Abstract
Variable speed drive systems of brushless DC motor have been widely used for industry applications, home electric appliances, and so on, due to the progress of the power electronics, because of simple structure, easy maintenance, high efficiency, etc.. However, structural imperfectness of brushless DC motor and its control system produce torque ripple, and cause mechanical vibration and torque ripple and acoustic noise.
In this paper, authors propose a suppression control method of vibration for brushless DC motor utilizing feedforward compensation control, and a generation method of compensating signals for the feedforward control by repetitive control with Fourier transform utilizing a vibration signal acquired by an acceleration sensor attached to the motor frame.
Because the vibration signals detected by the acceleration sensor contain various complicated frequency components due to motor torque vibrations and mechanical resonant vibrations around the motor load system, we can not stabilize the repetitive control system and reduce the vibration by directly using the vibration signals from sensor itself. So we propose a generation method of the compensating signals of the repetitive controller considering the periodicity of motor torque ripples, and using Fourier transformer which can select particular frequency components. In order to realize on-line generation of feedforward compensating signals to reduce the vibration, auto-tuning method of the repetitive control parameters is also presented.
An experimental system to detect and reduce the motor torque vibration is constructed, and the effectiveness of the proposed method is confirmed by experimental results.
