The paper proposes a AC and DC mixed output VPS(vehicle power supply). It is composed of a two-stage circuit with the input stage and the output stage. The input stage contains a single-phase PWM inverter, a HFT (high-frequency transformer) and an uncontrolled rectifier. The single-phase PWM inverter adopts the open-loop control strategy to convert the low DC voltage into a high-frequency one with square wave. The HFT enhances the voltage and insulates the low-voltage side from the high-voltage side. The uncontrolled rectifier transforms the square voltage into DC voltage. In the output stage, one output uses single-phase PWM inverter and the other uses a DC chopper, both of which adopt the double-loop PWM control mode. The mode consists of an outer voltage loop and an inner current loop to produce desirable voltage and power. With the two-stage control strategy, ideal output currents and the output voltages are obtained, and the input power factor is controllable. The VPS model is established on MATLAB/SIMULINK, and this system is also implemented in laboratory based on DSP TMS320F28335. The results of simulation and experiment verify the proposed VPS system.
A Smooth LVRT Control Strategy for Single-Phase Two-Stage Grid-Connected PV Inverters
