STEPPER MOTOR

STEPPER MOTOR

PERMENANT MAGNET MOTOR

HYBRID MOTOR

VARIABLE RELUCTANCE MOTOR

PERMANENT MAGNET MOTOR

Cutaway diagram of a typical permanent magnet stepper motor.

Canstack rotor that is used in permanent magnet stepper motors.

VARIBLE RELUCTANCE STEPPER MOTORS

• Does not use permanent magnets, so the field strength can be varied.

• The amount of torque for this type of motor is still small, so it is generally used for small positioning tables and other small positioning loads.

• Since this type of motor does not have permanent magnets, it cannot use the same type of stepper controller as other types of stepper motors.

HYBRID MOTOR• The hybrid stepper motor is the most widely

used and combines the principles of the permanent magnet and the variable reluctance motors.

• Most hybrid stepper motors have two phases and operate on the principle used to explain the 12-step motor previously.

Hybrid stepper motor combines features of the permanent magnet stepper and the variable reluctance stepper motors.

STAPPER MOTOR ADVANTAGE• The rotation angle of the motor is proportional to the

input pulse.• The motor has full torque at standstill (if the

windings are energized).• Precise positioning and repeatability of movement

since good stepper motors have an accuracy of 3 to 5% of a step and this error is non-cumulative from one step to the next.

• Excellent response to starting/stopping/reversing.

• Very reliable since there are no contact brushes in the motor. Therefore the life of the step motor is simply dependent on the life of the bearing.

• The stepper motors response to digital input pulses provides open-loop control, making the motor simpler and less costly to control.

• It is possible to achieve very low speed synchronous rotation with a load that is directly coupled to the shaft.

• A wide range of rotational speeds can be realized as the speed is proportional to the frequency of the input pulses.