Nonsinusoidal Power Supply Analysis for Concentrated-Full-Pitch-Winding Multiphase Induction Motor

This paper investigates a nonsinusoidal power supply technique for a multiphase motor with a concentrated full-pitch winding. The technique focuses on how to select harmonics, how to determine the harmonics ratio, and the effects on the air-gap and yoke flux densities. Generally, the third-harmonic current is utilized for the air-gap flux density optimization in a five-phase motor. However, the method has a negative effect on the yoke flux density, and the yoke iron width should be increased. Alternatively, this problem can be solved by providing more control freedom degrees of the motor with a phase number greater than five. A nine-phase motor is employed to achieve the air-gap and yoke flux density distribution optimization simultaneously. Moreover, the performance of both motors is compared in the sinusoidal and nonsinusoidal power supply modes. The analysis of the torque density and the efficiency demonstrates that a nonsinusoidal power supply is more suitable for a heavy-load operation. Theoretically obtained results are verified by experiments.