Title of Invention	HIGH POWER DENSITY EXTERNAL ROTOR SWITCHED RELUCTANCE MOTOR.
Abstract	A high power density switched reluctance motor comprising a ring shaped segmented external rotor (2) rotatably disposed over a cylindrical stator (3) and adapted to be coupled to a driven part. The rotor comprises a plurality of discrete rotor poles (5) made of a magnetic material and embedded in a light weight thermally conducting non-magnetic material rotor body (6). The stator is mounted on the stationary shaft of the motor and comprises a magnetic material body having a plurality of stator slots (7) radially spaced apart around the circumference thereof. The stator further comprises phase windings (8) wound in each of the stator slots over the stator body 180 electrical degrees apart.

Title of Invention

HIGH POWER DENSITY EXTERNAL ROTOR SWITCHED RELUCTANCE MOTOR.

Abstract

A high power density switched reluctance motor comprising a ring shaped segmented external rotor (2) rotatably disposed over a cylindrical stator (3) and adapted to be coupled to a driven part. The rotor comprises a plurality of discrete rotor poles (5) made of a magnetic material and embedded in a light weight thermally conducting non-magnetic material rotor body (6). The stator is mounted on the stationary shaft of the motor and comprises a magnetic material body having a plurality of stator slots (7) radially spaced apart around the circumference thereof. The stator further comprises phase windings (8) wound in each of the stator slots over the stator body 180 electrical degrees apart.

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) As amended by the Patents (Amendment) Act, 2005 & The Patents Rules, 2003 As amended by the Patents (Amendment) Rules, 2006 COMPLETE SPECIFICATION (See section 10 and rule 13) TITLE OF THE INVENTION A high power density switched reluctance motor APPLICANTS Indian Institute of Technology, Bombay, an autonomous research and educational institution established in India by a special Act of the Parliament of the Republic of India under the Institutes of Technology Act 1961, Powai, Mumbai 400076, Maharashtra, India INVENTORS Fernandes Baylon and Vatti Kuti Naresh, both of Department of Electrical Engineering and Rallabandi Vandana, Department of Energy Science and Engineering, all of IIT Bombay, Powai, Mumbai 400076, Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the nature of this invention and the manner in which it is to be performed: FIELD OF THE INVENTION This invention relates to a high power density switched reluctance motor. BACKGROUND OF THE INVENTION Switched reluctance motors (SRMs) are well known rotating electric machines having phase windings on the stator but not on the rotor. Switched reluctance motors are ideal machines for variable speed drive applications because of their advantages like rugged construction, reliability on account of mechanical simplicity, high efficiency and lack of conductors on the rotor. Switched reluctance motors are driven through power electronic interface and a control circuit which generates the gate triggering pulses. US 5111096 describes a two phase internal rotor switched reluctance motor comprising a rotor disposed for rotation in the central bore of a stator. The rotor comprises a plurality of radially extending pairs of teeth. Each tooth is formed of stacked laminations with each stack being magnetically isolated from every other stack of laminations. The stator comprises an even and equal number of stator poles and salient teeth. The stator is wound with phase windings comprising coils disposed over the stator and spanning two adjacent stator teeth. The windings selectively generate magnetic fields extending from the stator poles into the central bore of the stator. When each phase is energized all the rotor and stator teeth produce positive torque for a specific angular span of rotor rotation. In such a motor the power or torque output of the motor depends upon the difference between maximum flux and minimum flux values of the magnetic fields generated. As the number of poles increases the value of maximum flux increases thereby reducing the power output of the motor. US 2002/0134118 describes a washing machine including an internal rotor segmented stator switched reluctance motor. The motor includes a stator comprising a 2 plurality of circumferentially spaced stator segment assemblies that include a stator segment core and winding wire wound around the stator segment core. A rotor comprising a plurality of rotor poles is disposed for rotation in the stator. The rotor tends to rotate relative to the stator to maximize the inductance of an energized winding. Due to the torque to weight ratio of the motor being low the size and cost of the motor are increased. Oyama et al describes a segmented internal rotor switched reluctance motor comprising a rotor made of discrete iron segments embedded in aluminium and a stator wound with windings each comprising two coil sides disposed over the stator at 180 electrical degrees apart. [J Oyama, T Higuchi, T Abe and N Kifuji, "Switched reluctance motor with segmented core embedded in Aluminum rotor", Proc of Japan Industry Applications society conference, Vol.3 pp.493-496 (2004)]. In such a motor, the phase windings have increased resistance as the windings are large extending across the stator outside the rotor. Therefore, temperature rise in the windings is high and efficiency of the motor is reduced. Also the power density is reduced. The inner rotor switched reluctance motors generally require a gear box and belt for taking the drive from the motor shaft to the driven part. Because of the use of gear box and belt, drive is not efficiently transmitted to the driven part and operation of the motor is noisy and also creates torque ripple. The motor also tend to heat up and require extensive maintenance. Multistage drive from the motor shaft will further reduce efficiency of the motor. US 4998052 describes a variable speed external rotor switched reluctance motor for driving a laundry machine. The motor has a stator and rotor each of which includes a plurality of poles with the stator to rotor pole ratio being selected from the ratios of 6:4 and 8:6 with the actual number of poles being a multiple of three or more times those numbers. Coils are wound on each of the stator poles wherein every third or more phases of the coils are connected to form three or more phases for energisation of the switched reluctance 3 motor. The motor shaft is directly coupled to the agitator shaft of the laundry machine. As a result, all the disadvantages associated with gear box and belt drive have been eliminated. However, the torque to weight ratio of the motor is low resulting in increase in the size and cost of the motor. OBJECTS OF THE INVENTION An object of the invention is to provide a high power density switched reluctance motor having low winding resistance and low temperature rise in the windings and high efficiency and high power or torque output. Another object of the invention is to provide a high power density switched reluctance motor which can be directly coupled to a driven part and which eliminates the use of belt and gear box and disadvantages associated therewith. Another object of the invention is to provide a high power density switched reluctance motor which is light weight and compact and is economical. Another object of the invention is to provide a high power density switched reluctance motor, which can be used as an ideal substitute for brushless DC motor and derive the benefits associated with brushless DC motor. DETAILED DESCRIPTION OF THE INVENTION According to the invention there is provided a high power density switched reluctance motor comprising a ring shaped segmented external rotor rotatably disposed over a 4 cylindrical stator and adapted to be coupled to a driven part, the rotor comprising a plurality of discrete rotor poles made of a magnetic material and embedded in a light weight thermally conducting non-magnetic material rotor body, the stator being mounted on the stationary shaft of the motor and comprising a magnetic material body having a plurality of stator slots radially spaced apart around the circumference thereof, the stator further comprising phase windings wound in each of the stator slots over the stator body 180 electrical degrees apart. The following is a detailed description of the invention with reference to the accompanying drawings, in which: Fig 1 is an isometric view of the segmented external rotor and stator assembly of a high power density switched reluctance motor according to an embodiment of the invention; Fig 2 is an isometric view of the stator in Fig 1; Fig 3 is an isometric view of the rotor in Fig 1; Fig 4 is a graphical representation of torque variations with rotor position of four motors; and Figs 5 and 6 are graphical representations of applied voltage and resulting current in one phase of a motor of the invention, respectively. 5 The segmented external rotor and stator assembly 1 as illustrated in Figs 1 to 3 of the accompanying drawings comprises a ring shaped segmented external rotor 2 rotatably disposed over a cylindrical stator 3 which in turn is mounted on a stationary shaft (not shown) through the shaft hole 4 therein. The rotor 2 comprises a plurality of discrete rotor poles 5 of trapezoidal shape made of a magnetic material selected from, for instance, cold rolled non-grain oriented silicon steel (CRNO M - 45) and embedded in a light weight thermally conducting non-magnetic material rotor body 6 made of a material selected from, for instance, aluminium. The rotor poles also can be of other shapes. Preferably the rotor poles are made by wire cutting and embedded in the aluminium rotor body cast with molten aluminium poured on the rotor poles. The stator 3 is made of a magnetic material selected from, for instance cold rolled non-grain oriented silicon steel (CRNO M - 45) and comprises a plurality of stator slots 7 radially spaced apart around the circumference thereof. The stator further comprises phase windings 8 wound in the stator slots 180 electrical degrees apart. Only two phase windings have been shown in Fig 2 for the purpose of clarity and simplicity. Preferably the motor shaft is hollow for the power cables (not shown) connected to the phase windings to pass therethrough. Preferably the stator is made by wire cutting stator laminations and stacking the laminations together. On energising the phase windings, the rotor rotates about the stator and develops the required torque or power output to derive the driven part connected to it. Preferably the stator comprises six poles and the rotor comprises four poles for simplicity of construction and optimum power output. The stator slots are preferably circular so as to have increased surface area for the phase windings and to reduce the length of the flux paths substantially. According to the invention the segmented external rotor switched reluctance motor gives high power or torque output ie high power density because of the high flux due to the short flux paths. At the same time 6 the length of the end winding connections is reduced as the windings are only extending over the stator disposed within the rotor and hence over a small diameter. As a result the resistance of the phase windings is reduced and the temperature rise in the windings is reduced. Further the motor is compact and also can be directly coupled to a driven part so as to eliminate use of belt and gear box drive and disadvantages associated therewith. The SRM of the invention is an Ideal substitute for brushless DC motors which have high torque or power output but are at the same time very expensive because of the use of costly permanent magnet rotor, Because of the high power output and compactness of the motor of the invention, it can also be advantageously used in constrained areas such as small electric vehicles where brushless DC motors are advantageously used and derive the benefits associated with brushes DC motors. Comparative simulation studies were carried out using a segmented external rotor switched reluctance motor of the invention and three other conventional motors. All the four motors were of six stator poles and four rotor poles and had the same outer diameter of 184mm, stack length of 110mm. air-gap of 0.4mm, electric loading of 8300 ampere conductors / m and rated speed of 600 RPM. The material used for the rotor and stator of each motor was cold rolled non-grain oriented silicon steel (CRNO M - 45) with saturation flux density of 2 T The bodies of the segmented rotors were made of aluminium. The motors were simulated using Flux 2D, a commercially available finite element package for the performance analysis of electrical machinery. Further details of the motors and the test results were as given in. the following Table: 7 Table Type of SRM Inner diameter (mm) Torque (N-m) Active Weight Kg Torque to weight ratio Torque to winding Loss ratio Winding resistance a (1) Inner rotor SRM of US5111096 130 9.67 18.37 0.526 0.125 0.75 (2) Segmented inner rotor SRM of Oyama et al 126 14.2 20.8 0.682 0.086 1.65 (3) External rotor SRM of US 4998052 137 11 19.14 0.575 0.1466 0.75 (4) Segmented external rotor SRM of the Invention with circular stator slots 137 17.12 17.5 0.978 0.128 1.33 It is seen from the Table that the power or torque output of the motor of the invention was the highest and was 75 % higher than that of the conventional segmented inner rotor SRM of Oyama. Further the winding resistance of the motor of the invention was lower and the efficiency (torque to winding loss ratio) of the motor of the invention was higher as compared to the conventional segmented inner rotor SRM of Oayama. Because of the high torque or high power or high torque density (ratio of power or torque to output machine volume if the machine is considered as a cylinder), and compact nature, the motor of the invention can be advantageously used for high torque applications especially as an ideal substitute for brushless DC motors. The torque variation with rotor position was studied under on load and no load conditions in all the four motors and the results were as shown in Fig 4 of the accompanying drawings. Fig 4 shows that the torque output of the invention was the highest for the dimensions (84 mm, stack length of 110 mm air-gap of 0.4 mm and electrical loading 8300 ampere conductors /m and rated speed of 600 RPM). The applied voltage and resulting current in one phase of the motor of the invention were studied and the results were as shown in Figs 5 8 and 6 of the accompanying drawings. These results in Figs 5 and 6 indicate the normal healthy operation of the motor of the invention. We claim: 1. A high power density switched reluctance motor comprising a ring shaped segmented external rotor rotatably disposed over a cylindrical stator and adapted to be coupled to a driven part, the rotor comprising a plurality of discrete rotor poles made of a magnetic material and embedded in a light weight thermally conducting non-magnetic material rotor body, the stator being mounted on the stationary shaft of the motor and comprising a magnetic material body having a plurality of stator slots radially spaced apart around the circumference thereof, the stator further comprising phase windings wound in each of the stator slots over the stator body 180 electrical degrees apart. 2. The motor as claimed in claim 1, wherein the rotor comprises discrete rotor poles which are trapezoidal shaped and are made of cold rolled grain oriented silicon steel and are embedded in a rotor body made of aluminium. 3. The motor as claimed in claim 2, wherein the rotor poles are made by wire cutting and are embedded in an aluminium rotor body by casting with molten aluminium. 4. The motor as claimed in any one of claims 1 to 3, wherein the stator slots are circular and the stator body is made of cold rolled grain oriented silicon steel. 5. The motor as claimed in claim 4, wherein the stator body comprises a plurality of laminations wire cut and stacked together. \0 6. The motor as claimed in any one of claims 1 to 5, wherein the motor shaft is hollow for the power cables connected to the phase windings to pass therethrough. 7. The motor as claimed in anyone of claims 1 to 6, which comprises six stator slots and four rotor poles. Dated this 2nd day of February 2009 (Jose M A) ofKhaitan&Co Agent for the Applicants 11

Full Text

FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
As amended by the Patents (Amendment) Act, 2005
& The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)

TITLE OF THE INVENTION
A high power density switched reluctance motor
APPLICANTS
Indian Institute of Technology, Bombay, an autonomous research and educational institution established in India by a special Act of the Parliament of the Republic of India under the Institutes of Technology Act 1961, Powai, Mumbai 400076, Maharashtra, India
INVENTORS
Fernandes Baylon and Vatti Kuti Naresh, both of Department of Electrical Engineering and Rallabandi Vandana, Department of Energy Science and Engineering, all of IIT Bombay, Powai, Mumbai 400076, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

FIELD OF THE INVENTION
This invention relates to a high power density switched reluctance motor.
BACKGROUND OF THE INVENTION
Switched reluctance motors (SRMs) are well known rotating electric machines having phase windings on the stator but not on the rotor. Switched reluctance motors are ideal machines for variable speed drive applications because of their advantages like rugged construction, reliability on account of mechanical simplicity, high efficiency and lack of conductors on the rotor. Switched reluctance motors are driven through power electronic interface and a control circuit which generates the gate triggering pulses. US 5111096 describes a two phase internal rotor switched reluctance motor comprising a rotor disposed for rotation in the central bore of a stator. The rotor comprises a plurality of radially extending pairs of teeth. Each tooth is formed of stacked laminations with each stack being magnetically isolated from every other stack of laminations. The stator comprises an even and equal number of stator poles and salient teeth. The stator is wound with phase windings comprising coils disposed over the stator and spanning two adjacent stator teeth. The windings selectively generate magnetic fields extending from the stator poles into the central bore of the stator. When each phase is energized all the rotor and stator teeth produce positive torque for a specific angular span of rotor rotation. In such a motor the power or torque output of the motor depends upon the difference between maximum flux and minimum flux values of the magnetic fields generated. As the number of poles increases the value of maximum flux increases thereby reducing the power output of the motor. US 2002/0134118 describes a washing machine including an internal rotor segmented stator switched reluctance motor. The motor includes a stator comprising a
2

plurality of circumferentially spaced stator segment assemblies that include a stator segment core and winding wire wound around the stator segment core. A rotor comprising a plurality of rotor poles is disposed for rotation in the stator. The rotor tends to rotate relative to the stator to maximize the inductance of an energized winding. Due to the torque to weight ratio of the motor being low the size and cost of the motor are increased. Oyama et al describes a segmented internal rotor switched reluctance motor comprising a rotor made of discrete iron segments embedded in aluminium and a stator wound with windings each comprising two coil sides disposed over the stator at 180 electrical degrees apart. [J Oyama, T Higuchi, T Abe and N Kifuji, "Switched reluctance motor with segmented core embedded in Aluminum rotor", Proc of Japan Industry Applications society conference, Vol.3 pp.493-496 (2004)]. In such a motor, the phase windings have increased resistance as the windings are large extending across the stator outside the rotor. Therefore, temperature rise in the windings is high and efficiency of the motor is reduced. Also the power density is reduced. The inner rotor switched reluctance motors generally require a gear box and belt for taking the drive from the motor shaft to the driven part. Because of the use of gear box and belt, drive is not efficiently transmitted to the driven part and operation of the motor is noisy and also creates torque ripple. The motor also tend to heat up and require extensive maintenance. Multistage drive from the motor shaft will further reduce efficiency of the motor. US 4998052 describes a variable speed external rotor switched reluctance motor for driving a laundry machine. The motor has a stator and rotor each of which includes a plurality of poles with the stator to rotor pole ratio being selected from the ratios of 6:4 and 8:6 with the actual number of poles being a multiple of three or more times those numbers. Coils are wound on each of the stator poles wherein every third or more phases of the coils are connected to form three or more phases for energisation of the switched reluctance
3

motor. The motor shaft is directly coupled to the agitator shaft of the laundry machine. As a result, all the disadvantages associated with gear box and belt drive have been eliminated. However, the torque to weight ratio of the motor is low resulting in increase in the size and cost of the motor.
OBJECTS OF THE INVENTION
An object of the invention is to provide a high power density switched reluctance motor having low winding resistance and low temperature rise in the windings and high efficiency and high power or torque output.
Another object of the invention is to provide a high power density switched reluctance motor which can be directly coupled to a driven part and which eliminates the use of belt and gear box and disadvantages associated therewith.
Another object of the invention is to provide a high power density switched reluctance motor which is light weight and compact and is economical.
Another object of the invention is to provide a high power density switched reluctance motor, which can be used as an ideal substitute for brushless DC motor and derive the benefits associated with brushless DC motor.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a high power density switched reluctance
motor comprising a ring shaped segmented external rotor rotatably disposed over a
4

cylindrical stator and adapted to be coupled to a driven part, the rotor comprising a plurality of discrete rotor poles made of a magnetic material and embedded in a light weight thermally conducting non-magnetic material rotor body, the stator being mounted on the stationary shaft of the motor and comprising a magnetic material body having a plurality of stator slots radially spaced apart around the circumference thereof, the stator further comprising phase windings wound in each of the stator slots over the stator body 180 electrical degrees apart.
The following is a detailed description of the invention with reference to the accompanying drawings, in which:
Fig 1 is an isometric view of the segmented external rotor and stator assembly of a high power density switched reluctance motor according to an embodiment of the invention;
Fig 2 is an isometric view of the stator in Fig 1;
Fig 3 is an isometric view of the rotor in Fig 1;
Fig 4 is a graphical representation of torque variations with rotor position of four motors; and
Figs 5 and 6 are graphical representations of applied voltage and resulting current in one phase of a motor of the invention, respectively.
5

The segmented external rotor and stator assembly 1 as illustrated in Figs 1 to 3 of the accompanying drawings comprises a ring shaped segmented external rotor 2 rotatably disposed over a cylindrical stator 3 which in turn is mounted on a stationary shaft (not shown) through the shaft hole 4 therein. The rotor 2 comprises a plurality of discrete rotor poles 5 of trapezoidal shape made of a magnetic material selected from, for instance, cold rolled non-grain oriented silicon steel (CRNO M - 45) and embedded in a light weight thermally conducting non-magnetic material rotor body 6 made of a material selected from, for instance, aluminium. The rotor poles also can be of other shapes. Preferably the rotor poles are made by wire cutting and embedded in the aluminium rotor body cast with molten aluminium poured on the rotor poles. The stator 3 is made of a magnetic material selected from, for instance cold rolled non-grain oriented silicon steel (CRNO M - 45) and comprises a plurality of stator slots 7 radially spaced apart around the circumference thereof. The stator further comprises phase windings 8 wound in the stator slots 180 electrical degrees apart. Only two phase windings have been shown in Fig 2 for the purpose of clarity and simplicity. Preferably the motor shaft is hollow for the power cables (not shown) connected to the phase windings to pass therethrough. Preferably the stator is made by wire cutting stator laminations and stacking the laminations together. On energising the phase windings, the rotor rotates about the stator and develops the required torque or power output to derive the driven part connected to it. Preferably the stator comprises six poles and the rotor comprises four poles for simplicity of construction and optimum power output. The stator slots are preferably circular so as to have increased surface area for the phase windings and to reduce the length of the flux paths substantially. According to the invention the segmented external rotor switched reluctance motor gives high power or torque output ie high power density because of the high flux due to the short flux paths. At the same time
6

the length of the end winding connections is reduced as the windings are only extending over the stator disposed within the rotor and hence over a small diameter. As a result the resistance of the phase windings is reduced and the temperature rise in the windings is reduced. Further the motor is compact and also can be directly coupled to a driven part so as to eliminate use of belt and gear box drive and disadvantages associated therewith. The SRM of the invention is an Ideal substitute for brushless DC motors which have high torque or power output but are at the same time very expensive because of the use of costly permanent magnet rotor, Because of the high power output and compactness of the motor of the invention, it can also be advantageously used in constrained areas such as small electric vehicles where brushless DC motors are advantageously used and derive the benefits associated with brushes DC motors.
Comparative simulation studies were carried out using a segmented external rotor switched reluctance motor of the invention and three other conventional motors. All the four motors were of six stator poles and four rotor poles and had the same outer diameter of 184mm, stack length of 110mm. air-gap of 0.4mm, electric loading of 8300 ampere conductors / m and rated speed of 600 RPM. The material used for the rotor and stator of each motor was cold rolled non-grain oriented silicon steel (CRNO M - 45) with saturation flux density of 2 T The bodies of the segmented rotors were made of aluminium. The motors were simulated using Flux 2D, a commercially available finite element package for the performance analysis of electrical machinery. Further details of the motors and the test results were as given in. the following Table:
7

Table

Type of SRM Inner
diameter
(mm) Torque (N-m) Active
Weight
Kg Torque to
weight ratio Torque to
winding Loss ratio Winding resistance
a
(1) Inner rotor SRM of US5111096 130 9.67 18.37 0.526 0.125 0.75
(2) Segmented inner rotor SRM of Oyama et al 126 14.2 20.8 0.682 0.086 1.65
(3) External rotor SRM of US 4998052 137 11 19.14 0.575 0.1466 0.75
(4) Segmented external rotor SRM of the Invention with circular stator slots 137 17.12 17.5 0.978 0.128 1.33
It is seen from the Table that the power or torque output of the motor of the invention was
the highest and was 75 % higher than that of the conventional segmented inner rotor SRM of Oyama. Further the winding resistance of the motor of the invention was lower and the efficiency (torque to winding loss ratio) of the motor of the invention was higher as compared to the conventional segmented inner rotor SRM of Oayama. Because of the high torque or high power or high torque density (ratio of power or torque to output machine volume if the machine is considered as a cylinder), and compact nature, the motor of the invention can be advantageously used for high torque applications especially as an ideal substitute for brushless DC motors.
The torque variation with rotor position was studied under on load and no load conditions in
all the four motors and the results were as shown in Fig 4 of the accompanying drawings.
Fig 4 shows that the torque output of the invention was the highest for the dimensions (84
mm, stack length of 110 mm air-gap of 0.4 mm and electrical loading 8300 ampere
conductors /m and rated speed of 600 RPM). The applied voltage and resulting current in
one phase of the motor of the invention were studied and the results were as shown in Figs 5
8

and 6 of the accompanying drawings. These results in Figs 5 and 6 indicate the normal healthy operation of the motor of the invention.

We claim:
1. A high power density switched reluctance motor comprising a ring shaped segmented external rotor rotatably disposed over a cylindrical stator and adapted to be coupled to a driven part, the rotor comprising a plurality of discrete rotor poles made of a magnetic material and embedded in a light weight thermally conducting non-magnetic material rotor body, the stator being mounted on the stationary shaft of the motor and comprising a magnetic material body having a plurality of stator slots radially spaced apart around the circumference thereof, the stator further comprising phase windings wound in each of the stator slots over the stator body 180 electrical degrees apart.
2. The motor as claimed in claim 1, wherein the rotor comprises discrete rotor poles which are trapezoidal shaped and are made of cold rolled grain oriented silicon steel and are embedded in a rotor body made of aluminium.
3. The motor as claimed in claim 2, wherein the rotor poles are made by wire cutting and are embedded in an aluminium rotor body by casting with molten aluminium.
4. The motor as claimed in any one of claims 1 to 3, wherein the stator slots are circular and the stator body is made of cold rolled grain oriented silicon steel.
5. The motor as claimed in claim 4, wherein the stator body comprises a plurality of laminations wire cut and stacked together.
\0

6. The motor as claimed in any one of claims 1 to 5, wherein the motor shaft is hollow for the power cables connected to the phase windings to pass therethrough.
7. The motor as claimed in anyone of claims 1 to 6, which comprises six stator slots and four rotor poles.
Dated this 2nd day of February 2009

(Jose M A)
ofKhaitan&Co
Agent for the Applicants
11

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Patent Number

270751

Indian Patent Application Number

197/MUM/2009

PG Journal Number

03/2016

Publication Date

15-Jan-2016

Grant Date

15-Jan-2016

Date of Filing

02-Feb-2009

Name of Patentee

INDIAN INSTITUTE OF TECHNOLOGY, BOMBAY

Applicant Address

POWAI, MUMBAI

Inventors:

#	Inventor's Name	Inventor's Address
1	VATTI KUTI NARESH	Indian Institute of Technology, POWAI, MUMBAI 400 076,
2	FERNANDES BAYLON	INDIAN INSTITUTE OF TECHNOLOGY, POWAI, MUMBAI 400 076,
3	RALLABANDI VANDANA	Indian Institute of Technology, POWAI, MUMBAI 400 076,

PCT International Classification Number

H02K23/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA