Phase current estimation of BLDC motor drive system by using source side current of DC-link

This paper proposes an estimation algorithm of phase currents of inverter systems with the planar bus bars for brushless DC motors (BLDCM). In these inverters, a DC-link single current sensor measures the sum of a smooth capacitor current and phase currents of BLDCM. It is essential to extract phase currents from the measured single current to control BLDCM. Therefore, in this paper, the phase current is estimated by analyzing equivalent circuits of BLDCM in ON and OFF periods of switching elements. The usefulness of the proposed algorithm is verified through simulation and experimental results.