Analysis of phase current reconstruction precision for PWM-VSI

In order to lower the cost and volume, the operation of pulse width modulation voltage source inverter (PWM-VSI) fed permanent magnet synchronous machine (PMSM) vector control system without AC current sensors is investigated. The information of AC motor currents is obtained through current reconstruction algorithm by using only a DC-link current sensor. An adjusting scheme for switching states is developed to fulfil the requirements of DC-link current detection and realize the reconstruction of AC motor currents. The errors between the reconstructed phase currents and the real phase currents are discussed. The causes of reconstructed current errors are analyzed in detail and some solutions are proposed. Experimental and simulation results show that, by using the developed methods, the operation of PWM-VSI fed PMSM drive system by using single DC-link current sensor is implemented and the reconstructed current errors are reduced. These works are also beneficial for the performance improvement of other AC adjustable speed drives.