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BLDC Reference Design for Ceiling Fans

Part Number: BLDC Reference Design for Ceiling Fans

Summary:

What if there was a way to drive a fan so that it could do the same amount of work using a quarter of the power?

Microchip has developed a reference design that demonstrates how you can drive a ceiling fan at 300 RPM and only draw 25W—about the same amount of power that an LED bulb requires. This demo uses a Brushless DC (BLDC) motor and an electronic

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Product Features

    • The dsPIC33EP32MC202 is a 16-bit Digital Signal Controller (DSC) that features a 70 MIPS core with integrated DSP and enhanced on-chip peripherals. It enables the design of high-performance, precision motor control systems that are more energy efficient, offer quieter operation and have a great range and extended life.
    • Wireless connectivity is implemented via our Sub-GHz MICRF220 receiver and MICRF110 transmitter. The antenna is a PCB routing that is perfectly tuned to get the best reception despite being enclosed within a metal case. In this demo, the RF transmitter transmits at 433 KHz to offer a range of more than 20 meters. The design also includes our MIC38HC44 AC/DC controller to convert the line AC voltage to 24V DC. This circuit uses a low-cost and highly efficient flyback topology. Passive Power-Factor Correction (PFC) is implemented to keep the power factor above 0.9, even during low-power conditions. Since the fan’s DC motor runs on 24V, it is also easy to convert the design to run from a solar panel.
    • The motor commutator is a three-phase power stage controlled by the dsPIC33EP32MC202. This circuit uses three of our MIC4605 85V half-bridge MOSFET drivers and six MOSFETs to perform the six-step commutation that is required. The 85V operating voltage provides the flexibility to use 48V, 36V and even 12V motors. Since the MIC4605 needs biased voltage to drive the MOSFET, we used an MIC4684 synchronous buck regulator with internal MOSFETs and adjustable current limit. This devices provides 12V DC voltage to ensure the lowest Rds(on) from the MOSFET, resulting in the highest power efficiency. The current limit allowed us to use the smallest inductor, resulting in a lower BOM cost.
    • Since the dsPIC33EP32MC202 draws very low power, the 3.3V supply voltage can easily be driven from the 12V supply rail with our MIC5235 low dropout regulator. This device requires a very small footprint and only an input and output capacitor, while also offering reverse current protection and polarity protection.

    This BLDC fan control demo is just one example of many motor control applications that can benefit from Microchip’s complete ecosystem of solutions and development tools. Most of the same circuitry can be used for developing e-bikes, kitchen appliances, HVAC and many other motor-driven applications.

    Visit our BLDC Motor Design Center to learn more about our resources to help you design low-power, low-cost appliances and other products.


Summary

What if there was a way to drive a fan so that it could do the same amount of work using a quarter of the power?

Microchip has developed a reference design that demonstrates how you can drive a ceiling fan at 300 RPM and only draw 25W—about the same amount of power that an LED bulb requires. This demo uses a Brushless DC (BLDC) motor and an electronic commutator to enable active devices, such the microcontroller’s power stage, to drive the motor and power management devices to regulate power and connectivity devices.