Field Weakening Operation of High Torque Density Five-Phase Permanent Magnet Motor Drives

This paper investigates the field weakening operation of a five-phase permanent magnet motor. The proposed motor has concentrated windings such that the produced back-EMF is almost trapezoidal. The motor is supplied with the combined sinusoidal plus third harmonic of currents. This motor, while generating the same average torque as an equivalent permanent magnet brushless DC motor, overcomes its disadvantages. It is shown that torque producing and flux producing components of current for this motor can be decoupled by using multiple reference frame transformation. Therefore, vector control is easily applicable to the motor. Field weakening algorithm is derived and implemented. This motor benefits from high torque density of a BLDC motor below the rated speed and controllability of PMSM above the rated speed and during the field weakening region. Simulation and experimental results are provided to prove the validity of the superior performance of this drive