Traditional ultralocal model-based predictive current control (UL-PCC) method has strong robustness on current control; however, the UL-PCC still relies on inductance to design the controller gain, which really deteriorates its robustness on parameter. To solve it, a parameter-free ultralocal model-based deadbeat predictive current control (PF-DPCC) method using finite-time gradient method (FGM) is proposed in this article for permanent magnet vernier motor (PMVM) drives. The UL-PCC is first modified considering rotor speed without any extra parameter. Then, the impact of initial controller gain on robustness is analyzed and an extreme low duty-cycle current signal which has negligible impact on current is injected to estimate the controller gain of PF-DPCC adaptively on the basis of the deadbeat concept and the FGM. Hence, all motor parameters are not required in advance and the initial controller gain can be set as 1 directly. Then, the robustness can be effectively improved and the dependence on initial value of controller gain can be eliminated. Finally, the effectiveness and the correctness of the proposed PF-DPCC are experimentally verified on a 400-W PMVM drive platform.

This article proposes a multiobjective optimization design framework for a double stator brushless hybrid excitation motor (DSBHEM) to provide high torque, wide flux regulation ability and low torque ripple. The design variables are divided into sensitive level and insensitive level by sensitivity analysis. The response surface model (RSM) and nondominated sorting genetic algorithm 2 (NSGA2) are organically combined to generate a set of Pareto solutions for the sensitive level variables, from which the optimal values of the sensitive level variables are obtained. In addition, the optimal values of insensitive variables are obtained through single parameter scanning optimization, and a set of final optimal design variables are obtained. The electromagnetic performance of the initial design and the optimal design are compared with finite element analysis. Finally, a prototype is manufactured to verify the proposed concepts.

This article proposes a consequent-pole unequal Halbach vernier wheel motor (CPUHVWM), which effectively reduces the self-flux leakage between permanent magnets, and an optimization method is proposed to improve the motor optimization efficiency and shorten the optimization time. The key variables are selected by the sensitivity analysis, and a polynomial function suitable for the optimization algorithm is constructed based on the response surface method. Based on the particle swarm optimization algorithm, the weights of different particle search areas are assigned to improve the overall optimization efficiency of the algorithm. Furthermore, to verify the superiority of the performance of the proposed structure and the applicability of the algorithm, the other two similar motor structures are compared, and the algorithm is adopted for the optimization. The optimized electromagnetic characteristics are compared by the finite element method. Finally, the prototype with the optimal parameters is built, and the effectiveness and advantages of the optimization algorithm are verified by experiments.

Due to the complex boundary conditions of the thermal analysis method (AM), the error of the calculation results is large, and the lumped-parameter thermal network (LPTN) mostly focuses on the solution of the average temperature. This paper proposes a thermal analytical model for wheel-motor windings, which includes LPTN and AM to solve the problems of boundary condition extraction and maximum temperature solution in AM. The heat transfers between the end caps of electric vehicle wheels and the outside air are considered by the model. The node temperature of LPTN can be adopted as the boundary condition of the proposed analytical method to predict and calculate the maximum temperature and average temperature of the wheel motor and improve the accuracy of temperature rise calculation. To further analyze the winding temperature, the armature winding is divided into active winding and end winding for calculation respectively. In the calculation of active winding, based on the equivalent area method, the active winding and other materials are layered into a series of equal-width rectangular rings through a novel layered strategy. The compensated thermal resistance (TR) is introduced into the analytical model of end winding, and the accuracy of the end temperature solution is improved by the iteration of compensated TR. Finally, the effectiveness and correctness of the proposed analytical thermal model for motor temperature rise prediction are verified on a 2kW distributed double-layer winding wheel motor.

A radial-axial consequent pole hybrid excitation machine (RACP-HEM) with the advantages of interior permanent magnet synchronous machine (IPMSM) and electric excitation machine is studied, which has high torque output and wide speed range for electric vehicles (EVs). The radial-axial d-q axis model is established to solve the problem that the inherent asymmetry of the airgap density of consequent pole leads to difficult mathematical modeling. The current region control strategy with torque and speed as the criteria is proposed to efficiently improve operation performance of the RACP-HEM, which divides the operation region into different modes to realize high output torque and wide speed region. The maximum torque per ampere (MTPA) control of armature and excitation currents is integrated with the advantages of AC excitation and compared with i_d =0 control for low-speed region to obtain higher output torque. In high-speed region, the hybrid advanced angle field weakening control with three-dimensional (3-D) current vector is adopted to utilize the excitation current to solve the problem of the field weakening out of control caused by the traditional voltage feedback field weakening control to achieve higher speed. Finally, the simulation results and prototype experiments verify the effectiveness of the proposed control strategy for RACP-HEM.

A new consequent-pole permanent magnet (CPM) machine with segmented structure/unequal teeth (CPM-SU machine) is proposed in this article. The segmented structure is adopted to decrease the torque ripple. To improve the torque density, the structure of unequal teeth is used in this proposed machine. The five-phase winding located in the stator is composed of three fractional-slot concentrated windings (FSCWs), which are helpful to improve the fault-tolerant capability. Permanent magnets (PMs) are placed in the rotor. To decrease the PM cost, V-type PMs and iron cores are arranged with the sequence of S-iron-S-N-iron-N. The magnetic field generated by PMs is investigated, which is helpful to demonstrate the working mechanism of this proposed CPM-SU machine. To verify the superiority of the proposed CPM-SU machine, a conventional CPM machine with unsegmented structure/equal teeth (CPM-UE machine) is proposed. The electromagnetic properties of these two machines, including the electromagnetic torque, the cogging torque, and the back electromotive force (back EMF), are analyzed by the finite element (FE) method. The simulating results show that the CPM-SU machine can exhibit excellent performances, such as low torque ripple and high torque density.