Design of IPM type BLDC Motor Considering Demagnetization Characteristics

Abstract

INTERIOR permanent magnet type brushless DC (IPM type BLDC) motors are widely used in industrial appliances [1]. An IPM type BLDC motor has high saliency ratio that produces additional reluctance torque. However, the IPM type BLDC motor has a large leakage flux and a structure which is vulnerable to demagnetization. To improve this, various design methods have been researched [2]-[6]. The flux path was installed to reduce leakage flux, and a large permanent magnet was used to suppress demagnetization of the permanent magnet [5]. The magnetic material was changed to prevent the leakage flux and demagnetization [6]. However, if the flux path is installed or the grade and the size of the permanent magnet are changed, the cost increases. Therefore, it is necessary to decrease leakage flux and improving demagnetization performance of the magnet without much change in the usage amount or material grade. In this paper, a rotor was designed for the purpose of improving performance of the IPM type BLDC motor with concentrated flux taking demagnetization characteristics into consideration. Through the design of the rotor which consists of the novel segment rotor core with a salient part, demagnetization characteristics of the motor are improved, and the back-EMF and the torque are increased. The simulation result is compared with the experiment result using a manufactured motor.