CA1136200A - Slotless motor with amorphous metal stator - Google Patents
Slotless motor with amorphous metal statorInfo
- Publication number
- CA1136200A CA1136200A CA000333494A CA333494A CA1136200A CA 1136200 A CA1136200 A CA 1136200A CA 000333494 A CA000333494 A CA 000333494A CA 333494 A CA333494 A CA 333494A CA 1136200 A CA1136200 A CA 1136200A
- Authority
- CA
- Canada
- Prior art keywords
- stator
- slotless
- machine
- tape
- coil
- 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.)
- Expired
Links
Landscapes
- Iron Core Of Rotating Electric Machines (AREA)
- Insulation, Fastening Of Motor, Generator Windings (AREA)
Abstract
Abstract of the Disclosure A slotless motor includes a stator comprising a coil wound from an amorphous metal tape, which coil has a smooth interior diameter surface. A stator winding is distributed along-the stator interior surface to define a slotless stator structure. The rotor of the machine is disposed inside the interior diameter of the distributed stator winding.
Description
~6~3~ RD 10,230 This invention relates to slotless rotating machines, and more specifically to a slotless machine in which the stator is formed of a coil of low loss amorphous metal tape.
Slotless machines wherein stator teeth are nonexistent and the stator winding is simply laid along the smooth slotless inner circumferential surface of the stator, are well known. The usual slotless stator is made up of a stack of punched laminations. An arrangement of this general type is disclosed in United States patent 3,529,192 issued September 15, 1970 to Davies. Typically, the laminations are comprised of silicon steel.
The major advantage of the slotless design is that the stator winding no longer has to be laid into the interior stator slots, so that the motor can be made more economically. Moreover, the slots do not have to be formed in the laminations and slot insulation problems are eliminated. The slotless machine, however, has - -, . ............... , .. . . ,, " ~ , . ..
- : . , :, : ,. . .
-- RD 10,230 ~3~
a large air gap. Thus, the power factor of the machine is relatively small and the stator current relatively large.
The stator winding in the slotless stator design is distributed along the stator interior surface. This diminishes the magnetomotive force harmonics which are caused by windings placed at discrete angular locations, as in a slotted type stator. Thus, the stator harmonic differential leakage reactance is negligible and the slot reactance is zero. The remaining leakage reactance component is the end connection reactance, and constitutes essentially the total stator leakage reactance.
TGoth and slot fringing fluxes are usually accommodated in the machine by increasing the air gap by Carter's coefficient. This factor (kc) is typically about 1.25 in a conventional machine. The factor kc -~
is unity, however, for the slotless stator, and is nearly unity for the rotor.
From the foregoing, it can be seen that the slotless machine is not presently competitive with conventional induction motors or permanent magnet machines, even though the wound stator of the slotless machine is less expensive and can `~
. '
Slotless machines wherein stator teeth are nonexistent and the stator winding is simply laid along the smooth slotless inner circumferential surface of the stator, are well known. The usual slotless stator is made up of a stack of punched laminations. An arrangement of this general type is disclosed in United States patent 3,529,192 issued September 15, 1970 to Davies. Typically, the laminations are comprised of silicon steel.
The major advantage of the slotless design is that the stator winding no longer has to be laid into the interior stator slots, so that the motor can be made more economically. Moreover, the slots do not have to be formed in the laminations and slot insulation problems are eliminated. The slotless machine, however, has - -, . ............... , .. . . ,, " ~ , . ..
- : . , :, : ,. . .
-- RD 10,230 ~3~
a large air gap. Thus, the power factor of the machine is relatively small and the stator current relatively large.
The stator winding in the slotless stator design is distributed along the stator interior surface. This diminishes the magnetomotive force harmonics which are caused by windings placed at discrete angular locations, as in a slotted type stator. Thus, the stator harmonic differential leakage reactance is negligible and the slot reactance is zero. The remaining leakage reactance component is the end connection reactance, and constitutes essentially the total stator leakage reactance.
TGoth and slot fringing fluxes are usually accommodated in the machine by increasing the air gap by Carter's coefficient. This factor (kc) is typically about 1.25 in a conventional machine. The factor kc -~
is unity, however, for the slotless stator, and is nearly unity for the rotor.
From the foregoing, it can be seen that the slotless machine is not presently competitive with conventional induction motors or permanent magnet machines, even though the wound stator of the slotless machine is less expensive and can `~
. '
- 2 ~
':
:
~3~
~ 0,.'30 be more easily fabricated, Brief Description of the Present Invention In accordance with the present invention, the stator of a slotless motor machine is formed of a coil of amorphous metal tape. The coil thereby presents a smooth inner diameter surface for reception of the stator winding, which is to be fixed to the interior of the stator surface. Use of a low loss amorphous metal tape compensates for the larger power loss in the slotless motor, ~nd the low cost of the amorphous metal tape makes the slotless motor more competitive with conventional slotted stator motor designs.
Amorphou~ metal tape having excellent magnetic properties has recently become available and has a potential of costing less than the conventional transformer steel used in electric machines. These tapes exhibit a core 10BS about one-fourth that of the conventional silicon iron and have very high permeability. Amorphous metal tapes, however, are not ayailable in the usual lamination form now needed for the construction of conventional electric machines so that the desirable 20` magnetic properties of the amorphous metal glass has not been used for an electric machine. The tape ls made very ~hin (of from 0.0005 to 0.003 inch thick) and in widths of up to about two inches.
Amorphous metal tapes having magnetic properties desired for application to electric machines are disclosed in United - States Letters Patent 3,856,513, dated December 24, 1974, in the name of Chen et aL; 3,881,542, dated May 6, 1975, in the name of Polk et al.; 4,052,201, dated October 4, 1977, in the name of Polk et a~; 4,059,441, dated November 22, 1977, in the name of Ray et al, and 4,067,732, dated January 10, 1978-, .. ..
~3~
RD-10,230 in the name of Ray. A survey of metal glass technology is given in the article "Metallic Glasses" by John J. Gilman appearing in Physics Today, May 1975, pages 46-53. Some attempts are being made to exploit the advantages of the properties of these metal tapes, for example, for acoustic devices as shown in United States Letters Patent 3,838,365.
An object of the present invention is to employ amorphous metal tape in the manufacture of a core having a smooth inside diameter surface which receives the distributed winding of a conventional slotless machine design. The low loss o the ~ound stator and the low cost of the stator structure make the -slotless machine of the invention more competitive with presently existing slotted stator motor structures.
Brief Description of the Drawings FIGURE 1 is a cross-sectional view along the axis of a slotless motor constructed in accordance with the present invention.
FIGURE 2 ~s a cross-sectional view of FIGURE 1 taken across the saction line 2-2 in FIGURE 1.
Detailed Description of the Drawings FIGURES 1 and 2 schematically illustrate a slotless motor constructed in accordance with the principles of the present invention. Motor housing and support details are not shown, since these will be apparent to those skilled in the art.
The motor, as schematically iLlustrated, comprises a central rotor lO which may be formed of a stack of punched laminations, or may be formed in any other convenient manner.
Rotor 10 has afflxed théreto a central rotating shaft 11.
The motor stator 12 is formed of an annular coil of one _4_ 2~
RD-10,230 or more s~rips of amorphous metal tape. By way of example, stator 12 may be formed of 500 turns of tape having a thick-- ness of about 0.002 inch and a width of about 1 or 3 inches.
The inner diameter of stator 12 may be about 2-1/2 inches and its axial length may be about 3 inches. Other dimensions can be selected, depending upon the intended application.
Note that the stator can be wound in a helical pattern in order to obtain a coil length exceeding ~he width of the ` individual tape elements used to wind the coil.
A stator winding'13 is next affixed to the interior diameter of coil 12 and is distributed around the smooth inner diameter surface of coil 12. By way of example, stator winding 13 in FIGURES i and 2 is shown for a two-pole machine configuration, with the individual conductors carrying current into and out of the plane of the paper, as schematically indicated by crosses and dots, respectively. In practice, for the stator specified above, the stator winding may have 131, turns formed within a total air gap of about 0.271 inch. If , desired, stator winding l3 may take the form disclosed in the above mentioned U.S. Patent 3,529,192.
The outer diameter of stator winding 13 is fixed to the inner surface of stator 12, but insulated therefrom by an insulating sle,eve 14. Sleeve 14 and winding 13 can be secured ~' to stator 12 in any desired manner as by clam~ing or cementing or the like. An inner sleeve 15 of insulating material may be fixed to the inner diameter of the winding 13 to ensure presence o insulation between winding 13 and the outer sur-face of rotor 10. For the motor c.f dinensions specified above, a small'air gap of 0.008-0.010 inches is provided between the inner,diameter of insulating sleeve 15 and the outer ' diameter of rotor 10.
-5- ' ,';, .
'~
~3&~
RD-10,23~
The resulting slotless machine shown in FIGURES 1 and 2 has an effective air gap resulting from mlnute separation between individual adjacent layers of coil 12. This overall air gap is small in comparison to the air gap across winding 13, and is therefore not a significant factor in the motor opera-tion. However, the wound stator 12 exhibits very low loss in comparison to a conventional silicon iron stator and has a potentially .low cost in view of the relatively.low cost of amorphous metal tape mat~rial. Thus the advantage of the slotless machine, that of reduced cost of assembling the wind-ings, is retained, rendering the machine more competitive with the conventional slotted stator machine.
Although only certain preferred.features of this invention have been described, many variations and modifications will now - 15 be apparent to those skilled in the art, and it is therefore to be understood that the appended claims are intended to cover all such variations and modifications as fall within the true spirit of the invention.
':
:
~3~
~ 0,.'30 be more easily fabricated, Brief Description of the Present Invention In accordance with the present invention, the stator of a slotless motor machine is formed of a coil of amorphous metal tape. The coil thereby presents a smooth inner diameter surface for reception of the stator winding, which is to be fixed to the interior of the stator surface. Use of a low loss amorphous metal tape compensates for the larger power loss in the slotless motor, ~nd the low cost of the amorphous metal tape makes the slotless motor more competitive with conventional slotted stator motor designs.
Amorphou~ metal tape having excellent magnetic properties has recently become available and has a potential of costing less than the conventional transformer steel used in electric machines. These tapes exhibit a core 10BS about one-fourth that of the conventional silicon iron and have very high permeability. Amorphous metal tapes, however, are not ayailable in the usual lamination form now needed for the construction of conventional electric machines so that the desirable 20` magnetic properties of the amorphous metal glass has not been used for an electric machine. The tape ls made very ~hin (of from 0.0005 to 0.003 inch thick) and in widths of up to about two inches.
Amorphous metal tapes having magnetic properties desired for application to electric machines are disclosed in United - States Letters Patent 3,856,513, dated December 24, 1974, in the name of Chen et aL; 3,881,542, dated May 6, 1975, in the name of Polk et al.; 4,052,201, dated October 4, 1977, in the name of Polk et a~; 4,059,441, dated November 22, 1977, in the name of Ray et al, and 4,067,732, dated January 10, 1978-, .. ..
~3~
RD-10,230 in the name of Ray. A survey of metal glass technology is given in the article "Metallic Glasses" by John J. Gilman appearing in Physics Today, May 1975, pages 46-53. Some attempts are being made to exploit the advantages of the properties of these metal tapes, for example, for acoustic devices as shown in United States Letters Patent 3,838,365.
An object of the present invention is to employ amorphous metal tape in the manufacture of a core having a smooth inside diameter surface which receives the distributed winding of a conventional slotless machine design. The low loss o the ~ound stator and the low cost of the stator structure make the -slotless machine of the invention more competitive with presently existing slotted stator motor structures.
Brief Description of the Drawings FIGURE 1 is a cross-sectional view along the axis of a slotless motor constructed in accordance with the present invention.
FIGURE 2 ~s a cross-sectional view of FIGURE 1 taken across the saction line 2-2 in FIGURE 1.
Detailed Description of the Drawings FIGURES 1 and 2 schematically illustrate a slotless motor constructed in accordance with the principles of the present invention. Motor housing and support details are not shown, since these will be apparent to those skilled in the art.
The motor, as schematically iLlustrated, comprises a central rotor lO which may be formed of a stack of punched laminations, or may be formed in any other convenient manner.
Rotor 10 has afflxed théreto a central rotating shaft 11.
The motor stator 12 is formed of an annular coil of one _4_ 2~
RD-10,230 or more s~rips of amorphous metal tape. By way of example, stator 12 may be formed of 500 turns of tape having a thick-- ness of about 0.002 inch and a width of about 1 or 3 inches.
The inner diameter of stator 12 may be about 2-1/2 inches and its axial length may be about 3 inches. Other dimensions can be selected, depending upon the intended application.
Note that the stator can be wound in a helical pattern in order to obtain a coil length exceeding ~he width of the ` individual tape elements used to wind the coil.
A stator winding'13 is next affixed to the interior diameter of coil 12 and is distributed around the smooth inner diameter surface of coil 12. By way of example, stator winding 13 in FIGURES i and 2 is shown for a two-pole machine configuration, with the individual conductors carrying current into and out of the plane of the paper, as schematically indicated by crosses and dots, respectively. In practice, for the stator specified above, the stator winding may have 131, turns formed within a total air gap of about 0.271 inch. If , desired, stator winding l3 may take the form disclosed in the above mentioned U.S. Patent 3,529,192.
The outer diameter of stator winding 13 is fixed to the inner surface of stator 12, but insulated therefrom by an insulating sle,eve 14. Sleeve 14 and winding 13 can be secured ~' to stator 12 in any desired manner as by clam~ing or cementing or the like. An inner sleeve 15 of insulating material may be fixed to the inner diameter of the winding 13 to ensure presence o insulation between winding 13 and the outer sur-face of rotor 10. For the motor c.f dinensions specified above, a small'air gap of 0.008-0.010 inches is provided between the inner,diameter of insulating sleeve 15 and the outer ' diameter of rotor 10.
-5- ' ,';, .
'~
~3&~
RD-10,23~
The resulting slotless machine shown in FIGURES 1 and 2 has an effective air gap resulting from mlnute separation between individual adjacent layers of coil 12. This overall air gap is small in comparison to the air gap across winding 13, and is therefore not a significant factor in the motor opera-tion. However, the wound stator 12 exhibits very low loss in comparison to a conventional silicon iron stator and has a potentially .low cost in view of the relatively.low cost of amorphous metal tape mat~rial. Thus the advantage of the slotless machine, that of reduced cost of assembling the wind-ings, is retained, rendering the machine more competitive with the conventional slotted stator machine.
Although only certain preferred.features of this invention have been described, many variations and modifications will now - 15 be apparent to those skilled in the art, and it is therefore to be understood that the appended claims are intended to cover all such variations and modifications as fall within the true spirit of the invention.
Claims (5)
1. A slotless machine comprising in combination:
a stator structure including an annular coil of substantially concentric turns of a thin tape of amorphous metal, said coil having a smooth slotless inner circumferential surface; a stator winding affixed to and distributed around said inner circumferential surface of said coil; and a rotor disposed coaxially with said annular coil of tape and adjacent said inner circumferential surface thereof, said rotor being rotatable relative to said stator structure about the axis of said annular coil of tape.
a stator structure including an annular coil of substantially concentric turns of a thin tape of amorphous metal, said coil having a smooth slotless inner circumferential surface; a stator winding affixed to and distributed around said inner circumferential surface of said coil; and a rotor disposed coaxially with said annular coil of tape and adjacent said inner circumferential surface thereof, said rotor being rotatable relative to said stator structure about the axis of said annular coil of tape.
2. The slotless machine of claim 1, wherein said rotor is formed of a stack of laminations.
3. The slotless machine of claim 2, wherein said stator winding is contained between and affixed to an inner insulating sleeve and an outer insulating sleeve, said outer insulating sleeve being affixed to said inner circumferential surface of said annular coil of tape.
4. The slotless machine of claim 3, wherein said inner insulating sleeve and said rotor are separated from one another by an air gap.
5. The slotless machine of claim 1, 2 or 4, wherein said tape has a thickness of about 0.002 inch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000333494A CA1136200A (en) | 1979-08-09 | 1979-08-09 | Slotless motor with amorphous metal stator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000333494A CA1136200A (en) | 1979-08-09 | 1979-08-09 | Slotless motor with amorphous metal stator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1136200A true CA1136200A (en) | 1982-11-23 |
Family
ID=4114899
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000333494A Expired CA1136200A (en) | 1979-08-09 | 1979-08-09 | Slotless motor with amorphous metal stator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1136200A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1994007295A1 (en) * | 1992-09-14 | 1994-03-31 | Cadac Holdings Limited | Dynamoelectric machine and stators therefor |
| US5391954A (en) * | 1992-04-17 | 1995-02-21 | Seiko Instruments Inc. | Direct current motor |
| WO2011014934A1 (en) | 2009-08-03 | 2011-02-10 | Atlas Copco Airpower | Turbocompressor system |
| WO2012012925A1 (en) * | 2010-07-26 | 2012-02-02 | 深圳华任兴科技有限公司 | Slotless amorphous ferroalloy motor with radial magnetic circuit and manufacturing method thereof |
-
1979
- 1979-08-09 CA CA000333494A patent/CA1136200A/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5391954A (en) * | 1992-04-17 | 1995-02-21 | Seiko Instruments Inc. | Direct current motor |
| WO1994007295A1 (en) * | 1992-09-14 | 1994-03-31 | Cadac Holdings Limited | Dynamoelectric machine and stators therefor |
| WO2011014934A1 (en) | 2009-08-03 | 2011-02-10 | Atlas Copco Airpower | Turbocompressor system |
| US9470238B2 (en) | 2009-08-03 | 2016-10-18 | Atlas Copco Airpower, Naamloze Vennootschap | Electric motor having segmented stator windings |
| WO2012012925A1 (en) * | 2010-07-26 | 2012-02-02 | 深圳华任兴科技有限公司 | Slotless amorphous ferroalloy motor with radial magnetic circuit and manufacturing method thereof |
| EP2587630A1 (en) * | 2010-07-26 | 2013-05-01 | Shenzhen Hopewin Technology Co., Ltd. | Slotless amorphous ferroalloy motor with radial magnetic circuit and manufacturing method thereof |
| EP2587630A4 (en) * | 2010-07-26 | 2014-05-07 | Shenzhen Hopewin Technology Co Ltd | Slotless amorphous ferroalloy motor with radial magnetic circuit and manufacturing method thereof |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |