Reconstruction Strategies for Phase Currents in Three Phase Voltage-Source PWM Inverters

Based on the relationship among DC-link current,switching states and three phase current,a new method using DC-link current and switching states is proposed to reconstruct all inverter phase currents.The generation of switching states is based on the improved current hysteresis-band digital controller.The IIR (Infinite Impulse Response) digital filter is designed to reduce the measurement noise and the errors from reconstructing the phase currents.The simulation results obtained from a vector-controlled induction motor are used to show the effectiveness and accuracy of the new method.Within the scheme,only one DC-link current sensor is used,which reduces the cost and enhances the fault-tolerance performance of the drive system.The proposed algorithm is independent of the motor model parameters and the load applied;therefore,it can be applied to any 3-phase motor drive systems operating under balanced phase current regulation.