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.

This letter proposes a novel sliding mode (SM) disturbance observer-based technique to diagnose demagnetization fault of interior permanent magnet (IPM) motors with stator parameter mismatch impacts eliminated. First, the IPM motor model incorporating the disturbances caused by the PM demagnetization and stator parameter mismatch is established. Then, an SM disturbance observer is constructed to identify the overall disturbance caused by all parameters, with its stability discussed by using the Lyapunov function. Third, a current-analysis-based method is developed to extract the disturbance only caused by flux linkage mismatch from the overall disturbance. Third, the extracted disturbance is adopted to calculate the real flux linkage, achieving demagnetization fault judgment and demagnetization degree calculation. Finally, experiment is conducted on two IPM motors to validate the proposed flux linkage estimation and fault diagnosis methods.

A novel parallel-hybrid dual-PM machine topology with both enhanced torque density and improved flux weakening capability, is proposed for electric vehicle propulsion in this paper. The key is to artificially construct the harmonics diversity with a single-layer concentrated armature winding in the stator and thus simultaneously couple the armature field with the excitation field produced by slot PM, rotor PM and stator DC source, respectively. Enhanced torque density is obtained in this new topology due to the symmetrical flux modulation effect between dual PM sources. Moreover, benefiting from a parallel excitation characteristic of hybrid magnetic circuit, the demagnetization risk is significantly mitigated for slot PM source and thus an extended flux weakening range is obtained. In this paper, the proposed new topology and its design mechanism are investigated, along with its electromagnetic performance evaluated based on finite element analysis. Further, some leading design parameters are analyzed and determined to provide a design guideline for the proposed new topology. Finally, a prototype is built and fully tested. Relevant experimental results agree well with the finite element predication.

This paper presents a new magnetic-gear pole-changing hybrid excitation machine (MG-PCHEM), which can provide high torque density and improved flux-weakening ability. The key is to flexibly change the pole-pair number of inner excitation sources by injecting variable dc field currents, and, hence, regulate the dominant pole-pair flux components to realize an effective magnetic field adjustment. In the following paper, the machine configuration and its operation principle of flux control are introduced first. Then, the influences of some leading design parameters are analyzed including the slot-pole combination and other dimension parameters, and after which a comparative study is carried out with traditional single-stator topology. Based on the optimal design, electromagnetic performance of the MG-PCHEM is further evaluated by using the finite-element method. Finally, a prototype is designed, manufactured, and fully tested. Relevant experimental results verify the feasibility of this new hybrid solution as well as the finite-element predictions.

Efficiency remains a key challenge in wireless charging in academia and industry. In this article, a new wireless power transfer (WPT) system based on a double-half-bridge (DHB) inverter with two variable inductors (VIs) is proposed. Compared with conventional full-bridge (FB) inverters, the DHB inverter can reduce the current through the mosfet s under the same output power and thus, reduce the conduction loss. Next, by adjusting the inductances of the VIs instead of using phase shift (PS) method, the output voltage or current can be controlled, while the circulating current can be eliminated and wide-range zero voltage switching operation can be achieved. Consequently, the power loss can be further reduced. Circuit analysis, VI design, as well as hardware implementation, are provided in detail. A laboratory prototype is built to verify the feasibility of the proposed method. Close agreement is obtained between simulation and experimental results. The maximum efficiency can reach 92.4%, which is 3.65% higher than traditional PS control.

Benefiting from flexible flux control and short-circuit withstand ability, hybrid excitation machine is an emerging starter generator solution for hybrid electric vehicle propulsion. However, to realize a brushless hybrid design in conventional PM machines, a three-dimensional magnetic circuit is usually adopted, leading to complicated mechanical structure and torque density sacrifice. To address this issue, a new relieving-DC-saturation hybrid excitation Vernier machine is proposed in this paper, which integrates good torque density and bidirectional flux control within a simple and brushless structure. The key is to artificially construct reluctance effect in a consequent-pole Vernier PM machine (CP-VPMM) by introducing extra DC field excitation equipped with relieving-DC-saturation ability. In this way, the advantages of bidirectional flux control in stator-DC-excited reluctance machine and good torque density in CP-VPMM are well combined in this topology, making it especially suitable for multi-mode starter generator application. In this paper, the machine structure and its design mechanism are introduced, with its electromagnetic performance evaluated by the finite element simulation. A prototype is manufactured and tested. Experiment results verify the feasibility of this new topology.