CA2350485A1 - Endless core for a multiphase transformer and a transformer incorporating same - Google Patents
Endless core for a multiphase transformer and a transformer incorporating same Download PDFInfo
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- CA2350485A1 CA2350485A1 CA002350485A CA2350485A CA2350485A1 CA 2350485 A1 CA2350485 A1 CA 2350485A1 CA 002350485 A CA002350485 A CA 002350485A CA 2350485 A CA2350485 A CA 2350485A CA 2350485 A1 CA2350485 A1 CA 2350485A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F27/00—Details of transformers or inductances, in general
- H01F27/24—Magnetic cores
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F30/00—Fixed transformers not covered by group H01F19/00
- H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
- H01F30/12—Two-phase, three-phase or polyphase transformers
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- Coils Or Transformers For Communication (AREA)
Abstract
Endless core (10) for a multiphase transformer (12) is formed as an endless circular or annular loop. A plurality of windows (14) are formed through and about the core (10). Adjacent windows (14) share a common portion or leg (16 ). Thus magnetic flux is shared between windows (14). Transformer (12) is constructed by winding respective primary windings (18) and secondary windin gs (20) through the windows (14). The core (10) and transformer (12) allow for an infinite possibility of phase shifting or combining because portions of the second windings (20) can be wound through more than one of the windows (14).
Description
WO 00!30130 PCT/AU99/01006 Title ENDLESS CORE FOR A MULTIPHASE TRANSFORMER AND
A TRANSFORMER INCORPORATING SAME
Field of the Invention The present invention relates to an endless core for multiphase transformer and a transformer incorporating such a core.
Background of the Invention Multiphase transformers are well known and are used in a variety of applications including for stepping up or stepping down line voltage in power transmission systems, to provide phase shifting, modulation, star-delta. converters and general power supplies.
A typical multiphase transformer has a planar care provided with a number of square or rectangular windows each window being bound by upper and lower branches of the core, and on opposite sides by vertical legs forming part of the core.. A
primary winding is wound through each window, either on a branch or leg of the window.
similarly a secondary winding is would through each window. Irrespective of the number of phases, if the core has N windows then it will have N + 1 vertical legs.
This provides an inherent magnetic and therefore electrical imbalance between the phases. This arises because the magnetic flux created by current flow in the primary windings cannot circulate equally about the rest>ective windows because of the additional vertical leg. As a result, assuming each primary phase voltage is of the same magnitude and each secondary winding has the same number of turns, then the secondary outputs cannot be the same. The transformation process is not identical between the phases due to the difference in magnetic paths surrounding each window. In order to produce equalised outputs o:n the secondary windings, ie the same magnitude output on each winding, some of the primary or secondary windings must vary the number of turns to take account of the difference in flux distribution circulating about different windows of the transforrner core. Such transformers also have an inherent inefficiencies due to flux leakage caused by the end windows having only a single flux return path.
A TRANSFORMER INCORPORATING SAME
Field of the Invention The present invention relates to an endless core for multiphase transformer and a transformer incorporating such a core.
Background of the Invention Multiphase transformers are well known and are used in a variety of applications including for stepping up or stepping down line voltage in power transmission systems, to provide phase shifting, modulation, star-delta. converters and general power supplies.
A typical multiphase transformer has a planar care provided with a number of square or rectangular windows each window being bound by upper and lower branches of the core, and on opposite sides by vertical legs forming part of the core.. A
primary winding is wound through each window, either on a branch or leg of the window.
similarly a secondary winding is would through each window. Irrespective of the number of phases, if the core has N windows then it will have N + 1 vertical legs.
This provides an inherent magnetic and therefore electrical imbalance between the phases. This arises because the magnetic flux created by current flow in the primary windings cannot circulate equally about the rest>ective windows because of the additional vertical leg. As a result, assuming each primary phase voltage is of the same magnitude and each secondary winding has the same number of turns, then the secondary outputs cannot be the same. The transformation process is not identical between the phases due to the difference in magnetic paths surrounding each window. In order to produce equalised outputs o:n the secondary windings, ie the same magnitude output on each winding, some of the primary or secondary windings must vary the number of turns to take account of the difference in flux distribution circulating about different windows of the transforrner core. Such transformers also have an inherent inefficiencies due to flux leakage caused by the end windows having only a single flux return path.
~'eceived 19 December 2000 Summary of the Invention It is an object of the present invention to provide a transformer core and an associated transformer that attempts to alleviate at least the above;mentioned problems in the prior art.
According to one form of the present invention there is provided a core for a multiphase transformer, said core including a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent W ndows so that said mutually l0 adjacent windows have a leg in common whereby the number of windows is equal to the number of legs, said opposite branches and opposite legs of each window defining a path of substantially uniform magnetic permeability about which magnetic flux circulates.
Preferably the core includes a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn wound directly about a branch or a leg of a corresponding window.
Preferably said primary windings are wholly wound directly about one or more of the 2 o branches or legs of said corresponding window.
Preferably said primary windings are evenly spaced about said central axis.
Preferably said windows are formed as an array of windows circumferentially about and 2 5 axially along said body.
Preferably in one embodiment each primary winding; has a plurality of turns and said turns are wound about more than one branch or one leg of said corresponding window.
According to one form of the present invention there is provided a core for a multiphase transformer, said core including a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent W ndows so that said mutually l0 adjacent windows have a leg in common whereby the number of windows is equal to the number of legs, said opposite branches and opposite legs of each window defining a path of substantially uniform magnetic permeability about which magnetic flux circulates.
Preferably the core includes a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn wound directly about a branch or a leg of a corresponding window.
Preferably said primary windings are wholly wound directly about one or more of the 2 o branches or legs of said corresponding window.
Preferably said primary windings are evenly spaced about said central axis.
Preferably said windows are formed as an array of windows circumferentially about and 2 5 axially along said body.
Preferably in one embodiment each primary winding; has a plurality of turns and said turns are wound about more than one branch or one leg of said corresponding window.
3 0 According to another form of the present invention there is also provided a core for a multiphase transformer including:
Received 19 December 2000 a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows, each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent windows so that said mutually adjacent windows have a leg in common whereby the number of windows is equal to the number of legs; and, a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn being wound directly about at least one branch or leg of a corresponding l0 window to produce lines of magnetic flux to correlate about said corresponding window when said each primary winding is energised within electric current.
According to the present invention there is also provided a multiphase transformer including at least:
a core according to said one form of the present invention;
a plurality of primary windings; and a plurality of secondary windings;
wherein at least one primary winding for each electrical phase of said multiphase 2 0 transformer is wound directly about at least one branch or at least one leg of one of said windows to produce lines of magnetic flux to circulate about said one window when said primary winding is energised with an electric current, and at least one secondary winding having at least one turn wound directly about a branch or a leg of a window about which said lines of magnetic flux circulates to 2 5 thereby induce a current in said secondary winding.
According to the present invention there if also provided a multiphase transformer including at least:
a core according to said other form of the invention; and, 3 0 a plurality of secondary windings, e2~ch secondary winding having at least one turn wound directly about a branch or leg of a window about which said lines of magnetic circulate to thereby induce a current in said each secondary winding.
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i.-. .' .
. PCT/AU99/01006 Received 19 December 2000 Brief Description of the Drawings Embodiments of the present invention will now be dc;scribed by way of example only with reference to the accompany drawings in which:
Figure 1 is a perspective view of a core in accordance with the present invention and a six phase transformer incorporating that core;
Figure 2 is a perspective view of a second err~bodiment of the core and a 12 phase transformer incorporating that core;
Figure 3 is a perspective view of a third embodiment of the core in accordance with the present invention;
Figure 4 is a perspective view of a fourth embodiment of the core; and, Figure 5 is a cutaway perspective view of an electric motor incorporating a core in accordance with the present invention.
2 0 Detailed Description of the Preferred Embodiments Referring to Figure l, there is illustrated an endless core 10 for a multiphase (in this example, six phase) transformer 12. The core 10 is formed as an endless circular or annular loop. A plurality of windows 14,-146 (referred to in general as windows 14;) are formed through and about the core 10. Adjacent windows 14; share a common portion or 2 5 leg 16;~ where ; and ~ designate the adjacent windows. For example, leg 16,,~ is the portion of core 10 between adjacent windows 14, and 142; and leg 164,5 is the portion or leg of core 10 between adjacent windows 144 and 145. It will be appreciated that because the core 10 is endless, there are no dead ends in so far as magnetic flux is concerned and therefore the core 10 facilitates the existence of "... ;-a_..:
Received 19 December 2000 a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows, each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent windows so that said mutually adjacent windows have a leg in common whereby the number of windows is equal to the number of legs; and, a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn being wound directly about at least one branch or leg of a corresponding l0 window to produce lines of magnetic flux to correlate about said corresponding window when said each primary winding is energised within electric current.
According to the present invention there is also provided a multiphase transformer including at least:
a core according to said one form of the present invention;
a plurality of primary windings; and a plurality of secondary windings;
wherein at least one primary winding for each electrical phase of said multiphase 2 0 transformer is wound directly about at least one branch or at least one leg of one of said windows to produce lines of magnetic flux to circulate about said one window when said primary winding is energised with an electric current, and at least one secondary winding having at least one turn wound directly about a branch or a leg of a window about which said lines of magnetic flux circulates to 2 5 thereby induce a current in said secondary winding.
According to the present invention there if also provided a multiphase transformer including at least:
a core according to said other form of the invention; and, 3 0 a plurality of secondary windings, e2~ch secondary winding having at least one turn wound directly about a branch or leg of a window about which said lines of magnetic circulate to thereby induce a current in said each secondary winding.
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i.-. .' .
. PCT/AU99/01006 Received 19 December 2000 Brief Description of the Drawings Embodiments of the present invention will now be dc;scribed by way of example only with reference to the accompany drawings in which:
Figure 1 is a perspective view of a core in accordance with the present invention and a six phase transformer incorporating that core;
Figure 2 is a perspective view of a second err~bodiment of the core and a 12 phase transformer incorporating that core;
Figure 3 is a perspective view of a third embodiment of the core in accordance with the present invention;
Figure 4 is a perspective view of a fourth embodiment of the core; and, Figure 5 is a cutaway perspective view of an electric motor incorporating a core in accordance with the present invention.
2 0 Detailed Description of the Preferred Embodiments Referring to Figure l, there is illustrated an endless core 10 for a multiphase (in this example, six phase) transformer 12. The core 10 is formed as an endless circular or annular loop. A plurality of windows 14,-146 (referred to in general as windows 14;) are formed through and about the core 10. Adjacent windows 14; share a common portion or 2 5 leg 16;~ where ; and ~ designate the adjacent windows. For example, leg 16,,~ is the portion of core 10 between adjacent windows 14, and 142; and leg 164,5 is the portion or leg of core 10 between adjacent windows 144 and 145. It will be appreciated that because the core 10 is endless, there are no dead ends in so far as magnetic flux is concerned and therefore the core 10 facilitates the existence of "... ;-a_..:
symmetrical magnetic flux through the core 10.
Each window 14; is bound on opposite sides by the adjacent, core portions or legs 16;~ and, by upper and lower branches B" and B;. Thus, for example window 14, is bound on the left side by common core portion 1 ~6,,2; on the right side by common core portion 166,,; upper branch B,;; and, lower branch B,.
Multiphase transformer 12 is constructed by winding respective primary and secondary windings through the windows 14;. In the embodiment shown, primary windings 181 and 186 (referred to in general as primary windings 18;) link with respective windows 14;. More particularly, two primary windings I8; (of the same phase) are provided for each window 14;, with onf; primary winding about the upper branch B~ and another primary winding about a IorNer branch B, of each window 14;.
For example, looking at window 14, a pair of primary windings 18, is provided, one of each formed about the upper branch Bt, and lower branch B, of the window 141.
When the primary windings 18; are coupled to respective phases of a six phase AC
power supply lines of magnetic flux ~; are generated and circulate about at least the window through which the primary winding I8; is wound. Again taking for example window 14, when the primary windings 18, are connected to one phase of the six phase AC power supply, lines of magnetic flux ~, are generated that circulate about window 14,. However, it must be appreciated that the magnetic flux generated can also circulate or return about other windows 14;. Thus a part of the magnetic flux ~1 can circulate about both windows 14; and 142 returning through legs 162,3 and 166,;
and circulate about windows 14,, 142 and 146 returning via legs 162,3 and 165,6.
The placement of secondary windings through the windows 14; is dependent upon the desired output. If it is desired that the phase of the output from the secondary windings is to be the same as the phase of the corresponding primary winding then secondary windings 20s, - 20ø6 can be wound for e:Kample about the lower branch B, of each window 14~ - 146 respectively. (Of course in a variation, the secondary windings 20øi - 20s6 can be placed about the upper branches B~ of each window or WO 00130130 PCTlAU99/01006 even alternate between the upper and lower branches.) it will be appreciated that because of the symmetric distribution of magnetic flux ~; about each of the windows 14;, assuming that the primary voltage for each phase is of the same magnitude, the magnitude of the voltage output from the secondar'~ windings 20s; will be the same if each of the secandary windings 20s; have the same. number of turns. Thus, the core and transformer 12 provide the ability to have secondary output of equal magnitude where the secondary windings 20s, - 2Os6 have the same number of turns.
As discussed above in relation to the prior art, because of the inherent magnetic imbalance of known cores and transformers, in order to have secondary outputs of 10 equal magnitude in a multiphase transformer one must deliberately design some of the coils to have different number of turns.
The core 10 and transformer 12 also allow .for an in finite possibility of phase shifting or combining. If one wanted to obtain a secondary output of a phase halfway between the phase of say the primary voltages supplying primary windings 18, and 182 then a secondary winding 20p (shown in phantom) can be wound through bath windows 14, and 142 ie about the common care portion 161,2. Now, the second winding 2Up links with the magnetic flux ~I and ~;t and thus the secondary output is of a magnitude and phase corresponding to the vector or phasor addition of the voltage induced by fluxes ~, and ~2. This provides a 1:1 transformed combination of the phases feeding primary windings 181 and 182. However combinations of other ratios and thus different amounts of phase shifting can be achieved at will by simply winding the secondary winding 20~ about the upper or lower branches B",B, or common core portions 16;~ of different windows. For example, in the embodiment shown in Figure l, the primary phases are 60° ap~~rt. To obtain a secondary output having a phase 15° (ie '/ the phase difference) in advance of the phase of the primary voltage feeding primary winding 181 a secondary winding {not shown) is provided having a 1:4 turn ratio about branch B, of window 141 and branch B, of window 142, ie the secondary winding has four turns passing through window 142 for every turn passing through window 141.
-Figure 2 illustrates a core 10' suitable for constructing a twelve phase transformer 12'. Here, the core 10' is again in shape of a ring; or annulus but this time provided with twelve windows 141 - 14,,2 and twelve common core portions 16;x, one of each between respective adjacent windows 14;. A primary winding 18; is wound about lower branch B, of each window 14;. A secondary winding 20; is wound about the upper branch B~ of each window 14;. The phase of the output of any secondary winding 20; is the same as the phase of voltage driving the corresponding primary winding 18;. However, as with the previous embodiment, the secondary winding 20;
can be wound partially about the upper and lower branches B~ and B, or common core portions I6;a of different windows in any desired combination to produce a desired phase output in accordance with standard transformer design technics.
Figure 3 illustrates an extending (vertically stacked) core 10" and a multiphase transformer 12" constructed using the core 10". 'The core 10" can be considered as being two six window cores vertically stacked upon each other. Thus the core 10"
has a lower set of windows 141 - 146 and an upper set of windows 14~ - 14,2 with windows 14; and 14;+6 in vertical alignment. Primary windings 181 - I86 are wound about the lower branches B, of windows 14, - 146 respectively; and, primary windings 18~ - 18,,2 are wound about the upper branches B, of the upper set of windows 14~ - 14,,2. A set of secondary windings 20 are wound about the middle branch Bm between vertically adjacent windows 14;, 14;+6. Therefore, in this particular illustrated embodiment, there are only ~;ix secondary coils 20. The output of any particular secondary winding 20 would be the transformed phasor or vector addition of voltages induced by the magnetic flux generated by the primary windings linked with the windows common to that particular secondary winding 20. In order 2S to avoid saturation it is preferred that the volunne of core constituting the middle branch Bm is the sum of the volume of the core constituting the lower branch B, and upper branch B" of the windows 14;, 14;+6. 'This embodiment then allows the combination of two six phase supplies that are out of phase with each other.
For example, if there are two six phase power supplies, one providing input to coils 18, -I86 and another providing input to primary windings 18., - 181,2, the two power sources can be combined to provide a six phase output through the secondary WU 00/30130 PCT/AU9910100b windings 20. This could be particularly useful in :f'or example coupling two multiple phase power supplies to a common power transmission grid. The core configuration will also allow for the ability to have 6 primary and 12 secondary windings.
Also a turns ratio of 1/0.5 primary to secondary, or secondary to primary, as well as incorporating other windows will produce any fraction of volts required.
In a different configuration (not illustrated) the primary windings 18, -18,.2 of transformer 12" can be connected to a different phase of a twelve phase power supply and primary windings 20 round through various windows 14; to provide a transformed twelve phase output. Again, the phasing of the output from the Itl secondary windings can be arranged as required in accordance with known transformer design techniques to provide the desired secondary phase output.
Figure 4 further illustrates a further embodiment of the core 10"' and a corresponding 12"'. In the embodiments shown in Figures 1-3 the core 10 and windows 14; are arranged so that the core 10, 10' and 10"' is endless about a first axis that is I5 perpendicular to the axis of any particular window 14;. With the core 1 ()"' of Figure 4, the axis of the core 10 is parallel with the axis of any window 14;. As with all previous embodiments, core i 0"' is configured as an endless loop having a plurality of windows 14; where adjacent windows share a common portion of core lb;~ so that they number of windows 14; equals the number of common core portions lb;~.
Mare 20 specifically, three windows 141 - 143 are formed in the core 10"' with a primary winding 18, - 183 respectively wound about the louver (radially outer most) branches B, of each window 14;. Respective secondary windings 20, - 20, axe wound through the windows 14! - I43 respectively about the corresponding upper (radially inner most) branches B". It is preferred that the core 10"'' is configured so that the volume 25 of core in the upper and lower branch portions B,, B" of each window 14; is the same. This assists in avoiding saturation of the core. This can be achieved by appropriate placement or configuration of the windows 14;.
Figure 5 illustrates an application of the core 10 shown in Figure 1. The core 10 is used in this application in a transverse flux nnotor 26. Full operation and _g_ constructional details of the transverse flux motor are described in the Applicant's Australian Application No PP 7124 the contents of which is incorporated herein by way of reference. The structure of core 10 and tlhe placement of primary windings 18, - 186 is identical to that described in the first embodiment described in relation to Figure 1. However, instead of mufti turn electricaHly separate secondary windings a single turn secondary winding between 2U; is provided about each common core portion 16;~ with each of the single turn second~~ry windings 2(); being in mutual electrical connection. Thus, the single turn secondary windings 20, - 206 form a wheel like structure 30 having an inner rim 32 and outer rim 34 joined by radially extending spokes 36. The outer rim 34 is depicted as residing in the air gap 38 of a cockcroft ring 40. Without going into the detail of operation of the motor 26, currents are induced through the single turn secondary windings 20, - 206 that interact with magnetic t7ux passing through the air gap 38 of the cockcroft ring 40 thereby generating transverse forces on the outer ri~rn 34 of the wheel 30 causing it to move. The path of motion of the wheel 30 can bf; controlled at will by variation of the magnitude and frequency of the primary voltages supplied to the primary coil 18, - 186 and the phase relationship therebetween.
Now that embodiments of the present invention have been described in detail it will be apparent to those skilled in the relevant arts and numerous modifications and variations may be made without departing from the basic inventive concepts.
For example, in each of the embodiments shown, the core 10 is depicted essentially as being in a ring, annulus or circular type form. However it can assume other shapes provided that it is continuous or endless and is provided with equal numbers of windows and common core pouions. Also, the exaict number of windows provided is simply dependent upon the application and in particular the number of primary phases. Also, the position and placement of the secondary windings 20; is dictated solely by the desired magnitude and phase of the secondary outputs. The core 10, 10', 10", 10"' can be made by casting; continuous stamping and winding of an insulated strip of magnetically permeable materiall; winding of a strip of material then machininglcutting the windows. Further the core can be split through a plane passing through the windows 14; to facilitate me,chanical/autornatic winding of the _y_ primary and/or secondary windings about the window branches B", B,, or loading of prewound bobbins on the common core portions 16;x. All such variations and modifications together with others that would be obvious to a person of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the aforegoing descuption.
Each window 14; is bound on opposite sides by the adjacent, core portions or legs 16;~ and, by upper and lower branches B" and B;. Thus, for example window 14, is bound on the left side by common core portion 1 ~6,,2; on the right side by common core portion 166,,; upper branch B,;; and, lower branch B,.
Multiphase transformer 12 is constructed by winding respective primary and secondary windings through the windows 14;. In the embodiment shown, primary windings 181 and 186 (referred to in general as primary windings 18;) link with respective windows 14;. More particularly, two primary windings I8; (of the same phase) are provided for each window 14;, with onf; primary winding about the upper branch B~ and another primary winding about a IorNer branch B, of each window 14;.
For example, looking at window 14, a pair of primary windings 18, is provided, one of each formed about the upper branch Bt, and lower branch B, of the window 141.
When the primary windings 18; are coupled to respective phases of a six phase AC
power supply lines of magnetic flux ~; are generated and circulate about at least the window through which the primary winding I8; is wound. Again taking for example window 14, when the primary windings 18, are connected to one phase of the six phase AC power supply, lines of magnetic flux ~, are generated that circulate about window 14,. However, it must be appreciated that the magnetic flux generated can also circulate or return about other windows 14;. Thus a part of the magnetic flux ~1 can circulate about both windows 14; and 142 returning through legs 162,3 and 166,;
and circulate about windows 14,, 142 and 146 returning via legs 162,3 and 165,6.
The placement of secondary windings through the windows 14; is dependent upon the desired output. If it is desired that the phase of the output from the secondary windings is to be the same as the phase of the corresponding primary winding then secondary windings 20s, - 20ø6 can be wound for e:Kample about the lower branch B, of each window 14~ - 146 respectively. (Of course in a variation, the secondary windings 20øi - 20s6 can be placed about the upper branches B~ of each window or WO 00130130 PCTlAU99/01006 even alternate between the upper and lower branches.) it will be appreciated that because of the symmetric distribution of magnetic flux ~; about each of the windows 14;, assuming that the primary voltage for each phase is of the same magnitude, the magnitude of the voltage output from the secondar'~ windings 20s; will be the same if each of the secandary windings 20s; have the same. number of turns. Thus, the core and transformer 12 provide the ability to have secondary output of equal magnitude where the secondary windings 20s, - 2Os6 have the same number of turns.
As discussed above in relation to the prior art, because of the inherent magnetic imbalance of known cores and transformers, in order to have secondary outputs of 10 equal magnitude in a multiphase transformer one must deliberately design some of the coils to have different number of turns.
The core 10 and transformer 12 also allow .for an in finite possibility of phase shifting or combining. If one wanted to obtain a secondary output of a phase halfway between the phase of say the primary voltages supplying primary windings 18, and 182 then a secondary winding 20p (shown in phantom) can be wound through bath windows 14, and 142 ie about the common care portion 161,2. Now, the second winding 2Up links with the magnetic flux ~I and ~;t and thus the secondary output is of a magnitude and phase corresponding to the vector or phasor addition of the voltage induced by fluxes ~, and ~2. This provides a 1:1 transformed combination of the phases feeding primary windings 181 and 182. However combinations of other ratios and thus different amounts of phase shifting can be achieved at will by simply winding the secondary winding 20~ about the upper or lower branches B",B, or common core portions 16;~ of different windows. For example, in the embodiment shown in Figure l, the primary phases are 60° ap~~rt. To obtain a secondary output having a phase 15° (ie '/ the phase difference) in advance of the phase of the primary voltage feeding primary winding 181 a secondary winding {not shown) is provided having a 1:4 turn ratio about branch B, of window 141 and branch B, of window 142, ie the secondary winding has four turns passing through window 142 for every turn passing through window 141.
-Figure 2 illustrates a core 10' suitable for constructing a twelve phase transformer 12'. Here, the core 10' is again in shape of a ring; or annulus but this time provided with twelve windows 141 - 14,,2 and twelve common core portions 16;x, one of each between respective adjacent windows 14;. A primary winding 18; is wound about lower branch B, of each window 14;. A secondary winding 20; is wound about the upper branch B~ of each window 14;. The phase of the output of any secondary winding 20; is the same as the phase of voltage driving the corresponding primary winding 18;. However, as with the previous embodiment, the secondary winding 20;
can be wound partially about the upper and lower branches B~ and B, or common core portions I6;a of different windows in any desired combination to produce a desired phase output in accordance with standard transformer design technics.
Figure 3 illustrates an extending (vertically stacked) core 10" and a multiphase transformer 12" constructed using the core 10". 'The core 10" can be considered as being two six window cores vertically stacked upon each other. Thus the core 10"
has a lower set of windows 141 - 146 and an upper set of windows 14~ - 14,2 with windows 14; and 14;+6 in vertical alignment. Primary windings 181 - I86 are wound about the lower branches B, of windows 14, - 146 respectively; and, primary windings 18~ - 18,,2 are wound about the upper branches B, of the upper set of windows 14~ - 14,,2. A set of secondary windings 20 are wound about the middle branch Bm between vertically adjacent windows 14;, 14;+6. Therefore, in this particular illustrated embodiment, there are only ~;ix secondary coils 20. The output of any particular secondary winding 20 would be the transformed phasor or vector addition of voltages induced by the magnetic flux generated by the primary windings linked with the windows common to that particular secondary winding 20. In order 2S to avoid saturation it is preferred that the volunne of core constituting the middle branch Bm is the sum of the volume of the core constituting the lower branch B, and upper branch B" of the windows 14;, 14;+6. 'This embodiment then allows the combination of two six phase supplies that are out of phase with each other.
For example, if there are two six phase power supplies, one providing input to coils 18, -I86 and another providing input to primary windings 18., - 181,2, the two power sources can be combined to provide a six phase output through the secondary WU 00/30130 PCT/AU9910100b windings 20. This could be particularly useful in :f'or example coupling two multiple phase power supplies to a common power transmission grid. The core configuration will also allow for the ability to have 6 primary and 12 secondary windings.
Also a turns ratio of 1/0.5 primary to secondary, or secondary to primary, as well as incorporating other windows will produce any fraction of volts required.
In a different configuration (not illustrated) the primary windings 18, -18,.2 of transformer 12" can be connected to a different phase of a twelve phase power supply and primary windings 20 round through various windows 14; to provide a transformed twelve phase output. Again, the phasing of the output from the Itl secondary windings can be arranged as required in accordance with known transformer design techniques to provide the desired secondary phase output.
Figure 4 further illustrates a further embodiment of the core 10"' and a corresponding 12"'. In the embodiments shown in Figures 1-3 the core 10 and windows 14; are arranged so that the core 10, 10' and 10"' is endless about a first axis that is I5 perpendicular to the axis of any particular window 14;. With the core 1 ()"' of Figure 4, the axis of the core 10 is parallel with the axis of any window 14;. As with all previous embodiments, core i 0"' is configured as an endless loop having a plurality of windows 14; where adjacent windows share a common portion of core lb;~ so that they number of windows 14; equals the number of common core portions lb;~.
Mare 20 specifically, three windows 141 - 143 are formed in the core 10"' with a primary winding 18, - 183 respectively wound about the louver (radially outer most) branches B, of each window 14;. Respective secondary windings 20, - 20, axe wound through the windows 14! - I43 respectively about the corresponding upper (radially inner most) branches B". It is preferred that the core 10"'' is configured so that the volume 25 of core in the upper and lower branch portions B,, B" of each window 14; is the same. This assists in avoiding saturation of the core. This can be achieved by appropriate placement or configuration of the windows 14;.
Figure 5 illustrates an application of the core 10 shown in Figure 1. The core 10 is used in this application in a transverse flux nnotor 26. Full operation and _g_ constructional details of the transverse flux motor are described in the Applicant's Australian Application No PP 7124 the contents of which is incorporated herein by way of reference. The structure of core 10 and tlhe placement of primary windings 18, - 186 is identical to that described in the first embodiment described in relation to Figure 1. However, instead of mufti turn electricaHly separate secondary windings a single turn secondary winding between 2U; is provided about each common core portion 16;~ with each of the single turn second~~ry windings 2(); being in mutual electrical connection. Thus, the single turn secondary windings 20, - 206 form a wheel like structure 30 having an inner rim 32 and outer rim 34 joined by radially extending spokes 36. The outer rim 34 is depicted as residing in the air gap 38 of a cockcroft ring 40. Without going into the detail of operation of the motor 26, currents are induced through the single turn secondary windings 20, - 206 that interact with magnetic t7ux passing through the air gap 38 of the cockcroft ring 40 thereby generating transverse forces on the outer ri~rn 34 of the wheel 30 causing it to move. The path of motion of the wheel 30 can bf; controlled at will by variation of the magnitude and frequency of the primary voltages supplied to the primary coil 18, - 186 and the phase relationship therebetween.
Now that embodiments of the present invention have been described in detail it will be apparent to those skilled in the relevant arts and numerous modifications and variations may be made without departing from the basic inventive concepts.
For example, in each of the embodiments shown, the core 10 is depicted essentially as being in a ring, annulus or circular type form. However it can assume other shapes provided that it is continuous or endless and is provided with equal numbers of windows and common core pouions. Also, the exaict number of windows provided is simply dependent upon the application and in particular the number of primary phases. Also, the position and placement of the secondary windings 20; is dictated solely by the desired magnitude and phase of the secondary outputs. The core 10, 10', 10", 10"' can be made by casting; continuous stamping and winding of an insulated strip of magnetically permeable materiall; winding of a strip of material then machininglcutting the windows. Further the core can be split through a plane passing through the windows 14; to facilitate me,chanical/autornatic winding of the _y_ primary and/or secondary windings about the window branches B", B,, or loading of prewound bobbins on the common core portions 16;x. All such variations and modifications together with others that would be obvious to a person of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the aforegoing descuption.
Claims (20)
1. A core for a multiphase transformer, said core including a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent windows so that said mutually adjacent windows have a leg in common whereby the number of windows is equal to the number of legs, said opposite branches and opposite legs of each window defining a path of substantially uniform magnetic permeability about which magnetic flux circulates.
2. The core according to claim 1 further including a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn wound directly about a branch or a leg of a corresponding window.
3. The core according to claim 2 wherein said primary windings are wholly wound directly about one or more of the branches or legs of said corresponding window.
4. The core according to claim 2 wherein said primary windings are evenly spaced about said central axis.
5. The core according to claim 1 wherein said windows are formed as an array of windows circumferentially about and axially along said body.
6. The core according to claim 2 wherein each primary winding has a plurality of turns and said turns are wound about more than one branch or one leg of said corresponding window.
7. A core for a multiphase transformer including:
a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows, each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent windows so that said mutually adjacent windows have a leg in common whereby the number of windows is equal to the number of legs; and, a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn being wound directly about at least one branch or leg of a corresponding window to produce lines of magnetic flux to correlate about said corresponding window when said each primary winding is energised within electric current.
a body made from a magnetically permeable material forming a closed loop about a central axis, said body further provided with a plurality of windows, each window bound by opposite branches that extend between opposite legs wherein respective legs separate mutually adjacent windows so that said mutually adjacent windows have a leg in common whereby the number of windows is equal to the number of legs; and, a plurality of primary windings, one primary winding being provided for each electrical phase, each primary winding having at least one turn being wound directly about at least one branch or leg of a corresponding window to produce lines of magnetic flux to correlate about said corresponding window when said each primary winding is energised within electric current.
8. The core according to claim 7 wherein each window defines a path of substantially uniform magnetic permeability about which said magnetic flux circulates.
9. The core according to claim 7 wherein each primary winding is wholly wound about a branch or a leg of said corresponding window.
10. The core according to claim 7 wherein said primary windings are evenly spaced about said central axis.
11. A core according to claim 7 wherein each primary winding has a plurality of turns and said turns are wound about more than one branch or one leg of said corresponding window.
12. A multiphase transformer including at least:
a core according to claim 1;
a plurality of primary windings; and a plurality of secondary windings;
wherein at least one primary winding for each electrical phase of said multiphase transformer is wound directly about at least one branch or at least one leg of one of said windows to produce lines of magnetic flux to circulate about said one window when said primary winding is energised with an electric current, and at least one secondary winding having at least one turn wound directly about a branch or a leg of a window about which said lines of magnetic flux circulates to thereby induce a current in said secondary winding.
a core according to claim 1;
a plurality of primary windings; and a plurality of secondary windings;
wherein at least one primary winding for each electrical phase of said multiphase transformer is wound directly about at least one branch or at least one leg of one of said windows to produce lines of magnetic flux to circulate about said one window when said primary winding is energised with an electric current, and at least one secondary winding having at least one turn wound directly about a branch or a leg of a window about which said lines of magnetic flux circulates to thereby induce a current in said secondary winding.
13. The multiphase transformer according to claim 12 wherein said primary windings are evenly spaced about said axis of said body.
14. The transformer according to claim 12 wherein at least one of said secondary windings includes at least one turn wound directly about a branch or a leg of one of said windows and at least a second turn wound directly about a branch or leg of another window.
15. The core according to claim 12 wherein each primary winding has a plurality of turns and said turns are wound about more than one branch or one leg of a corresponding window.
16. A multiphase transformer including at least:
a core according to claim 7; and, a plurality of secondary windings, each secondary winding having at least one turn wound directly about a branch or leg of a window about which said lines of magnetic circulate to thereby induce a current in said each secondary winding.
a core according to claim 7; and, a plurality of secondary windings, each secondary winding having at least one turn wound directly about a branch or leg of a window about which said lines of magnetic circulate to thereby induce a current in said each secondary winding.
17. The multiphase transformer of claim 16 wherein each window defines a path of substantially uniform magnetic permeability about which said magnetic flux circulates.
18. The multiphase transformer of claim 16 wherein each primary winding is wholly wound about a branch or a leg of said corresponding window.
19. The multiphase transformer of claim 16 wherein said primary windings are evenly spaced about said central axis.
20. The multiphase transformer of claim 16 wherein each primary winding has a plurality of turns and said turns are wound about more than one branch or one leg of said corresponding window.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AUPP7124 | 1998-11-13 | ||
| AUPP7124A AUPP712498A0 (en) | 1998-11-13 | 1998-11-13 | Electric motor |
| AUPQ0358A AUPQ035899A0 (en) | 1999-05-13 | 1999-05-13 | Endless core for a multiphase transformer and transformer incorporating same |
| AUPQ0358 | 1999-05-13 | ||
| PCT/AU1999/001006 WO2000030130A1 (en) | 1998-11-13 | 1999-11-12 | Endless core for a multiphase transformer and a transformer incorporating same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2350485A1 true CA2350485A1 (en) | 2000-05-25 |
Family
ID=25645928
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002350485A Abandoned CA2350485A1 (en) | 1998-11-13 | 1999-11-12 | Endless core for a multiphase transformer and a transformer incorporating same |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP1129458A4 (en) |
| JP (1) | JP2002530852A (en) |
| BR (1) | BR9915261A (en) |
| CA (1) | CA2350485A1 (en) |
| IL (1) | IL143108A0 (en) |
| NO (1) | NO20012270L (en) |
| WO (1) | WO2000030130A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102187234A (en) * | 2008-10-10 | 2011-09-14 | 有限会社山崎养世事务所 | Magnetic bridge for sensor using magnetic fluid, and current sensor and magnetic sensor using the magnetic bridge |
| JP5896371B2 (en) * | 2011-08-18 | 2016-03-30 | 東北電力株式会社 | Three-phase electromagnetic equipment |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE140502C (en) * | ||||
| US3323069A (en) * | 1961-11-21 | 1967-05-30 | High Voltage Engineering Corp | High voltage electromagnetic chargedparticle accelerator apparatus having an insulating magnetic core |
| US4099066A (en) * | 1976-08-17 | 1978-07-04 | Beggs William C | Pulse generating system with high energy electrical pulse transformer and method of generating pulses |
| AU4209585A (en) * | 1984-05-09 | 1985-11-14 | Tyree, A.W., Transformers Pty. Ltd. | Three phase transformer core |
| US5146198A (en) * | 1991-06-28 | 1992-09-08 | Westinghouse Electric Corp. | Segmented core inductor |
| DE4310199A1 (en) * | 1993-03-29 | 1994-10-06 | Michael Krafft | Three-phase transformer |
| RU2082245C1 (en) * | 1994-11-08 | 1997-06-20 | Сингаевский Николай Алексеевич | Multiphase transformer |
| DE29503048U1 (en) * | 1995-02-23 | 1995-04-13 | Krafft Michael | Three-phase transformer |
-
1999
- 1999-11-12 WO PCT/AU1999/001006 patent/WO2000030130A1/en active IP Right Grant
- 1999-11-12 BR BR9915261-4A patent/BR9915261A/en not_active Application Discontinuation
- 1999-11-12 CA CA002350485A patent/CA2350485A1/en not_active Abandoned
- 1999-11-12 IL IL14310899A patent/IL143108A0/en unknown
- 1999-11-12 EP EP99957729A patent/EP1129458A4/en not_active Withdrawn
- 1999-11-12 JP JP2000583051A patent/JP2002530852A/en active Pending
-
2001
- 2001-05-09 NO NO20012270A patent/NO20012270L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| IL143108A0 (en) | 2002-04-21 |
| NO20012270D0 (en) | 2001-05-09 |
| BR9915261A (en) | 2002-07-30 |
| EP1129458A1 (en) | 2001-09-05 |
| EP1129458A4 (en) | 2002-02-06 |
| WO2000030130A1 (en) | 2000-05-25 |
| NO20012270L (en) | 2001-07-05 |
| JP2002530852A (en) | 2002-09-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |