PWM Plus Phase-Shift-Modulated Three-Port Three-Level Soft-Switching Converter Using GaN Switches for Photovoltaic Applications

Gallium nitride (GaN) high-electron mobility transistors (HEMTs) are a promising technology for high-efficiency and high-power density applications. In this paper, a stacked three-port three-level converter (STPTLC) using GaN switches is proposed for interfacing the renewable energy sources (RESs) with load for applications that the presence of energy storage device is necessary. Derived from the asymmetrical bidirectional half-bridge (ABHB) converter, the proposed converter presents valuable advantages in terms of simple control scheme, extended soft-switching over a wide range of operating conditions, and reduced voltage stress across switches. The soft-switching for all switches at turn-on instant is guaranteed, thanks to the active clamp configuration, resulting in the high-efficiency performance. The pulsewidth-modulation (PWM) plus phase-shift control technique paves the way for decoupled regulation of the output voltage and power by presenting two control freedoms, which allows the input voltage to vary in a wide range. To diminish the current stress of switches and minimize the conduction loss, the root-mean-square (rms) current of inductance and the boundary condition of the phase-shift controller in different operation cases are studied. Finally, the experimental results of a 1-kW, 100-kHz prototype of STPTLC using GaN switches are given to confirm the validity of the proposed concept.