High-voltage IGBT (insulated gate bipolar transistor) series conversion voltage-sharing circuit

Abstract

The invention discloses a high-voltage IGBT (insulated gate bipolar transistor) series conversion voltage-sharing circuit which comprises at least two main IGBTs in series connection. Each main IGBT is connected with a buffering voltage-sharing unit; each buffering voltage-sharing unit comprises a resistance voltage-sharing branch circuit parallelly connected to a collector and an emitter of the corresponding main IGBT; a middle of each resistance voltage-sharing branch circuit is connected with an input end of a voltage follower / voltage comparator; an output end of each voltage follower / voltage comparator and one end of the corresponding resistance voltage-sharing branch circuit are connected with a first input end and a second input end of a primary winding of a corresponding voltage transformer respectively; two ends of an auxiliary winding of each voltage transformer are connected with a grid and an emitter of a corresponding auxiliary IGBT respectively; the emitter of each auxiliary IGBT is connected with the second input end of the primary winding of the corresponding voltage transformer; the auxiliary IGBT collectors of all buffering voltage-sharing units are connected with an auxiliary buffering branch circuit which is connected with the other end of each resistance voltage-sharing circuit. The high-voltage IGBT series conversion voltage-sharing circuit has the advantages that influences of the auxiliary IGBTs on resistance sampling can be avoided to improve sampling precision, and circuit voltage balance can be guaranteed.

Description

technical field [0001] The invention relates to a high-voltage IGBT series commutation and voltage equalization circuit. Background technique [0002] Offshore wind power generation has recently become a research hotspot at home and abroad, and light direct current transmission technology can provide more reactive power support for wind farms, reduce the investment in reactive power compensation equipment for wind farms; avoid the impact of wind farm voltage fluctuations on system reliability. It also improves the anti-interference ability of the wind farm to system voltage fluctuations; the light DC transmission technology is much less affected by the voltage transmission distance than the AC voltage transmission, and is more suitable for long-distance power transmission; and the light DC transmission technology can improve the wind farm. Low voltage ride through capability. Therefore, it is the best choice to adopt light direct current transmission for large-scale long-di...

AI Technical Summary

Problems solved by technology

However, the voltage balance problem of the IGBT converter valve has always been a difficulty in light DC transmission technology.

In practical engineering applications, the stability and reliability of the system must be considered. Therefore, the IGBT series converter valve selects the size of the buffer capacitor for the most extreme situation, resulting in a longer turn-off time of the IGBT series valve and a larger turn-off loss.

[0004] The existing high-voltage IGBT series commutation and voltage equalization circuit that solves the above problems is shown in figure 1 , the defect is that there is no isolation measure between the resistance of the sampling voltage and the voltage comparator, which leads to the auxiliary structure such as the auxiliary IGBT having a great influence on the voltage sampling, and the sampling is inaccurate; the circuit includes multiple independent auxiliary buffer branches, each auxiliary The buffer branch includes a capacitor, and the number of capacitors is large. When overvoltage occurs on multiple main IGBTs, voltage balance cannot be achieved; the existence of the RCD buffer branch reduces the switching speed of the IGBT

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