How stepper motor works
In our today’s known modern world motors are playing key role to drive our technology.
Different types of motor are there in market all are divided on basis of there construction, application, working principle etc.
In this article we are going to learn some basics of stepper motors.
As name suggest there is something like steps involved in working of this types of motors that we’ll learn further in the post.
We’ll also see how stepper motor works , and its construction details in this post.
Working principle of stepper motor
Basically stepper motors are brushless DC motors, normally a permanent magnet rotor placed in between of stator winding.
Stator winding then energize step by step in a sequential way so it get magnetize and force rotor to align with the magnetic field of stator coil.
in this way rotor begin rotate in small steps, due to this behavior the motor gets its name “stepper motor”
As we can see now by controlling the stator winding generations sequence we can precisely control the position of rotor without any position feedback system.
this quality of stepper motor makes is best suitable to be used were high precision motion is required like CNC machines.
Also here we have to note another best quality of stepper motor is High torque at low RPM & Holding torque.
We know that rotor of stepper motor rotates by sequentially energising stator coils.
if we energize a single set of coil with time delay respectively we get slower RPM of stepper motor.
hence we also get high torque because rotor is always in hold within the magnetic field of energized stator coils.
If we keep energize a single set of stator coil the rotor will be stay on its place with maximum torque.
Single coil excitation mode
There are many methods to drive stepper motor.
how stepper motor works with single coil excitation is basic method to drive stepper motor.
Full step Mode
In full step drive mode 2 coils are excited at same time because of this it provide higher torque to the motor.
Micro stepping mode is the now most famous way to control stepper motor, high precision can achieve by this drive mode.
Micro stepping mode give smooth and silent motion to stepper motor by providing variable controlled current to the coil in form of sine wave.
Driver to control stepper motor
This A4988 stepper driver is very famous among the DIY community.
This stepper driver can control bipolar stepper motor it can handle approx 1Amps current per phase.
Types of stepper motors
Below are the three main types of stepper motors based on there physical construction.
- Permanent Magnet stepper motor
- Variable reluctance stepper motor
- Hybrid synchronous stepper motor
Permanent Magnet stepper motor
In this type of stepper motors permanent magnet rotor is placed in center electromagnet stator.
The permanent magnet of rotor attract and repel in effect of stator electromagnets,
this attraction and repulsion cause rotation of rotor in stepper motor.
Variable reluctance stepper motor
A ferromagnetic metal material used as rotor in this type of motors.
this motor works on principle of electromagnetic reluctance.
means minimum reluctance at minimum air gap between rotor and stator
Hybrid synchronous stepper motor
As the name suggest this types of motors are the mixture of both parmanent magnet & variable reluctance motor.
Hence this motors are more practical and efficient to use. now days Hybrid synchronous stepper motors are widely famous.