A novel mechanical variable-leakage-flux interior permanent magnet machine (MVLF-IPMM) is proposed for electric vehicles (EVs) in this paper, which employs a mechanical flux-regulating device and auxiliary rotatable magnetic poles. The magnetic poles acting as the flux adjustors can be rotated by the additional device to vary the leakage flux in magnetic circuit and realize the adjustment of the PM flux linkage. Due to the flux-regulating effect, the flux distribution in this machine is complex and changeable. Therefore, the working principle is illustrated in detail. To obtain the perfect coordination between the dominant magnetic poles and auxiliary magnetic poles, a multi-objective optimization method is presented based on the parameter sensitivity analysis combining with the Coefficient of Prognosis (CoP). Then, some design parameters with strong sensitive are selected by the sensitivity analysis and the initial model of the proposed motor is optimized by utilizing the multi-objective genetic algorithm (MOGA). According to the result of the optimization, the machine performances of the initial and the optimal design under the different flux states are compared and analyzed to verify the validity of the new variable-flux motor and the optimization method.

In this study, a novel mechanical‐variable‐flux interior permanent magnet motor (MVF‐IPMM) is presented, which employs rotatable magnetic poles and a mechanical flux‐adjusting device placed on both sides of the rotor. The device can regulate the magnetic circuit by rotating magnetic poles and adjusting the angle of the magnetisation direction relative to the d ‐axis. Consequently, the flux‐weakening capability is enhanced. The configuration and additional mechanical devices of the MVF‐IPMM are introduced, respectively. Then, the operation principle and flux‐adjusting mechanism are deeply investigated by using analytical models, whose parameters are computed by automatic dynamic analysis of mechanical system and finite‐element analysis. Based on the simulation results, an electromechanical model is established to predict the performance of the motor. In addition, the electromagnetic characteristics of the mechanical‐variable‐flux‐ and conventional interior permanent magnet machines are compared. Finally, the effectiveness of the design is successfully proven by experimenting with a prototype.

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