Noise reduction by torque ripple suppression in brushless DC motor

The acoustic noise of a brushless DC motor is thought to be partly due to torque ripple. This paper examines, both analytically and experimentally, the effect of ripple reduction on the noise reduction. To realize the torque ripple reduction an overlapping of phase current is utilized here. In the simulation, motor parameters such as inductance, and counter EMF are derived from two dimensional FEM of magnetic field analysis. The characteristics of currents, voltages and torque of the motor are analyzed by using our own circuit simulator. It is clarified that the current overlapping is useful for the torque ripple reduction and noise reduction.