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Velocity control and sensorless drive of slim axial flux permanent magnet BLDC motors for blowers in vacuum cleaners

This paper presents a novel sensorless drive method of the Axial flux permanent magnet (AFPM) brushless direct current (BLDC) motors by detecting zero-crossing points of back electromotive force signals from the standstill state to the desired velocity. A soft-switching mechanism is combined with the sensorless drive approach to achieve low electronic noise that produced by transistor switching. Furthermore, coreless design can reduce mass, normal attractive force and torque pulsation and can increase efficiency of machines as compared with conventional design with cores. Consequently, this study focuses on slim sensorless AFPM BLDC motor design for blowers in vacuum cleaners to follow the concepts of axial flux, flat wire with high lamination factors, and stators without ferromagnetic cores. Besides, three fixed gain coefficients of PID controllers are tuned by adopting fuzzy inferences which provide mapping from the error and the derivation of the error to PID parameters. As a result, the settling time of velocity control with self-tuning fuzzy PID controllers is converged within 1.0 second; i.e. the vacuum cleaners can switch different speed rapidly when they operate at different dust-disposal environments, and the control approach has strong robustness and well precision in steady state. Therefore, velocity control by adopting self-tuning fuzzy PID control algorithm has been demonstrated effectively for slim sensorless AFPM BLDC motors of blowers in vacuum cleaners.