Permanent Magnet Dc Motor
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Permanent Magnet Dc Motor as PDF for free.
More details
- Words: 305
- Pages: 14
Permanent Magnet DC Motor
Construction Field -Permanent magnet -Continuous ring
Operation Supply 6V,12 V or 24 V Bt. or rectified ac T α ØI B-H curve - top left quadrant segment is referred to as the “demagnetizing curve”
Demagnetizing Curve
Permanent Magnetic Materials Alnico - good properties but too low a coercive force and too square a B-H loop => permanent demagnetization occurs easily Ferrites (Barium and Strontium) - low cost, moderately high service temperature (400° C), and straight line demagnetization curve. However, Br is low => machine volume and size needs to be large.
Permanent Magnet Materials… Samarium-Cobalt (Sm-Co) - very good properties but very expensive (because Samarium is rare) Neodymium-Iron-Boron (Nd-Fe-B) very good properties except the Curie temperature is only 150°C
Performance Characteristics N-T
I-T ŋ
Performance Characteristics… Efficiency
Torque Power output
Power Input
Current
Speed (rpm)
Speed Control The speed-torque characteristic of a PM motor can be controlled by changing the supply voltage or the effective resistance of the armature circuit. The change in the supply voltage varies the no-load speed of the motor without affecting the slope of the characteristics.
Speed Control... with the change in the effective resistance of the armature circuit, the slope of the curve is controlled and the no-load speed of the motor remains the same
Advantages Lower manufacturing cost Smaller in size Higher efficiency (no field Cu loss) Less noise Little radio and TV interference
Disadvantages Heating effect (magnetic shielding) Can be demagnetized by armature reaction due to i . Improper design ii. Excessive Ia by fault or transient iii. Improper brush shift iv. Temperature effects Limited in size (large magnets are expensive)
Applications 12 V PM DC motor Automobiles
Windshield Wipers Door locks Window lifts Seat adjust Mirror adjust Anti-lock Braking System Fans
Toys Electric Toothbrush
http://www.walter-fendt.de/ph11e/electricmotor.htm
http://www.freescale.com/files/microcontrollers/doc/train_ref_material/MOTORDC
Construction Field -Permanent magnet -Continuous ring
Operation Supply 6V,12 V or 24 V Bt. or rectified ac T α ØI B-H curve - top left quadrant segment is referred to as the “demagnetizing curve”
Demagnetizing Curve
Permanent Magnetic Materials Alnico - good properties but too low a coercive force and too square a B-H loop => permanent demagnetization occurs easily Ferrites (Barium and Strontium) - low cost, moderately high service temperature (400° C), and straight line demagnetization curve. However, Br is low => machine volume and size needs to be large.
Permanent Magnet Materials… Samarium-Cobalt (Sm-Co) - very good properties but very expensive (because Samarium is rare) Neodymium-Iron-Boron (Nd-Fe-B) very good properties except the Curie temperature is only 150°C
Performance Characteristics N-T
I-T ŋ
Performance Characteristics… Efficiency
Torque Power output
Power Input
Current
Speed (rpm)
Speed Control The speed-torque characteristic of a PM motor can be controlled by changing the supply voltage or the effective resistance of the armature circuit. The change in the supply voltage varies the no-load speed of the motor without affecting the slope of the characteristics.
Speed Control... with the change in the effective resistance of the armature circuit, the slope of the curve is controlled and the no-load speed of the motor remains the same
Advantages Lower manufacturing cost Smaller in size Higher efficiency (no field Cu loss) Less noise Little radio and TV interference
Disadvantages Heating effect (magnetic shielding) Can be demagnetized by armature reaction due to i . Improper design ii. Excessive Ia by fault or transient iii. Improper brush shift iv. Temperature effects Limited in size (large magnets are expensive)
Applications 12 V PM DC motor Automobiles
Windshield Wipers Door locks Window lifts Seat adjust Mirror adjust Anti-lock Braking System Fans
Toys Electric Toothbrush
http://www.walter-fendt.de/ph11e/electricmotor.htm
http://www.freescale.com/files/microcontrollers/doc/train_ref_material/MOTORDC
Related Documents
Permanent Magnet Dc Motor
November 2019 27
Dc Motor
June 2020 31
Dc Motor
May 2020 29
