Drive machines of hybrid electric vehicles (HEVs) employ axial flux permanent magnet (AFPM) motors on account of its high power density and high efficiency. The technique takes full advantage of the performance and manufacturing preponderances of soft magnetic composites (SMC). Specifically, it includes low iron consumption at high frequency and high speed, convenient machining and small relative magnetic permeability. An extra DC excitation winding is appended to the motor to conquer the drawbacks of the constant power speed ratio. It can provide an extremely wide constant power speed region, which ensures the excellent property of the machine. Finite element algorithm (FEA) is used to assess the property of axial flux hybrid excitation motor (AFHEM). Comprehensive analysis has fully indicated that larger torque density and wider speed range can be obtained by the AFHEM, which is appropriate for the application of HEV drives.

The multi-disc axial flux permanent magnet synchronous machine (AFPMSM) can provide high fault tolerance capability in applications requiring high reliability. Firstly, a topological structure of coreless AFPMSM is proposed, the magnetic circuit and the air-gap flux intensity are discussed in detail to improve stable operation of machine in this paper. The relationship between air-gap flux density and the parameters of rotor are clarified respectively based on finite element algorithm (FEA). Furthermore, the winding structure and power driver topology with fault tolerance are presented. And the 3D FEA analyzes the operation characteristics and stress of the machine. Finally, the prototype is manufactured. The results are demonstrated that the torque output and fault tolerance performance is better.

One of the parameters required for a high-performance drive of a surface-mounted permanent magnet synchronous motor (SPMSM) operating in the flux-weakening region is the torque ripple reduction. In general, the torque ripple results from many reasons, such as the machine structure, oscillations of measured speed, etc. Hence, this article proposes an optimized strategy that works in conjunction with a variable switching frequency pulsewidth modulation algorithm to reduce the torque ripple peak. For the modulating algorithm, the updated frequency changes linearly with the desired torque ripple and its predicted maximum peak. For the proposed strategy, the reflection of proportional-integral (PI) parameters is observed at the torque ripple caused by the current ripples. Therefore, a robust method for adjusting PI parameters is proposed that relies on the improved fitness function that can minimize the regulators' error and maximize the drive stability bandwidth in the flux-weakening region. This objective function is optimized offline using a genetic algorithm optimization technique. Meanwhile, a third-order generalized integral flux observer is applied in this article, providing evidence of torque ripple reduction. For driving in the flux-weakening region, the reference magnitude of the duty cycles can produce the required d -axis reference current to prevent the saturation of current controllers. Finally, comprehensive simulations and experiments are presented to validate the proposed strategy effectively. In comparison with the conventional method, the proposed strategy can reduce the copper and switching losses simultaneously and control the current and speed in the flux-weakening region efficiently.

The model predictive thrust control (MPTC) is emerging as a promising control technique for the linear induction machine (LIM) drive applications. However, the weighting factor is designed based on empirical procedures that are tedious and time consuming. In this work, a novel fuzzy weighting factor optimization method for LIM is developed to identify the suitable control action. Different from conventional fuzzy methods, the tuning process of weighting factors is regarded as a fuzzy chance constraint so as to constitute a new optimal problem without weighting factors. Hence, the optimal model can be solved by probability optimization algorithm and the corresponding equivalence class is also conducted. At last, simulation results are presented to validate the feasibility and effectiveness of this method.

This paper presents a multi-disc coreless axial flux permanent magnet synchronous machine (MDC-AFPMSM) with N pole and S pole type series magnetic circuit and open-end winding for high-reliability applications, such as small power actuator system. Firstly, the topology and driving modes of MDC-AFPMSM are presented in detail. In this paper, a multi-objective optimization function is proposed to design the machine with full consideration of various influence factors. The drive performance indexes of four-phase, five-phase and six-phase machines are analyzed and discussed. Furthermore, the main parameters of the five-phase MDC-AFPMSM with open-end winding are calculated. In order to reduce the torque ripple, the air gap magnetic flux is optimized. Finally, the operation characteristics under short-circuit and open-circuit faults are fully analyzed based on the three-dimensional (3D) finite element algorithm. Comprehensive simulation results and theoretical analysis have demonstrated that the open-end winding MDC-AFPMSM has much stronger fault-tolerant ability in comparison to that of conventional machines.

We study the two-site Hubbard-Holstein model by using an extended phonon coherent state. For the nontrivial singlet bipolarons, the double occupancy probability, the fidelity and the entanglement entropy are calculated to characterize the ground-state properties in both two-site and single-site bipolaron-dominated regimes. We use the localized minimum of the fidelity to define a crossover and plot the bipolaron phase diagram, which separates the large and small entanglement region. Furthermore, the relation between the bipolaron entanglement and the correlation functions demonstrates that the large entanglement corresponds to the large magnitude of lattice deformations induced by electrons.