Abstract
To understand the limitation of maximizing the switching speed of SiC low-current discrete devices and high-current power modules in hard switching applications, double pulse tests are conducted and the testing results are analyzed. For power modules, the switching speed is generally limited by the parasitics rather than the gate drive capability. For discrete SiC devices, the conventional voltage source gate drive (VSG) is not sufficient to maximize the switching speed even if the external gate resistance is minimized. The limitation of existing current source gate drives (CSG) is analyzed, and a CSG dedicated for SiC discrete devices is proposed, which can provide constant current during the switching transient, regardless of the high Miller voltage and large internal gate resistance. Compared with the conventional VSG, the proposed CSG achieves 67% faster turn on time and 50% faster turn off time, and 68% reduction in switching loss at full-load condition.
