A High-Efficiency Bidirectional Single-Stage AC-DC Converter Under Wide Voltage Range for Fast Chargers

In this article, a single-stage four-phase interleaved totem-pole AC–DC converter for fast charger applications that require high power, wide battery voltage range, and bidirectional operation capabilities is proposed. Due to the four-phase interleaving effect, the grid side switches can operate at duty cycle of 0.25 or 0.5 so that the grid current always achieves ripple-free. A method for secondary side duty cycle generation is proposed for reducing the circulating power and input current total harmonic distortion (THD) under a wide voltage range. The control system is shown to be simple and reliable. An integrated four-phase transformer is designed using one core. Experimental results from a 7.5 kW prototype with an output voltage range of 150 to 750 V are provided to validate the proposed concept.