Assortment of slot and pole relation for a permanent magnet brushless DC motor

Abstract

Brushless DC motors are permanent magnet motors which are well known for their durability due to simplicity in design and high-speed capability. These types of Permanent motors are limited to few applications such as radiator fans, heater blower fan, water pump, etc. These motors are used for medium power appliances, and for high speed and higher efficiency. For BLDC it is preferable to adopt fractional slot concentrated winding. With the fractional slot concentrated winding for any electrical machine having radial air gap there are many advantages such as reduction in copper, Joule losses are decreased there by improving efficiency. For having a balanced winding the EMF amplitude, shape and relative phase has to be met. This paper presents the possible combinations of slots and poles, winding coefficient which determines the motor performance, winding configuration for a three phase brushless dc motor and design calculations for a particular application.