Unit 4 permanent magnent synchronous macnine
- 1. I. PREPARED BY: MERAJ AKHTAR II. ELECTRICAL DEPARTMENT, III. JAHANGIRABAD INSTITUTE OF TECHNOLOGY IV. BARABANKI UP Permanent Magnet Synchronous Machine
- 2. Permanent Magnet Technology The use of permanent magnets (PMs) in construction of electrical machines brings the following benefits: No electrical energy is absorbed by the field excitation system and thus there are no excitation losses which means substantial increase in the efficiency, Higher torque and/or output power per volume than when using electromagnetic excitation, Better dynamic performance than motors with electromagnetic excitation (higher magnetic flux density in the air gap), Simplification of construction and maintenance, Reduction of prices for some types of machines.
- 3. Permanent Magnet Classification Permanent Magnet Permanent Magnet Synchronous Machine (PMSG) Permanent Magnet Brushless Machine (BLDC)
- 5. Introduction PM Synchronous Machine are widely used in Wind mile generation Industrial servo-applications due to its high-performance characteristics. General characteristics Compact High efficiency (no excitation current) Smooth torque Low acoustic noise Fast dynamic response (both torque and speed) Expensive
- 6. Construction PMSM Stator Rotor Inner Rotor & Outer Rotor Longitudinal & Transversal Radial Flux & Axial Flux
- 7. Radial & Axial Rotor If the normal vector is perpendicular to axis, machine is called Radial. If the normal vector is parallel with the axis, the machine is called Axial. Radial Rotor Higher power rating achieved by increasing the length of machine. Used in Ship propulsion Robotics Traction Wind systems
- 8. Radial & Axial Rotor Axial Rotor Smaller than Radial machine High torque density Used in Gearless elevator systems Rarely used in Traction Generation
- 9. Longitudinal & Transversal Rotor In transversal flux machines, the plane of flux path is perpendicular to the direction of rotor motion. Transversal flux machines can be adjusted independently current loading and the magnetic loading. Used in Applications with high torque density requirement. Free piston generators for hybrid vehicles. Ship propulsion and wind system.
- 10. Inner and Outer Rotor
- 11. Inner Rotor The interior-magnet rotor has radially magnetized and alternately poled magnets. Because the magnet pole area is smaller than the pole area at the rotor surface, the air gap flux density on open circuit is less than the flux density in the magnet. The magnet is very well protected against centrifugal forces. Such a design is recommended for high frequency high speed motors.
- 12. Outer Rotor The surface magnet motor can have magnets magnetized radially or sometimes circumferentially. An external high conductivity non-ferromagnetic cylinder is sometimes used. It protects the PMs against the demagnetizing action of armature reaction and centrifugal forces, provides an asynchronous starting torque, and acts as a damper. The magnet is very well protected against centrifugal forces. Such a design is recommended for high frequency high
- 13. PM Configuration PM (Permanent Magnet ) Surface Magnet Inset Magnet Buried Magnet
- 14. Surface and Buried Magnet Surface Magnets Simple construction Small armature reaction flux Permanent magnets not protected against armature fields Eddy-current losses in permanent magnets Expensive damper Buried Magnets Relatively complicated construction High armature reaction flux Permanent magnets protected against armature fields No eddy-current losses in permanent magnets Less expensive damper
- 15. Permanent magnet B-H curve
- 16. Operating Principle In the permanent magnet synchronous generator, the magnetic field is obtained by using a permanent magnet, but not an electromagnet. The field flux remains constant in this case and the supply required to excite the field winding is not necessary and slip rings are not required. All the other things remain the same as normal synchronous generator. The EMF generated by a synchronous generator is given as follows
- 17. Equivalent Circuit – rotor side Voltage Equation of PM machine in rotor reference
- 18. Equivalent Circuit – rotor side Fig: PM equivalent for d-axis & q-axis
- 19. Equivalent Circuit – rotor side Flux Linkage equations The Flux Linkage can be generated field current
- 20. Vector Diagram Stator reference axis X-Y axis Rotor reference axis d-q axis