THis is about the PMSm

1. PERMANENT MAGNET
SYNCHRONOUS MOTOR

2. • Introduction
• Advantagesof Permanent
Magnet
• Construction
• Types of Rotor
• Working principle
• Torque equation
• Comparisonwith induction
motor
• Advantagesand
disadvantagesof PMSM
• Applications
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3. Introduction
Permanent magnet Synchronous motor is a synchronous electric motor
whose rotor is made of permanent magnet and its stator is identical to
that of an induction motor. It rotates with speed synchronized with the
frequency of the supply current. PMSM is an attractive solution for
servo-drives in the kW range. They are being used in a wide range of
applications from general purpose to high performance.
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4. Materials of PMSM
The desirable properties of the materials used for the construction of
permanent magnets in PMSMs are:
a.High flux density
b. High coercivity
• Certain "rare earth" magnetic materials best satisfy these
requirements. Samarium-Cobalt, with high flux density (up to 1T)
and very large coercive force (upto 7000 A/cm), is one of
the materials used.
• These days, Neodymium-Iron-Boron magnets are being used for
their low cost. Further the magnets made of these materials require
less space and, with proper design, there is no danger of accidental
demagnetization through short circuit.
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5. Advantages of using Permanent
magnet
The permanent magnets in construction of electric machines
gives us the following benefits:
• No electrical energy is necessary for field excitation and
thus there are no excitation losses and hence giving higher
efficiency.
• Permanent magnets do not require brushes or sliprings.
• Permanent magnets occupy less space compared to dc
excitation winding.

6. Advantages of using Permanent
magnet
The permanent magnets in construction of electric machines
gives us the following benefits:
• PMSM provide better torque control and dynamic response.
• It can deliver more power in a smaller physical size making
them suitable for applications in limited space.
• It has simple construction and maintenance.
• Reduction of prices.

7. Construction
PMSM consists of two parts
• Stator
• Rotor

8. Stator
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9. The stator of PMSM is similar to that of an induction
motor which is the stationary part that caries the armature
winding of the motor. This armature winding is the main winding
because of which the EMF is induced in the motor.
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10. The stator consists of cylindrical core made of laminated iron.
It consists of slots where armature windings are placed. The
primary function of stator is to generate rotating magnetic field
when supplied with three-phase ac current. The number of poles
on the stator determines the speed of RMF. For example, a four
pole stator will create an RMF that completes four cycles per
revolution.
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11. Rotor
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12. The Rotor consists of permanent magnets. Materials with
high coercive force are used as permanent magnets.
According to the rotor design, synchronous motors are
divided into:
• electric motors with salient pole rotor;
• electric motors with non-salient pole rotor.
An electric motor with non-salient pole rotor has an equal
direct and quadrature inductances L d = Lq, whereas for an
electric motor with salient pole rotor the quadrature
inductance is not equal to the direct Lq ≠ Ld.
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13. Also, according to the design of the rotor, the PMSM are
divided into:
• surface mounted permanent magnet synchronous motor.
• interior mounted permanent magnet synchronous motor.
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14. Surface Mounted Permanent Magnet
SPM motors have the magnets affixed to the exterior of the
rotor surface, their mechanical strength is so weaker than
IPM one. The weakened mechanical strength limits the
motor’s maximum safe mechanical speed. In addition, these
motors exhibit very limited magnetic saliency (Ld ≈ Lq).
Inductance values measured at the rotor terminals are
consistent regardless of the rotor position. Because of the
near unity saliency ratio, SPM motor designs rely
significantly, if not completely, on the magnetic torque
component to produce torque.
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15. Interior Mounted Permanent Magnet
IPM motors have the permanent magnet imbedded into the rotor itself.
Unlike their SPM counterparts, the location of the permanent magnets
make IPM motors very mechanically sound, and suitable for operating
at very high speeds. These motors also are defined by their relative
high magnetic saliency ratio (Lq > Ld). Due to their magnetic saliency,
an IPM motor has the ability to generate torque by taking advantage of
both the magnetic and reluctance torque components of the motor
making them adapted to various EVs. 15

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17. Working of PMSM
• When a 3-phase supply is given to the stator of a 3-phase
wound synchronous motor, a revolving field is set up (say in
anticlockwise) which rotates at a synchronous speed. (NS =
120 f/ P )
• This field is represented by the imaginary stator poles. At
an instant as shown in Fig. 2(a), the opposite poles of
stator and rotor are facing each other (for simplicity two-
pole machine is considered)
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18. PRESENTATION TITLE 18

19. • As there is a force of attraction between them, an
anticlockwise torque is produced in the rotor as the rotor
poles are dragged by the stator revolving poles or field.
• After half a cycle, polarity of the stator poles is reversed
whereas the rotor poles could not change their position due
to inertia.
• Thus, like poles are facing each other and due to force of
repulsion a clockwise torque is produced in the rotor as
shown in Fig. 2 (b).
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20. • Hence, the torque produced in a 3-phase synchronous
motor is not unidirectional and as such this motor is not
self-starting.
• However, if rotor of synchronous motor is rotated by some
external means at the start so that it also reverses its
polarity as the polarity of stator poles is reversed after half
a cycle as shown in Fig. 2 (c).
• A continuous force of attraction between stator and rotor
poles exists. This is called magnetic locking.
• Once the magnetic locking is obtained, the rotor poles
are dragged by the stator revolving field (imaginary poles)
and a continuous torque is obtained.
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21. • As the rotor poles are dragged by the stator revolving field,
hence the rotor rotates at the same speed as that of stator
revolving field, i.e., synchronous speed. Thus, a synchronous
motor only runs at a constant speed called synchronous speed
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22. TORQUE EQUATION OF IDEAL PMSM
When a balanced three phase
voltage is applied to the
armature, a three phase current
flows through the conductors.
This current produces armature
flux for deriving the torque
equation, the concept of
armature ampere conductor
density is used. A sinusoidally
distributed ampere conductor
density is assumed as shown in
the figure.
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23. PRESENTATION TITLE 23
The torque equation is given by :
T=π Amax Bmax sin(β)
• β is the torque angle or power angle
• Amax is maximum Ampere turn density
• Bmax is the maximum flux density

24. SPEED CONTROL
• Speed Controlled at Reference Speed of PMSM Drive System
by PI Control
• Speed Controlled at Reference Speed of PMSM Drive System
by PID Control
• SMC Controlled at Reference Speed in PMSM Drive System
• SMC Plus PID Controlled at Reference Speed in PMSM Drive
System
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25. COMPARISION WITH INDUCTION MOTOR
25
PRESENTATION
TITLE
PERMANENT MAGNET SYNCHRONOUS
MOTOR
INDUCTION MOTOR
• It will rotates at synchronous speed.
• It is not a self-starting motor.
• A permanent magnet motor’s full load
efficiency is higher than an AC induction
motor.
• A permanent magnet synchronous motor are
often smaller in size and more efficient than
induction motor solutions.
• Permanent magnet synchronous motor More
expensive than induction motor
• Permanent magnet synchronous motor are
more difficult to start up
• It rotates at speed less than synchronous speed.
• It is a self-starting motor.
• An AC induction motor’s full load efficiency is less
than a permanent magnet motor
• An induction motor are often larger in size and less
efficient than permanent magnet motor
solutions.
• Induction motor are less expensive than permanent
magnet synchronous motor
• Induction motors are less difficult to start
up than permanent magnet synchronous motor

26. Advantages of PMSM
• PMSM is very efficient, brushless, very fast, safe and give
high dynamic performance.
• It produces smooth torque, low noise and mainly used for
high speed applications.
• It has a high power density, it can deliver a high amount of
power in a relatively small and compact package.
• It provides high torque output for a given rotor inertia.
• It offers excellent control capabilities.
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27. DISADVANTAGES OF PMSM
• Permanent magnet synchronous motors require a drive –
Its rotor has constant magnetic but it needs the variable
magnetic field so these motors want to variable frequency power source to
start. Permanent magnet synchronous motors require a drive to operate it
cannot run without a driver.
• Cost –
Permanent magnet motor solutions tend to need a higher initial
cost than AC induction motors so more difficult to start up than AC induction
motors. (High-cost magnet-Permanent magnets and their performance is also
based on the quality of magnet).
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28. DISADVANTAGES OF PMSM
• Complex control system-
Basically two
methods of controlling motors there are armature current controlling
and field current controlling. But in this type of motors, we can
change only stator current. There is only one source in this motor
AC supply on stator so the only way to control the motor is by
controlling the AC supply on the stator. This needs a complex control
system including power electronics and microcontrollers.
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29. APPLICATIONS OF PMSM
• Permanent Magnet synchronous motor are widely used in
electric vehicles, both in hybrid and fully electric models.
• PMSM is used in refrigerators, air conditioners, and AC
compressors.
• PMSMs are utilized in robotic systems, including robotic
arms, grippers and mobile robots.
• These are widely used in aerospace and aviation such
as aircraft actuators, flight control systems and
electric propulsion systems.
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30. Thank you sir