Design of efficient BLDC motor for DC operated mixer-grinder

In residential applications, DC operated appliances along with DC power distribution can provide considerable energy savings compared to the present AC system. In future, most of the domestic AC operated appliances will be replaced by efficient, DC operated appliances. Presently, domestic mixer-grinders employ universal motor, which has an efficiency of the order of 70%. This paper proposes a low cost ferrite magnet based BLDC motor as an efficient alternative to universal motor. The buried magnet type rotor design is generally preferred for such high speed application, however, it suffers from high armature reaction and increased core loss. Instead, design with surface mounted ring permanent magnet is found to be most suitable for this application. Effect of rotor overhang is investigated to improve the magnetic loading. The proposed BLDC motor has iron and copper losses of about 5.2%, thus resulting in high efficiency motor.