Thermal capability of electric vehicle PMSM with different slot areas via thermal network analysis

In this paper, the effect that a varied stator slot size has on the efficiency and thermal capability of a permanent magnet synchronous machine for an electric vehicle, is evaluated and quantified. A machine with four differently sized slot areas was electromagnetically evaluated with finite element analysis, and thermally with a lumped parameter network model. By decreasing the slot size while keeping other dimensions fixed, the core losses reduce due to the wider magnetic path, whereas the winding losses increase. Additionally, a higher maximum torque is reached due to reduced saturation. Results are compared in the machine\u27s torque-speed operating area regarding machine-part and total losses, continuous torque and transient overload capability, as well as during 19 low, middle and high-speed drive cycles regarding energy losses and peak winding temperature. The largest slot showed the lowest winding losses and thus the highest thermally limited torque capability. In contrast, the energy losses with the largest slot were the highest in 13 of the drive cycles, and the lowest in 11 of them with the smallest slot due to its lower part load (i.e. core) losses. The smallest slot would also result in the lowest material cost since it has the least copper

Battery Electric Vehicle Performance Evaluation by Considering Punching Effect on PMSM Iron Cores

Increasing demand for electric vehicles has put significant stress on designing highly efficient electric machines. Manufacturing processes of the electrical steel sheets used in the iron cores of machines deteriorate the electromagnetic properties of the material and increase iron losses. The improved quantification of iron losses in the early stages of the machine design is crucial and enables designers to properly account for losses. However, the complexity and variety of contributing factors in determining these losses have led machine designers to use empirical correction factors to predict iron losses reasonably well. In this work, deterioration of electromagnetic properties of electrical steel sheets due to punching has been considered when simulating the torque and loss performance of a permanent magnet synchronous machine. Three levels of degradation are investigated and the results show up to 10 %, 20 %, and 35 % increase in the hysteresis losses of the machine for a low, a medium and a high degradation level, respectively. Furthermore, the machine performance in selected test-driving cycles is determined as well

Statistical Assessment of Core Loss Measurement Techniques for Laminated Steel

In this paper, a comparative study of core losses in laminated steel samples by means of inferential statistics is presented. In particular, core loss measurements taken upon Epstein Frame, Single-Strip tester, and Ring Core specimens at several frequencies and induction levels are compared via Analysis of Variance and two-sample t-tests. The hypothesis of a statistically significant difference among the testing procedures is sustained and ring cores showed a lower magnetic performance when compared to Epstein Frame and Single-Strip tester