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Stepper motor(encrypted)
This document discusses stepper motors, which are AC motors that convert input electrical pulses into precise rotational movements. It describes types of stepper motors, such as permanent magnet and variable reluctance, as well as their operation and applications. Additionally, it provides numerical calculations for step angles based on motor specifications.
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Stepper motor(encrypted)
- 1. STEPPER MOTOR By, Rohini Haridas AssistantProfessor, Dept of Electrical Engineering, SSGM College of Engineering,Shegaon
- 2. Introduction A stepper motoris a form of ac motor. The input given to this motor is in the form of electric pulses. Stepper motor is known by its important property to convert a train of input pulses i.e. square wave pulse into a precisely defined increment in the shaft position. Each pulse moves the shaft through a fixed angle. The angle through which the motor turns or shaft moves for each pulse is known as the step angle, expressed in degrees As such angle is dependent on the number of input pulses,the motor is suitable for controlling position by controlling the number of input pulses
- 3. Step Angle The magnitudeof step angle for stepper motor is given by Where, α = Step angle ms = number of stator phases Nr= Number of rotor poles or teeth Steps per revolution is given by i.e. resolution = 360 α 0
- 4. Numerical 1. Calculate thestepping angle for a three phase ,24 pole permanent magnet stepper motor Given: ms = 3 Nr = 24 Solution : = 360/(3*24) = 0 5 / step
- 5. Numerical 2. Calculate thestepping angle for a three phase ,16-teeth variable reluctance stepper motor Given: ms = 3 Nr = 16 Solution : = 360/(3*16) = 0 7.5 / step
- 6. Difference between Conventional Motorand Stepper motor Input to SM is in the form of electric pulses whereas input to CM is from constant voltage source A CM has a free running shaft whereas shaft of SM moves through angular steps
- 7. Types of steppermotors Permanent Magnet Stepper Motor Variable Reluctance Stepper Motor
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- 12. Rotor will alwaysorient so that the nearest rotor south pole is aligned with the energized stator poles
- 13. Rotor will alwaysorient so that the nearest rotor south pole is aligned with the energized stator poles
- 14. Cross Section ofa Stepper Motor Stators 1 S N 2 2 S N 1 Rotor
- 15. Four Steps perrevolution i.e. 90 deg. steps.
- 16. Eight steps per.revolution i.e. 45 deg. steps.
- 17. Variable Reluctance StepperMotor The principle of operation of a variable reluctance stepper motor is based on the property of flux lines to occupy low reluctance path. The stator and rotor therefore get aligned such that the magnetic reluctance is minimum
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- 19. Practical Stepper motoroperation The top electromagnet (1) is turned on, attracting the nearest teeth of a gearshaped 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.
- 20. 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.
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- 24. Advantages Advantages:Low cost forcontrol achieved Simplicity of construction Low maintenance Will work in any environment
- 25. Control sequence toturn a stepper motor + 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