Single current sensor operation with fixed sampling points based on TSPWM

The single current sensor operation (SCSO) is favorable for cost reduction and fault-tolerance purposes in three-phase inverter-driven systems. This paper addresses a SCSO method based on tri-state pulse-width modulation technique (TSPWM). It enables fixed sampling points with minimal hardware and software requirements. Simultaneous three phase currents can be easily computed due to symmetrical sampling. No change to TSPWM is needed for most working points, thus it maintains advantages in common-mode voltage (CMV), switching loss and DC current ripple reduction. Based on the detailed analysis of non-ideal factor effects, regional modifications enlarge the feasible voltage region to almost the whole hexagon. It works well in close-loop systems and enables seamless transition in fault-tolerance operation for current sensor. Experimental results on a 4-kW induction motor drive are presented to verify the above-mentioned conclusions.