Altered PWM for DC link current translation to phase currents for electric drives

Abstract

It is possible to deduce the phase currents by sensing only the DC link current. However its effectiveness is limited by zero vectors and the minimum time needed for a stable sample and hold. This paper attempts to alleviate these drawbacks by modifying the PWM technique to increase the range and robustness of the phase current reconstruction in three phase inverters. Active pulse placement and discontinuity is introduced in the modulator to achieve it. The consequences of the proposed technique on the waveform quality are studied as well. The proposed technique is meant for applications where a cheap, efficient and robust electric drive is required. A suitable application could be that for Hybrid Electric & Electric Vehicles.