# Relation Between a Pole, a Phase, and a Slot

3-phase motors are a common type of motor.
The most basic 3-phase brushless motor is a 2-pole 3-slot motor.
There are various combinations such as 4-pole 3-slot, 4-pole 6-slot, and 16-pole 12-slot.
When the number of poles and the number of slots increases, a large torque can be obtained and the torque pulsation also decreases.

• The pole represents the number of permanent magnet poles for the rotating rotor, and a motor with one pair of N pole/S poles is called a two-pole motor.
The number of poles can be 2, 4, 6, 8,..., etc.
(From the viewpoint of motor control, when the number of poles is doubled, the speed will be halved, and when the number of poles is quadrupled, the speed will be quartered, therefore the control method does not depend on the number of poles.)
• The phase represents the number of independent coils for fixed stators. Three-phase motor is a motor with three independent coils at 120 degree intervals.
• A slot represents the number of coils of fixed stators. Three-phase motor has a multiple of 3 slots.

## Chapter 2 Driving Principle of a Brushless Motor

Driving Principle of a Motor (1)
Driving Principle of a Motor (2)
Brushed DC Motors and Brushless Motors
Sequence of a Brushed DC Motor
Sequence of a Brushless Motor