier bridge; the buffer circuit includes a buffer contactor and a buffer resistor connected in parallel; the reactor is a filter reactor.

[0014] The following is a technical solution further defined by the present utility model, wherein the input circuit also includes an input current transformer, an input ammeter and an input voltmeter, the input current transformer cooperates with the output circuit of the three-phase power supply and its output is connected in series with the input ammeter, and the input voltmeter is connected in parallel to the output circuit of the three-phase power supply.

[0015] The following is a technical solution further defined by the present utility model: each IGBT inverter bridge is connected in parallel with an independent filter capacitor and an absorption capacitor.

[0016] The following is a technical solution further defined by the present utility model, wherein the output circuit further includes an output current transformer, and the output current transformer cooperates with the output circuit of the IGBT inverter bridge.

[0017] The following is a technical solution further defined by the utility model, which also includes a control circuit, wherein the control circuit includes a main control board and a multi-channel distribution and control board;

[0018] The multi-channel distribution and control board is electrically connected to the main control board. The multi-channel distribution and control board is connected to multiple IGBT isolation drive boards through multiple signal interfaces, wherein the number of IGBT isolation drive boards corresponds to the number of IGBT inverter bridges, and the IGBT isolation drive boards are electrically connected to the IGBT inverter bridges.

[0019] The following is a technical solution further defined by the present utility model, wherein the control circuit includes a control power supply and an internal switching power supply, the control power supply is electrically connected to the internal switching power supply through a circuit breaker and a buffer contactor, and the output end of the internal switching power supply is electrically connected to the main control board.

[0020] The following is a technical solution further defined by the present utility model: the main control panel is electrically connected to the display button unit 1, and the multi-channel distribution and control panel is electrically connected to the display button unit 2.

[0021] The following is a technical solution further defined by the present utility model, wherein the main control board is electrically connected to a remote control interface, an RS485 communication interface, a 24V power indicator light, an alarm status indicator light and a fault status indicator light.

[0022] Compared with the prior art, the utility model has the following technical effects:

[0023] The utility model realizes an induction heating power supply with eight independently operated channels through the design of the overall circuit structure. The IGBT inverter bridges of the eight channels share the same input circuit and common DC bus and other components, which not only saves the power supply cost but also prevents the backflow of coupled induced current from the inductor, which may cause overvoltage of the power supply DC bus and even burn out components (although the three-band staggered frequency structure can prevent this coupled induced current, it cannot be ruled out that the channel lines may be connected incorrectly during the installation and debugging process, resulting in the frequency bands not being staggered).

[0024] The eight channels use three operating frequencies to avoid the same-frequency coupling resonance between adjacent inductors, prevent current and power oscillation and control instability, and prevent DC bus overvoltage caused by coupling current.

[0025] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 It is a schematic diagram of the overall circuit connection relationship of the utility model;

[0028] Figure 2 It is an enlarged schematic diagram of the circuit connection relationship of the input circuit in the utility model;

[0029] Figure 3 It is an enlarged schematic diagram of the connection relationship of part of the circuit of the control circuit in the utility model;

[0030] Figure 4 It is an enlarged schematic diagram of the circuit connection relationship between the IGBT inverter bridge and the output circuit in the utility model;

[0031] Figure 5 It is a schematic diagram of the position distribution of eight channels in the utility model. DETAILED DESCRIPTION

[0032] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0033] like Figure 1-5 As shown, a multi-channel induction heating power supply is provided, including an input circuit, a common DC bus, an eight-channel IGBT inverter bridge, an output circuit and a control circuit.

[0034] like Figure 2 As shown, the input circuit includes three circuit breakers K1, two fuses F1 and F2, a rectifier bridge, a buffer circuit and a reactor. The input circuit is shared by eight channels. The 380VAC three-phase power supply enters the circuit breaker K1, is connected to the three-phase rectifier bridge through fuses F1 and F2, and then is connected to the common DC bus after the buffer contactor, buffer resistor and filter reactor to supply power to the IGBT inverter bridge of each channel. Furthermore, an input current transformer and an input ammeter are designed to detect the input current; an input voltmeter is designed to detect the input voltage.

[0035] like Figure 1 , 4 As shown in Figure 5, eight IGBT inverter bridges 1 to 8 are independently driven by IGBT driver boards 1 to 8, and output 8 intermediate frequency voltages, of which 1, 4, and 7 are one frequency band, 2, 5, and 8 are another frequency band, and 3 and 6 are the third frequency band. Each IGBT inverter bridge has an independent filter capacitor and absorption capacitor. The output circuit includes a DC isolation capacitor group, an isolation transformer, and a resonant capacitor group; the output of the IGBT inverter bridge 1 to 8 of each channel is connected to the primary of the isolation transformer 1 to 8 through the DC isolation capacitor group, and the secondary of the isolation transformer 1 to 8 and the resonant capacitor group 1 to 8 and the inductor / evaporation crucible 1 to 8 form a series resonant circuit. Furthermore, an output current transformer is designed to detect the inverter output current of each channel.

[0036] The control circuit includes a main control board, a multi-channel distribution and control board, a control power supply and an internal switch power supply. The 220VAC control power supply is connected to the circuit breaker CK1, and then electrically connected to the internal switch power supply SPOW through the buffer contactors KP2 and KP3 (where KP2 is the coil of the buffer contactor and KP3 is the relay that controls the buffer contactor), and finally connected to the main control board.

[0037] The multi-channel distribution and control board is electrically connected to the main control board, receives synchronization and signal coordination instructions from the main control board, generates three operating frequencies and distributes them to 8 signal interfaces, connects to 1 to 8 IGBT isolation driver boards, and can then drive 8 IGBT inverter bridges to generate medium frequency voltages in three frequency bands.

[0038] Display button unit 1 is connected to the main control panel and is used for displaying and operating the power of the main control panel; display button unit 2 is connected to the multi-channel distribution and control panel and is used for displaying and operating the power of each channel.

[0039] The main control panel is electrically connected to the remote control interface, RS485 communication interface, 24V power indicator light, alarm status indicator light and fault status indicator light.

[0040] It should be noted that the programs or instruction controls involved between the above-mentioned circuits are not within the protection scope of the present utility model, and the programs or instruction controls involved can be obtained by those skilled in the art through conventional techniques.

[0041] like Figure 5 As shown, eight channels are arranged independently, the eight channels are distributed in a wave-like pattern in sequence, and the three adjacent channels are distributed in a triangular pattern. Figure 5 1 to 8 represent eight evaporation crucibles or inductors, each of which is connected to an independent channel of a power supply. Figure 5 In the figure, fa, fb, and fc represent three frequency bands (three different operating frequencies), "1(fa)" represents the operating frequency of the first evaporation crucible or inductor as fa, "2(fb)" represents the operating frequency of the second evaporation crucible or inductor as fb, "3(fc)" represents the operating frequency of the third evaporation crucible or inductor as fc, and so on. It can be seen that the operating frequencies of the four adjacent evaporation crucibles or inductors (2, 3, 5, 6) around any evaporation crucible or inductor, such as 4(fa), are different from those of 4. Since the output circuit of each channel of the power supply is a series resonant circuit composed of an isolation transformer + resonant capacitor group + evaporation crucible or inductor, only the induced voltage / current close to its frequency resonance point will show low impedance, so the induced voltage / current that is out of frequency band will be suppressed and will not interfere with other circuits.

[0042] The three different operating frequencies have a step difference of 20% to 200%. The product of the utility model is designed with a step difference of 50%, and uses three operating frequencies of 6kHz, 9kHz and 13.5kHz. This frequency is the resonant frequency of each channel induction coil and each channel resonant capacitor built into the power supply. If the inductance of the induction coil (also known as the inductor) is L and the capacitance of the resonant capacitor is C, then the resonant frequency value is:

[0043] Three operating frequencies are used to avoid the same-frequency coupling resonance between adjacent induction coils, prevent current and power oscillation and control instability, and prevent DC bus overvoltage caused by coupling current.

[0044] The above is only a preferred embodiment of the utility model, and does not limit the utility model in any form. Any technician familiar with the field can make many possible changes and modifications to the technical solution of the utility model by using the above disclosed methods and technical contents without departing from the scope of the technical solution of the utility model, or modify it into an equivalent embodiment of equivalent changes. Therefore, all equivalent changes made according to the shape, structure and principle of the utility model without departing from the content of the technical solution of the utility model should be included in the protection scope of the utility model.

Claims

1. A multi-channel induction heating power supply, characterized in that: It includes an input circuit, a common DC bus, an IGBT inverter bridge with multiple channels and an output circuit; The input circuit includes a circuit breaker, a fuse, a rectifier bridge, a buffer circuit and a reactor; the three-phase power supply enters the circuit breaker, is connected to the rectifier bridge through the fuse, and is then connected to the common DC bus after passing through the buffer circuit and the reactor, and the output end of the common DC bus is connected to the IGBT inverter bridge of each channel, thereby supplying power to the IGBT inverter bridge of each channel; The output circuit includes a DC-isolating capacitor group, an isolation transformer and a resonant capacitor group; the output of the IGBT inverter bridge of each channel is connected to the primary of the isolation transformer via the DC-isolating capacitor group, and the secondary of the isolation transformer, the resonant capacitor group and the load of each channel form a series resonant circuit.

2. A multi-channel induction heating power supply as claimed in claim 1, characterized in that: The multiple channels are independently arranged, and the multiple channels are distributed in a wave-like manner in sequence, and three adjacent channels are distributed in a triangle-like manner.

3. A multi-channel induction heating power supply as claimed in claim 1, characterized in that: There are three circuit breakers, which are respectively connected to each phase of a three-phase power supply; the rectifier bridge is a three-phase rectifier bridge; the buffer circuit includes a buffer contactor and a buffer resistor connected in parallel; and the reactor is a filter reactor.

4. A multi-channel induction heating power supply as claimed in claim 1, characterized in that: The input circuit also includes an input current transformer, an input ammeter and an input voltmeter. The input current transformer cooperates with the output circuit of the three-phase power supply and its output is connected in series with the input ammeter. The input voltmeter is connected in parallel to the output circuit of the three-phase power supply.

5. A multi-channel induction heating power supply as claimed in claim 1, characterized in that: Each IGBT inverter bridge is connected in parallel with an independent filter capacitor and absorption capacitor.

6. A multi-channel induction heating power supply as claimed in claim 1, characterized in that: The output circuit also includes an output current transformer, which cooperates with the output circuit of the IGBT inverter bridge.

7. A multi-channel induction heating power supply as claimed in claim 1, characterized in that: Also included is a control circuit, the control circuit including a main control board and a multi-channel distribution and control board; The multi-channel distribution and control board is electrically connected to the main control board. The multi-channel distribution and control board is connected to multiple IGBT isolation drive boards through multiple signal interfaces, wherein the number of IGBT isolation drive boards corresponds to the number of IGBT inverter bridges, and the IGBT isolation drive boards are electrically connected to the IGBT inverter bridges.

8. A multi-channel induction heating power supply as claimed in claim 7, characterized in that: The control circuit includes a control power supply and an internal switch power supply. The control power supply is electrically connected to the internal switch power supply through a circuit breaker and a buffer contactor. The output end of the internal switch power supply is electrically connected to the main control board.

9. A multi-channel induction heating power supply as claimed in claim 7, characterized in that: The main control panel is electrically connected to the display button unit 1, and the multi-channel distribution and control panel is electrically connected to the display button unit 2.

10. A multi-channel induction heating power supply as claimed in claim 7, characterized in that: The main control panel is electrically connected to the remote control interface, the RS485 communication interface, the 24V power indicator light, the alarm status indicator light and the fault status indicator light.

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