Asymmetrical IGBT design for three-level NPC1 converter in a bidirectional power conversion system

Abstract:
The neutral-point-clamped topology is becoming popular in field applications, such as medium voltage drives, UPS, solar inverter etc. However, the power loss distribution in such a topology is concentrated only on some chips. This paper introduces a novel IGBT module design, which has an optimized silicon chip area for achieving the best cost-performance balance in a bi-directional converter. The proposed IGBT module adopts a new low-cost package of the latest generation IGBT chips. A demonstration prototype has been designed to evaluate the module’s performance. Laboratory test evaluations include the stray inductance of four commutation loops, IGBT/diode switching behavior, and thermal performance. Based on the measured results, a simulation model has been built to obtain accurate losses and junction temperature. The simulated junction temperature value is used to assess the utilization of the chip area.