A Current-Balancing Gate Driver for Dynamic Current Sharing of Paralleled SiC MOSFETs With Kelvin-Source Connection

Paralleling the silicon carbide (SiC) mosfets is a cost-effective solution to augment the current handling capabilities. Furthermore, the utilization of the Kelvin-source configuration has been demonstrably beneficial in improving switching performance. Nevertheless, the dynamic current imbalance among paralleled devices poses significant risks, including disproportionate losses, unequal junction temperatures, and, in extreme cases, thermal runaway, eventually leading to device failure. In this article, a time-domain mathematical model for dynamic current sharing is first derived, and the process can be described by an equivalent circuit model. Subsequently, a comprehensive parameter study is conducted to investigate the impact of parasitic components on dynamic current sharing, accompanied by practical layout suggestions. By utilizing the mechanism of current sharing, a differential-mode choke (DMC) is integrated into the gate driver to balance the dynamic currents. A comprehensive analysis of DMC gate driver for paralleled SiC mosfets is carried out, and this method is low-cost, easy-to-implement, and requires no active control. With the aids of derived mathematical model, the DMC can be designed for various applications. A prototype with paralleled discrete SiC mosfets is built to verify the parasitic study and effectiveness of the DMC gate driver. Based on the experimental results, the DMC gate driver can enhance the dynamic current sharing under scenarios of mismatched power- and gate-driving layouts, multiple devices, and unbalanced gate-driving signals.