MAYURBHANJ SCHOOL OF ENGINEERING�ELECTRICAL ENGINEERING DEPARTMENT�5th Semester�Energy Conversion – II�Topic: Special Electric Machines
By
Dr. Mrutyunjay Das
AY: 2021 – 22
Stepper Motor / Electro magnet
Rotor
Stator
Coils
Outside Casing
Stator
Rotor
Internal components of a Stepper Motor
Stators
Rotor
Cross 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 1
Winding number 2
One step
6 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
The top electromagnet (1) is turned off, and the right electromagnet (2) is energized, pulling the nearest teeth slightly to the right. This results in a rotation of 3.6° in this example.
Practical Stepper motor operation
The bottom electromagnet (3) is energized; another 3.6° rotation occurs.
The left electromagnet (4) is enabled, rotating again by 3.6°. When the top electromagnet (1) is again enabled, the teeth in the sprocket will have rotated by one tooth position; since there are 25 teeth, it will take 100 steps to make a full rotation in this example.
Stepping Motor to move read-write head
Stepper motor applications
Paper feeder on printers
CNC lathes
Stepper motors
Stepper motor applications
Rotor
Stator coils
CNC Stepping Motor
Advantages:-
Disadvantages:-
Advantages / Disadvantages
.
.
Step 1 | 0 | 0 | 1 | 1 |
Step 2 | 1 | 0 | 1 | 0 |
Step 3 | 1 | 1 | 0 | 0 |
Step 4 | 0 | 1 | 0 | 1 |
+
CW
CCW
Control sequence to turn a stepper motor
Servo Motor Detail
+ 5V
Actuator
Reduction gear
Position feedback
Potentiometer
(closed loop system)
Small electric DC motor
Thank you