A Gallium Nitride (GaN)-Based Single-Inductor Multiple-Output (SIMO) Inverter With Multi-Frequency AC Outputs

In this paper, a gallium nitride (GaN)-based single-inductor multiple-output (SIMO) dc-ac inverter, which generates multiple frequencies at the ac outputs, is introduced. The proposed time-multiplexed switching sequences enable the SIMO inverter to simultaneously generate sinusoidal-like outputs with different frequencies. In the absence of a parasitic body diode in the GaN transistor and with correct bias voltage, the proposed inverter requires no additional blocking diodes and/or cascaded power switches while still ensuring unidirectional flow of the inductor current for proper circuit operation. Compared with its silicon counterpart, this GaN-based inverter achieves a simplified circuit structure, reduced component count, small form factor, increased power density, and high efficiency. A practical application of this inverter is to act as a single wireless power transmitter which concurrently drives multiple transmitter coils at different frequencies for multi-standard wireless power transfer. A hardware prototype of a single-inductor three-output inverter producing three distinct resonant frequencies, namely, 100, 200, and 300 kHz, is constructed. The effectiveness of the proposed switching sequences and control method for this inverter is experimentally verified. No cross regulation is observed across the three individual ac outputs.