HIGH TEMPERATURE SUPERCONDUCTING MOTOR WITH IRON CORE
STATOR AND AIR CORE ROTOR
TECHNICAL FIELD
[0001] The present disclosure, in general, relates to high Temperature Superconducting
Motor. In particular, it relates to high Temperature Superconducting Motor with iron core
stator and air core rotor.
BACKGROUND
[0002] Background description includes information that may be useful in
understanding the present invention. It is not an admission that any of the information
provided herein is prior art or relevant to the presently claimed invention, or that any
publication specifically or implicitly referenced is prior art.
[0003] The High Temperature Superconducting (HTS) motor has at least either or both
windings on stator and rotor made of HTS wire/HTS tape. The conventional synchronous
motors employ high permeability core material in rotor as well as stator. The stator
windings are excited with alternating currents (AC) whereas the rotor windings are excited
with direct currents (DC). In principle, for synchronous machine, the flux generated by
rotor gets locked with rotating magnetic field of the stator during all load conditions of the
motor.
[0004] Hence, the motor always spins at fixed speed called synchronous speed of the
motor. On thermal side, most of the conventional synchronous motors have forced air
ventilation to manage the operational heat generated inside the motor. Sometimes, for
better thermal management, an additional fan is also provided on the shaft. The ventilation
system puts a limit on the output of the motor, beyond which the motor must not operate,
otherwise it is detrimental to the motor.
[0005] In case of HTS motor, the rotor employs HTS coils kept in a rotating cryostat.
These HTS coils are maintained at desired cryogenic temperatures with the help of
cryocooler. As the rotor is a rotating component, there shall be a rotary joint, sometimes

termed as helium transfer coupling, to enable the transfer of cryogen from stationary
cryocooler to rotating cryostat and collecting it back to cryocooler and completing the
closed loop. Such HTS rotors, if retrofitted, have potential to enhance the operating
efficiency of the conventional motors. Also, if the stator core and windings are made to
cool with the help of liquid coolant, there is further potential to enhance the overall
operational rating of the motor.
[0006] Therefore, there is a need to develop a high temperature superconducting
(HTS) motor with two or higher even multiple (equal to number of poles in the motor)
HTS coils placed in a rotating cryostat encapsulated in a vacuum chamber equipped with
high mechanical strength and high thermal resistivity material based torque transfer media
to transfer the electromagnetic force to the load along with reduced thermal load.
OBJECTS OF THE DISCLOSURE
[0007] Some of the objects of the present disclosure, which at least one embodiment
herein satisfies, are listed hereinbelow.
[0008] A general object of the present disclosure is to develop a high temperature
superconducting (HTS) motor with iron core stator and air core rotor.
[0009] An object of the present disclosure is to develop a high temperature
superconducting (HTS) motor which is less bulky, smaller in size and highly efficient.
[0010] Another object of the present disclosure is to develop a high temperature
superconducting (HTS) motor whose ventilation schemes are highly effective as compared
with combined effect of liquid coolant and forced air ventilation.
[0011] An object of the present disclosure is to develop a high temperature
superconducting (HTS) motor with iron core stator having liquid cooling arrangement for
stator winding as well as stator core along with a frame mounted blower.
[0012] Another object of the present disclosure is to develop a high temperature
superconducting (HTS) motor with two or higher even multiple (equal to number of poles
in the motor) HTS coils placed in a rotating cryostat encapsulated in a vacuum chamber

equipped with high mechanical strength and high thermal resistivity material based torque
transfer media to transfer the electromagnetic force to the load along with reduced thermal
load.
[0013] One another object of the present disclosure is to develop HTS motor in which
the stator has a liquid coolant (water, ethylene glycol or water ethylene glycol water
mixture) based ventilation for handling the thermal load of stator winding and stator core,
augmented with a forced air ventilation
[0014] Still another object of the present disclosure is to develop HTS motor which
requires lesser length of HTS tape or HTS wire and lesser ampere-turns in the rotor.
[0015] Yet another object of the present disclosure is to enable the retrofitting of the
rotor of any existing iron cored synchronous machine with air core rotor of HTS motor to
improve the overall efficiency of the machine by eliminating operational electrical losses
generated the rotor.
[0016] Yet one another object of the present disclosure is to develop HTS motor with
liquid coolant based ventilation augmented with forced air ventilation and keeping the
temperatures of active components of stator well within insulation class limits at full load
as well as all intermediate loads, thereby increasing the outstanding life of the motor.
[0017] Further an object of the present disclosure is to operate the HTS motor near
magnetic saturation with the help of air core HTS rotor thereby making the motor compact
with lesser size and weight.
[0018] Still an object of the present disclosure is to fabricate the laminations of stator
core of HTS motor in angular sectors allowing easier manufacturing and assembly of
larger capacity motor.
[0019] Yet another object of the present disclosure is to develop HTS motor with
common single liquid coolant header for ventilation of stator core and stator winding to
make the HTS motor compact with improved thermal management and lesser size and
weight.

[0020] These and other objects and advantages of the present invention will be
apparent to those skilled in the art after a consideration of the following detailed
description taken in conjunction with the accompanying drawings in which a preferred
form of the present invention is illustrated.
SUMMARY
[0021] This summary is provided to introduce concepts related to a high temperature
superconducting coils placed in the rotor of a typical High Temperature Superconducting
(HTS) motor. The concepts are further described below in the detailed description. This
summary is not intended to identify key features or essential features of the claimed subject
matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0022] In an embodiment, the present disclosure relates to a high temperature
superconducting (HTS) motor with iron core stator and air core rotor comprising an iron
core stator made of high electrical resistivity and high magnetic permeability material with
a multi-layer multi-phase winding, an air core rotor provided with a plurality of HTS coils
placed in a rotating cryostat encapsulated in a vacuum chamber, a stator frame (702) with a
liquid coolant header and a forced air blower to handle thermal load of stator winding and
stator core augmented with a forced air ventilation, a Helium transfer coupling (HTC)
(113); a Cryocooler (114); and a Heat exchanger (824) for liquid coolant.
[0023] In an aspect, the iron core stator having iron core made of high electrical
resistivity and high magnetic permeability material is selected from but not limited to
silicon steel, CRNGO steel, cobalt steel etc. and having multi-layer multi-phase winding
made of copper or copper alloy or silver or silver alloy or copper silver alloy.
[0024] In an aspect, the HTS rotor is provided with two or higher even multiple HTS
coils placed in a rotating cryostat encapsulated in a vacuum chamber equipped with high
mechanical strength and high thermal resistivity material based torque transfer media to
transfer the electromagnetic force to the load along with reduced thermal load.

[0025] In an aspect, the stator has a liquid coolant (water or ethylene glycol or water
ethylene glycol water mixture) based ventilation for handling the thermal load of stator
winding and stator core augmented with a forced air ventilation.
[0026] In an aspect, the iron core stator and air core rotor topology, require lesser
length of HTS tape or HTS wire and lesser ampere-turns in the rotor.
[0027] In an aspect, air core rotor of HTS motor can be used as retrofit rotor for any
existing iron cored synchronous machine to improve the overall efficiency of the machine
by eliminating operational electrical losses generated in the rotor.
[0028] In an aspect, the common single liquid coolant header for ventilation of stator
core and stator winding makes the motor compact with improved thermal management and
lesser size and weight.
[0029] 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.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] The illustrated embodiments of the subject matter will be best understood by
reference to the drawings, wherein like parts are designated by like numerals throughout.
The following description is intended only by way of example, and simply illustrates
certain selected embodiments of devices, systems, and methods that are consistent with the
subject matter as claimed herein, wherein:
[0031] Fig. 1 illustrates Longitudinal section of high temperature superconducting
rotor;
[0032] Fig. 2 illustrates Sectional view of complete stator core assembly, in
accordance with an embodiment of the present disclosure;
[0033] Fig. 3 illustrates Stator lamination sector, in accordance with an embodiment of
the present disclosure;

[0034] Fig. 4 illustrates Stator slot fill details, in accordance with an embodiment of
the present disclosure.
[0035] Fig. 5 illustrates Stator core assembly, in accordance with an embodiment of
the present disclosure.
[0036] Fig. 6 illustrates a Stator coil, in accordance with an embodiment of the present
disclosure.
[0037] Fig. 7 illustrates Sectional view of High Temperature Superconducting (HTS)
motor, in accordance with an embodiment of the present disclosure.
[0038] Fig. 8 illustrates longitudinal sectional view of High temperature
superconducting (HTS) motor, in accordance with an embodiment of the present disclosure
[0039] 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.
DETAILED DESCRIPTION
[0040] The detailed description of various exemplary embodiments of the disclosure is
described herein with reference to the accompanying drawings. It should be noted that the
embodiments are described herein in such details as to clearly communicate the disclosure.
However, the amount of details provided herein is not intended to limit the anticipated
variations of embodiments; on the contrary, the intention is to cover all modifications,
equivalents, and alternatives falling within the scope of the present disclosure as defined by
the appended claims.
[0041] It is also to be understood that various arrangements may be devised that,
although not explicitly described or shown herein, embody the principles of the present
disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments
of the present disclosure, as well as specific examples, are intended to encompass
equivalents thereof.

[0042] The terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of example embodiments. As used
herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as
well, unless the context clearly indicates otherwise. It will be further understood that the
terms “comprises”, “comprising”, “includes” and/or “including,” when used herein,
specify the presence of stated features, integers, steps, operations, elements and/or
components, but do not preclude the presence or addition of one or more other features,
integers, steps, operations, elements, components and/or groups thereof.
[0043] In addition, the descriptions of "first", "second", “third”, and the like in the
present invention are used for the purpose of description only, and are not to be construed
as indicating or implying their relative importance or implicitly indicating the number of
technical features indicated. Thus, features defining "first" and "second" may include at
least one of the features, either explicitly or implicitly.
[0044] It should also be noted that in some alternative implementations, the
functions/acts noted may occur out of the order noted in the figures. For example, two
figures shown in succession may, in fact, be executed concurrently or may sometimes be
executed in the reverse order, depending upon the functionality/acts involved.
[0045] Unless otherwise defined, all terms (including technical and scientific terms)
used herein have the same meaning as commonly understood by one of ordinary skill in
the art to which example embodiments belong. It will be further understood that terms,
e.g., those defined in commonly used dictionaries, should be interpreted as having a
meaning that is consistent with their meaning in the context of the relevant art and will not
be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0046] In the present subject matter, a high temperature superconducting coils placed
in the rotor of a typical High Temperature Superconducting (HTS) motor is explained. The
rotating cryostat or HTS rotor contains two or higher even multiple HTS coils along with
necessary electrical and instrumentation connections. A torque transfer media is connected
at each end of rotating cryostat for enabling the transfer of electromagnetic torque to the
load along with minimizing conductive heat load of the cryostat whereas a vacuum sleeve

is provided to reduce the convective heat load of the cryostat. This rotating cryostat does
not have any high permeability iron core, hence, termed as air core rotor. On the other
hand, the stator under consideration in the present invention is an iron cored one having
multi-layer multi-phase winding made of hollow conductors. The stator is cooled with
liquid coolant based ventilation system augmented with forced air ventilation system to
maintain the operating temperatures of active components of the motor well within the
prescribed insulation class limits.
[0047] Now, reference may be made to Figure. 1, which illustrates the longitudinal
section and details of high temperature superconducting (HTS) rotor. It looks like a
rotating cryostat (102) encapsulating all the HTS coils in the designated space (101) and
fashion. There are two torque transferring media (TTM) (105, 104) provided at each drive
end (DE) and non-drive end (NDE) to transfer the generated electromagnetic forces to the
load as well as to reduce the conduction heat load of the rotating cryostat. Both DE and
NDE TTMs are fastened to DE and NDE shafts (109, 108) respectively with the help of
DE and NDE connecting flanges (107, 106). Over DE and NDE shafts, a cylindrical
vacuum sleeve (103) is welded. During operation, inside hollow space of the cryostat other
than the cryogen flow path is maintained under ultra-high vacuum to reduce convective
heat load on the rotating cryostat. On each DE and NDE shafts, high surface finish steps
(111, 110) are provided to place the DE and NDE bearings. The DE shaft has a flange
(115) for connecting it to the mechanical load. At NDE shaft, there is a slip-ring
connection (112) for feeding the current to HTS coils. The extreme end of NDE shaft is
provided with helium transfer coupling (HTC) (113) which enables the flow of cryogen
from cryocooler (114) to HTS coil and back to cryocooler.
[0048] Figure 2 illustrates the sectional view (201) of the complete stator core
assembly. The core is made of angular sectors assembled together to realize a circular
lamination. Such lamination is stacked one over the other to realize the active length of the
core. This complete core assembly looks like a hollow cylinder whose outer cylindrical
surface (202) is attached to bore of stator frame with the help of one or more keys placed in
key slots (204) and inner surface (203) has consecutive stator slots (208) and teeth (209).
In stator slots, a multi-layer multi-phase winding made of copper or copper alloy or silver

or silver alloy or copper silver alloy is provided over the slot insulation (210). This
winding employs hollow conductors (207) to enable flow of liquid coolant (water or
ethylene glycol or ethylene glycol water mixture). There is an inter layer space (206)
within the slot to allow flow of forced air. The core has multiple through holes to assemble
the core as well as for liquid coolant flow.
[0049] Figure 3 illustrates an angular sector of the stator lamination. When such two
or more sectors are assembled together, they realize a circular lamination. The outer
circular surface (301) of the sector has key slot (305) for assembly and inner surface (302
has consecutive slots (303) and teeth (304). In slots, the stator winding is placed. Each
sector has multiple through holes (306) to assemble the core as well as for liquid coolant
flow.
[0050] Referring to Fig. 4, regarding the stator slot fill details. The main purpose of the
stator slot is to contain multi-layer multi-phase winding made of hollow conductors. The
hollow portion (409) of the conductor has liquid coolant during operation of the motor.
Between top and bottom layer conductors, an inter-layer insulation space (405) is leftover
to allow flow of forced air. Before placing the winding inside the slots, each slot is first
provided with slot insulation (401). Then bottom layer conductors (406, 408) are placed
along with their insulation (403). Then, the top layer conductors (407, 408) along with
their insulation (404 are placed. At the opening of the slot, a wedge (402) is provided for
better mechanical integrity of the winding within the slots.
[0051] Figure 5 illustrates the complete stator core assembly. Complete stator core
assembly (506) has core end plates (503, 504) mostly made of high mechanical strength
non-magnetic material. The stator core has one or more axial duct(s) (507) to allow the
flow of liquid coolant. Core stack also has one or more radial vent(s) (505) for allowing the
flow of forced air. The outer surface (501) of the core has one or more key slot(s) to
assemble the core inside the stator frame. Inside the bore (502) of the core stack, the HTS
rotor is placed.

[0052] Figure 6 illustrates an insulated coil of multi-layer multi-phase stator winding.
Each coil has two end terminals (603). It has two rectilinear portions (601 connected with
overhangs (602). In present invention, these coils are made of hollow conductors.
[0053] Figure 7 the cross section complete assembly of HTS motor assembly. HTS
motor has HTS rotor (716) placed in the bore of stator separated by a physical airgap (717)
and having two or more even multiple HTS coils (715) (equal to the number of poles of the
motor). The stator comprises of stator core (701, stator winding, stator frame (702), liquid
coolant ventilation system and forced air ventilation system. The stator core is assembled
by keeping laminations one over the other and finally bolting them all at through holes
(706) given in laminations. The laminations have consecutive slots (707) and teeth (705)
wherein the stator winding made of hollow conductors (704) is placed inside the slots.
Within the slot, an interlayer space (703) is provided for forced air ventilation within the
slot. The stator core is assembled inside the frame at designated one or more key slot(s)
(712).
[0054] Further, there is a space (708) between stator frame and core outer surface for
forced air ventilation. For forced air ventilation, a blower (710) is provided at the top of
frame on an extension (709) and mounted over a flange (711. On inner surface of stator
core, consecutive stator slots (707) and teeth (705) are provided. The slots enhouses multi-
layer multi-phase winding. The overall stator frame is supported at bottom at base frame
(713). At bottom, there are one or more through hole(s) (714) for mounting the stator
frame to base plate.
[0055] Figure 8 illustrates the longitudinal section of complete assembly of HTS
motor. HTS motor has HTS rotor (801) placed inside the stator. Rotor has two shafts viz.
DE shaft (803) and NDE shaft (802). On each DE and NDE shafts, high surface finish
steps (804, 805) are provided to place the DE and NDE bearings. The DE shaft has a
flange (809) for connecting it to the mechanical load. At NDE shaft, there is a slip-ring
connection (806) for feeding the current to HTS coils. The extreme end of NDE shaft is
provided with helium transfer coupling (HTC) (807) which enables the flow of cryogen
from cryocooler (808) to HTS coil and back to cryocooler.

[0056] The stator core is assembled inside the frame at designated one or more key
slot(s). There is space (829) between stator core stack outer surface and frame inner surface
to allow the flow of forced air. The stacked stator core has DE and NDE core end plates
(813, 814) along with one or more duct(s) to allow the flow of liquid coolant. The stator
core stack contains the stator winding made of hollow conductors (823). The Core stack
also has one or more radial vent(s) (828) for allowing the flow of forced air provided by a
blower (827 placed on the mounting arrangement over the frame (830). The stator frame
has two end covers viz. DE side end cover (811) and NDE side end cover (812) to close
the complete stator-rotor assembly. The overall stator frame is supported at bottom at base
frame (826). At bottom, there are one or more through hole(s) (825) for mounting the
stator frame to base plate. On DE side of motor, there is a main cold liquid coolant inlet
header (818), which takes coolant from outer stator coolant heat exchanger (824) through a
fixed pipe (816), for providing cold coolant to cool stator core and stator winding. On NDE
side of motor, there is a main hot liquid coolant outlet header (817) for collecting back the
warm coolant from stator core and stator winding. There are two sets of cold (820, 822)
and hot (819, 821) extension pipes to connect stator core and stator winding to hot and cold
headers respectively. The warm coolant which is sent back to heat exchanger through a
pipe (815) is cooled again with an outer stator coolant heat exchanger that finally dumps
the collected heat to outside atmosphere. The arrows in the figure denote the flow of the
liquid coolant inside the stator of the HTS motor.
[0057] Advantages associated with the application.
[0058] The advantages that may be gathered from objectives and claims of present
invention can be summarized around the application of concept of air cored HTS based
rotor placed in a conventional iron cored stator which is thermally managed better than the
conventional motors. The combined liquid coolant and forced air ventilation gives better
thermal performance of stator and maintains the temperature of active portions of stator
well within the threshold temperatures defined by the temperature insulation class. Also,
the usage of HTS windings in the rotor increases the overall efficiency of the motor, when
retrofitted with HTS rotor.

[0059] The stator core is made of angular sectors which allows easier manufacturing
and assembly of larger capacity motor.
[0060] A common single liquid coolant header for ventilation of stator core and stator
winding makes the motor compact with improved thermal management and lesser size and
weight.
[0061] The air core HTS rotor makes the HTS motor to operate near magnetic
saturation thereby making the motor compact with lesser size and weight and, if HTS rotor
is retrofitted, it augments the output rating of the motor.
[0062] The air core HTS rotor can be used as retrofit rotor for any existing iron cored
synchronous machine to improve the overall efficiency of the machine by eliminating
operational electrical losses generated in the rotor.
[0063] The present iron core stator and air core rotor topology require lesser length of
HTS tape or HTS wire and lesser ampere-turns in the rotor.
[0064] The materials, coolant are given as example without restricting scope of the
invention to the same. Thus, other materials, coolant readily apparent to a person skilled in
the art are understood to be within purview of the invention.
[0065] Further, the terminology used herein is for the purpose of describing particular
embodiments only and is not intended to be limiting of the disclosure. It will be
appreciated that several of the above-disclosed and other features and functions, or
alternatives thereof, may be combined into other systems or applications. Various presently
unforeseen or unanticipated alternatives, modifications, variations, or improvements
therein may subsequently be made by those skilled in the art without departing from the
scope of the present disclosure as encompassed by the following claims.
[0066] It will be appreciated that variants of the above-disclosed and other features and
functions, or alternatives thereof, may be combined into many other different systems or
applications. Various presently unforeseen or unanticipated alternatives, modifications,
variations, or improvements therein may be subsequently made by those skilled in the art
which are also intended to be encompassed by the following claims.

[0067] While the foregoing describes various embodiments of the invention, other and
further embodiments of the invention may be devised without departing from the basic
scope thereof. The scope of the invention is determined by the claims that follow. The
invention is not limited to the described embodiments, versions or examples, which are
included to enable a person having ordinary skill in the art to make and use the invention
when combined with information and knowledge available to the person having ordinary
skill in the art.
List of Referral Numerals
101- Space for High Temperature Superconducting (HTS) coils
102- Rotating cryostat containing HTS coils
103- Vacuum sleeve
104- NDE toque transfer media
105- DE toque transfer media
106- NDE flange connecting torque transfer media and NDE shaft
107- DE flange connecting torque transfer media and DE shaft
108- NDE shaft
109- DE shaft
110- Step for NDE bearing
111- Step for DE bearing
112- Slip ring connections for feeding the current
113- Helium transfer coupling

114- Cryocooler
115-Flange for connecting to load
201- Sectional view of complete stator core assembly
202- Stator core outer surface
203- Stator bore inner surface
204- Key slot for placing stator core inside the stator frame
205- Through holes for stator laminations assembly
206- Interlayer space for slot ventilation
207- Stator conductors
208- Stator core slots
209- Stator core teeth
210- Slot insulation

301- Stator core outer surface
302- Stator bore inner surface
303- Stator core slots
304- Stator core teeth
305- Key slot for placing stator core inside the stator frame
306- Through holes for stator laminations assembly

307- Slot insulation
308- Slot wedge
309- Bottom coil insulation
310- Top coil insulation
311- Interlayer space for slot ventilation
312- Bottom layer conductors
313- Top layer conductors
314- Top or bottom layer conductors
315- Space for stator conductor coolant flow

501- Stator core outer surface
502- Stator bore inner surface
503- Stator core DE side end plate
504- Stator core NDE side end plate
505- Stator core radial air cooling channels for ventilation
506- Stator core stack / stacked laminations
507- Stator core axial liquid cooling channels for ventilation

601- Active portion of stator coil
602- Overhang portion of stator coil

603- End terminals of the stator coil
701- Stator core
702- Stator frame
703- Interlayer space for slot ventilation
704- Stator conductors
705- Stator core teeth
706- Through holes for stator laminations assembly
707- Stator core slots
708- Air flow space for stator core ventilation
709- Frame Extension for blower assembly
710- Blower
711- Flange for blower assembly
712- Key slot for placing stator core inside the stator frame
713- Stator frame base
714- Through holes for stator frame mounting
715-High Temperature Superconducting coils in rotor
716-High temperature superconducting rotor
717-Physical air gap

715- High Temperature superconducting (HTS) rotor
716- NDE shaft
717- DE shaft
718- Step for NDE bearing
719- Step for DE bearing
720- Slip ring connections for feeding the current
721- Helium transfer coupling
722- Cryocooler
723- Flange for connecting to load
724- NDE side stator end cover
725- DE side stator end cover
726- Stator core stack / stacked laminations
727- Stator core NDE side end plate
728- Stator core DE side end plate
729- Inline of stator liquid coolant heat exchanger/ Outline of hot sub header
730- Outline of stator liquid coolant heat exchanger/ Inline of cold sub header
731- Hot sub header for liquid coolant
732- Cold sub header for liquid coolant

733- Out line of liquid coolant for stator core
734- In line of liquid coolant for stator core
735- Out line of liquid coolant for stator coil
736- In line of liquid coolant for stator coil
737- Hollow conductor type liquid cooled stator coil
738- Stator liquid coolant heat exchanger
739- Through holes for stator frame mounting
740- Stator frame base
741- Blower
742- Stator core radial ventilation ducts
743- Air flow space for stator core ventilation
830 – Mounting arrangement for blower assembly

We Claim:
1. A high temperature superconducting (HTS) motor with iron core stator and air core rotor
comprising:
an iron core stator made of high electrical resistivity and high magnetic permeability
material with a multi-layer multi-phase winding;
an air core rotor provided with a plurality of HTS coils placed in a rotating cryostat
(102) encapsulated in a vacuum chamber;
a stator frame (702) with a liquid coolant header and a forced air blower to handle
thermal load of stator winding and stator core augmented with a forced air ventilation;
a Helium transfer coupling (HTC) (113);
a Cryocooler (114); and
a Heat exchanger (824) for liquid coolant.
2. The HTS motor as claimed in claim 1, wherein the iron core stator having iron core made
of high electrical resistivity and high magnetic permeability material including silicon
steel, CRNGO steel, cobalt steel and having multi-layer multi-phase winding made of
material including copper/copper alloy/silver /silver alloy/copper silver alloy.
3. The HTS motor as claimed in claims 1 to 2, wherein the HTS rotor is provided with at least
two even multiple HTS coils placed in a rotating cryostat (102) encapsulated in a vacuum
chamber equipped with mechanical strength and thermal resistivity material based torque
transfer media to transfer the electromagnetic force to the load along with reduced thermal
load.
4. The HTS motor as claimed in claim 1 to 3, wherein the stator has a liquid coolant based
ventilation for handling the thermal load of stator winding and stator core augmented with
a forced air ventilation, in which the liquid coolant includes water/ethylene glycol/water
ethylene glycol mixture.

The HTS motor as claimed in claim 1 to 4, having iron core stator and air core rotor
topology, requires lesser length of HTS tape or HTS wire and lesser ampere-turns in the
rotor.
The HTS motor as claimed in claim 1 to 4, wherein the air core rotor can be used as retrofit
rotor for any existing iron cored synchronous machine to improve the overall efficiency of
the machine by eliminating operational electrical losses generated in the rotor.
The HTS motor as claimed in claim 1 to 4, with liquid coolant based ventilation augmented
with forced air ventilation helps in keeping the temperatures of active components of stator
well within insulation class limits at full load as well as all intermediate loads, thereby
increasing the life of the motor.
The HTS motor as claimed in claim 1 to 4, wherein air core HTS rotor makes the HTS
motor to operate near magnetic saturation thereby making the motor compact with lesser
size and weight and, if HTS rotor is retrofitted, it augments the output rating of the motor.
The HTS motor as claimed in claim 1 to 4, wherein laminations of stator core are made of
angular sectors which allows easier manufacturing and assembly of larger capacity motor.
The HTS motor as claimed in claim 1 to 4, wherein the common single liquid coolant
header for ventilation of stator core and stator winding makes the motor compact with
improved thermal management and lesser size and weight.