IDC_Chap_6_Special_Motor_Drive-1.pdf

IDC_Chap_6_Special_Motor_Drive-1.pdf - Special Motor Drives...

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Special Motor Drives By: M. P. Girnari (SSEC, Bhavnagar) For more visit :- For more visit:- 1
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Outlines Stepper motor drive Stepper motor Types of stepper motor Permanent magnet stepper motor Variable reluctance stepper motor Hybrid stepper motor Features of stepper motor Torque vs. Stepping rate characteristics Drive circuits for stepper motor Brushless DC motor DC Servo motor & its control For more visit:- 2
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Introduction to Stepper motor As it name implies, stepper motor rotates in discrete steps , each step corresponding to a pulse that is supplied to its stator windings. A stepper motor is digital electromechanical device where each step command pulse result in a movement of shaft by a discrete angle called step angle of the motor. It is used when motion and position have to be precisely controlled. By keeping count of number of command pulse ? By changing frequency of command pulses ? Ideally suited to open loop position and speed control. How ? For more visit:- 3
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Cont.. Some applications in which stepper motor is used… Printer Machine tools Robotics Disk drive X-Y recorder Textile industries Electrical watches etc. Mostly used because… Compatible to digital system Can be used in open loop configuration (no need of sensors) Accurate control of speed and position can be achieved For more visit:- 4
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Types of stepper motor Three types : 1. Variable reluctance motor 1. Single-stack type 2. Multi-stack type 2. Permanent magnet motor 1. 2-phase 4/2 pole 2. Disk type 3. Hybrid stepper motor For more visit:- 5
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Single Stack VR stepper motor : 4/2 pole VR motor Construction: As shown in the figure it has 4-poles in stator and 2-poles in rotor . Four phases namely A, B, C, D are connected to DC source through semi-conductor switches (? ? , ? ? , ? ? , ? ? ) respectively. In order to rotate the rotor in particular direction, the phases must be excited in proper sequence with the help of semi-conductor switches. For more visit:- 6
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