A Passive Balancing Method for Dynamic Current Sharing of Paralleled SiC MOSFETs with Kelvin-Source Connection

Paralleling the SiC MOSFETs is a popular solution to increase the current capacity. However, the unbalanced current sharing among paralleled SiC MOSFETs yields issues of unbalanced losses, unequal junction temperatures, or even thermal runaway, which may eventually lead to the device failure and reduce stability. To address the issue, this paper proposed a passive balancing method for unbalanced dynamic current sharing. The proposed solution requires only a differential mode choke (DMC) and does not need active control which is suitable for low-cost applications. The mechanism of dynamic current sharing is firstly analyzed. Based on the discovered feedback mechanism, the DMC is placed on the gate driving path to suppress the unbalanced gate currents and further balance the power currents. Both simulation and experimental results are shown to verify the performance of the proposed method. The proposed solution has negligible impact on the switching speed and does not increase the commutation loop inductance.