1. STEPPER MOTOR SKN

2. CONTENT 1:-INTRODUCTION 2:-OPERATING PRINCIPLE 3:-CONSTRUCTIONAL FEATURES AND WORKING 4:-TYPES OF STEPPER MOTOR 5:-OPERATION 6:-Variable Reluctance Motors 7:-REFERENCE

3. Introduction step motor rotates in discrete step angles It is a Electromechanical device It is Brushless more accurately controlled than a normal motor allowing fractional turns or n revolutions to be easily done low speed, and lower torque than a comparable D.C. motor It is forms a synchronous motor Its controls by a PLC or online Microcomputer.

4. OPERATING PRINCIPLE:. It can be easily explained by considering a series of solendoids or electromagnets arranged in a circle and an iron bar (rotor), When these solenoids are energized in sequence.the mmf developed in them interact with the iron bar (or rotor) and causes it to turn either in clockwise or counter – clockwise direction, depending upon the switching sequence

5. CONSTRUCTIONAL FEATURES AND WORKING The construction of the stepper motor is quite simple and consists of a slotted stator equipped with a multi-pole, multi-phase winding unlike the windings of the conventional machines Rotor structure that carries no winding they typically use three and four phase windings, the number of poles being determined by the required angular change per input, pulse. The rotors are either of the permanent magnet type or the variable reluctance type

6. TYPES OF STEPPER MOTOR It is 3 types Permanent Magnet Variable Reluctance Motors. Hybrid Stepper Motors

7. PERMANENT MAGNET STEPPER MOTOR:. – The representative structure of permanent magnet type stepper motor having 4 stator poles and 6 rotor poles producing a fully step angle of 30 0. – The end terminals of all the windings are brought out to the terminal box for dc excitations. The rotor of such a motor has even number of poles made of high retentively steel alloy (Alnico). Both rotor and stator may employ salient or non salient pole constructio0n.Use ally the stepper motors having small stepping angles are of non salient pole construction

8. OPERATION.For instance if switch a is closed, energizing stator pole windings A, the rotor will align as shown in the If switch a is opened and the switch B is then closed, so that only windings B is energized, the rotor will step 300 clockwise, This step will uncur due to the tendency of the south pole nearest the windings B to align with the north stator pole. If the switch B is then opened and switch C subsequently closed. The rotor will make a second 30 0 clockwise step, due to attractive tendency of the north stator pole (C) for the rotor pole nearest

9. Variable Reluctance Motors :- – In this type, stator is similar to that of Permannet magnet type – It has no permanent Magnet on the rotor and rotor employed is a ferro-magnetic multitooth one – The torque is develop due to large difference in magnetic reluctance that exists between the direct and quardrature axis. Starter field by direct current in some stator coil.

10. REFERENCE :- Dr. J.B Guptafundamental of AC & DC Machine, S.K Kataria & sons Publication Dr. D.P Kothari & Dr. I.J Nagrath fundamental of Machine, Newage Publication

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