With respect of designing a PMSG, the permanent magnetic pole lies on the rotor and armature winding are in the inner part of stator that is electrically connected to the load. Armature winding consists of the set of three conductors which has phase difference 120 derg apart to each other and providing a uniform force or torque on the generator’s rotor. To operate PMGS, it is connected to wind turbine through a shaft without gear box and rotate at slow speed. This uniform torque produced by the resultant magnetic flux which induces current in the armature winding. The stator magnetic field combined spatially with rotor magnetic flux and rotates as the same speed of the rotor. So the two magnetic fields synchronously rotate in PGSM to maintain the relative motion of rotor and stator. Thus the permanent magnets rotates at constant speed without any DC excitation system, which means it has not required any slip rings and contact brushes to make it more reliability or efficient.

1. Permanent Magnent Synchronous Macnine
I. By Rajeev
Kumar

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)

4. Permanent Magnet Classification

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
Radial Flux &
Axial Flux
Inner Rotor &
Outer Rotor
Longitudinal &
Transversal

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

21. Thank You
Queries Suggesti
on
Feedbac
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