The design of permanent magnet motors for the battery-powered electric vehicle has different aspects. In this study, the conceptual design process of an electric machine for Sedan Low car is presented. Based on the vehicle requirements an interior permanent magnet motor with a maximum power of 120 kW with different slot/pole combinations is designed. To obtain the best slot/pole combination, The New European Driving Cycle in term of crucial performance characteristics is compared. Given the importance of irreversible demagnetization phenomenon to an electric vehicle application, an accurate approach to determine the irreversible demagnetization rate is first introduced. Design tips are then proposed to reduce the probability of the irreversible demagnetization. Finally, fault-tolerant design in case of irreversible demagnetization withstand capability is carried out using a two-level Taguchi optimization approach. The results obtained from this study indicated that the proposed approach is effective in the fault-tolerant design of the permanent magnet machine for the electric vehicle applications.

Permanent Magnet (PM) machines have attracted much attention due to their high power-torque density, high efficiency, high dynamic response performance, high power factor, and simple structure. Even though there are some uncertainties about their reliable chain supply, PM machines still are the first choice for high-performance applications. Therefore, paying attention to the development and improvement of the performance of these types of electric machines is of great importance. One of the challenges of the PM machines is their vulnerability to Irreversible Demagnetization (ID), especially for applications such as Electric Vehicle (EV) which the working temperature and Magnetic Motive Force (MMF) produced by stator winding are higher than in conventional applications. Therefore, the ID phenomenon must be regarded as a leading design and control parameter for PM machine designers. The ID can be defined as an irreversible reduction of the remnant flux density of the PM or the EMF of the PM machine due to severe temperature conditions, high external Demagnetization Field (DF), or non-proper design of PM machines, resulting in degradation in performance of the PM machines. The lack of a good source that gives a deep inside into this phenomenon in designing and developing PM machines encourages the author to conduct a comprehensive literature review. For proper design of the PM machines in terms of ID, it is necessary to consider four critical steps, i.e.: (a) accurate non-linear modelling of the PM demagnetization curve, (b) analytical model taking into account local ID, (c) geometry optimization methods targeting ID, (d) accurate experimental testing to evaluate the ID fault-tolerant capability of the manufactured PM machines. In this paper, the above four aspects are surveyed exclusively, and the advantages and disadvantages of the existing methods in these areas are highlighted. Furthermore, design tips towards the design of ID fault-tolerant PM machines and other research opportunities to enhance the reliability of PMs machines are also presented.

With growing environmental concerns and the limitations of fuel cell resources, replacing petrol-based engines with electric machines as the traction motor for electric vehicles (EVs) is gaining attention. Among the different electric machines topology, for lower power applications such as three-wheel motorcycle, the Brushless Direct Current (BLDC) motors are the most favorable due to their simple structure, simple control algorithm, etc. One of the key aspects of developing BLDC motors in EV applications is utilizing the fast and efficient optimization algorithm over driving cycles. Another aspect is considering manufacturing tolerances to eliminate the failure product rate in mass production. The combination of optimization algorithms with consideration of manufacturing tolerances leads to a complex and time-consuming optimization procedure. To overcome this problem, the robust design by utilizing the Design of Experiment (DOE) method can be utilized. In this study, first, a developed systematic multi-physics multi-level optimization algorithm with consideration of manufacturing tolerances and driving cycles is proposed. Then, to evaluate the accuracy of the optimization process, a prototype of the optimized motor is manufactured. The efficiency and accuracy of the optimization algorithm are compared through Finite Element Method (FEM) and experimental results, showing the effectiveness of the proposed algorithm.

In this paper, a sequential Taguchi method for design optimization of an induction motor (IM) for an electric vehicle (EV) is presented. First, a series of empirical and mathematical relationships is systematically applied to reduce the number of possible stator slot rotor bar (SSRB) combinations. Then, the admissible optimal combinations are investigated and compared using finite element (FE) simulation over the NEDC driving cycle, and the three best combinations are selected for further analysis. Each topology is optimized over the driving cycle using the k-means clustering method to calculate the representative working points over the NEDC, US06, WLTP Class 3, and EUDC driving cycles. Then, using the Design of Experiment (DOE)-based Taguchi method, a multi-objective optimization is carried out. Finally, the performance of the optimized machines in terms of robustness against manufacturing tolerances, magnetic flux density distribution, mechanical stress analysis, nominal envelope curve and efficiency map is carried out to select the best stator slot rotor bar combination. It is also found that the K-means clustering method is not completely robust for the design of electric machines for electric vehicle traction motors. The method focuses on regions with high-density working points, and it is possible to miss the compliant with the required envelope curve.

The manufacturing processing of Electrical Steel Laminations (ESLs) for electric machines comprises cutting, stacking, and housing techniques which can result in plastic deformation and residual stress in the soft magnetic material. These manufacturing processes result in decreasing the magnetic quality and a local increase in both the static and dynamic hysteresis losses near the cut edges and consequently a reduction in the performance of the designed motor. The iron losses resulting from cutting can vary by a factor of two or more depending on geometrical, material, and processing parameters as well as the magnetic field strength. It is advantageous to consider these manufacturing effects in the design stage to reduce the probability of underperforming mass production. In this paper, the manufacturing processes of ESLs and their modelling methods are comprehensively surveyed. The gaps in scientific understanding and the research need for the expansion of accurate modelling of the cutting and joining of ESLs are subsequently discussed.