Switched reluctance motor

The switched reluctance motor (SRM) is a type of a stepper motor, an electric motor that runs by reluctance torque. The SRM has wound field coils for the stator windings. The rotor has no magnets or coils attached. It is a solid salient-pole rotor (having projecting magnetic poles) made of soft magnetic material (often laminated-steel). When power is applied to the stator windings, the rotor's magnetic reluctance creates a force that attempts to align the rotor pole with the nearest stator pole. In order to maintain rotation, an electronic control system switches on the windings of successive stator poles in sequence so that the magnetic field of the stator "leads" the rotor pole, pulling it forward

The switched reluctance motor (SRM) is a type of a stepper motor, an electric motor that runs by reluctance torque. The radial movement is carried out by 4 double stator coils. The main motor contains 4 n double stator coils, which are controlled by the PB--- board in the power control box of the main motor. The stepper motor does not rotate in a continuous fashion like a conventional DC motor but moves in discrete “Steps” or “Increments”, with the angle of each rotational movement or step dependent upon the number of stator poles and rotor teeth the stepper motor has. Because of their discrete step operation, stepper motors can easily be rotated a finite fraction of a rotation at a time, such as 1.8, 3.6, 7.5 degrees etc. 

So for example, lets assume that a stepper motor completes one full revolution 360 degree in exactly 100 steps. Then the step angle for the motor is given as 360 degrees/100 steps = 3.6 degrees per step. This value is commonly known as the stepper motors Step Angle.

A stepper motor drive is a circuit which is used to drive or run a stepper motor. It is often called a stepper motor driver. A stepper motor drive usually consists of a controller, a driver and the connections to the motor.

Essential Components of Stepper Motor Drive

1. Controller(Essentially a microprocessor)
2. A driver IC to handle the motor current
3. A power supply unit

Miscellaneous Components

1. Switches, Potentiometers
2. Heat sink
3. Connecting wires

The steps of a stepper motor represent discrete angular movements, that take place in a successive fashion and are equal in displacement, when functioning correctly the number of steps performed must be equal to the control impulses applied to the phases of the motor. The final position of the rotor is given by the total angular displacement resulting from the number of steps performed

switched   reluctance /sumo/stepped motor(Download Link)