Applied Control SystemsStepper Motors

Stepper Motor / Electro magnet

RotorStatorCoils

StatorsRotorCross Section of a Stepper Motor

Four Steps per revolution i.e. 90 deg. steps.Full Step Operation

Eight steps per. revolution i.e. 45 deg. steps.

Half Step Operation

Winding number 1Winding number 2One step6 pole rotor

How many steps are required for one complete revolution?Six pole rotor, two electro magnets.

The top electromagnet (1) is turned on, attracting the nearest teeth of a gear-shaped iron rotor. With the teeth aligned to electromagnet 1, they will be slightly offset from electromagnet 2 Practical Stepper motor operation

The bottom electromagnet (3) is energized; another 3.6 rotation occurs.

Stepping Motor to move read-write headStepper motor applications

Paper feeder on printersCNC lathesStepper motorsStepper motor applications

RotorStator coilsCNC Stepping Motor

Advantages:-Low cost for control achievedRuggednessSimplicity of constructionCan operate in an open loop control systemLow maintenanceLess likely to stall or slipWill work in any environment

Disadvantages:-Require a dedicated control circuitUse more current than D.C. motorsHigh torque output achieved at low speeds

Advantages / Disadvantages

+CWCCWControl sequence to turn a stepper motor

Step 10011Step 21010Step 31100Step 40101

Servo Motor Detail+ 5VActuatorReduction gearPosition feedbackPotentiometer(closed loop system)Small electric DC motor