Study of EMU Auxiliary Inverter Double-Loop Control Strategy with PR Controller in Nonlinear Load Condition

As the main nonlinear load of EMU auxiliary inverter, battery charger has a great impact on the quality of inverter´s output voltage. Based on the nonlinear load harmonic model, this paper analyses the theory of AC side voltage distortion caused by 3-phase uncontrolled rectifier load, and proposes a double-loop control strategy with load current voltage reference feed-forwards. The strategy is established from 3-phase SVPWM inverter in synchronous rotating reference system. Furthermore, output voltage distortion is eliminated with a proportional resonant (PR) controller. Finally, it turns out to be reliable and feasible to apply the control strategy after being tested with virtual DSP simulation model set with MATLAB, and on a 3KVA experimental prototype.