A study on optimization exemplary for permanent magnet V straight shape of rotor in interior permanent magnet synchronous motor (IPMSM) is presented, aiming to achieve higher efficiency map in the operating duty cycle US06. The reduction of PM material is valuable as the cost of rare earth is increasing. The finite element analysis (FEA) is used to simulate d- and q-axis inductance, develop the efficiency map at the speed of 4500 and 9000 rpm, and analyze the energy loss. The optimal design process is introduced to reduce magnet material based on the efficiency map of IPMSM produced using FEA. This study has resulted in 20% reduction of magnet size, comparing with the original designs. The FEA result is confirmed by the tests of the prototype machine. As a result, the high-efficiency IPMSM optimizing process is concluded for electric vehicles as providing some reference in the future work.

Permanent magnet synchronous motors are the core components of electric vehicles and widely used in the field of electric vehicles. The existence of vibration will reduce the operating efficiency and service life of the motor, which is the key factor to determine whether the motor is running normally. In this paper, a certain type of permanent magnet synchronous motor is taken as the test object. The permanent magnet synchronous motor is divided into three substructures: stator, rotor and shell. The finite element modal results are obtained respectively. The modal parameters of the whole PMSM are calculated by using the substructure modal synthesis method. The weak links of the motor are found out and the structure optimization is carried out. Through the calculation of the modal analysis, it can be seen that each vibration mode of the optimized motor has been reduced, and the amplitude difference between the 2nd order and the 5th order is the largest. Finally, the modal test is carried out on the motor using the exciter method, the test results are analyzed, and the modal parameters of the motor are obtained through the frequency domain analysis method, the FEA result is confirmed by the modal test of the motor.

In order to optimize the electromagnetic performance of a permanent magnet synchronous motor (PMSM) during operation, this paper takes the size of the stator slot structure of the motor as the optimization variable and the peak cogging torque and no-load back electromotive force (EMF) amplitude of the motor as the optimization objectives. A multi-objective optimization method based on the particle swarm optimization (PSO) algorithm is adopted to obtain a structural parameter combination that minimizes the peak cogging torque and no-load back EMF amplitude while meeting the reasonable range requirements of magnetic flux density amplitude. The optimized motor structure design prototype is experimentally verified. The results show that through multi-objective optimization based on the PSO algorithm, the electromagnetic performance of the motor has been improved, with a reduction of 36.33% in peak cogging torque and 2.65% in peak no-load back EMF, indicating a reasonable magnetic flux density amplitude. The experimental results of the optimized prototype show that the difference between the theoretical simulation values and the experimental values is within a reasonable range, which verifies the effectiveness of the multi-objective optimization method.

Thermal analysis of Electric Machine for Electric Vehicles (EVs), is crucial for precisely predicting the temperature distribution. In the paper, for a forced-air cooled induction machine, two methods of thermal models analysis are compared with measurements. The first numerical method is Computational Fluid Dynamics (CFD) over Finite Element Method (FEM). And the second one uses Lumped Parameter Method (LPM). For the analysis based on CFD over FEM, a 3D induction machine is modeled with force-air cooling housing. The air flow is simulated and the losses are calculated as heat source for thermal models. FEM is coupled with CFD to get the thermal field distribution. For the LPM, the equivalent thermal resistance of winding, the heat transfer coefficients of the airgap and forced air are calculated in the LP thermal model. Finally, Measurement results are determined by PT100 embedded in winding end, as well by infrared instrumentation for measuring the image on the shell thermal distribution. Experimental validation is presented and the conclusion can be drawn from comparing these aspects of two methods, providing some reference for the research applied in motor for EVs.

Brushless direct current (BLDC) permanent magnet (PM) synchronous motors are in high demand for ventilator applications owing to their high speed, high efficiency, and other significant features. However, it has become an important problem in eddy current loss calculations with high-speed motors, which leads to low motor (ventilator) life and PM demagnetization. This paper focuses on the eddy current loss calculation and the structure improvement design for the two-pole 90 W, 47,000 r/min toothless BLDC motor. First, the influencing factors of eddy current loss are comprehensively investigated, and a multiparameter improvement methodology is proposed accordingly. Second, by finite element analysis (FEA), the effective winding length ratio and the number of parallel wires were mainly researched for the winding, and the influence on the eddy current loss and the efficiency was determined, providing a reference for BLDC high-speed motors. This study has resulted in a 34.75% reduction in the winding losses, and a 4.6% increase in the efficiency of the improved model compared with the original design. Third, the new rotor structure is proposed, saving PM volume 15% more than original. THD of gap flux density is decreased 20.97%; the eddy current loss in the new rotor is decreased 22% more than original. Furthermore, by coupling simulation of the magnetic–thermal field, the maximum temperature of winding of the improved model is 13.4% lower than that of the original model at the thermal steady state. Finally, the electromagnetic and thermal properties simulation results were verified by testing the prototype. It is of great significance to the structure design and efficiency improvement of the BLDC high-speed motor.

An improved rotor position observer based on sliding mode control was proposed to eliminate estimation error and harmonic ripples for PMSM sensorless control. A multi-proportional resonant filter was designed instead of a low-pass filter to filter out the specific harmonics of back EMF. The improved filter can solve the phase delay problem caused by a low-pass filter, eliminate the rotor angle compensator, simplify the system structure, and effectively suppress the system chattering. Then, a fractional normalized phase-locked loop was adopted to calculate the speed and rotor position, further eliminating the influence of noise. Compared with the traditional sliding mode control and the improved sliding mode control, the improved sliding mode observer can effectively suppress the back EMF chattering and reduce the speed estimation error. The correctness and effectiveness of the proposed improved sliding mode observer were verified through the simulation model and experimental platform of PMSM sensorless control.