Sinusoidal commutation of slotless permanent magnet synchronous machines using discrete Hall sensor feedback

An implementation for sinusoidal current control of a slotless Permanent Magnet Synchronous Motor (PMSM) with discrete Hall sensor position feedback is presented. To estimate the rotor position of the slotless PMSM, a flux estimation technique is used that takes advantage of the slotless machine's characteristically low inductance to limit flux estimation error. The rotor position is estimated using a reference model and the measured phase currents and voltages. Discrete Hall sensors are used at very low speeds to bound the position estimation error to approximately ±30 electrical degrees and to prevent the flux estimators from drilling due to measurement noise and offset. The proposed control reduces the torque pulsations present when Hall sensor position feedback alone is used. The proposed control strategy is applied to a slotless PMSM motor drive system and implemented using a digital signal processor (DSP). Simulations and experiments are carried out for the system and the results demonstrate the effectiveness of the control.