매입형 영구자석 동기전동기의 MTPA 영역에서의 자석 온도 추정 및 토크 보상 기법

초록

Recently, interior permanent magnet synchronous motors using NdFeB permanent magnets have been widely adopted in electric vehicles owing to their high efficiency and power density. However, NdFeB magnets are vulnerable to temperature rise, necessitating real-time temperature monitoring and compensating the motor’s reduced output torque. In this paper, we theoretically analyze the interrelationship among the fundamental reactive energy, flux, torque, and magnet temperature. A method is proposed to simultaneously estimate the magnet temperature and compensate for torque variation in the maximum torque per ampere region by utilizing a common look-up table (LUT) for estimating the dq-axis flux linkage. The proposed method does not require separate magnet temperature or torque sensors, enabling a simple implementation using the shared LUT. The effectiveness of the proposed method is validated through finite element analysis-based simulations. In addition, a temperature estimation experiment is conducted over approximately 9,500 s, during which the magnet temperature is estimated with an error within 4 °C. Proposed method maintains consistent compensation performance throughout across all torque ranges without the magnet temperature measurement.

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