Capacitance estimation of DC-link capacitor in brushless DC motor drive systems

This paper proposes a capacitance estimation method for the dc-link capacitor in brushless DC motor (BLDCM) drive systems. The proposed method is performed in the generating mode of the BLDCM. In this mode, the inverse dc current flows to the capacitor and the capacitor voltage is increased by the generating operation. Hence, the capacitance can be obtained from the variation of the capacitor voltage and average charging current to the capacitor. The proposed method provides a reliable and sensitive indication of capacitance without additional hardware requirements. The usefulness of the proposed capacitance estimation method is verified through the simulation and experimental results.