An Ultra-wide Output Voltage Range Bidirectional Single-stage Resonant Converter with CMVM for Series Battery Formation Power Supply

This paper proposes a bidirectional single-stage resonant converter with the center-aligned midpoint voltages modulation (CMVM) method for the series battery formation power supply system to meet the tight requirements of output voltage variation from zero to maximum battery voltage, bidirectional power transfer and high output current. The proposed converter consists of two series resonant converter (SRC) submodules with input-series-output-parallel (ISOP) structure to reduce the device stress under the condition of high voltage input and low voltage high current output. With the proposed CMVM method, ultra-wide output voltage range can be achieved in this converter with fixed switching frequency. Moreover, the driving logics under bidirectional operation are identical, and thus automatic and smooth bidirectional power transfer can be achieved to improve the dynamic performance of battery charging and discharging mode switching. In addition, ZCS without synchronous rectifier (SR) control can be achieved for the secondary side switches, which reduces the control complexity and the switching loss caused by high output current. The performance of the proposed converter is verified by the experiment based on a 12-kW prototype with 720-880V input and 0-60V, 200A output.