IEEE Workshop on Wide Bandgap Power Devices and Applications in Asia (WiPDA Asia 2018)

277 / 2017-12-05 22:05:50

An Asynchronous-Switched-Capacitor DC-DC Converter Based on GaN and SiC Devices

Switched capacitor circuits, DC-DC power converters, Gallium nitride, Silicon carbide, Wide band gap semiconductors

Plenary track > Very high efficiency and compact converters

For the state-of-the-art switched-capacitor DC-DC converters at high-voltage low-power levels, switching loss becomes a major concern and challenge. Existing switching schemes operate power semiconductors at a signle common frequency, which does not optimally address the switching losses, especially for a high-conversion-ratio design. This paper presents a concept of Asynchronous-Switched-Capacitor (ASC), which is applied to the GaN switches that are combined with the SiC diodes to improve the efficiency and the power density. The ASC operation is named when the switches can be operated with uncorrelated frequencies, with unnecessary phase/clock synchronization of the control signals. A 380 V, 6 W, 4:1 conversion ratio converter experimentally validates the concept. The efficiency is improved by 4% and the peak-to-peak output voltage ripple is reduced by 39%, with the proposed ASC switching, compared to the conventional switching. A peak efficiency of 95.4% is achieved.