Design of GaN based ultra-high efficiency, high power density resonant Dickson converter for high voltage step-down ratio

Abstract

In the realm of power conversion, Dickson type and other switched capacitor converters (SCCs) offer numerous advantages such as ease of control, bidirectional operation, high power density and high efficiency. However, it finds limited use in high voltage (over 250 V) and high step-down ratio (typically over 8) systems. At higher voltage gains, SCCs require many floating switches and capacitors. This leads to increased system losses and lower overall power density. This paper addresses some of the key design challenges in a GaN based resonant Dickson converter to achieve high efficiency and power density at high-voltage gains. Design revolves around delivering the key benefits of GaN switches at a system level. These include optimal topology and switch selection, design of a compact and high-efficiency gate drive, minimization of different loss components and passive component design. A 300 W, 280 V/28 V resonant Dickson converter prototype is built and experimentally validated. Such a converter is suitable for deriving the low-voltage 28 V bus required in more-electric aircrafts. A peak efficiency of 99.1% with a power density of 87 W/in3 is achieved for the said prototype