Comparison among inverters with D-Σ digital control

This paper presents a comparative study of three multi-function three-phase inverters, which include three-phase three-wire full-bridge (FB) inverter, three-phase four-wire half-bridge (HB) inverter and neutral-point-clamped (NPC) inverter. Each inverter is controlled by the division-summation (D-Σ) digital control and the control law for each inverter is derived in short. The comparison among these inverters is based on the criteria of common-mode voltage (CMV) issue for a PV system, component stress/count, efficiency, application and control complexity. Moreover, operation in both grid-connection and rectification modes are considered in the comparison. Experimental results measured from the inverters are included for performance evaluation.