This paper proposes a novel auto-reset forward DC-DC converter with inductor-switching technique to obtain the high performance by means of zero voltage switching and the fast transient response at steep load variations. The performance of the forward converter is strongly depending on the transformer reset-method. The Auto-reset method is used to recover the energy stored in leakage inductances of the transformer to the power supply and makes sure the zero voltage switching. Furthermore fast transient response is achieved by applying the inductor-switching technique, which keeps the output voltage constant in case of heavy burden load changes. The design of the proposed concept is verified by experiment of 12 V input and 1.8 V/12 A output.

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 delivering high power to high resistance loads such as 50Ω, which is typically used in radio frequency (RF) systems. High resistance load causes hard-switching also and reduction of power efficiency. The proposed topology overcomes these difficulties by utilizing a proposed ‘L-S network’. This network is effective 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 efficiency is achieved in the power circuit in 471W experimental prototype.