Soft-Switching Control for a Resonant Four-Switch Inverting Buck–Boost DC/DC Converter With Wide Voltage Range

A resonant four-switch inverting buck–boost converter is a good choice for dc/dc applications that require an inverting voltage solution. A soft-switching control scheme with four segments of resonance current has been examined using duty ratio and phase shift as control variables. As a result, the rms value of the resonance current is low compared with discontinues current mode (DCM), which is directly proportional to the conduction loss. This control scheme allows the converter to regulate its output voltages more efficiently with soft-switching operations. Thus, it contributes to an increment in efficiency improvement and board size reduction. At the same time, a simple closed loop is designed to meet the requirement of a wide voltage range with the corresponding simplified real-time proportional integral (PI) control algorithm. For the verification of the proposed control scheme, a resonant four-switch inverting buck–boost dc/dc converter is designed and experimentally tested, which has recorded over 98.5% peak efficiency at a 1:1 inverting case (−48 V_dc–48 V_dc). The converter's wide operating range is from −48 V_dc input to 28–60 V_dc output voltage with a power density of 500 W/in³.