New control strategy of variable reluctance direct drive motor for robotic applications

Dual Stator Variable Reluctance Motors (VRM) are electrically commutated ac machines and can be used as direct drive actuators, but inherent nonlinearity of VRM results in difficulties, when smooth and quiet operation are required. In this paper, a high performance control system for VRM is presented. The whole control algorithms consist of four closed-loop controllers: position, velocity, torque and current controller. In the torque controller, the torque ripple is reduced via the torque-sharing function and current PWM control, and the command current is easily obtained from the shared torque command via the proposed nonlinear model of the motor. The velocity controller is a combination of fuzzy and proportional-integral algorithm. The lead angle algorithm is also introduced to improve the performance of system in high speed. The position controller is intended for velocity trajectory tracking. The experimental results illustrate the effectiveness of the control system.