一种三电平中点箝位型逆变器保护控制策略

A Protection Control Strategy of a Three-level Neutral Point Clamped Inverter

研究了一种三电平中点箝位型(NPC)逆变器保护控制策略。针对三电平NPC逆变器内外管损耗不均,可能导致个别开关发生热过载的问题,研究了一种基于空间矢量脉宽调制(SVPWM)的热过载保护容差控制策略。当逆变器个别开关由于某种原因发生热过载时,利用冗余小矢量改变开关策略使热过载的IGBT模块负载减少并使得损耗重新分配。因此,热量从受影响的开关模块转移到其他开关器件,过热的开关热量将减少。使用这种控制方法,可使逆变器的可靠性和寿命达到最大化。该方法同样能保证三电平逆变器的中点电位平衡,且无需增加额外的硬件。实验结果验证了该控制策略的可行性。

This paper studies a protection control strategy of a three-level neutral point clamped （NPC） inverter.It studies a thermal overload protection tolerance control strategy based on space vector pulse width modulation （SVPWM）, which aims at the problem that the inner and outer tube uneven loss of a three-level NPC inverter may cause thermal overload on individual switch.The method is ：when the inverter＇s individual switch occurs thermal overload due to some reason, we can use redundant small vector to change switch strategy in order to make thermal overload of IGBT module load reduce and make the loss from the new allocation.Therefore,heat from the affected switch module is transferred to other switch device and overheat switch will reduce the heat.Using this control method,we can maximize the reliability and the lifetime of inverter.The method can ensure neutral voltage balance of the three level inverter without the need for additional hardware.The experimental results verify the feasibility of this control strategy.