Abstract
Electric power steering (EPS) motors need to have characteristics like precision machines. They should be small and produce high power. Moreover, both their loss torque and the change in their loss torque should be ultra low. In this study, dividing the stator core into small blocks and winding the coils densely on the blocks were shown to be effective techniques for achieving small high-power motors. For this paper, we examined whether “I-shaped divided cores” or “T-shaped divided cores” were more suitable for EPS motors in terms of motor performance and productivity. We built two experimental motors, one with “I-shaped divided cores” and the other with “T-shaped divided cores”, and measured three important characteristics for EPS motors: output torque, loss torque, and loss torque change. As a result, the “T-type” motor proved to have better performance for all three characteristics. Moreover, the motor productivity of the “T-type” motor was shown to be higher than that of the “I-type” motor. So, we clarified that overall, T-shaped divided cores are advantageous for the stators in EPS motors. Next, we considered a new winding method for the continuous winding of two “T-shaped cores” in order to achieve a compact terminal connection part. The extending line that was made by the new winding method stays at the coil end. Therefore, this method will contribute to the axial miniaturization of EPS motors.
