13.56MHz Half-Bridge GaN-HEMT Resonant Inverter Achieving High Power, Low Distortion, and High Efficiency by 'L-S Network'

SUMMARY This paper proposes a topology of high power, MHz- frequency, half-bridge resonant inverter ideal for low-loss Gallium Nitride high electron mobility transistor (GaN-HEMT). General GaN-HEMTs have drawback of low drain-source breakdown voltage. This property has prevented conventional high-frequency series resonant inverters from deliv- ering high power to high resistance loads such as 50 Ω , which is typically used in radio frequency (RF) systems. High resistance load causes hard- switching also and reduction of power e ffi ciency. The proposed topology overcomes these di ffi culties by utilizing a proposed ‘L-S network’. This network is e ff ective combination of a simple impedance converter and a series resonator. The proposed topology provides not only high power for high resistance load but also arbitrary design of output wattage depending on impedance conversion design. In addition, the current through the series resonator is low in the L-S network. Hence, this series resonator can be designed specifically for harmonic suppression with relatively high quality-factor and zero reactance. Low-distortion sinusoidal 3kW output is verified in the proposed inverter at 13.56MHz by computer simulations. Further, 99.4% high e ffi ciency is achieved in the power circuit in 471W experimental prototype.