Open Collections

Feng, Ziliang (Bruce)

University of British Columbia

Hall-sensor-controlled brushless DC (BLDC) motors are extensively utilized in many applications due to their simple manufacturing and straightforward control. The conventional commutation methods use the 120º and 180º commutation logics. The 120º commutation directly derives from the Hall signals and naturally approximates the maximum torque per Ampere (MTPA) operation, achieving higher efficiency. The 180º commutation is preferred in applications requiring higher DC voltage utilization. The common drawback of the 120º and 180º commutated BLDC motors is the presence of a significant torque ripple. This represents a challenge for high-precision applications and necessitates further research and improvements. This thesis proposes three novel control schemes to advance the state-of-the-art torque ripple reduction of BLDC motors. First, a proportional-plus-integral (PI) controller is proposed to directly regulate the torque under 180º commutation. Second, a more accurate torque control under 180º commutation is proposed, which adjusts the pulse-width-modulation (PWM) duty cycle of the inverter in every switching interval based on the torque derivatives to minimize the torque ripple while tracking the torque reference. This method achieves better dynamic response and torque ripple reduction by 86.3% compared to the conventional 180º commutation. Third, the switching logic is extended to cover any conduction angle between 120º and 180º while maintaining effective torque control during the conduction and commutation intervals for BLDC motors with either sinusoidal or trapezoidal back EMFs. The proposed generalized algorithm is demonstrated to effectively reduce torque ripple over a wide range of speeds by extending the conduction angle beyond 120º and achieving higher DC link voltage utilization. The new method is envisioned for many applications utilizing Hall-sensor controlled BLDC motors where reduced torque ripple, higher efficiency, and faster transient response are desirable.

Text; Still Image

2025-05-01

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/90930

Electrical and Computer Engineering

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/