Study On BLDC Motor Ceiling Fans And Controller Based On Pre-BUCK

Because the function of traditional ceiling fans is single and the popularity of home air conditioners, it have begun to gradually disappear. However, as people's higher demands of energy efficiency, indoor air quality, comfort and noise, an intelligent ceiling fan is in rapid development. It has different operation modes and lighting, ornamental features. At present, high quality ceiling fans on the market are still using traditional motor-driven, such as single-phase asynchronous motor, or single-phase commutator motors, which performances index is low and operating costs is high. It is difficult to meet the control requirements of high quality ceiling fans. So Permanent magnet brushless DC motor has received much attention in the high quality ceiling fans because of its good control performance.As we know, when the speed of BLDC motor is low, the duty is low that making winding current is not continuous, resulting in more high-order harmonic components, this will result in poorly smooth operation of ceiling fan, in particularly, large electromagnetic noise problems. The reasons of electromagnetic noise are numerous, but the motor winding current is discontiguous, current with high frequency harmonics have a significant effect. To this end, it regulates brushless motor's winding terminal voltage by adding a BUCK circuit between the power supply and inverter, so that the inverter don't need PWM chopper in a commutation cycle, that is, through the controller's pre-chopper to improve winding currents waveform and suppress electromagnetic noise.In this paper, the status and trends of ceiling fans as well as the outer-rotor brushless motor are introduced; the hardware and software design of pre-chopper high quality ceiling fan controller based on IPM C8051F MCU and IPM PS21964 are developed; pole-slot combinations and auxiliary slot-opening, which contribute to the generation of electromagnetic noise and ripple torque are studied; based on the hardware and software of pre-BUCK circuit controller are established and tested. The testing results show that pre-BUCK circuit brushless motor controller can improve the current waveform and reduce electromagnetic noise.