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High-power IGBT induction heating parallel connection method

A technology of induction heating and induction heating equipment, applied in the direction of induction heating, induction current source, etc., can solve problems such as failure and loss expansion, difficult current balance, current distribution influence, etc., to achieve timely and reliable protection, reduce failure rate, and improve stability sexual effect

Inactive Publication Date: 2019-07-23
山东迪热电气科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because the internal resistance of the IGBT is too small, it is on the same order of magnitude as the internal resistance and distributed impedance of the lead wire. The slight difference in the value of the impedance caused by the length of the lead wire, the irregularity of the material, and the asymmetry of the direction makes the two branch currents large differences, sometimes a few millimeters of movement on the lead can have a large effect on the current distribution
And the more the number of IGBTs connected in parallel, the more difficult it is to solve the current balance problem between the branches
[0008] 2. If one IGBT unit is damaged, it will directly cause a short circuit of the other bridge arm of the unit connected in parallel with it, causing the IGBTs connected in parallel to it to be damaged at the same time, resulting in the expansion of failure and loss
However, since J2 and J4 are connected in parallel, U2 and U4 are equal and the lower one prevails. When a problem occurs in a certain branch and the voltage rises, it cannot be detected quickly and accurately, resulting in untimely protection.
In connection with the second item above, it is easy to cause damage to the IGBT
[0013] To sum up, the traditional IGBT parallel connection method has poor stability and low reliability, and the more parallel connections, the worse the situation

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0043] The symmetrical arrangement of the transformers, the outgoing end of the current bus is close to one transformer, and the incoming end of the current bus is close to the other transformer.

[0044] Such as Figure 5 As shown, it is easy to ensure that the secondary incoming current and outgoing current path of each transformer have the same length and opposite directions in the project, so the internal resistance and distributed impedance of each branch are easy to be equal. This method can meet the parallel application of 5 groups of IGBTs and below.

Embodiment 2

[0046] Since the internal resistance of the device and the distributed impedance of the leads are of very small order of magnitude—both at the 10-3 level, the resonant capacitance of the IGBT induction heating device can be used as the matching impedance to make the impedance of each branch equal.

[0047] Such as Figure 6 As shown, L is the inductance of the coil, C1 and C2 are respectively located in the two branches C1=C2, the capacitive reactance is Z1=1 / (2πfC1), Z2=1 / (2πfC2), the order of magnitude of Z1 and Z2 can be known from the calculation At the 10-1 level, relative to the impedance of the capacitor, the internal resistance of the device and the distributed impedance of the lead wire can be ignored. Usually, the error of the capacitor is within 5%, so the current error of the branch circuit can also be guaranteed within 5%. The purpose of IGBT parallel current sharing is achieved. This method can realize the application of parallel connection of more than 5 groups...

Embodiment 3

[0049] In Embodiment 2, both the resonant capacitor and the inductance coil are on the secondary side of the transformer, which is secondary resonance, but in some applications, for load matching, primary resonance is required, that is, the resonant capacitor is on the primary side of the transformer, and the inductance coil is on the transformer side. Secondary, this case uses Figure 7 in the way. In the same way, it can be seen that the internal resistance of the device and the distributed impedance of the leads in this circuit can also be ignored. This method is suitable for quenching or other applications with small coil inductance.

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Abstract

The invention relates to a high-power IGBT induction heating parallel connection method; the method is characterized by comprising an IGBT group, wherein the two IGBTs in the IGBT group form an H bridge and then are coupled through a transformer to form a basic group; the secondary sides of the transformers in the two basic groups are connected in parallel and then are output; and the plurality ofgroups of IGBT groups are used in parallel. The current of each IGBT can be easily shared, the IGBT does not need to be used in a de-rate mode, and the IGBT parallel connection of the high-power induction heating equipment is truly realized. Due to the introduction of the transformers, electric isolation is realized between a load and a three-phase power supply, and the safety of equipment is improved.

Description

[0001] Technical field: [0002] The invention relates to a high-power IGBT induction heating parallel connection method, which belongs to the field of IGBT heating. [0003] Background technique: [0004] Induction heating equipment is widely used in various metal heating fields - diathermy, smelting, heat treatment, etc. The inverter part of traditional high-power induction heating equipment (intermediate frequency furnace) adopts thyristor parallel resonance, and the switching device is thyristor, which has high switching loss and low efficiency; after the birth of IGBT, it has small switching loss, high operating frequency, The advantages of easy control have replaced other high-power switching devices in the fields of super-audio, high-frequency, and low-power medium-frequency induction heating. However, in the field of high-power intermediate frequency, due to the small current of a single IGBT tube, multiple IGBTs need to be connected in parallel to achieve power expans...

Claims

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Application Information

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IPC IPC(8): H05B6/04
CPCH05B6/04
Inventor 魏长江纪圣辉
Owner 山东迪热电气科技有限公司
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