The design is specifically tailored to control a low-voltage, three-phase BLDC ceiling fan motor with a power output of up to 40 watts.
To minimize residential energy consumption, ceiling fans and other household fans are transitioning from large and heavy single-phase AC induction motors (ACIM) to smaller, lighter, and more efficient three-phase brushless DC (BLDC) or permanent magnet synchronous motors (PMSM) that offer higher power density. Microchip has launched a reference design for a low-voltage ceiling fan that provides a cost-effective and energy-efficient solution for a low-voltage PMSM fan. The design can operate a ceiling fan at 300 Revolutions Per Minute (RPM) while consuming approximately 17.5W of power, equivalent to the energy required by two Light-Emitting Diode (LED) bulbs that are approximately 60 Watt. This Reference Design controls a low-voltage, three-phase PMSM/BLDC ceiling fan motor. The board operates from the input AC power within the 90-265 VAC voltage range. The design can drive BLDC/PMSM motors with a power output of up to 40W.
The Reference Design incorporates several key features such as a three-phase motor control power stage, a 32V, 45W flyback power supply with switched valley-fill power factor correction (PFC), an auxiliary power supply to support the on-board circuitry and external interfaces, DC bus current feedback for overcurrent protection and the implementation of a single shunt current reconstruction algorithm. It also includes DC bus voltage feedback for voltage protection and compensation, an AC voltage measurement circuit, phase voltage feedback for sensorless back-electromotive force (BEMF) control or flying start (windmilling), and an ICSP header for interfacing with a Programmer or a Debugger.
The design is based on the Digital Signal Controller (DSC), dsPIC33CK64MC102 that is equipped with enhanced on-chip peripherals, including high-speed Pulse Width Modulation (PWM), high-speed ADC, operational amplifiers, comparators, communication peripherals, timers, and more. Transitioning from a high-voltage single-phase ACIM to a lower-voltage 3-phase PMSM/BLDC motor necessitates a two-stage power conversion circuit. Firstly, a flyback converter circuit transforms the input power ranging from 90-265 VAC into an intermediate 32 VDC, incorporating high Power Factor Correction (PFC) to ensure energy efficiency. The power factor remains above 0.9, even during low-power scenarios, creating the necessary voltage bus to drive most PMSM motors. The 32 VDC is then reduced to 10V using a PWM DC/DC Converter. Additionally, the 10 volts is further decreased to 3.3V with a highly efficient Low Drop-Out (LDO) Voltage Regulator, serving to power the DSC.
Microchip has tested this reference design. It comes with a Bill of Material (BOM), schematics, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.