Stepper motor A stepper motor is a special

  • Slides: 12
Download presentation
Stepper motor A stepper motor is a special electrical machine which rotates in discrete

Stepper motor A stepper motor is a special electrical machine which rotates in discrete angular steps in response to a programmed sequence of input electrical pulses. Working Principle A magnetic interaction takes place between the rotor and the stator, which make rotor move.

Construction • The stator has windings • The rotor is of salient structure without

Construction • The stator has windings • The rotor is of salient structure without any windings, and it may or may not have permanent magnets Application • Application of stepper motor in diverse areas ranging from a small wrist watch to artificial satellites. • Power range 1 W to 2. 5 KW • Torque range 1µN to 40 Nm

Stepper motor (1) Variable (2) Permanent reluctance magnet (3) Hybrid stepper motor (HSM) (1.

Stepper motor (1) Variable (2) Permanent reluctance magnet (3) Hybrid stepper motor (HSM) (1. 1) Single stack VR Stepper Motor (4) Other type (1. 2) Multi stack VR Stepping motor

1. Variable reluctance motor Variable reluctance stepper motor works on the principle that a

1. Variable reluctance motor Variable reluctance stepper motor works on the principle that a magnetic material placed in magnetic field experience a force to align minimum reluctance path Variable reluctance motor (1. 1) Single stack VR Stepper Motor (1. 2) Multi stack VR reluctance Stepping motor

1. 1 Single stack VR Stepper Motor Construction • Stator 1. 2. 3. The

1. 1 Single stack VR Stepper Motor Construction • Stator 1. 2. 3. The stator made up of silicon steel stampings. It has projecting poles, usually even no of poles. The pole carry concentric windings • Rotor 1. 2. 3. Usually made up of silicon steel. Solid silicon steel also used for core of rotor. The rotor has projecting teeth on its outer periphery. The no of rotor teeth and stator pole should not be equal. this make motor self starting

Working Rotor teeth can assume any position until the stator winding energized. For a

Working Rotor teeth can assume any position until the stator winding energized. For a four phase (eight pole) single stack VR stepper motor the angle rotated by the rotor (Φ) is given by Φ=360/Mx. Nr degree Where M = the number of stator phase Nr= the number of rotor phase In the present case M=4, Nr=6 Φ=360/4 x 6 degree = 15 degree

Switching Circuit

Switching Circuit

Modes of Excitation a) 1 Phase ON or full step mode b) 2 -1

Modes of Excitation a) 1 Phase ON or full step mode b) 2 -1 -Phase ON (Half Stepping) c) Two phase ON mode d) Micro-stepping

1 Phase ON (Full Stepping)

1 Phase ON (Full Stepping)

Rotor position for phase excitation

Rotor position for phase excitation

2 -1 -Phase ON (Half Stepping)

2 -1 -Phase ON (Half Stepping)

Two phase ON mode

Two phase ON mode