A DC brushless motor has been developed as the traction motor for the FCX, the world’s first commercially marketed fuel cell electric vehicle.This motor is adopted a salient pole type surface permanent magnet (SPM) rotor, which enables both to produce reluctance torque and to minimize the use of magnets, for improving dynamic performance. The inductance value is set at the limit value of enabling output at the maximum rotor speed, which suppresses field-weakening current. The motor, therefore, achieves both high output and high efficiency. The utilization of the magnets enables continuous operation at the maximum rotor speed by suppressing eddy current loss by means of magnet surface insulation and magnet segmentation, and by raising the limit of irreversible demagnetization by means of high coercive force of the magnet material. Strength reliability at high rotor speed in consideration of degradation has been assured by applying the Weibull theory as a method of evaluating the strength of magnets which was formed of brittle material.The employment of the methods described above has resulted in a maximum output of 60kW, a maximum torque of 272Nm, a maximum speed of 11,000rpm, and a continuous rated torque of 200Nm. In addition, the combined efficiency of the motor and inverter achieves 93% in average of LA4 mode.
Article of Honda R&D Technical Review Vol.15 No.2 (73 - 78)