Triple-half-bridge bidirectional converter controlled by phase shift and PWM

This paper presents a transformer-coupled three-port triple-half-bridge bidirectional dc-dc converter controlled by phase shift in combination with pulse-width-modulation (PWM). A typical application of the proposed converter is a fuel cell system with a supercapacitor/battery as the storage. The boost-half-bridge that connects to the supercapacitor plays a key role in accommodating the wide operating voltage of the supercapacitor. With this technique, the zero-voltage-switching (ZVS) operating range is extended to the entire phase shift region. Furthermore, both the current stress and the conduction losses of the power switches are reduced compared to other methods. In addition, a control scheme employing multiple PI regulators for this converter is presented. A prototype has been built. Simulation and experimental results show the effectiveness of the proposed converter and the control scheme.