Low-Cost BLDCM Ceiling Fan with Improved Power Quality and Efficiency

This paper presents the low-cost solution for the permanent magnet brushless direct current motor (PMBLDCM) based ceiling fan (CF) with reduced harmonics distortion and unity power factor (UPF) operation. The bridgeless switched inductor Cuk (BL-SIC) converter improves the step-down gain with the switched-inductor branch. It provides the variable voltage output (DC-link voltage) with improved power quality indices (PQI) at the supply input. The change in voltage output of the power factor correction converter (PFCC) is utilized to control the CF speed, which provides the commutation frequency operation of the voltage source inverter (VSI). It leads to reduced switching losses in the VSI and improves the CF efficiency. Moreover, the bridgeless structure of the PFCC reduces the conduction losses, which further enhances the overall efficiency of CF. The front-end PFCC is designed in discontinuous inductor current mode (DICM) to get the inherent PFC at the supply input. The operating duty cycle for the PFCC is estimated from the reference speed of the fan with appropriated gain to generate the fixed frequency (200kHz) PWM pulses. It eliminates the required complex sensing circuit, DC-link voltage sensor, and voltage controller, which reduces the overall cost of the CF. The input supply voltage is considered constant throughout its operation, just like a single-phase induction motor CF. Furthermore, the position sensors are eliminated using back-EMF sensorless control. Simulated results are shown to validate the concept and design of the front-end PFCC for the CF.