A current reconstruction algorithm for three-phase inverters using integrated current sensors in the low-side switches

Power semiconductor switches that include integrated pilot current sensors create opportunities to eliminate external current sensors in three-phase inverter applications. Each of the three conventional low-side power switches in a three-phase inverter can be replaced by one of these special devices that is designed to provide a sensing level current that accurately mirrors its total forward current. Recognizing that the output current in each phase flows through the low-side switch for only a portion of the fundamental cycle, a technique has been developed to reconstruct the full phase current waveforms for R-L loads using only the incomplete phase current measurements. The performance characteristics of the proposed current reconstruction technique are experimentally verified, including demonstration of a closed-loop three-phase current regulator using the reconstructed current feedback from the integrated pilot current sensors.