Ultra-Voltage Gain Bidirectional DC–DC Converter With Reduced Switch Voltage Stress and Improved Efficiency

Abstract

Bidirectional dc-dc converters (BDCs) play a significant role in battery/ultracapacitor-based applications. A novel ultra-gain BDC (UGBDC) is proposed with improved voltage transfer ratio (VTR), continuous source current and symmetrical VTR. The UGBDC architecture reduces voltage and current stress on MOSFETs and capacitors. The enhancement of VTR reduces the parasitic effect and the core saturation problem. Further, lowered voltage stress of the MOSFETs reduces the switching losses. The output voltage of the UGBDC is calculated for ideal and with parasitic. The component voltage stress, voltage gain and efficiency are compared to those of reported BDC topologies. A 500 W, 650 V, 50 kHz converter prototype is built, and steady-state waveforms are shown. The significant transfer functions are derived from the state-space model, and the PI controllers for step-up and stepdown operation are designed. The designed controller is implemented in Xilinx System Generator and closed loop experimental results are presented.