Power factor correction in sensorless BLDC motor drive

Abstract

This work presents a sensorless brushless DC motor (BLDCM) drive with power factor correction (PFC). The speed control of BLDCM is achieved by varying the DC bus voltage of the voltage source inverter (VSI) feeding BLDCM. The BLDCM is electronically commutated using a VSI operating at low frequency switching for reducing the switching losses in VSI. A canonical switching cell (CSC) converter is used for varying the DC bus voltage of VSI. This CSC converter is operated in discontinuous inductor current mode (DICM) for achieving a power factor correction (PFC) inherently without any sensing requirement. The rotor position sensors are eliminated by using sensorless control of BLDCM. Hence, a sensorless BLDCM drive is developed as a cost effective solution for low power applications. Its performance is evaluated on a developed prototype at various speeds with unity power factor (UPF) at AC mains.