A digital igbt series voltage equalizing circuit based on look-up table method

Abstract

The invention provides a digital IGBT (Insulated Gate Bipolar Transistor) series connection voltage-sharing circuit based on a look-up table. The circuit comprises a voltage sampling circuit, an AD (Alternating current-Direct current) conversion circuit, an FPGA (Field Programmable Gate Array) circuit, a DA (Direct current-Alternating current) conversion circuit, and an IGBT (Insulated Gate Bipolar Transistor) driving circuit. The digital IGBT series connection voltage-sharing circuit has the advantages of being quick in voltage-sharing speed, high in precision, and simple in circuit, can comprehensively solve the technical problems of voltage-sharing, over-current and short circuit protection of the series connection, is suitable for IGBT control and protection circuits of high-voltage occasions (based on IGBT series connection) such as soft direct current power transmission, power electronics transformers, high-voltage inverters, active power filters and static var generators.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a digital IGBT series voltage equalizing circuit based on a look-up table method. Background technique [0002] Insulated gate bipolar transistor IGBT (InsulatedGateBipolarTransistor) has become the best choice for high-power electric energy conversion applications due to its high rated voltage and rated current, fast switching speed, and easy driving, and has been widely used . At present, the withstand voltage value of a single IGBT tube is still very limited, which is far from being able to meet the application in high voltage occasions. Although many manufacturers at home and abroad are developing large-capacity IGBT devices, there are currently no commercial products that can be directly applied to 10kv and above occasions; therefore, the series use of IGBTs, especially the series use of module-type IGBTs, improves its durability. It is of great signi...

AI Technical Summary

Problems solved by technology

[0005] l. The inconsistency of the IGBT turn-off impedance (static voltage equalization) - after the IGBT is turned off, the leakage current flowing through the series devices is the same, so different turn-off impedances will cause the static voltage of the IGBT to be unbalanced. In addition, the junction of the device The temperature difference will also affect the static pressure equalization

[0006] 2. The inconsistency of the drive signal and the difference of the drive circuit parameters - the inconsistency of the drive signal and the difference of the drive circuit parameters will cause the delay of the IGBT gate drive signal, which greatly affects the IGBT collector. Equalization of emitter voltage

[0007] 3. The discreteness of the parasitic parameters of the IGBT itself - the inconsistency of device parasitic inductance, parasitic capacitance and other characteristics (especially parasitic capacitance), will lead to different switching characteristics and voltage spikes

[0008] 4. Differences in reverse diode recovery characteristics——In the case of inductive loads, there is a commutation process between the IGBT and the freewheeling diode when it is turned on. Due to the reverse recovery problem of the diode, at the moment the IGBT is turned on, the freewheeling diode will overvoltage across the

This approach creates three problems: the voltage comparator circuit causes a delay in the drive signal; using too many op amps in the feedback and control loops can cause system instability; the gate voltage may over-regulate, causing The through short circuit of the upper and lower bridge arms in series

The control circuit of this method is composed of reference voltage generation circuit, feedback loop and other parts, the control circuit is complicated, the reliability is poor and it is difficult to realize

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