Temperature distribution analysis of permanent magnet in interior permanent magnet synchronous motor considering pwm carrier harmonics

To cope with the demagnetization risk of permanent magnets used in interior permanent magnet synchronous motor (IPMSM), an accurate thermal analysis of the permanent magnets is very important at the motor design stage. In this paper, an approach to predict the permanent magnet temperature distribution in IPMSM installed on traction drive for hybrid vehicles is presented. To achieve an accurate thermal analysis, the motor losses under PWM -voltage source inverter (VSI) drive are firstly estimated by 3D-FEM using measured current waveform including PWM carrier harmonics. Based on the calculated motor losses, 3D-FEM-based thermal analysis is employed to clarify the temperature distribution of the permanent magnet. Through comparisons of the measured permanent magnet temperature with the calculated one, it is demonstrated that the proposed approach makes it possible to evaluate the temperature distribution of the permanent magnet quantitatively.