Stepper Motors : Basic, Working and Advantages or Merits , Disadvantages or Demerits

 The stepper motor is a synchronous motor, which is the design state of the degree of specific numbers for each electrical pulse received by its control unit. There are 2,2.5, 5,7.5 and 15 ° per pulse typical steps. GoStepper motors are used in digital control systems, where the motor receives the open loop command as a train of pulses. It moves a shaft turn and plate through the specic distance
 

★Working principle - 

Stepper motors operate on the principle of electromagnetism. Accordingly, when the stepper winding is supplied, the magnetic field develops in the stepper. The rotor of the stepper motor being of permanent magnets attempts to move along the revolving magnetic field of the stator. 

The stepper motor is usually designed with a multipole. The multiphase motor winding is different from the winding of the conventional machine. Three and four phase windings are used in this and the number of poles required is determined by the angular change per unit pulse required. Rotors are of variable reactance or permanent magnet type.

The stepper motor operates with an external drive logic circuit. Pulse train with it. Applies to the input of the drive circuit. This circuit delivers the proprietary current for stator winding of the motor. After this, the axis of the air gap field step is formed which is in coherence around the input pulses. The air gap follows the axis of the magnetic field due to rotor, relative torque, or permanent magnet torque. The pulse rate, load torque and materia effect are dependent on the rotor.

Elementary operation of four phase stepper motor with two pole rotor is shown in the figure. It consists of a rotor ferromagnetic element or a permanent magnet. Let, the rotor angle is excited with winding sequences Na.Na + Nb.Nb, etc., θ = 0°, 45°, 90° etc. Stepper motors can generally be used for a 90° angle by single coil excitation. In this situation only the permanent magnet rotor is used.

★Advantages or Merits - 

The following are the major lam or properties of the stepper motor 

1. It is called P.C. Can be easily interfaced with microprocessors and PLCs. 
2.  It does not require brushes and commutators. 
3. It reduces the error for the finite predesign value with a relative clean tap 
4. It offers low velocity at load without any gear reduction. 
5. It drives large load at sure speed.  
6. It does not require feedback 
7. The motor automatically stops when there is any breakdown in it. 
8. It has good repeatability 
9. It does not cause damage due to mechanical overload. 
10. It has low size and performance as standard 
11. It has low speed torque. 
12.  It has a longer lifespan. 

★Disadvantages or Demerits -

Following are the major disadvantages or faults of the stepper motor 

1. It has low efficiency 
2. It requires a low frequency device. 
3. It has limited load inertia 
4. If the value of input frequency increases more than its assured value, then the motor misses some step movements 
5. If the input frequency is higher than the critical frequency, the motor does not self-start. 
6. It has instant torque drop with speed 
7. Its accuracy is low 
8. There is no feedback to indicate missed steps in it 
9. In this, the ratio of forceful and inertia is Kang 
10. It becomes hot in high performance configuration 
11. The motor becomes more noisy as the speed increases. 

★Write applications of stepper motor 

 Following are the major applications of stepper motors 

1. In computers, it is used in Paloppy Dry, Printer, Plotter, Type Writer etc. 
2. It is used in business machines, card readers, photocopy machines, baking systems, etc. 
3. Its use in process control, carburetor adjusting, valve control, fluid. Gas metering is done in conveyors, assembly lines etc. 
4. It is used in machine tools such as milling machines, drilling machines, automatic grinding machines, laser cutting machines, latches, swing machines, X - Y plotter etc 
5. It is used in commercial and products 
6. Mixing, cutting, blending etc. of chemical is done by it. 
7. It is used in making robotics