Alternative Vector PWM for CSI Common-Mode Voltage Reduction During Voltage-Boost Operation with Low Modulation Index

This paper proposes a new pulse-width modulation (PWM) scheme named alternative vector PWM (AVM) algorithm that reduces the common-mode voltage (v
CM
) generated by a 3-phase current source inverter (CSI) during operation within a portion of its voltage-boost regime when the CSI’s modulation index is below $1/\sqrt 3 ( = 0.5774)$. Three different active current vector pairs (one conventional pair with adjacent active current vectors and two proposed pairs with non-adjacent active current vectors) are used to reduce v
CM
based on the CSI’s output voltage conditions. Experimental results confirm significant reductions in major v
CM
spectral components by up to approx. 85% between the 3
^rd
harmonic of the fundamental frequency and the CSI’s PWM frequency, validating the advantages of the proposed AVM algorithm over the conventional PWM.