Permanent magnet synchronous machines (PMSMs) are widely used in electric vehicles due to their high power density, high efficiency, etc. Core losses account for a significant component of the total loss in PMSMs. Therefore, it is necessary to carefully consider it when designing PMSMs according to actual scientific research project applications. This paper extracts the characteristic operating points of the PMSMs under different operating conditions at different speeds. Then a harmonic analysis of air-gap flux density, phase current, core loss was completed, and detailed comparative analysis was performed. A novel method for comprehensively analyzing the stator core loss of PMSMs for vehicles is proposed, which reveals the law of the core loss of the PMSM under Maximum-Torque-Per-Ampere (MTPA) and Space Vector Pulse Width Modulation (SVPWM). The method was verified by a prototype experiment where the actual core loss of PMSMs was measured to verify the correctness of the method. This research provides a reference for accurately predicting core loss during the forward design of PMSMs and completing core loss evaluation for existing PMSMs.

The rotor eccentricity and manufacturing tolerances caused by unavoidable uncertainties in the process of manufacturing deteriorate the cogging torque of permanent magnet (PM) motors. To guide the design and optimization of PM motors, this paper proposes an analytical model to reveal the effects of mixed-eccentricity (ME) and manufacturing tolerances on the harmonic components of cogging torque. A coefficient is introduced to intuitively characterize the impact of ME on the distribution of the air-gap length. Then a modified analytical model is developed to theoretically identify the additional harmonic components (AHCs) of cogging torque associated with the eccentricity and tolerances. And the main AHCs of cogging torque are quantitatively determined through the finite element method. Finally, suggestions to improve the robustness considering uncertainties by selecting pole/slot combination and pole-arc ratio are proposed.

This paper proposes a computationally efficient approach for mapping permanent magnet (PM) power loss in permanent magnet synchronous machines (PMSMs). The PM loss mapping method here uses time-step finite element analysis (FEA) to determine the function parameters representing the loss variation with speed (frequency), amplitude modulation ratio, carrier ratio, and stator current and is suitable for rapid evaluation of machine performance over the entire torque–speed envelope. The PM loss can be accurately mapped across the full operational envelope, including the field-weakened mode. The loss mapping procedure takes into account the equivalent resistivity of axial segmentation of the PM array calculated by three-dimensional (3-D) FEA. The effect of temperature on the PM loss is also considered. The proposed methodology is validated on two surface-mounted PMSM designs. The results of the loss mapping procedure are consistent with those from direct 3-D finite element prediction and experimental results of PM power loss at each operating point of the machine.

The rotor loss of rare earth permanent magnet synchronous motor (PMSM) affects the efficiency and reliability of the motor and is an important research direction of rare earth permanent magnet synchronous motors. In this paper, the influence of rotational speed on the loss of the rotor core and the permanent magnet is analyzed through the analysis of the motor magnetic field and rotor loss calculation. Specifically, with the increase in rotational speed, the weak magnetic current increases, the amplitude of flux density change in the rotor core decreases, and the loss of the rotor core also decreases. The greater the influence of the harmonic current magnetic field on the outside of the rotor, the greater the loss. The core loss on the rotor is mainly distributed on the outside of the rotor. For further engineering applications, this paper analyzes the loss composition of three kinds of motors with different rotor structures and judges the optimal scheme based on the minimum loss. Finally, the correctness of this research is verified by comparing the experimental and simulation results of two kinds of motors with different rotor structures. The research content of this paper can provide a reference for the loss analysis and optimization and rotor structure selection of rare earth permanent magnet synchronous motor rotor design.

In this study, the influence of slot opening on the leakage reactance, power factors, winding current, and air gap flux density, as well as other parameters of the surface-mounted permanent magnet synchronous motor driven by an inverter is analyzed using the two-dimensional time-step finite element method. Thus, the law of permanent magnet power loss caused by slot opening under PWM qa obtained. The results show that the leakage reactance of the motor increased when the slot opening decreased from 7 mm to 2 mm. Then, the armature ripple current caused by the inverter was found to be suppressed well, and the high harmonic current was filtered well. This reduced the amplitude of the high-order harmonic of the air gap flux density, and the permanent magnet power loss was reduced by nearly 75%. Finally, two prototypes with different slot openings were tested for permanent magnet temperature rise, which verified the analysis method and calculation results proven in this paper.

Permanent magnet synchronous machines (PMSMs) are widely used owing to high power density, high efficiency, etc. Core losses account for a significant component of the total loss in PMSMs beside winding losses. Therefore, it is necessary to consider core losses when designing PMSMs according to actual research applications. In this paper, taking four typical rotor structures (surface-mounted, embedded, “—” shape, “V” shape) as examples, an analysis method is proposed to predict the influence of different rotor structures on core loss of PMSMs. In the case of the same stator and winding structures, due to the influence of the rotor structure on the magnetic circuit, the corresponding variation law of the magnetic field in the stator core is studied. This method analyzes the radial and tangential components of magnetic flux density vector of the 4 representative points (stator tooth tip, middle tooth and yoke part), and then evaluates the entire core loss through finite element analysis results. In order to verify the method, a prototype was manufactured. The experimental results show good performance of the proposed method of this paper. It provides reference for selecting the appropriate rotor structure and designing the corresponding PMSM according to different specification.