Dual-channel high-power induction heating power supply

Abstract

The utility model belongs to the technical field of heating power supplies, and particularly relates to a dual-channel high-power induction heating power supply, which comprises a three-phase input circuit, a dual-channel shunt circuit, a temperature rise section inverter circuit, a temperature rise section output circuit, a heat preservation section inverter circuit, a heat preservation section output circuit and a connection relation thereof. According to the utility model, the dual-channel shunt circuit, the temperature rise section inverter circuit, the temperature rise section output circuit, the heat preservation section inverter circuit and the heat preservation section output circuit are arranged, so that a temperature rise power supply and a heat preservation power supply can be integrated; besides, the resonant capacitor bank and the induction coils are arranged, so that the temperature rise power supply and the heat preservation power supply adopt two different operation frequencies, coupling resonance between the induction coils of the temperature rise power supply and the heat preservation power supply is avoided, current and power oscillation and unstable control are prevented, and direct-current bus overvoltage caused by coupling current is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of heating power supplies, in particular to a dual-channel high-power induction heating power supply, which is used for solution heat treatment, annealing heat treatment and tempering heat treatment of large stainless steel pipes, carbon steel pipes, titanium alloy pipes and the like. Background Art

[0002] At present, there are two forms of induction heating power supplies used for solution heat treatment of large stainless steel pipes with heating and insulation control functions:

[0003] The first type is a single-channel power supply connected to an induction coil, and the heating section and the insulation section are realized by the density design of the induction coil. The induction coil in the heating section is denser and has a high operating power density, while the induction coil in the insulation section is sparser and has a low operating power density.

[0004] This structure is feasible for heating a certain type of stainless steel pipe with a fixed induction coil, but the size and processing speed of the steel pipe cannot be changed; when the outer diameter, wall thickness, and processing speed of the steel pipe change, the power density ratio between the heating section and the insulation section changes, and it is no longer applicable. Therefore, this power supply and induction coil structure cannot meet the production requirements of users' diversified products.

[0005] The second structure is two independent power supplies, each of which is connected to an induction coil. The heating power of the heating section and the heating power of the heat preservation section are controlled by the independent operation of the two power supplies.

[0006] This structure can theoretically meet the needs of users for diversified products, but there are two major problems in practical applications: First, due to the mutual electromagnetic coupling between the two induction coils in the heating section and the insulation section, the energy of one induction coil can easily couple to the other induction coil, and then flow back to the DC bus through the loop, causing overvoltage and often burning out the main circuit components. In the application, the method of increasing the distance between the two coils is used to reduce this coupling, but it will cause the temperature of the stainless steel pipe to drop too much in the middle section from the heating section to the insulation section, which does not meet the requirements of the heat treatment process, and also causes the insulation section power supply to bear the need to heat up again, resulting in insufficient power.

[0007] Another problem is that due to the mutual electromagnetic coupling between the two induction coils in the heating section and the insulation section, the sinusoidal wave of the resonant voltage will have harmonics or be distorted, causing the frequency and phase tracking phase-locked loop circuit to work unstably. As a result, the power supply control is also unstable, the accuracy of power and temperature control is reduced, and even operation oscillations may occur, burning out components. Utility Model Content

[0008] The purpose of the utility model is to solve the technical problems existing in the background technology. To this end, a dual-channel high-power induction heating power supply is provided, which can integrate the heating power supply and the heat preservation power supply into one.

[0009] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0010] A dual-channel high-power induction heating power supply, comprising a three-phase input circuit, a dual-channel shunt circuit, a temperature rise section inverter circuit, a temperature rise section output circuit, a temperature holding section inverter circuit and a temperature holding section output circuit;

[0011] The positive and negative ends of the rectifier output of the three-phase input circuit are connected to the positive and negative ends of the DC bus respectively;

[0012] The dual-channel shunt circuit includes a first shunt and a second shunt;

[0013] The positive end of the DC bus is connected to the positive end of the inverter circuit of the temperature rising stage and the positive end of the inverter circuit of the temperature keeping stage through a reactor;

[0014] The negative end of the DC bus is connected to the negative end of the temperature rising stage inverter circuit through a first shunt;

[0015] The negative end of the DC bus is connected to the negative end of the insulation section inverter circuit through a second shunt;

[0016] The output end of the temperature rising stage inverter circuit is electrically connected to the input end of the temperature rising stage output circuit, and the output end of the temperature keeping stage inverter circuit is electrically connected to the input end of the temperature keeping stage output circuit.

[0017] The following is a technical solution further defined by the utility model, wherein the three-phase input circuit includes a three-phase power supply, an electric intelligent air switch, a circuit breaker, a buffer contactor, a buffer resistor and a three-phase bridge rectifier;

[0018] The three-phase electricity of the three-phase power supply is electrically connected to the three-phase input terminals of the three-phase bridge rectifier through the electric intelligent air switch, and the positive terminal and negative terminal of the rectifier output of the three-phase bridge rectifier are respectively connected to the positive terminal and negative terminal of the DC bus;

[0019] The circuit breaker, the buffer contactor and the buffer resistor are connected in series and then in parallel at both ends of the electric intelligent air switch.

[0020] The following is a technical solution further defined by the present utility model, wherein the temperature rise stage inverter circuit comprises a plurality of IGBT inverter half-bridges, a discharge resistor and a non-inductive capacitor;

[0021] A discharge resistor is connected between the positive end and the negative end of the DC bus of the inverter circuit in the temperature rising stage;

[0022] The DC bus positive end of the temperature rising stage inverter circuit is connected to the input positive end of each IGBT inverter half-bridge, and the DC bus negative end of the temperature rising stage inverter circuit is connected to the input negative end of each IGBT inverter half-bridge;

[0023] A non-inductive capacitor is connected between the positive input terminal and the negative input terminal of each IGBT inverter half-bridge.

[0024] The following is a technical solution further defined by the present utility model, wherein the temperature rise stage output circuit comprises two resonant capacitor groups 1 and an induction coil 1;

[0025] The positive output terminal of each IGBT inverter half-bridge is connected to one end of a resonant capacitor group 1, and the other end of the resonant capacitor group 1 is connected to an induction coil 1;

[0026] The negative output terminal of each IGBT inverter half-bridge is connected to one end of another resonant capacitor group one, and the other end of the resonant capacitor group one is connected to the induction coil one.

[0027] The following is a technical solution further defined by the present utility model, wherein the insulation stage inverter circuit includes a plurality of IGBT inverter half-bridges and non-inductive capacitors;

[0028] The number of IGBT inverter half-bridges of the inverter circuit in the insulation stage is half the number of IGBT inverter half-bridges of the inverter circuit in the heating stage;

[0029] The DC bus positive terminal of the insulation section inverter circuit is connected to the input positive terminal of each IGBT inverter half-bridge, and the DC bus negative terminal of the insulation section inverter circuit is connected to the input negative terminal of each IGBT inverter half-bridge;

[0030] A non-inductive capacitor is connected between the positive input terminal and the negative input terminal of each IGBT inverter half-bridge.

[0031] The following is a technical solution further defined by the utility model, wherein the insulation section output circuit includes two resonant capacitor groups 2 and an induction coil 2;

[0032] The positive output terminal of each IGBT inverter half-bridge is connected to one end of a resonant capacitor group 2, and the other end of the resonant capacitor group 2 is connected to the induction coil 2;

[0033] The negative output terminal of each IGBT inverter half-bridge is connected to one end of another resonant capacitor group 2, and the other end of the resonant capacitor group 2 is connected to the induction coil 2.

[0034] Compared with the prior art, the utility model has the following technical effects:

[0035] The utility model can integrate the heating power supply and the insulation power supply into one by arranging a dual-channel shunt circuit, a heating section inverter circuit, a heating section output circuit, a insulation section inverter circuit and an insulation section output circuit; in addition, by arranging a resonant capacitor group and an induction coil, the heating power supply and the insulation power supply adopt two different operating frequencies to avoid coupling resonance between the induction coils of the two, prevent current and power oscillation and control instability, and prevent overvoltage of the DC bus caused by coupling current.

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] 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.

[0038] Figure 1 It is a circuit connection relationship diagram of the three-phase input circuit and the dual-channel shunt circuit in the utility model;

[0039] Figure 2 It is a circuit connection relationship diagram of the temperature rise section inverter circuit, the temperature rise section output circuit, the temperature holding section inverter circuit and the temperature holding section output circuit in the utility model;

[0040] Figure 3 It is a circuit connection relationship diagram of the temperature rise stage inverter circuit and the temperature rise stage output circuit in the utility model;

[0041] Figure 4 The utility model is a circuit connection diagram in which a heat preservation section inverter circuit and a heat preservation section output circuit are connected. DETAILED DESCRIPTION

[0042] 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.

[0043] like Figure 1-4As shown, a dual-channel high-power induction heating power supply is provided, including a three-phase input circuit, a dual-channel shunt circuit, a temperature rise section inverter circuit, a temperature rise section output circuit, a temperature keeping section inverter circuit and a temperature keeping section output circuit.

[0044] The three-phase input circuit includes a 380VAC three-phase power supply, an electric intelligent air switch K1, circuit breakers AA, BB, CC, a buffer contactor KP2, a buffer resistor and a three-phase bridge rectifier BD1.

[0045] The temperature rise stage inverter circuit includes eight IGBT inverter half-bridges BRG1-8, a discharge resistor RF1 and sixteen non-inductive capacitors C1-C16.

[0046] The temperature rise stage output circuit includes two resonant capacitor groups and an induction coil.

[0047] The insulation section inverter circuit includes four IGBT inverter half-bridges BRG9-12 and eight non-inductive capacitors C17-C24.

[0048] The insulation section output circuit includes two resonant capacitor groups and two induction coils.

[0049] The 380VAC three-phase power supply is connected to the three-phase bridge rectifier BD1 after passing through the electric intelligent air switch K1, buffer contactor KP2, and buffer resistor; VD1 is the input voltmeter, and VD2 is the DC voltmeter; after filtering by the reactor, it is connected to the positive end of the DC bus of the inverter circuit (the two inverter circuits of the heating stage inverter circuit and the insulation stage inverter circuit share the DC bus positive end P1.1). The negative end of the DC bus is divided into two paths, namely P1.2 and P1.3. The negative end of the DC bus P1.2 is connected to the negative end of the DC bus of the heating stage inverter circuit after passing through the 800kW shunt; the negative end of the DC bus P1.3 is connected to the negative end of the DC bus of the insulation stage inverter circuit after passing through the 400kW shunt.

[0050] Heating stage (800kW):

[0051] like Figure 3 As shown, the inverter part of the temperature rise stage (i.e., the inverter circuit of the temperature rise stage) is 8 IGBT inverter half-bridges BRG1-8, all of which are connected to the DC bus P1.1 and P1.2; RF1 is a discharge resistor; the non-inductive capacitors C1-C16 are surge absorption capacitors on the IGBT inverter half-bridges, and 2 non-inductive capacitors are installed on each IGBT inverter half-bridge; the 8 inverter outputs are INVx.1 and INVx.2 (x is 1 to 8).

[0052] The output part of the temperature rise section (i.e., the temperature rise section output circuit) is a resonant capacitor group 1 and an induction coil 1, wherein the resonant capacitor group 1 is installed in the power cabinet, and the induction coil 1 is installed on the user's production line and connected to the power supply with a water-cooled cable assembly.

[0053] Insulation section (400kW):

[0054] like Figure 4 As shown, the inverter part of the insulation section (i.e., the insulation section inverter circuit) is composed of four IGBT inverter half-bridges BRG9-12, all of which are connected to the DC bus P1.1 and P1.3 (the heating section and the insulation section share a common positive pole, while the negative pole shares the total DC bus through a shunt); the non-inductive capacitors C17~C24 are surge absorption capacitors on the IGBT inverter half-bridges, and two non-inductive capacitors are installed on each inverter half-bridge; the four inverter outputs are INVx.1 and INVx.2 (x is 9~12).

[0055] The output part of the insulation section (i.e., the insulation section output circuit) is a resonant capacitor group 2 and an induction coil 2, wherein the resonant capacitor group 2 is installed in the power cabinet, and the induction coil 2 is installed on the user's production line and connected to the power supply with a water-cooled cable assembly.

[0056] The capacitance of the resonant capacitor group 1 and the resonant capacitor group 2 are different, and the inductance of the induction coil 1 and the induction coil 2 are different, so that the heating stage power supply and the insulation stage power supply of the utility model adopt two different operating frequencies to avoid coupling resonance between the two induction coils, prevent current and power oscillation and control instability, and prevent coupling current from causing DC bus overvoltage. Its basic principles are as follows:

[0057] This frequency is the resonant frequency F of each channel induction coil and the resonant capacitor of each channel built into the power supply. Assuming the inductance of the induction coil is L and the capacitance of the resonant capacitor is C, the resonant frequency value is:

[0058]

[0059] Therefore, by adjusting the inductance of the induction coil and the capacitance of the resonant capacitor, different operating frequencies can be set. The difference between the two different operating frequencies of the heating section power supply and the insulation section power supply is 50% to 200%, and in the present invention, the difference is 100%, that is, the insulation section operating frequency is twice the heating section operating frequency, for example, the heating section operating frequency and the insulation section operating frequency are 1000Hz and 2000Hz (or 1500Hz and 3000Hz, or 700Hz and 1400Hz) respectively.

[0060] 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 dual-channel high-power induction heating power supply, characterized in that: It includes a three-phase input circuit, a dual-channel shunt circuit, a temperature-raising stage inverter circuit, a temperature-raising stage output circuit, a temperature-keeping stage inverter circuit and a temperature-keeping stage output circuit; The positive and negative ends of the rectifier output of the three-phase input circuit are connected to the positive and negative ends of the DC bus respectively; The dual-channel shunt circuit includes a first shunt and a second shunt; The positive end of the DC bus is connected to the positive end of the inverter circuit of the temperature rising stage and the positive end of the inverter circuit of the temperature keeping stage through a reactor; The negative end of the DC bus is connected to the negative end of the temperature rising stage inverter circuit through a first shunt; The negative end of the DC bus is connected to the negative end of the insulation section inverter circuit through a second shunt; The output end of the temperature rising stage inverter circuit is electrically connected to the input end of the temperature rising stage output circuit, and the output end of the temperature keeping stage inverter circuit is electrically connected to the input end of the temperature keeping stage output circuit.

2. A dual-channel high-power induction heating power supply as claimed in claim 1, characterized in that: The three-phase input circuit includes a three-phase power supply, an electric intelligent air switch, a circuit breaker, a buffer contactor, a buffer resistor and a three-phase bridge rectifier; The three-phase electricity of the three-phase power supply is electrically connected to the three-phase input terminals of the three-phase bridge rectifier through the electric intelligent air switch, and the positive terminal and negative terminal of the rectifier output of the three-phase bridge rectifier are respectively connected to the positive terminal and negative terminal of the DC bus; The circuit breaker, the buffer contactor and the buffer resistor are connected in series and then in parallel at both ends of the electric intelligent air switch.

3. A dual-channel high-power induction heating power supply as claimed in claim 1, characterized in that: The temperature rise stage inverter circuit includes a plurality of IGBT inverter half-bridges, a discharge resistor and a non-inductive capacitor; A discharge resistor is connected between the positive end and the negative end of the DC bus of the inverter circuit in the temperature rising stage; The DC bus positive end of the temperature rising stage inverter circuit is connected to the input positive end of each IGBT inverter half-bridge, and the DC bus negative end of the temperature rising stage inverter circuit is connected to the input negative end of each IGBT inverter half-bridge; A non-inductive capacitor is connected between the positive input terminal and the negative input terminal of each IGBT inverter half-bridge.

4. A dual-channel high-power induction heating power supply as claimed in claim 3, characterized in that: The temperature rise stage output circuit includes two resonant capacitor groups 1 and an induction coil 1; The positive output terminal of each IGBT inverter half-bridge is connected to one end of a resonant capacitor group 1, and the other end of the resonant capacitor group 1 is connected to an induction coil 1; The negative output terminal of each IGBT inverter half-bridge is connected to one end of another resonant capacitor group one, and the other end of the resonant capacitor group one is connected to the induction coil one.

5. A dual-channel high-power induction heating power supply as claimed in claim 1, characterized in that: The insulation section inverter circuit includes a plurality of IGBT inverter half-bridges and non-inductive capacitors; The number of IGBT inverter half-bridges of the inverter circuit in the insulation stage is half the number of IGBT inverter half-bridges of the inverter circuit in the heating stage; The DC bus positive terminal of the insulation section inverter circuit is connected to the input positive terminal of each IGBT inverter half-bridge, and the DC bus negative terminal of the insulation section inverter circuit is connected to the input negative terminal of each IGBT inverter half-bridge; A non-inductive capacitor is connected between the positive input terminal and the negative input terminal of each IGBT inverter half-bridge.

6. A dual-channel high-power induction heating power supply as claimed in claim 5, characterized in that: The insulation section output circuit includes two resonant capacitor groups 2 and induction coil 2; The positive output terminal of each IGBT inverter half-bridge is connected to one end of a resonant capacitor group 2, and the other end of the resonant capacitor group 2 is connected to the induction coil 2; The negative output terminal of each IGBT inverter half-bridge is connected to one end of another resonant capacitor group 2, and the other end of the resonant capacitor group 2 is connected to the induction coil 2.

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