PWM technique to extend current reconstruction range and reduce common-mode voltage for three-phase inverter using DC-link current sensor only

A PWM technique for three-phase inverter current reconstruction using only one current sensor is presented. As compared to previous work, the proposed technique not only can extend the current reconstruction range, but also decrease the common mode voltage of inverter output. Moreover, the theoretical analysis for the limitation to current reconstruction using only one current sensor is included in this paper. It will be shown that reduction of PWM switching frequency and acquisition time of AD conversion will extend the current reconstruction range for a given PWM technique. Experimental results derived from an FPGA-based controlled inverter show that using the presented PWM technique the three-phase current signals of inverter can be reconstructed even under very low modulation index range while reducing the common-mode noise of inverter output.