In this paper, a novel direct-drive double rotor Vernier panent magnet (DR-VPM) machine is proposed and analyzed. The key of the design is to incorporate two concentric rotors and the Vernier structure within one permanent magnet (PM) machine, while keeping the machine volume and slot number unchanged. The main merits of this proposed machine are its compact structure, improved torque density, reduced stator end winding length, and reduced copper loss. The operating principle of the machine is discussed and its steady and transient performances are analyzed using circuit-field-motion coupled time-stepping finite element method (CFM-TS-FEM). A dual-excitation PM Vernier (DE-VPM) machine and a single outer rotor PM Vernier (SR-VPM) machine are designed and compared with this proposed Vernier PM machine using CFM-TS-FEM. Comparison results as reported are used to confirm and validate the advantageous performance of the proposed machine.

This paper proposes a novel model predictive control for a three-phase permanent magnet synchronous motor (PMSM) with enhanced robustness against parameter variation and higher current control precision. First, the extended set of voltage vectors are adopted to increase the current control precision. Then the parameter sensitivity problem is avoided in the first stage using an indirect reference vector strategy for the sake of computation time reduction. Subsequently, the inductance disturbance observer is adopted in the current prediction process to enhance the robustness against machine parameter mismatch. The intrinsic connection between the discrete control sets precision and disturbance is analyzed. The proposed method improves the robustness against parameter mismatch and current control precision simultaneously. Experimentations are conducted to verify the effectiveness of the proposed method.

Electric motor is one of the core components of electronic propulsion systems and plays an essential role in the industry. The optimal design of an electric motor poses a complex nonlinear problem, often challenging traditional methods to strike a balance between accuracy and efficiency. Achieving accurate analysis and holistic optimization typically entails significant computational requirements, particularly when dealing with massive individuals. As a result, researchers begun to explore the utilization of data-driven surrogate models to resolve this dilemma. This review paper focuses on investigating the leading techniques employed for constructing data-driven surrogate models to assist and facilitate the design optimization process of electric motors. These techniques encompass statistical models, machine learning models, deep learning models, and other artificial intelligence-based technologies. The paper provides a comprehensive survey of the underlying principles and offers detailed examples of studies that have utilized these diverse models. Besides, the performances and potentials of these models are highlighted with comments, shedding light on their respective strengths and limitations. Furthermore, the research challenges that lie ahead and promising avenues for future improvements under this topic are discussed.

Vernier permanent magnet (VPM) machines can be utilized for direct drive applications by virtue of their high torque density and high efficiency. The purpose of this paper is to develop a general design guideline for split-slot low-speed VPM machines, generalize the operation principle, and illustrate the relationship among the numbers of the stator slots, coil poles, permanent magnet (PM) pole pairs, thereby laying a solid foundation for the design of various kinds of VPM machines. Depending on the PM locations, three newly designed VPM machines are reported in this paper and they are referred to as 1) rotor-PM Vernier machine, 2) stator-tooth-PM Vernier machine, and 3) stator-yoke-PM Vernier machine. The back-electromotive force (back-EMF) waveforms, static torque, and air-gap field distribution are predicted using time-stepping finite element method (TS-FEM). The performances of the proposed VPM machines are compared and reported.

This paper proposes and implements a new three-phase 12/8-pole brushless doubly fed doubly salient machine (BDFDS) for wind power generation. The key is to design and control the proposed BDFDS machine in such a way that the system can offer constant output voltage and efficiency optimization over a wide range of wind speeds. First, the machine output power equation is derived to initialize the machine dimensions. Second, finite-element analysis is performed to finalize the machine dimensions as well as to determine the machine parameters and characteristics. Third, the system model is formulated and applied for computer simulation. Finally, the whole system is prototyped for verification, with emphasis on the constant voltage regulation and efficiency optimization

This paper systematically studies a new kind of PM machines with both stator and rotor PM excitations, namely, dual-PM excited machines. The key is to rely on the PM-iron structure in the machine to provide both PM excitation and flux modulation. Besides the fundamental field component in the air-gap, some other predominant harmonics introduced by the flux modulating effect can also contribute to the electromagnetic torque production. Therefore, this kind of machines can be designed with high torque density. Four dual-PM excited machine concepts with the same rotor configuration but different stator structures are comparatively studied, which include double-stator PM machine, stator multitooth-PM machine, stator slot-PM machine, and stator tooth-PM machine (STPM). Based on the flux modulating effect, the general design principle of the dual-PM machines is proposed in this paper. Through analytically investigating the air-gap field harmonics, the physical insight of the dual-PM machines is brought forward. All the four machines are optimized using an improved Tabu search coupled with finite element method, and their electromagnetic performances are comprehensively studied and compared. A prototype of STPM is manufactured. Experimental tests are conducted and the results well verify the electromagnetic design.