Design and Implementation of a Low-cost and Compact Floating Gate Drive Power Circuit for GaN-based Flying Capacitor Multi-Level Converters

A major challenge in the implementation of flying capacitor multi-level (FCML) converters is providing power to the gate drive circuits. A common method is to use isolated DC/DC converters, which are bulky, expensive and energy inefficient. This work discusses the design and implementation of an alternative gate drive power supply circuit, which utilizes three techniques termed cascaded bootstrap, double charge pump and gate-driven charge pump. These techniques leverage the inherent properties of GaN switches and the FCML topology to transfer power to floating switches, and can be implemented with capacitors and diodes only. Experimental results show that the proposed circuit can cut the size of the power stage of a state-of-the-art 7-level FCML converter by half, at 1/6 of the cost.