High-precision Steady Speed Flywheel System based on Sine Wave Drive

In this paper, a set of flywheel system based on sine wave drive is designed and implemented. The brushless DC motor (BLDCM) is an important part of the flywheel in control moment gyro (CMG). In the system, sine wave drive is used to improve the steady speed accuracy and reduce torque ripple. Square wave drive is also implemented for performance comparison. The torque ripple of the square wave drive and the sine wave drive are analyzed in principle. The sine wave drive has smaller torque ripple and higher steady speed accuracy is proved by the BLDCM system model in the simulation. The resolver with its dedicated demodulation circuit is used to obtain the higher accuracy rotation angle instead of the Hall elements. The digital phase-locked loop (DPLL) control strategy is implemented by FPGA. The experiments prove again that compared to the square wave drive, the sine wave drive has higher steady speed accuracy and smaller torque ripple. It shows that the error of steady speed in the sine wave drive can be reduced to 0.03%.