A Novel Auxiliary Resonant Snubber Inverter Using Wide Bandgap Devices

In the application of power inverters, power density has become a key design specification where it has stringent requirements on system size and weight. Achieving high power density need to combine lasted wide bandgap (WBG) device technology and high switching frequency to reduce passive filter size thus further shrink overall space. While still maintaining decent power conversion efficiency and low electromagnetic interference (EMI) with higher switching frequency, soft-switching needs to be implemented.

A novel auxiliary resonant snubber is introduced. The design and operation are carried out, in which this snubber circuitry enables main Gallium Nitride (GaN) switches operating under zero voltage switching (ZVS) condition, and auxiliary Silicon Carbide (SiC) diodes switching under zero current switching (ZCS) condition. Besides, the auxiliary snubber circuitry gating algorithm is also optimized which allows reduction of the switching and conduction loss in auxiliary GaN switches to obtain higher system efficiency and better thermal performance. Here, this novel auxiliary resonant snubber circuitry is applied to a traditional full bridge inverter with flexible modulation suitability. This proposed inverter can be applied to a wide range of potential applications, such as string solar inverter, renewable energy combined distributed generation, dc-ac part of bi-directional electrical vehicle (EV) on-board charger, and uninterruptible power supply (UPS), etc.