GB2608624A - Shielding in electrical machine - Google Patents

Shielding in electrical machine Download PDF

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Publication number
GB2608624A
GB2608624A GB2109749.8A GB202109749A GB2608624A GB 2608624 A GB2608624 A GB 2608624A GB 202109749 A GB202109749 A GB 202109749A GB 2608624 A GB2608624 A GB 2608624A
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GB
United Kingdom
Prior art keywords
electrical machine
channel
rotor
ferrofluid
stator
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB2109749.8A
Other versions
GB202109749D0 (en
Inventor
Deodhar Rajesh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
IMRA Europe SAS
Original Assignee
IMRA Europe SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by IMRA Europe SAS filed Critical IMRA Europe SAS
Priority to GB2109749.8A priority Critical patent/GB2608624A/en
Publication of GB202109749D0 publication Critical patent/GB202109749D0/en
Publication of GB2608624A publication Critical patent/GB2608624A/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/20—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/12—Stationary parts of the magnetic circuit
    • H02K1/20—Stationary parts of the magnetic circuit with channels or ducts for flow of cooling medium
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K1/00—Details of the magnetic circuit
    • H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
    • H02K1/22—Rotating parts of the magnetic circuit
    • H02K1/32—Rotating parts of the magnetic circuit with channels or ducts for flow of cooling medium
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/01—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for shielding from electromagnetic fields, i.e. structural association with shields
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/01—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for shielding from electromagnetic fields, i.e. structural association with shields
    • H02K11/014—Shields associated with stationary parts, e.g. stator cores
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K9/00—Arrangements for cooling or ventilating
    • H02K9/19—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil
    • H02K9/197—Arrangements for cooling or ventilating for machines with closed casing and closed-circuit cooling using a liquid cooling medium, e.g. oil in which the rotor or stator space is fluid-tight, e.g. to provide for different cooling media for rotor and stator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/01—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection for shielding from electromagnetic fields, i.e. structural association with shields
    • H02K11/012—Shields associated with rotating parts, e.g. rotor cores or rotary shafts
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K5/00—Casings; Enclosures; Supports
    • H02K5/04—Casings or enclosures characterised by the shape, form or construction thereof
    • H02K5/20—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium
    • H02K5/203—Casings or enclosures characterised by the shape, form or construction thereof with channels or ducts for flow of cooling medium specially adapted for liquids, e.g. cooling jackets

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Motor Or Generator Cooling System (AREA)

Abstract

An electrical machine 100 comprising a rotor 110, a stator 120 and a first channel 125 arranged coaxially with the rotor and stator, where the first channel is arranged external to the rotor and the stator, the first channel comprising a first ferrofluid. The stator may be external to the rotor, and the first channel may be affixed to the stator where the stator comprises one or more stator windings 122, and where the first channel is configured to permit the transfer of heat from the windings to the first ferrofluid. The first ferrofluid within the first channel may be configured to prevent magnetic flux leakage outside the electrical machine. The first channel may form a cylindrical jacket around the electrical machine. A second channel (235, fig 2) may be provided internal to the rotor and the stator, the second channel comprising a second ferrofluid, where the first ferrofluid and the second ferrofluid may have the same composition and where the second channel may be affixed to the rotor. The second channel may be configured to permit the transfer of heat from the one or more rotor windings or one or more permanent magnets to the second ferrofluid. The ferrofluid may comprise between approximately 2% and 18% ferromagnetic particles by volume. A heat exchanger may also be provided.

Description

Shielding in Electrical Machine
Field of the Invention
The invention generally relates to electrical machines and providing electromagnetic shielding and cooling for electrical machines.
Background
As the world transitions away from fossil fuels and to cleaner, renewable sources of power, electrical machines are becoming increasingly important. Electrical machines include electric generators to generate electricity in, for example, a wind turbine or for regenerative braking applications in vehicles. Alternatively, electric motors, such as induction motors, can use electrical energy to generate torque to power vehicles, aeroplanes and many other machines.
With the use of electrical machines becoming increasingly prevalent in the modern word, improving the performance and efficiency of these electrical machines is an area of intense research. However, there are a number of separate ways in which performance or efficiency might be improved.
Certain types of electrical machine, such as resonant induction motors, can produce significant quantities of heat due to comparatively large currents in the windings of the motor. This heat decreases the efficiency of the motor and can potentially lead to component damage. As such, managing the temperature of electrical machines is crucial.
Furthermore, while traditional electrical machines are often provided with a ferromagnetic core, some more modern electrical machines are provided without such a ferromagnetic core, but rather with a non-magnetic core, or a so-called 'air-core'. In such air-core electrical machines, leakage of magnetic flux from the electrical machine is greater than in traditional electrical machines with ferromagnetic cores. Such magnetic flux leakage can lead to decreases in performance as well as electromagnetic interference. Accordingly, managing magnetic flux leakage is essential in electrical machines, in particular air-core electrical machines.
The present inventors have identified an improved approach for cooling an electrical machine, reducing magnetic flux from the electrical machine, and increasing the torque generated by an electrical machine.
Summary of the Invention
Aspects of the invention are set out in the accompanying claims.
In a first aspect of the invention, there is provided an electrical machine, the electrical machine comprising: a rotor; a stator; and a first channel arranged coaxially with the rotor and stator, wherein the first channel is arranged external to the rotor and the stator, the first channel comprising a first ferrofluid.
Accordingly, the first aspect of the invention provides an electrical machine that improves cooling of the electrical machine, but also reduces leakage of magnetic flux outside of the electrical machine, thereby reducing the effects of electromagnetic interference, as well as improving the efficiency of the electrical machine (for example by increasing the torque produced in an electric motor). The combination of all these factors allows the electrical machine to be made more compact without compromising the performance of the electrical machine.
In some aspects, the stator is external to the rotor, and wherein the first channel is affixed to the stator. In this manner, the ferrofluid improves cooling of the stator of the electrical machine, as well as reducing the leakage of magnetic flux outside of the electrical machine.
Advantageously in this aspect, the stator may comprise one or more stator windings, and wherein the first channel is configured to permit the transfer of heat from the one or more stator windings to the first ferrofluid. Accordingly, the stator windings may be effectively cooled, allowing larger currents to pass through the stator windings, increasing the torque output of the electrical machine.
In some aspects, the first ferrofluid within the first channel is configured to prevent magnetic flux leakage outside the electrical machine. As such, electromagnetic interference with other electronic devices in prevented, and the strength of the magnetic interaction between the stator and rotor is increased, thereby improving the efficiency of the electrical machine.
In some aspects, the first channel forms a cylindrical jacket around the electrical machine.
Accordingly, the ferrofluid within the channel is able to provide shielding and cooling along the entire external surface of the electrical machine.
Advantageously in some aspects, the electrical machine further comprises a second channel internal to the rotor and the stator, the second channel comprising a second ferrofluid. In this manner, the second channel additionally prevents magnetic flux from leaking into the core of the electrical machine, confining the magnetic flux to the region surrounding the air-gap. Accordingly, the strength of the magnetic interaction between the rotor and stator is increased, thereby increasing the output of the electrical machine. For example, for an induction motor, the output torque is increased for a given input current. Furthermore, by proving two channels, both the stator and the rotor of the electrical machine can be effectively cooled.
In some aspects, the first ferrofluid and the second ferrofluid may have the same composition, therefore providing a convenient arrangement with predictable electromagnetic properties.
In some aspects, the second channel is affixed to the rotor. Accordingly, the ferrofluid improves cooling of the rotor of the electrical machine, as well as reducing the leakage of magnetic flux into the core of the electrical machine.
Advantageously in this aspect, the rotor may comprise one or more rotor windings or one or more permanent magnets, and the second channel may be configured to permit the transfer of heat from the one or more rotor windings or one or more permanent magnets to the second ferrofluid. Accordingly, the rotor windings may be effectively cooled, allowing larger currents to pass through the rotor windings, increasing the torque output of the electrical machine.
In some aspects, the electrical machine further comprises a heat exchanger configured to transfer heat away from the first ferrofluid. As such, the cooling performance of the channel and ferrofluid is improved, as heat is more effectively transferred away from the electrical machine.
Advantageously in some aspects, the first channel has a radial thickness of approximately 1-3mm. This thickness of the channel provides a ferrofluid layer that is thick enough to prevent leakage of substantially all magnetic flux from the electrical machine, without unnecessarily increasing the size and weight of the electrical machine. In some aspects, a radial thickness of the first channel is less than a radial thickness of the rotor and a radial thickness of the stator.
Advantageously, the first ferrofluid may comprise between approximately 2% and 18% ferromagnetic particles by volume. This ferrofluid composition is able to provide effective electromagnetic shielding, as well as having a magnetic susceptibility that results in a large Kelvin body force to promote the flow of the ferrofluid within the channel, in order to improve cooling performance.
In some aspects, the first channel is configured to allow the first ferrofluid to circulate within the first channel. For example, the first channel may be a single contiguous channel, such that the ferrofluid is able to flow along a full circumferential and axial length of the channel. As such, the ferrofluid is able to effectively cool the electrical machine and avoid hot spots.
In some aspects, the first channel is formed from a non-magnetic material. As such, the weight of the electrical machine can be minimised, while still providing effective electromagnetic shielding to prevent the leakage of magnetic flux outside the electrical machine.
In some aspects, the electrical machine is an air-core electrical machine. In other words, the electrical machine does not include a core formed of a magnetic material, but rather has a hollow core. As such, the overall weight of the electrical machine may be reduced. Air-core electrical machines may involve higher electrical currents (for example an air-core electrical induction motors require a larger current to produce a given output torque) than traditional electrical machines with magnetic cores. As such, air-core electrical machines are more susceptible to excessive heat generation. Consequently, the cooling (and shielding) effects provided by the first aspect of the invention are particularly advantageous in air-core electrical machines.
In some aspects, the machine comprises a core formed of a magnetic material. The features of the first aspect are equally applicable to traditional electrical machines with magnetic cores. That is, more effective cooling, improved shielding, and increased torque can be achieved with traditional electrical machine designs. In some examples, the channel comprising the ferrofluid may be retrofitted to existing electrical machines.
In some aspects, the electrical machine is a resonant electrical machine. In this manner, the electrical machine has an electromagnetic resonant frequency. Accordingly, when a driving voltage for the circuitry of the electrical machine is close to the electromagnetic resonant frequency, the output of the electrical machine (for example, an output torque) is greatly enhanced. In this manner, the electrical machine can be made lighter and more compact. Accordingly, the claimed invention which improves cooling and shielding, is particularly beneficial in such resonant machines due to their comparatively small size.
Brief Description of the Drawings
Embodiments of the invention will now be described, by way of example only, with reference to the following figures.
In accordance with one (or more) embodiments of the present invention the Figures show the following: Figure 1 shows an electrical machine according to a first example teaching of the disclosure.
Figure 2 shows an electrical machine according to a second example teaching of the disclosure.
Any reference to prior art documents in this specification is not to be considered an admission that such prior art is widely known or forms part of the common general knowledge in the field. As used in this specification, the words "comprises", "comprising", and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean "including, but not limited to". The invention is further described with reference to the following examples. It will be appreciated that the invention as claimed is not intended to be limited in any way by these examples. It will also be recognised that the invention covers not only individual embodiments but also combination of the embodiments described herein.
The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and/or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects described herein are not to be considered limitations on the scope of the invention as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the invention may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc., other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.
Detailed Description
Figure 1 is an electrical machine 100 according to a first example teaching of the disclosure. The electrical machine 100 includes a stator 120 and a rotor 110 configured to rotate relative to the stator 120. The electrical machine 100 in an electric induction motor, and as such, the stator 120 includes stator windings 122 and the rotor 110 includes rotor windings 112 in the present example. However, it is appreciated that the electrical machine may be substantially any type of electrical machine and thus that, depending on the type of electrical machine, the stator 120 and rotor 110 may, for example, include permanent magnets instead of windings.
Figure 1 shows the stator 120 as having six stator windings 122 and the rotor 110 as having six rotor windings 112, however it is appreciated that substantially any number of windings (or permanent magnets) may be provided on the stator 120 and the rotor 110. The stator 120 and rotor 110 may have a stator housing 124 (or stator body) and rotor body (or rotor housing) on which the stator and rotor windings (or permanent magnets) are mounted respectively. The rotor body may be formed of a ferromagnetic material, such as iron, a non-magnetic material, or the rotor may be hollow (i.e. the electrical machine is an air-core electrical machine).
The stator 120 and rotor 110 are arranged coaxially, and in the example of Figure 1, the stator 120 has a radius larger than that of the rotor 110 such that the stator 120 is arranged external to the rotor 110. However, in other examples, the stator 120 may have a radius smaller than that of the rotor 110 such that the rotor 110 is arranged external to the stator 120. The stator 120 and rotor 110 are arranged with an air-gap 115 therebetween to allow the rotor 110 to rotate relative to the stator 120.
In the electrical machine 100 of Figure 1, an electrical current passes through the stator windings 122 to create a rotating magnetic field. The electrical current may pass through the stator windings 122 with three phases, however other modes of operation, such as single or dual-phase operation, are equally as applicable. This magnetic field induces an opposing current in the rotor windings 112, causing the rotor windings 112 to produce their own magnetic field, creating a torque on the rotor 110, thereby causing the rotor 110 to rotate. The size of the torque on the rotor 110 depends on the strength of the interaction between the magnetic fields of the stator windings 122 and the rotor windings.
Increasing the amount of the current in the stator windings 122 increases the strength of the magnetic field and increases the torque on the rotor, however increasing the current in the stator windings 122 causes greater heating of the stator windings 122. Furthermore, with a stronger magnetic field, magnetic flux will leak outside the electric machine 100 as well as into the core of the electrical machine to a greater extent. Accordingly, increasing the current in the stator windings 122 to increase torque is an inefficient process, as well as potentially causing electromagnetic interference with other electrical devices (due to the leakage of magnetic flux).
The electrical machine 100 of Figure 1 includes a channel 125 containing a ferrofluid. The channel 125 is arranged coaxially with the rotor 110 and stator 120 and arranged external to both the rotor windings 112 and the stator windings 122 and/or external to the stator 120 and the rotor 110. A ferrofluid is a colloidal fluid of magnetic particles. In some examples, the ferrofluid comprises between approximately 2% and 18% ferromagnetic particles by volume. The channel may extend along the full axial length of the rotor 110 and/or stator 120. As the ferrofluid itself is magnetic, the ferrofluid acts as a shield to prevent leakage of magnetic flux outside the electrical machine.
Accordingly, the efficiency of the electrical machine is increased, and electromagnetic interference is prevented. The channel may be, for example, approximately 1-3mm, more preferably 2mm, in radial thickness to ensure the thickness of the ferrofluid is sufficient to provide electromagnetic shielding, but without adding unnecessary size or weight.
The channel 125 surrounds the electrical machine 100, and in the example of Figure 1 is affixed to the stator 120. The channel 125 is arranged so as to provide a thermally conductive pathway from the stator windings 122 to the ferrofluid. Heat from the stator windings 122 is therefore transferred to the ferrofluid within the channel 125. For example, the channel 125 may be arranged proximate to the stator windings 122, or in close proximity to the stator windings 122. The channel 125 may be provided with a high thermal conductivity material forming a barrier between the ferrofluid and the stator windings 122. The channel 125 may be a single contiguous channel, or may be divided into various sub-chambers. The channel may be formed of a non-magnetic material in order to reduce the weight of the channel 125.
The ferrofluid flows within the channel 125 due to the phenomenon of thermomagnetic convection. That is, the heating of the ferrofluid by the stator windings 122 will not be perfectly uniform and as such, a temperature gradient will be created within the ferrofluid, causing varying magnetic susceptibility within the ferrofluid. This in combination with the magnetic field created by the windings of the electrical machine, creates a Kelvin body force within the ferrofluid, leading to thermomagnetic convection.
Accordingly, the ferrofluid flows within the channel 125 without using a pump to cause circulation of the ferrofluid. Accordingly, the channel 125 may be a closed channel that is not in fluid communication with any other component or the external environment. The circulation of the ferrofluid within the channel 125 helps to transfer heat away from the stator windings 122. In some examples, the electrical machine may be provided with a heat exchanger to transfer heat away from the ferrofluid within the channel 125 and improve cooling of the electrical machine 100. Such a heat exchanger may be arranged proximate to at least a portion of the channel 125.
In this manner, the use of a ferrofluid within the channel 125 acts not only to reduce the leakage of magnetic flux from the electrical machine 100, but also to improve cooling of the windings of the electrical machine 100. Furthermore, in preventing leakage of magnetic flux outside the electrical machine 100, the amount of magnetic flux within the electrical machine 100 is increased, thereby increasing the strength of the magnetic interaction between the stator 120 and the rotor 110, causing the amount of torque to be increased for a given electrical current input to the stator windings 120.
Figure 2 shows an electrical machine 200 according to a second example teaching of the disclosure. Electrical machine 200 is similar to electrical machine 100 of Figure 1 in a number of ways. Electrical machine includes a stator 220 and a rotor 210 mounted coaxially with an air-gap 215 therebetween, similar to electrical machine 100. Electrical machine also includes stator windings 222 and rotor windings 212, similar to electrical machine 100. Furthermore, electrical machine 200 includes a channel 225 including a ferrofluid in the same manner as electrical machine 100. The ferrofluid within the second channel 235 may have the same composition as the ferrofluid within channel 225, or the two ferrofluids may have different composition.
Electrical machine 200 further includes a second channel 235, second channel 235 also including a ferrofluid. Second channel 235 is provided internal to both the stator windings 222 and the rotor windings 212. In this manner, not only is magnetic flux prevented from leaking outside the electrical machine 225 by the shielding provided by the ferrofluid in channel 225, but magnetic flux is prevented from leaking into the core of the electrical machine 200. As such, magnetic flux is confined to the air-gap 215 and the region surrounding the stator windings 222 and the rotor windings 212. Consequently, the strength of the magnetic interaction between the stator 220 and the rotor 210 is increased for a given electrical current input to the stator windings 220.
Furthermore, the ferrofluid within the second channel 235 also transfers heat away from the rotor winding 212 in a similar manner to the ferrofluid within channel 225. That is, the second channel 235 is arranged to so as to provide a thermally conductive pathway from the rotor windings 212 to the ferrofluid. Heat from the rotor windings 212 is therefore transferred to the ferrofluid within the second channel 235. For example, the second channel 235 may be arranged proximate to the rotor windings 212, or in close proximity to the rotor windings 212. The second channel 235 may otherwise be substantially similar to channels 125 and 225.
The ferrofluid flows within the second channel 235 due to thermomagnetic convection, in a similar manner to the ferrofluid within channel 225. That is, a Kelvin body force within the ferrofluid, created by heating of the ferrofluid, causes the ferrofluid to flow within the second channel 235, thereby transferring heat away from the rotor windings 212.
Accordingly, the ferrofluid flows within the second channel 235 without using a pump to cause circulation of the ferrofluid. Accordingly, the second channel 235 may be a closed channel that is not in fluid communication with any other component or the external environment. The circulation of the ferrofluid within the second channel 235 helps to transfer heat away from the rotor windings 212. In some examples, the electrical machine may be provided with a heat exchanger to transfer heat away from the ferrofluid within the second channel 235 and improve cooling of the electrical machine 200. Such a heat exchanger may be arranged proximate to at least a portion of the second channel 235.
In this manner, the use of a ferrofluid within the second channel 235 acts not only to reduce the leakage of magnetic flux into the core of the electrical machine 200, but also to improve cooling of the windings of the electrical machine 200. Furthermore, in preventing leakage of magnetic flux into the core of the electrical machine 200, the amount of magnetic flux within the electrical machine is increased, thereby increasing the strength of the magnetic interaction between the stator 220 and the rotor 210, causing the amount of torque to be increased for a given electrical current input to the stator windings 220.
Accordingly, from one perspective, there has been described an electrical machine comprising a rotor, a stator and an external channel comprising a ferrofluid. The ferrofluid flows within the channel to improve cooling of the electrical machine, as well as to improve electromagnetic shielding. a channel may be provided in one or both of the rotor and stator.

Claims (18)

  1. Claims 1. An electrical machine, the electrical machine comprising: a rotor; a stator; and a first channel arranged coaxially with the rotor and stator, wherein the first channel is arranged external to the rotor and the stator, the first channel comprising a first ferrofluid.
  2. 2. The electrical machine according to claim 1, wherein the stator is external to the rotor, and wherein the first channel is affixed to the stator.
  3. 3. The electrical machine according to claim 2, wherein the stator comprises one or more stator windings, and wherein the first channel is configured to permit the transfer of heat from the one or more stator windings to the first ferrofluid.
  4. 4. The electrical machine according to any preceding claim, wherein the first ferrofluid within the first channel is configured to prevent magnetic flux leakage outside the electrical machine.
  5. 5. The electrical machine according to any preceding claim, wherein the first channel forms a cylindrical jacket around the electrical machine.
  6. 6. The electrical machine according to any preceding claim, further comprising: a second channel internal to the rotor and the stator, the second channel comprising a second ferrofluid.
  7. 7. The electrical machine according to claim 6, wherein the first ferrofluid and the second ferrofluid have the same composition.
  8. 8. The electrical machine according to claim 6 or claim 7, wherein the second channel is affixed to the rotor.
  9. 9. The electrical machine according to claim 8, wherein the rotor comprises one or more rotor windings or one or more permanent magnets, and wherein the second channel is configured to permit the transfer of heat from the one or more rotor windings or one or more permanent magnets to the second ferrofluid.
  10. 10. The electrical machine according to any preceding claim, further comprising: a heat exchanger configured to transfer heat away from the first ferrofluid.
  11. 11. The electrical machine according to any preceding claim, wherein the first channel has a radial thickness of approximately 1-3mm.
  12. 12. The electrical machine according to any preceding claim, wherein a radial thickness of the first channel is less than a radial thickness of the rotor and a radial thickness of the stator.
  13. 13. The electrical machine according to any preceding claim, wherein the first ferrofluid comprises between approximately 2% and 18% ferromagnetic particles by volume.
  14. 14. The electrical machine according to any preceding claim, wherein the first channel is configured to allow the first ferrofluid to circulate within the first channel.
  15. 15. The electrical machine according to any preceding claim, wherein the first channel is formed from a non-magnetic material.
  16. 16. The electrical machine according to any preceding claim wherein the electrical machine is a resonant electrical machine.
  17. 17. The electrical machine according to any preceding claim, wherein the rotor comprises a rotor core formed of a magnetic material.
  18. 18. The electrical machine according to any of claims 1-16, wherein the electrical machine is an air-core electrical machine.
GB2109749.8A 2021-07-06 2021-07-06 Shielding in electrical machine Withdrawn GB2608624A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2109749.8A GB2608624A (en) 2021-07-06 2021-07-06 Shielding in electrical machine

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2109749.8A GB2608624A (en) 2021-07-06 2021-07-06 Shielding in electrical machine

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Publication Number Publication Date
GB202109749D0 GB202109749D0 (en) 2021-08-18
GB2608624A true GB2608624A (en) 2023-01-11

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU955378A1 (en) * 1981-01-19 1982-08-30 Николаевский государственный педагогический институт им.В.Г.Белинского Closed electric machine
US4398108A (en) * 1979-02-15 1983-08-09 Danilevitsch Janusch Bronislav Stator of a cryogenic electric machine
US20110285339A1 (en) * 2010-05-19 2011-11-24 Searete Llc, A Limited Liability Corporation Of The State Of Delaware Heat removal from motor components
DE102019106801A1 (en) * 2019-03-18 2020-09-24 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Electric machine with cooling
DE102020118612A1 (en) * 2020-07-15 2022-01-20 Valeo Siemens Eautomotive Germany Gmbh Stator for an electric machine, electric machine and vehicle

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4398108A (en) * 1979-02-15 1983-08-09 Danilevitsch Janusch Bronislav Stator of a cryogenic electric machine
SU955378A1 (en) * 1981-01-19 1982-08-30 Николаевский государственный педагогический институт им.В.Г.Белинского Closed electric machine
US20110285339A1 (en) * 2010-05-19 2011-11-24 Searete Llc, A Limited Liability Corporation Of The State Of Delaware Heat removal from motor components
DE102019106801A1 (en) * 2019-03-18 2020-09-24 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Electric machine with cooling
DE102020118612A1 (en) * 2020-07-15 2022-01-20 Valeo Siemens Eautomotive Germany Gmbh Stator for an electric machine, electric machine and vehicle

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