Reduction of DC-Link Current Harmonics Over Wide Power-Factor Range for Three-Phase VSI Using Single-Carrier-Comparison Continuous PWM

This paper proposes a novel continuous PWM (CPWM) method to reduce DC-link current harmonics in voltage source inverters (VSIs) over wide range of load power factor. This modulation method contributes to a lifetime extension of smoothing capacitors in motor drive systems. Furthermore, a high cost digital hardware such as a field-programmable gate array (FPGA) is not necessary because this modulation is implemented with only one carrier. The DC-link current harmonics are reduced by shifting voltage references in every half control period to reduce a fluctuation of the DC-link current around its average value. Experimental results confirm that the application of the proposed CPWM reduces the DC-link current harmonics by 24.2 % at most.