FIELD OF INVENTION
[001] The present invention relates to a high-efficiency, high-torque
permanent magnet synchronous motor (PMSM) with a multi pole rotor
having good transient response, mechanical stability producing maximum
torque and having higher power density. In particular, the present
invention discloses PMSM to be utilized in the marine propulsion systems.
BACKGROUND OF THE INVENTION
[002] The Permanent Magnet Synchronous Motor (PMSM) is a type of
synchronous machine which uses permanent magnets for its field
winding. It does not require any excitation winding or unit for starting thus
no need of any excitation power, slip ring and brushes leading increased
reliability, simplicity of construction. With the advancement in rare earth
magnets, the power factor, power density and power to weight ratios have
been effectively improved when compared to the conventional induction
and synchronous motors. Permanent Magnet machines are being widely
used for applications in Naval ship and also for industrial applications.
PMSMs can be used in harsh working environments like that of petroleum,
Coal Mines, sea shore applications, fans and water pumps.
[003] For ship propulsion applications, it is required to propel the ship at
very much lower speeds of range 150 rpm -600 rpm with various power
ranges from 85 kW – 5 MW. Therefore there has been a demand to develop
a motor to meet the requirement.

[004] CN102255460A titled “Permanent magnet synchronous machine
(PMSM) possessing assembled magnetic effect” provides a PMSM
possessing an assembled magnetic effect. The invention has the provision
of optimization of distribution of air-gap flux density through improving a
rotor structure and the air gap flux can be very close to a sinusoidal
waveform by using the non-uniform air gaps. It reduces magnetic flux
leakage on the ends because the ends of the permanent magnet steel are
directly connected with each other, and simultaneously a magnetic
isolation bushing is not needed to be installed on a rotating shaft side so
that a requirement of a rotating shaft material can be reduced.
[005] WO2011062064A1 titled “Permanent-magnet synchronous motor”
relates to synchronous motor having Z annular stators with wire windings
and a permanent magnet with 2P poles, Z/(3∙2P) being either 2/5 or 2/7
(3 being the number of phases). In case of use of anisotropic ring magnet,
torque ripple can be minimized by magnetizing the radial anisotropic ring
magnet.
[006] US7772736B2 titled “Permanent magnet synchronous motor, rotor
of the same, and compressor using the same” discloses PMSM having a
rotor that has two-pole permanent magnets, as well as magnetic
substances in a peripheral direction between the magnetic poles of the
permanent magnets.
[007] US7453181B2 titled “Permanent magnet synchronous motor and
compressor using the same” discloses PMSM including a rotor having cage

windings and permanent magnets placed on an inner peripheral side of
these cage winding bars, where the permanent magnets are placed and
polarized so that a ratio θ/α between a circumferential pitch angle θ of
magnetic flux distribution of the permanent magnets and a magnet pole
pitch angle α is between 0.67 and 0.91.
[008] JP2002369422A titled “Permanent magnet dynamo-electric
machine” discloses a permanent magnet type rotating electric machine
capable of maximizing a driving torque under a predetermined current and
voltage conditions and reducing the size or improving the driving
efficiency. It includes a stator having a plurality of stator windings and a
plurality of permanent magnets embedded in a rotor core, and a
predetermined gap is formed between the stator and the stator and a rotor
that is rotatably arranged in a state of having the same. Here, the angle
(polar arc degree) θ of two points on the gap side of each of the permanent
magnets 8 of the rotor 6 is 96 electrical degrees.
[009] JP2002305859A titled “Permanent magnet type synchronous motor”
includes permanent magnets, an interpole section formed between
the permanent magnets, a plurality of stator poles, and a stator core
formed with slots between the respective stator poles. A pole opening angle
θa of the permanent magnet and an interpole opening angle of the
interpole section are determined from equations: θa=(Na+1/2). A reverse
voltage can be formed into a sine wave shape, and the amount of magnetic
flux passing through the interpole can be kept constant.

[010] JP2003309953A titled “Permanent magnet rotor for inner rotor type
rotary electric machine” provides a permanent magnet rotor of an inner
rotor type rotating electric machine in which permanent magnets are
buried near the outer peripheral surface of a rotor core which can be easily
magnetized, can reduce performance, and can suppress increase in
physique weight. By magnetizing all permanent magnets 42 of the IPM in
the same direction in the radial direction and providing a hole in the outer
peripheral surface region M between the magnets of the rotor core,
magnetization is easy, performance is reduced, and physical size and
weight are increased.
[011] CN1870396B titled “Self-start synchronous motor, method for
manufacturing the same and compressor” discloses a method of
manufacturing a self-start synchronous motor for preventing deterioration
of permanent magnets used in a rotor, and also for enhancing the
efficiency of the self-start synchronous motor, the self-start synchronous
motor comprising a stator having a stator core and windings wound
around the stator core, and a rotor having an outer diameter slightly
smaller than an inner diameter of the stator and arranged inside of the
stator. The rotor is provided with a rotor core, a plurality of conductor bars
embedded in the outer peripheral portion of the rotor core over an entire
periphery thereof.

[012] US6876119B2 titled “Permanent magnet synchronous motor”
includes a stator, a rotor and permanent magnets. The rotor includes a
rotor iron core and rotatable relative to the stator, a plurality of conductor
bars accommodated within corresponding slots in the rotor iron core. The
conductor bars have their opposite ends short circuited by respective short
circuit rings to form a starter cage conductor. The rotor also has a plurality
of magnet retaining slots defined therein at a location on an inner side of
the conductor bars, in which permanent magnets are embedded.
[013] DE102008036769A1 titled “Permanent magnet synchronous motor”
discusses about a PMSM suitable for an electric power steering system in
which the magnet thickness (amount of magnet use) can be reduced while
ensuring demagnetization resistance and torque characteristics. It
includes a rotor in which a plurality of permanent magnets are disposed
on the outer circumference of a rotor core supported so as to rotate freely,
and a stator provided on the outside of the stator and Stator windings and
a stator core, when a gap length between the outer circumference of
the permanent magnet and an inner circumference of the stator core "L"
[mm] and the thickness of the central portion of the permanent magnet in
the engine rotation direction is "t" [mm], that is Gap length "L" and the
thickness "t" are set both to a range of L <= 1 [mm] and t / (t + L) <= 0.9.
[014] CN102208854B titled “Synchronous rotating electric machine with
permanent magnets and flux concentration” relates to a synchronous

rotating electric machine with permanent magnets and flux concentration.
The rotor comprises a magnetic circuit for defluxing magnetic flux to
circulate. The magnetic circuit comprises a defluxing magnetic flux
resistance (Rf) determined by a function of an internal magnetic resistance
(Ra) of the magnets so as to ensure that the ratio (Rf/Ra) of the defluxing
magnetic flux resistance to the internal magnetic resistance (Ra) of the
magnets is within a preset-value range of offsetting the demagnetizing
risks. According to the type of the magnets, the range of the preset value
is approximately between 0.3 and 3.
OBJECTIVE OF THE INVENTION
[015] It is therefore a principal object of the present invention to provide a
system of a novel multi pole PMSM motor for propulsion applications.
[016] Another object of the present invention is to develop a damper bar
design for stable starting and running under transient conditions.
[017] Another object of the present invention to develop a rotor hub and
magnet slots design to contain magnets (machining of rotor hub without
any end plate on one side) and to reduce the breakage of magnets during
insertion.
[018] Further object of the present invention is to provide a system with
design of rotor hub for good ventilation, less noise and vibration.

[019] Yet another object of the present invention is to develop a design of
short circuit ring for the ease of assembly and brazing of damper bars.
SUMMARY OF THIS INVENTION
[020] The present disclosure aims to develop a PMSM with a multi pole
rotor having good transient response, mechanical stability producing
maximum torque and having higher power density, since permanent
magnet machines are highly efficient and occupies less space when
compared to the conventional machines, having application in marine
propulsion system.
[021] PMSM is developed depending on the magnets position or placement
in rotor: Surface type and Interior type. In surface type PMSM, permanent
magnets are placed on the outer surface of rotor hub and are secured by
epoxy bandage against mechanical and electrical forces. In case of surface
type PMSM, the inductance of the direct-axis and quadrature-axis are
equal. Surface mounted type rotor is further divided into inset type and
projected type.
[022] Present invention is inset type of construction, wherein magnets are
kept just below the surface of the rotor, secured by bandaging. The PMSM
is configured with stator assembly, rotor assembly with permanent
magnets inserted within slots therein. A plurality of copper damper bars
are inserted in between the magnets. The said damper bars are bent at the
ends in short circuiting ring to form a cage like structure. Supporting rings

are provided to support the short circuiting ring. The rotor hub is mounted
on shaft for secured placing.
[023] The present invention relates to a multi pole PMSM motor for
propulsion applications. The damper bar provides stable starting and
running of motor under transient conditions.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[024] It is to be noted, however, that the appended drawings illustrate only
typical embodiments of the present subject matter and are therefore not
to be considered for limiting of its scope, for the invention may admit to
other equally effective embodiments. The detailed description is described
with reference to the accompanying figures. In the figures, a reference
number identifies the figure in which the reference number first appears.
The same numbers are used throughout the figures to reference like
features and components. Some embodiments of system or methods or
structure in accordance with embodiments of the present subject matter
are now described, by way of example, and with reference to the
accompanying figures, in which:
[025] Figure 1 illustrates the Longitudinal Cross Section of PMSM,
configured with the following components:
101-Stator Frame
102-Stator core

103- Copper winding
104- Rotor hub
105-Permanent magnets
106- Damper bar
107-Epoxy bandage
108- Air gap
109-Short circuiting rings
110-Support rings
111-Shaft
112-Roller bearing
[026] Figure 2 illustrates Front View of Rotor assembly configured with
the following components:
104-Rotor hub
105-Magnets
106-Copper bars
109-Short circuit ring
110- Supporting ring

107- Epoxy Bandage
207- Circular slots for copper bars
111-Shaft
[027] Various objects, features, aspects, and advantages of the inventive
subject matter will become more apparent from the following detailed
description of preferred embodiments, along with the accompanying
drawing figures in which like numerals represent like components.
[028] The foregoing summary is illustrative only and is not intended to be
in any way limiting. In addition to the illustrative aspects, embodiments,
and features described above, further aspects, embodiments, and features
will become apparent by reference to the drawings and the following
detailed description.
[029] The figures depict embodiments of the present subject matter for the
purposes of illustration only. A person skilled in the art will easily
recognize from the following description that alternative embodiments of
the structures and methods illustrated herein may be employed without
departing from the principles of the disclosure described herein.

DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH
REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED
EMBODIMENTS
[030] While the embodiments of the disclosure are subject to various
modifications and alternative forms, specific embodiment thereof has been
shown by way of example in the figures and will be described below. It
should be understood, however, that it is not intended to limit the
disclosure to the particular forms disclosed, but on the contrary, the
disclosure is to cover all modifications, equivalents, and alternative falling
within the scope of the disclosure.
[031] Although embodiments for the present subject matter have been
described in language specific to package features, it is to be understood
that the present subject matter is not necessarily limited to the specific
features described. Rather, the specific features and methods are disclosed
as embodiments for the present subject matter. Numerous modifications
and adaptations of the system/device of the present invention will be
apparent to those skilled in the art, and thus it is intended by the
appended claims to cover all such modifications and adaptations which
fall within the scope of the present subject matter.
[032] The terms “comprises”, “comprising”, or any other variations thereof
used in the disclosure, are intended to cover a non-exclusive inclusion,

such that a device, system, assembly that comprises a list of components
does not include only those components but may include other
components not expressly listed or inherent to such system, or assembly,
or device. In other words, one or more elements in a system or device
proceeded by “comprises… a” does not, without more constraints, preclude
the existence of other elements or additional elements in the system or
device.
[033] The longitudinal cross section of Permanent magnet synchronous
motor (PMSM) of the present invention is illustrated in Figure 1.
[034] In one embodiment, the multipole PMSM comprises stator assembly
configured with aerodynamically designed, shock proof stator frame 101,
a silicon steel laminated stator core 102, having copper strip coil winding
103 in the slots of said stator core 102. The stator winding is three-phase
balanced winding, having shaped coils, made up of rows and columns of
rectangular copper strips winding 103. The rotatable solid steel rotor hub
104 of half hollow cylindrical shape has slots where permanent magnets
105 are inserted therein. The damper bars 106 are inserted in the slots
207 (referring to Figure 2) between magnets 105 inserted per pole. The
stator 102 and rotor 104 are separated by a clear air gap 108. Damper
bars 106 are brazed at both the ends through short circuiting rings 109
which are supported in place by support rings 110. The said damper bars
provides good transient stability response, reducing oscillations and
safeguard the magnets against armature reaction effect.

[035] The said rotor hub 104 is inserted on shaft 111 with the aid of shrink
fit for support and the said shaft 111 is supported on roller bearings 112
for having good clearances of rotor assembly. The said PMSM is
characterized in the said permanent magnet 105 of both NdFeB type and
SmCo type wherein the magnetic orientation of the magnets is in radial
direction.
[036] The said invention has a distributed stator winding 103 wound with
flat rectangular strip based coils using H class insulation system and
further enriched with Vacuum Pressure Impregnated system for longer
insulation life and enhanced mechanical strength. The distribution of the
winding is in 72 slots and more. The distributed winding 103 makes the
air-gap flux of motor better near to Sine distribution uniformly.
[037] The front view of the rotor assembly of Permanent magnet
synchronous motor (PMSM) of the present invention is shown in Figure 2.
The rotor assembly has rotor hub 104 made of solid electrical steel, having
plurality of (twenty four) slots for bread loaf shaped permanent magnets
105 made of rare earth materials to be inserted therewithin.
[038] Plurality of electrically conductive round shaped Copper damper bars
106 are drilled in each of the circular slots 207, drilled in the wall in
between the slots for magnets 105. The ends of the bars 106 are bent and
brazed in a short circuiting ring 109 forming a cage similar to that of an
induction motor. The rings 109 serves the purpose of shorting the bars
106 on axial end faces through brazing. The short circuiting ring is

supported by a supporting ring 110. The cage formation ensures the
armature reaction effect and reduction in the oscillations caused during
operation of the motor with sensor less control using a PWM controller.
The hub 104 is mounted on shaft 111 through shrink fit. The magnets
105 in the rotor hub 104 are held in place using an adhesive and are
prevented from the centrifugal forces during operation by the usage of
epoxy bandage 107. Epoxy bandage 107 is used to secure magnets 105
from radial forces and adhesive is used for proper adhesion of magnets to
the surface of rotor hub and to other magnets.
[039] The said rotor hub 104 reduces the total weight of the rotor
assembly, eases the air entry through the holes provided at collar and
enhances the response the response time of the motor by reducing its
inertia. Shaft collar is a place where it stops the movement of the rotor hub
on one side axially.
[040] As a general practice, end plates are kept on both sides of rotor hub
to arrest the axial movement of magnets and the height of the end plate is
more than the magnet height by 3-4mm. However, in the present
invention, during machining itself, one side of the machine diameter is
maintained higher than the magnet 105 outer diameter. So it needs only
end plate on one side, since other end plate is an integral part of hub 104.
[041] The PMSM as disclosed herein is configured with the number of poles
(P) of the permanent magnets 105 and the number of slots (N) in the stator
core 102 maintaining the ratio of N:P = 9:2. The stator has 9n slots and

rotor has 2n poles, with ‘n’ as any whole number. Number of poles in a
machine is always an even number. In the said disclosure, even numbered
plurality magnets are used, arranged axially, to form either North or South
polarity and are having adhesive layers in between axially. It is further
configured with even plurality of slots 207 provided axially in between the
magnet slots for inserting electrically conductive copper bars 106.
[042] Since it is not possible to manufacture and assemble very long
magnets, in order to build effective core length, each pole consists of
number of same polarity magnets arranged axially and there is adhesive
used in between the magnets for proper axial adhesion.
[043] Present invention is inset type of construction, wherein magnets are
kept just below the surface of the rotor, secured by bandaging. One surface
of said magnet is adhered to the rotor hub slot, positioned on the outer
surface of the rotor having inset type of construction. Inset type rotor
consists of magnets which span less than pole pitch, mounted into the
rotor surface with an iron tooth filling the space between the magnets.
[044] In the disclosed PMSM the motor rotates at various speeds and
performs the propulsion action with extended shaft connection to
propeller.
[045] It should be noted that the description and figures merely illustrate
the principles of the present subject matter. It should be appreciated by
those skilled in the art that conception and specific embodiment disclosed
may be readily utilized as a basis for modifying or designing other

structures for carrying out the same purposes of the present subject
matter. It should also be appreciated by those skilled in the art that by
devising various arrangements that, although not explicitly described or
shown herein, embody the principles of the present subject matter.
Furthermore, all examples recited herein are principally intended
expressly to be for pedagogical purposes to aid the reader in understanding
the principles of the present subject matter and the concepts contributed
by the inventor(s) to furthering the art and are to be construed as being
without limitation to such specifically recited examples and conditions.
The novel features which are believed to be characteristic of the present
subject matter, both as to its organization and method of operation,
together with further objects and advantages will be better understood
from the following description when considered in connection with the
accompanying figures.
[046] These and other advantages of the present subject matter would be
described in greater detail with reference to the following figures. It should
be noted that the description merely illustrates the principles of the
present subject matter. It will thus be appreciated that those skilled in the
art will be able to devise various arrangements that, although not explicitly
described herein, embody the principles of the present subject matter and
are included within its scope. The present invention will now be described
more specifically with reference to the following specification.
[047] It should be noted that the description and figures merely illustrate
the principles of the present subject matter. It should be appreciated by

those skilled in the art that conception and specific embodiment disclosed
may be readily utilized as a basis for modifying or designing other
structures for carrying out the same purposes of the present subject
matter. It should also be appreciated by those skilled in the art that by
devising various arrangements that, although not explicitly described or
shown herein, embody the principles of the present subject matter and are
included within its spirit and scope. Furthermore, all examples recited
herein are principally intended expressly to be for pedagogical purposes to
aid the reader in understanding the principles of the present subject
matter and the concepts contributed by the inventor(s) to furthering the
art and are to be construed as being without limitation to such specifically
recited examples and conditions. The novel features which are believed to
be characteristic of the present subject matter, both as to its organization
and method of operation, together with further objects and advantages will
be better understood from the following description when considered in
connection with the accompanying figures.
[048] Although embodiments for the present subject matter have been
described in language specific to package features, it is to be understood
that the present subject matter is not necessarily limited to the specific
features described. Rather, the specific features and methods are disclosed
as embodiments for the present subject matter. Numerous modifications
and adaptations of the system/device of the present invention will be
apparent to those skilled in the art, and thus it is intended by the

appended claims to cover all such modifications and adaptations which
fall within the scope of the present subject matter.
[049] It will be understood by those within the art that, in general, terms
used herein, and especially in the appended claims (e.g., bodies of the
appended claims) are generally intended as “open” terms (e.g., the term
“including” should be interpreted as “including but not limited to,” the
term “having” should be interpreted as “having at least,” the term
“includes” should be interpreted as “includes but is not limited to,” etc.).
It will be further understood by those within the art that if a specific
number of an introduced claim recitation is intended, such an intent will
be explicitly recited in the claim, and in the absence of such recitation no
such intent is present. For example, as an aid to understanding, the
following appended claims may contain usage of the introductory phrases
“at least one” and “one or more” to introduce claim recitations. However,
the use of such phrases should not be construed to imply that the
introduction of a claim recitation by the indefinite articles “a” or “an” limits
any particular claim containing such introduced claim recitation to
inventions containing only one such recitation, even when the same claim
includes the introductory phrases “one or more” or “at least one” and
indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically
be interpreted to mean “at least one” or “one or more”); the same holds
true for the use of definite articles used to introduce claim recitations. In
addition, even if a specific number of an introduced claim recitation is
explicitly recited, those skilled in the art will recognize that such recitation

should typically be interpreted to mean at least the recited number (e.g.,
the bare recitation of “two recitations,” without other modifiers, typically
means at least two recitations, or two or more recitations). Furthermore,
in those instances where a convention analogous to “at least one of A, B,
and C, etc.” is used, in general such a construction is intended in the sense
one having skill in the art would understand the convention (e.g., “a
system having at least one of A, B, and C” would include but not be limited
to systems that have A alone, B alone, C alone, A and B together, A and C
together, B and C together, and/or A, B, and C together, etc.). In those
instances where a convention analogous to “at least one of A, B, or C, etc.”
is used, in general such a construction is intended in the sense one having
skill in the art would understand the convention (e.g., “a system having at
least one of A, B, or C” would include but not be limited to systems that
have A alone, B alone, C alone, A and B together, A and C together, B and
C together, and/or A, B, and C together, etc.). It will be further understood
by those within the art that virtually any disjunctive word and/or phrase
presenting two or more alternative terms, whether in the description,
claims, or drawings, should be understood to contemplate the possibilities
of including one of the terms, either of the terms, or both terms. For
example, the phrase “A or B” will be understood to include the possibilities
of “A” or “B” or “A and B.”
[050] It will be further appreciated that functions or structures of a
plurality of components or steps may be combined into a single component
or step, or the functions or structures of one-step or component may be

split among plural steps or components. The present invention
contemplates all of these combinations. Unless stated otherwise,
dimensions and geometries of the various structures depicted herein are
not intended to be restrictive of the invention, and other dimensions or
geometries are possible. In addition, while a feature of the present
invention may have been described in the context of only one of the
illustrated embodiments, such feature may be combined with one or more
other features of other embodiments, for any given application. It will also
be appreciated from the above that the fabrication of the unique structures
herein and the operation thereof also constitute methods in accordance
with the present invention. The present invention also encompasses
intermediate and end products resulting from the practice of the methods
herein. The use of “comprising” or “including” also contemplates
embodiments that “consist essentially of” or “consist of” the recited feature.
[051] Although embodiments for the present subject matter have been
described in language specific to structural features, it is to be understood
that the present subject matter is not necessarily limited to the specific
features described. Rather, the specific features and methods are disclosed
as embodiments for the present subject matter. Numerous modifications
and adaptations of the system/component of the present invention will be
apparent to those skilled in the art, and thus it is intended by the
appended claims to cover all such modifications and adaptations which
fall within the scope of the present subject matter.

ADVANTAGE OF THE INVENTION
[052] The advantage of the present invention is that it provides a system
of a novel multi pole PMSM motor for propulsion applications.
[053] Another advantage of the present invention is that it develops special
damper bar design for stable starting and running under transient
conditions.
[054] Another advantage of the present invention is that it develops special
rotor hub and magnet slots design to contain magnets (machining of rotor
hub avoiding any end plate on one side) and reduces the breakage of
magnets during insertion.
[055] Further advantage of the present invention is that it develops a
system with design of rotor hub for good ventilation, less noise and
vibration.
[056] Further advantage of the present invention is that it develops a
design of short circuit ring for the ease of assembly and brazing of damper
bars.
[057] Yet another advantage of the present invention is that compared to
the conventional electromagnetic machines, it has high reliability, simple
structure, low maintenance.

[058] Yet another advantage of the present invention is that it performs
with no excitation winding thus avoiding slip rings and brushes.
[059] Yet another advantage of the present invention is that it provides
PMSM with High torque/ volume ratio and High power density.

We Claim:
1. A system of multi pole Permanent Magnet Synchronous Motor
(PMSM), comprises of:
- A stator assembly embedded with an aerodynamically designed,
shock proof stator frame 101 and a stator core 102, having
plurality of slots for holding copper coil winding 103 therein;
- A rotor assembly maintaining an air gap 108 from the said stator
assembly, wherein the said rotor assembly is embedded with
rotor hub 104 with multiple slots therein for inserting plurality
of Permanent magnets 105 of rear earth material, wherein a
plurality of electrically conductive Copper Damper bars 106 are
inserted in the slots 207 in between magnets 105 per pole of
PMSM, wherein an Epoxy bandage 107 secures said magnets
105 against radial centrifugal force due to rotor action and
adhesive provides proper adhesion of magnets 105 to the surface
of rotor hub 104 and to other magnets, wherein a plurality of
short circuiting rings 109 provides assembly and brazing of the
said damping bars 106 at both ends, wherein a plurality of
support rings 110 provides support to said short circuiting rings
109 in place and provides ventilation;
- A shaft 111 for providing support to rotor hub 104 held at collar,
atop roller bearings 112 for providing support and clearance to
rotor assembly.

2. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1, wherein the stator core 102 made of
silicon steel laminations having plurality of slots for holding winding
of three-phase balanced winding, configures rows and columns of
rectangular copper strips winding 103, wherein the said winding 103
using H class insulation system is enriched with Vacuum Pressure
Impregnated system for longer insulation life and is distributed in at
least 72 slots making the air-gap flux of PMSM to uniform Sine
distribution.
3. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1, wherein the rotor hub 104 embedded
with multiple slots, with permanent magnets 105 inserted
therewithin, structures one surface adhered to the said rotor hub slot,
positioned on the outer surface of the rotor having inset type of
construction, ensuring reduction in the breakage of magnets 105
during insertion.
4. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1 and 3, wherein the rotor hub 104
structured as a half hollow hub reduces the total weight of the rotor
assembly, eases the air entry through the holes provided at collor and
enhances the response time of the PMSM against its inertia.
5. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1, wherein the number of poles (P) of the

permanent magnets 105 and the number of slots (N) in the stator core
102 for inserting 103 maintains the ratio of N: P = 9:2, wherein even
numbered plurality magnets 105 are arranged axially in poles within,
arranged with even plurality of slots 207 provided axially in between
the magnet slots for inserting electrically conductive copper bars 106.
6. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1, wherein it rotates at multiple speeds of
range 150 rpm -600 rpm with power ranges from 85 kW – 5 MW and
performs the propulsion action with extended shaft.
7. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1, wherein it configures the said
permanent magnet 105 of NdFeB type and SmCo type with the
magnetic orientation of the magnets in radial direction.
8. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1, wherein a plurality of copper conductors
used as damper bars 106 embedded axially in slots 207 provided in
rotor hub 104 in between the magnet slots, forms cage structure and
gives transient stability response, reduces oscillations caused during
operation of the motor with sensor less control using a PWM controller
and safeguards the magnets 105 against armature reaction effect.
9. The system of multi pole Permanent Magnet Synchronous Motor
(PMSM) as claimed in claim 1 and 8, wherein the end of damper bars
106 are bent and brazed in a short circuiting ring 109 for shorting the

bar on axial end faces, wherein the said short circuiting ring 109 is
supported by supporting ring 110 thereunder.