Voltage Source Converters Using Series-Connected IGBTs Based on Active Clamping Module

This paper employs an active clamping module (ACM) to balance voltages of series-connected IGBTs in a medium voltage (MV) voltage source converter (VSC), which has been used for SiC MOSFETs. The principles of charging and discharging within the ACM are briefly introduced, revealing that the ACM capacitors have less charging current compared with series-connected SiC MOSFETs due to tail current. This process is modeled, leading to guidelines for selecting appropriate ACM capacitance. Design considerations for a MV VSC are discussed. Preliminary back-to-back tests on IGBT half-bridge modules were conducted at a DC voltage level of 400V and an AC current of 150A, confirming the effectiveness of the proposed analysis and design.