A Dynamic Current Balancing Method for Paralleled SiC MOSFETs Using Monolithic Si-RC Snubber Based on a Dynamic Current Sharing Model

The dynamic current imbalance between paralleled SiC mosfet s will cause unbalanced losses and reduce current capacity. The existing current balancing methods will make the circuit more complex or hard to design and implement. Hence, this article proposes a dynamic current balancing method by connecting monolithic Si- RC snubber between paralleled mosfet s, which maintains a simple circuit structure and is easy to implement. Balanced dynamic currents can be achieved by adjusting the RC snubber connecting location. Meanwhile, low voltage spike and low switching oscillation can be achieved by using RC snubber. First, an analytical current sharing model is established for paralleled SiC mosfet s. The key parameter affecting the balance of the drive circuit and then affecting the dynamic current sharing is obtained for the first time. Based on the conclusions of the model, this article then presents the current balancing method using RC snubber. Then, a power module with monolithic Si- RC snubber is designed, fabricated, and tested. Experimental results verify the current sharing model and the current balancing method. The current difference of the optimized module is reduced by more than 50% under different conditions. Finally, the effectiveness of this method in the module with more paralleled mosfet s is verified.