A Novel AC-to-DC Adaptor with Ultra-High Power Density and Efficiency

This paper proposes a novel ac-to-dc adaptor circuit with ultra-high power density and efficiency, which is based on a two-stage topology, consists of a bridgeless boost converter followed by a LLC converter. The bridgeless boost converter is in charge of regulating output voltage and minimizing bulk capacitor, while the LLC converter is operated as a dc transformer (DCX) and plays a role of providing isolated voltage step-down, maximizing circuit efficiency and simplifying the control circuit. Furthermore, in order to achieve ultra-high power density and high efficiency, the proposed circuit applies gallium nitride (GaN) devices and planar transformer, while operates the circuit to around 1MHz to shrink both the sizes of EMI filter and magnetic components. By applying the proposed circuit, both the features of high performance and compact volume could be achieved; up to 44.22W/in(3) power density and 94% efficiency are obtained from a 65W ac-to-dc adaptor prototype.