Predictive Instantaneous Torque Control for Disc Coreless Permanent Magnet Synchronous Motor With the Current Source Chopper

The disc coreless permanent magnet synchronous motor has several advantages, such as strong overload capacity, zero cogging torque, sinusoidal back EMF, and linear parameters. The motors tend to have low inductance because of the coreless structure. There is a stringent current ripple in the motor winding that produces unacceptable torque ripple if driven from conventional drivers with a pulse width modulation control method based on voltage source inverter. To solve this problem, a predictive instantaneous torque control method based on a current source chopper is proposed in this paper. As electromagnetic torque depends on the stator current magnitude and rotor angle, the relationship between these two variables is discussed. The current amplitude and switch state of the inverter are computed according to the rotor position, and the stator current magnitude can be regulated in real time by the current source chopper. The proposed control system can dramatically reduce the current ripple caused by low inductance and the validity of the proposed control method is verified by simulation and experimental results.