基于门极阻容补偿网络的IGBT串联均压方法

Voltage Balancing Method of Series-Connected IGBT Based on Resistor-Capacitor Circuit on Gate Side

针对IGBT串联应用中关断过程均压问题,对IGBT的关断过程进行了详细分析,总结出影响IGBT关断过程的核心等效电路和计算公式。在此基础上提出一种基于门极补偿阻容网络的IGBT串联均压方法,推导出增加门极阻容补偿网络后串联IGBT动态电压不均衡度和关断时间影响的计算公式,并提出门极阻容网络参数的选取原则。建立基于Lumped Charge方法的IGBT半物理数值模型,对IGBT门极阻容补偿网络进行仿真验证。给出了实际测试工况下的补偿网络参数,建立IGBT串联均压实验系统,进行多种电压、电流工况下的实验验证。仿真和实验表明:该方法可以有效控制串联IGBT的延迟时间和动态电压上升速率的差异,在母线电压为2 000V和关断峰值电流为1 500A时,采用该控制方法可将串联IGBT的动态尖峰电压不均衡度由14.4%降至6.3%。

Based on the detailed analysis of turning-off process of IGBT and the summarization of a series of key equivalent circuits and equations, a voltage-balancing method for series-connected IGBTs was put forward to solve voltage inequality. This method adopted a resistor-capacitor circuit on gate electrode. A mathematical formula was derived that can describe the influence of dynamic voltage unbalance and turning-off time inequality on series-connected IGBTs. The selection principle of the network parameters was also analyzed. A semi-physical model of IGBT based on Lumped Charge method was established, which was used to verify the IGBT gate resistance-capacity compensation network. The parameters of the compensation network under the actual test conditions were given. The test system of the series-connected IGBTs was established, and then the experimental verification was carried out under various voltage and current conditions. The results show that the proposed method can effectively control the deference between the turning-off delay time and the increasing speed of the turning-off voltage. That is, the dynamic peak voltage unbalance reduced from 14.4% to 6.3% under the condition of 2 000V/1 500A.