Static Current Balancing Strategy for Parallel IGBTs Based on Parametric Compensation

Abstract

Insulated gate bipolar transistor (IGBT) parallel connection is an effective way to solve the problem, which is the gradual increase in the capacity of the magnetic confinement power supply in a Tokamak device. Static current balance (SCB) is one of the key factors for the safe and stable operation of a parallel IGBT system. Therefore, to improve the stability of parallel IGBT systems, it is very important to study the current difference in the parallel IGBTs under various parameter differences. However, the existing results have focused mainly on device parameter matching through device screening, driving parameter matching using the active gate driving (AGD) method, or single parasitic parameter (PP) matching. These research results do not analyze the matching strategy between multiple parameters, which are the device parameter and the PP. The study showed that the collector inductance, emitter parasitic inductance, emitter parasitic resistance, collector equivalent resistance, and equivalent series voltage of the IGBTs have a significant impact on the SCB of the parallel IGBTs. When these five parameters are mismatched, there exists an equilibrium point that can reduce the static current difference (SCD) between the parallel IGBTs under the total influence of these parameter differences. Therefore, a current difference model (CDM) is created to analyze the equilibrium point of multiple parameter mismatches. The experimental results show that the multiparameter compensation scheme implemented by the CDM can effectively reduce the current difference between parallel IGBTs, which provides a feasible reference for device selection and circuit design.