Traditional perspective considers that there is a trade-off between the postfault operational performance and the implementation complexity of the control scheme. To approach this problem, this paper proposes a natural full range minimum-loss strategy by analyzing the current relation between torque subspace and harmonic subspace. The harmonic subspace current references satisfying full range minimum-loss are generated by a simple expression according to the real-time subspace current vector features. Compared with existing fault-tolerant control methods, the proposed strategy does not need complicate fault diagnosis, as well as offline or online optimization process. The experimental results demonstrate that the proposed fault-tolerant control strategy can achieve smooth prefault to postfault transition and FRML simultaneously.

In recent years, the power, torque, speed, and other performance of interior permanent magnet synchronous motor (IPMSM) for electric vehicles have improved. The temperature rise is an important factor limiting the performance of the motors. In this article, a novel hollow shaft oil injection cooling structure is proposed. The cooling oil is passed in from one end of the hollow shaft and enters the permanent magnet cavity through the radial oil channel. The centrifugal force generated by the rotation of the rotor causes the oil to be sprayed from the oil injection holes on the end caps at both ends of the rotor, and the winding ends and the stator are directly cooled, which reduces the internal temperature of the motor. The Taguchi method is used to analyze the influence of the novel hollow shaft oil injection cooling structure on the average temperature of the winding and the difference in the injection flow rate at both ends of the motor. Considering various operating conditions, the optimization scheme of the cooling structure is determined. Finally, the reliability of the structure is verified by stress calculation and modal analysis.

In this paper, a rotor magnetic potential (RMP) model is proposed, which can accurately describe the rotor surface magnetic potential distribution under the interaction of multi-excitation sources. Furthermore, a new magnetic equivalent circuit (MEC) model is used to model the complex saturation in the bridge region, which employs an improved nonlinear reluctance modeling method. Then, the unknown parameters in the RMP model are obtained by solving the MEC model. In this paper, the RMP model and MEC model are combined to consider the stator and rotor saturation effects, and the magnetic field is calculated accurately. Compared with the existing RMP model, the proposed one can take into account the effects of the stator saturation and PM magnetic field. Compared with the existing MEC and equivalent magnetic network (EMN), the area of the nonlinear reluctance in this paper varies with excitation conditions, which can accurately consider the saturation effects in the bridge region. This improvement can improve calculation accuracy on the basis of reducing the number of nonlinear reluctances. Moreover, the proposed method does not need to consider the change of the air-gap reluctances caused by rotor rotation. Finally, the proposed method is verified by both finite element analysis and experiments.

There are many space harmonics in the stator magnetomotive force (MMF) of fractional-slot concentrated winding (FSCW). These harmonics will produce high eddy current losses in the permanent magnet (PM), which will reduce motor efficiency and affect motor performance. Aiming at the above problems, the harmonic components of traditional stator MMF are first analyzed in this article, and then, a novel space-shifted unequal-turn winding structure is proposed for dual three-phase fractional-slot permanent magnet synchronous motors (PMSMs). Meanwhile, the sub- and super-harmonics in the stator MMF can be simultaneously eliminated using the proposed winding structure. To verify the effectiveness of the proposed structure, an 18-slot/8-pole motor and a 30-slot/14-pole dual three-phase fractional-slot PMSM with low space harmonic are designed by using the proposed space-shifted unequal-turn winding structure based on the analysis of nine-slot/eight-pole and 15-slot/14-pole motors. Finally, by comparing the finite element analysis (FEA) results, it is verified that the dual three-phase PMSM motor with the proposed structure has smaller eddy current losses in PM and better motor performance.