Random pulse width modulation for performance improvement of brushless DC motor drive

Brushless dc (BLDC) motor drives have gained significant attention due to their merits such as high efficiency, high dynamic response, high reliability etc. From the literatures, it is understood that there has been remarkable developments evolved in application of the feedback controllers for both the BLDC motor drive´s speed and current loops. The recent investigation and innovations in the pulse width modulation (PWM) methods are not encompassed in BLDC drives. The conventional PWM results mechanical vibration and acoustic noise, and limit the application scope the BLDC drives. This is due to the incapability of deterministic PWM in spreading the harmonic power. This paper presents random pulse width modulation (RPWM) for BLDC motor drive with better harmonic power distribution. The randomness is introduced in carrier wave by toggling between triangular wave (+fc) and its inverted form (-fc). The performance of the proposed RPWM is validated by using MATLAB software and results such as harmonic spread factor (HSF), total harmonic distortion (THD), and acoustic noise spectrum are presented. The comparison of results with the conventional PWM demonstrates the superiority of the proposed PWM.