Fault protection and bypass device of modular multilevel converter power module

Abstract

The invention relates to a fault protection and bypass device of a modular multilevel converter power module. The device comprises IGBTs and diodes in parallel with the IGBTs and a capacitor connectedin parallel with a plurality of IGBTs connected in series, wherein the capacitor is parallel to a thyristor; the anode of the thyristor is connected with the anode of the capacitor, and the cathode of the thyristor is connected with the cathode of the capacitor. When the power module has faults or failed, the thyristor is triggered, the capacitor discharges through the thyristor, the current density near the gate pole area is very high, huge heat pressure is generated, and the silicon and molybdenum wafers in the device can be melted and become alloy to form a short circuit state. No externalmechanical damage or burst exists due to the inherent characteristics of the thyristor device, and long-term stable and reliable through flow can be ensured. The thyristor and the diode together forma bypass path.

Description

technical field [0001] The invention proposes a thyristor-based bypass protection scheme for power modules, which is suitable for power modules of modular multilevel converters. Background technique [0002] At present, the large-capacity STATCOM, large-capacity flexible DC transmission converter valve, and high-power inverter are all based on the modular multi-level converter (MMC) scheme. The main circuit of each phase is composed of multiple power modules connected in series. The circuit type can be a full bridge or a half bridge, depending on the specific working conditions. The power module adopts fully-controlled power semiconductor switching IGBT. The IGBT package has two types: plastic module type and crimping type, and the crimping type has two types: round and square. Usually an anti-parallel connected diode is integrated inside the IGBT. Due to the use of bonding wires, the ability of plastic packaged IGBTs to withstand fault current impulses is weaker than that...

AI Technical Summary

Problems solved by technology

[0006] However, this solution has several defects. First, this switch is a complex mechanical device with many key components, and the failure rate cannot be guaranteed to be 0. If there is a failure to close the switch, it will cause the system to shut down and cause a major impact

2. If you want to add a thyristor as a backup bypass device, the thyristor needs to be triggered continuously, and it is difficult to guarantee this after a module failure

3. If the short circuit of T1 fails, when the mechanical bypass switch is closed, the capacitor C1 will discharge through T1 and Con, and the possibility of mechanical damage or bursting of T1 and Con is very high, especially when T1 uses a plastic module IGBT

The debris and plasma diffusion after the explosion may cause the following problems: affect the normal operation of the electronic components inside the module; cause leakage in the cooling water circuit, because the water pipe will be damaged; hot plasma or arc diffusion will affect and damage the phase. adjacent power module

[0007] The above problems may lead to more serious secondary failures of the system

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