Load-side control IGBT (insulated gate bipolar transistor) series voltage sharing circuit

Abstract

The invention discloses a load-side control IGBT (insulated gate bipolar transistor) series voltage sharing circuit which comprises at least two series main IGBTs. Each IGBT is connected with a buffer voltage sharing unit; each buffer voltage sharing unit comprises an RCD (residual current device) buffer branch circuit, and each RCD buffer branch circuit is arranged between a collector electrode and an emitter electrode of the corresponding main IGBT in a parallel connection manner; the RCD buffer branch circuits are connected with resistance voltage sharing branch circuits in parallel; a middle point of each resistance voltage sharing branch circuit is connected with one end of a primary winding of a corresponding voltage transformer, and one end of each resistance voltage sharing branch circuit is connected with the other end of the primary winding of the corresponding voltage transformer and an emitter electrode of a corresponding auxiliary IGBT; two ends of a secondary winding of each voltage transformer are connected with an input end of a corresponding voltage follower / voltage comparator and the emitter electrode of the corresponding auxiliary IGBT; collector electrodes of the auxiliary IGBTs of all the buffer voltage sharing units are connected with an auxiliary buffer branch circuit; the auxiliary buffer branch circuit is connected with the other end of each resistance voltage sharing branch circuit. The load-side control IGBT series voltage sharing circuit has the advantages that influence of the voltage followers / voltage comparators and the auxiliary IGBTs on resistance sampling can be prevented, and accordingly the sampling precision can be improved; voltage balance of the circuit can be guaranteed.

Description

technical field [0001] The invention relates to a load side control IGBT series voltage equalizing 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-distance offsho...

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 load-side control IGBT series voltage equalizing 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 accuracy is not high, and the circuit includes multiple independent auxiliary buffer branches, each Each auxiliary buffer branch includes a capacitor, and the number of capacitors is large. When overvoltage occurs on multiple main IGBTs and the overvoltage imbalance is large, voltage balance cannot be achieved.

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