2019 年 27 巻 1 号 p. 79-84
Development of a small, high-speed and high-power motor is necessary to improve the performance of machines such as robots, and drones. The motor is excited by a high frequency voltage when the motor rotates high-speed. Moreover, the motor is driven by the pulse width modulation (PWM) inverter because efficiency and controllability is good. The driving voltage of the PWM inverter contains many higher harmonics waves. In such a motor, generation of heat due to the loss is a major problem. The loss of the motor includes an iron loss, a copper loss, and a machine loss; here we focus on the iron loss. Eddy-current loss increases especially under a condition of high frequency excitation. To suppress the eddy-current loss, we produced the stator core for a small, high-speed and high-power motor using a 0.08-mm-thick ultrathin electrical steel sheet. Additionally, to evaluate the magnetic properties of this new stator core with complex shape, we also developed a stator winding excitation method using a dummy rotor made of the 0.08-mm-thick ultrathin electrical steel sheet. In this paper, the effectiveness of a small, high-speed, and high-power motor stator core made of the 0.08mm-thick ultrathin electrical steel sheet is shown using the stator winding excitation method when it is excited by the PWM wave.
