A Power Control Strategy for PWM Rectifier under Unbalanced Input Voltage

A control strategy of positive and negative sequence controllers for three phase voltage source PWM rectifier based on power-equation principle is proposed aim at eliminating the harmonic of dc output voltage. The strategy calculates the commands of positive and negative sequence currents using the equation principle of instantaneous power, and designs positive and negative sequence controllers to regulate the positive and negative sequence currents separately. By decoupling feed-forward and PI controller, this strategy can achieve good performance. The details of the strategy are given then. The phase of the unbalanced voltage is locked using phase locked loop (PLL). The positive and negative sequence currents are separated and picked up using notch filters, and controlled by decoupling feed-forward and PI controller. The results of the simulation verify the correctness of the proposed control strategy.