Description:FIELD OF THE INVENTION
[001]
The present invention relates to a rotary electrical machine. The present application is a patent of addition to the application 202141009890 filed on 09/03/2021.
5
BACKGROUND OF THE INVENTION
[002]
A typical rotary electrical machine consists of a stator and a rotor. Due to relative motion between the rotor and magnetic field produced by the stator, a back-emf is generated. Owing to mechanical limitations and design considerations of the rotor and the stator, the back-emf does not perfectly match an ideal sinusoidal 10 waveform and has several harmonics. Such harmonics cause additional heat in the machine.
[003]
Stator winding of rotary machines may either have a star connection or a delta connection. However, in case of delta connection, voltage waveform in the stator winding has a higher level of harmonics. The higher level of harmonics results into 15 formation of a circulating current inside the delta connection of the winding. Such circulating current causes additional heat, thereby heating the machine beyond safe and operable levels. Accordingly, in view of the heat generated due to the harmonics present in the back-emf, usage of delta connection for stator winding is restricted. Thus, to employ and take advantage of delta connection, it becomes necessary to 20 minimize the harmonics in the back-emf to obtain a more sinusoidal waveform.
3
[004]
Further, in conventional rotor designs of rotary machines, the torque characteristics have increased ripples. The increased ripples create a cogging torque. When the cogging torque is high, the rotary machine has higher levels of obstruction in forward and backward movement of the rotor. This also causes a poor waveform of the back-emf wherein the back-emf has greater harmonics in it and the waveform is 5 not purely sinusoidal.
[005]
The torque characteristics of the conventional rotor design having increased ripples, is also dependent on the combination of magnets in the rotor of the rotary machine. Especially, in a 6-pole and 36 slot variant of distributed winding combination in the rotary machine, the torque ripple is increased when the saliency of 10 the machine is increased. Saliency is defined as a measure of the reluctance difference between the rotor and the stator around the circumference of the rotor. A higher saliency has a detrimental effect on torque ripple causing a poor waveform, and hence, limiting the rotary machine in terms of not being able to employ delta connection in stator winding. 15
[006]
Another issue with the rotor design in the conventional rotary machines is that the permanent magnets utilised in the rotor are non-commonized, i.e. the permanent magnets required in different arrangements such as V-arrangement or a delta arrangement are different, hence, different permanent magnets need to be produced for different arrangements of the permanent magnets in the rotor, which increases the 20 manufacturing cost and assembly cost.
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[007]
Furthermore, saturation of lamination core is another limitation prevalent in rotor designs in conventional rotary machines.
[008]
Thus, there is a need in the art for a rotary electrical machine which addresses at least the aforementioned problems.
5
SUMMARY OF THE INVENTION
[009]
The rotary electrical machine described consists of a stator with multiple winding slots and a rotor with an even number of magnetic poles. Each pole has at least five magnets, organized into three sets: the first and second sets are in a V-shaped configuration, while the third set is positioned between them and the outer 10 periphery of the rotor. Flux barriers are strategically placed between these magnet sets. Additionally, specific angular relationships are defined for the magnets in each set. The arrangement allows for different pole numbers (n) to be symmetrically configured along central axes (A-A'). The machine exhibits a unique design, resembling a delta shape, with six magnetic poles and thirty-six winding slots. 15
[010]
The present invention is directed towards a rotary electrical machine having a stator with a plurality of slots for winding, and a rotor having an even number of magnetic poles. The rotor is rotatably engaged with the stator. Each of the magnetic poles of the rotor has at least three magnets wherein a first set of at least two magnets and a second set of at least two magnets are arranged in a substantially V-shaped 20 configuration and a third set of at least one magnet is arranged between the first set of magnets and an outer periphery of the rotor. Further, at least one flux barrier is
5
posi
tioned between the first set of magnets and the outer periphery of the rotor, and at least one flux barrier is positioned between the second set of magnets and the outer periphery of the rotor. Further at least one flux barrier is positioned between the third set of at least one magnet.
[011]
In another embodiment of the invention, poles numbered n= {2k, K=1} has 5 the first set of two magnets arranged in a substantially V-shaped configuration symmetrically along a central axis A-A’ of the pole, the third set of one magnet is arranged between the first set and the outer periphery of the rotor, and two flux barriers.
[012]
In another embodiment of the invention, the first set of two magnets are 10 arranged in V-shaped configuration together with the third set of one magnet to form a delta shape.
[013]
In another embodiment of the invention, specifies angular relationships for magnets in the first and second sets. The first set comprises two magnets with adjacent first ends, subtended by a second angle ?2. In another embodiment of the 15 invention, the second set comprises two magnets of the second set of two magnets with adjacent first ends, subtended by a fourth angle ?4.
[014]
In another embodiment of the invention, describes a third set of at least one magnet with subtended angles ?3 between their first and second ends and the associated flux barrier. 20
[015]
In another embodiment of the invention, for poles numbered n = {2k+1, K=0}, the rotary electrical machine configures the first and second sets of magnets
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symmetrically along a central axis, separated by a predefined distance, and includes
the third set arranged between the first set and the outer periphery.
[016]
In another embodiment of the invention, features two sets of flux barriers positioned at specified angles from the second ends of magnets in the first and second sets, with their second ends adjacent to the rotor's outer periphery. 5
[017]
In the rotary electrical machine, for poles numbered n = {2K, K=1}, the first and second sets of magnets are arranged symmetrically along a central axis, with the third set positioned between the first set and the rotor's outer periphery.
[018]
In a further embodiment of the invention, the number of magnetic poles is six and the number of slots for winding is thirty-six. 10
BRIEF DESCRIPTION OF THE DRAWINGS
[019]
Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope 15 of the invention to these particular embodiments.
Figure 1 illustrates a rotor of a rotary electrical machine in accordance with an embodiment of the invention.
Figure 2 illustrates the rotary electrical machine with the stator in accordance with an embodiment of the invention. 20
Figure 3 illustrates adjacent poles of the rotor of the rotary electrical machine 100 in accordance with an embodiment of the invention.
7
Figure 4 illustrates an exemplary pole (n= {2k+1, K=0}) 122A of the rotor.
DETAILED DESCRIPTION OF THE INVENTION
[020]
The present invention relates to a rotary electrical machine. In particular, the present invention relates to a rotary electrical machine with reduced harmonics and 5 reduced torque ripple.
[021]
It is an objective of the present invention to reduce the harmonics and the resultant heat generation.
[022]
It is also an object of the present invention to increase the reliability of the rotary electrical machine and ensure performance even upon failure of one or more 10 primary windings.
[023]
It is yet another object of the present invention to reduce the cogging torque within the rotary electrical machine.
[024]
Figure 1 illustrates a rotor 120 of a rotary electrical machine 100. As illustrated in the Figure, the rotor 120 has an even number of magnetic poles 122. 15 Each of the magnetic poles 122 have substantially similar outer geometry. In the embodiment illustrated in Figure 1, the rotor has six poles 122A,122B,122C,122D,122E,122F. The rotor 120 of the rotary electric machine 100 is rotatably engaged with a stator 110 (as shown in Figure 2). The stator 110 of the rotary electric machine 100 has a plurality of slots 112 (as shown in Figure 2) for 20 winding of a coil. In an embodiment of the invention, the slots 112 of the stator 110 accommodate three pairs of coil windings (not shown), each pair evenly offset by an
8
an
gle to each other, and equally distributed along the stator 110 depending on the positioning of the slots 112. In an embodiment of the invention, the rotary electric machine 100 has thirty-six slots 112, wherein each slot 112 is offset by an angle of 10 degrees to each other.
[025]
As illustrated in Figure 1, each of the magnetic poles 122 comprise at least 5 three magnets. Herein, a first set 124 of at least two magnets 124A,124B are arranged in a substantially V-shaped configuration and a third set 128 of at least one magnet 128A is arranged between the first set 124 of magnets and an outer periphery 134 of the rotor 120. Further, a second set 132 of at least two magnets 132A,132B are arranged in a substantially V-shaped configuration and a third set 128 of at least one 10 magnet 128A is arranged between the first set 124 of magnets and an outer periphery 134 of the rotor 120. At least one flux barrier as further illustrated in Figure 1, at least one flux barrier 126 is positioned between the first set 124 of magnets and the outer periphery 134 of the rotor 120, and at least one flux barrier 130 is positioned between the second set 128 of magnets and the outer periphery 134 of the rotor 120. As can be 15 seen in Figure 1, in an embodiment of the invention, the first set 124 of two magnets 124A,124B and the second set 132 of two magnets 132A, 132B are (as shown in Fig.3) arranged in V-shaped configuration together with the second set 128 of one magnet 128A to form a delta shape-configuration. The voltage that is obtained in delta-shape configuration of the present invention is lower as compared to the voltage 20 in star-shape configuration of the conventional rotor design. However, an increase in the voltage of the delta-shape configuration is obtained by increasing the number of
9
t
urns in the winding on the slots 112 of the stator 110. An increase in the number of turns in the winding on the stator 110 is preferable over higher strands of flux in the star-shape configuration for obtaining a sinusoidal voltage waveform.
[026]
Figure 3 illustrates a portion of the rotor 120 of the rotary electrical machine 100, depicting two adjacent poles 122A,122B in the rotor 120 in accordance with an 5 embodiment of the invention. Each magnet in the first set 124 of two magnets 124A,124B has a first end 124A’,124B’ (shown in Figure 4 and 5) and a second end 124A”,124B” (shown in Figure 3 and 4). Herein, the first end 124A’,124B’ of each of the magnets in the first set 124 are adjacent to each other. In an embodiment of the invention, the first end 124A’,124B’ of each magnet in the first set 124 are adjacent 10 to each other with a gap between them.
[027]
Figure 4 illustrates an exemplary odd numbered (n= {2k+1, K=0}) pole 122A of the rotor 120. As illustrated in Figure 1, and referenced in Figure 4, in poles numbered (n= {2k+1, K=0}) 122A,122C,122E, i.e. poles numbered 1, 3, 5 and so on, the first set 124 of two magnets 124A,124B are arranged in a substantially V-shaped 15 configuration symmetrically along a central axis A-A’ of the odd numbered pole 122A, and the second set 128 of one magnet 128A is arranged between the first set 124 and the outer periphery 134 of the rotor 120. The odd numbered poles 122A,122C,122E (shown in Fig.1) and so on, further have two flux barriers 126, wherein a first end 126A’,126B’ of each of the flux barriers 126A,126B is positioned 20 at a first angle ?1 from the second end 124A”,124B” of each magnet of the first set 124, and a second end 126A”,126B” of each of the flux barriers 126A,126B is
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positioned adjacent to the outer periphery
134 of the rotor 120. In an embodiment, the first end 126A’,126B’ of the flux barriers 126A,126B is curved so as to align with the magnets 124A,124B of the first set 124, that they are attached to.
[028]
In the rotary electrical machine 100, each magnet in the first set 124 of two magnets 124A,124B has a first end 124A’,124B’ and a second end 124A”,124B”. 5 The first ends 124A’,124B’ of the magnets 124A,124B in the first set 124 are positioned adjacent to each other, forming a second angle ?2 subtended between the first end 124A’ and the first end 124B’ of the first set 124 of two magnets 124A,124B.
[029]
The rotary electrical machine 100 specifies that each magnet within the 10 second set 132 of two magnets 132A,132B is defined by a first end 132A’,132B’ and a second end 132A”,132B”. The first ends 132A’,132B’ of the magnets 132A,132B in the second set 132 are positioned adjacent to each other, forming a fourth angle ?4 subtended between the first end 132A’ and the first end 132B’ of the second set 132 of two magnets 132A,132B. 15
[030]
The rotary electrical machine 100 describes that the first end 128A’’ and the second end 128A’’ of the third set 128A of at least one magnet 128 form a third angle ?3 between the first end 128A and the second end 128B of the third set 128 and the flux barrier 130A, 130B.
[031]
In the rotary electrical machine 100, for poles 122 numbered n= {2k+1, K=0}, 20 the first set 124 of two magnets 124A,124B and the second set of two magnets 132A, 132B are arranged in a substantially V-shaped configuration symmetrically along a
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central axis
A-A’ of the pole 122. The first set of magnets 124A, 124B and the second set of magnets 132A, 132B are separated by a pre-defined distance along the central axis A-A’, with the third set 128 of one magnet 128A positioned between the first set 124 and the outer periphery 134 of the rotor 120.
[032]
The rotary electrical machine features two sets of flux barriers 5 126A,126B,136A, 136B. The first end 126A’,126B’,136A’,136B’ of each flux barrier 126A,126B 136A, 136B is positioned at a first angle ?1 from the second end 124A”,124B” 132A’’,132B’’ of each magnet 124A,124B,132A,132B of the first set 124 and the second set 132. The second end 126A”,126B”136A’’,136B’’ of each flux barrier 126,126B is positioned adjacent to the outer periphery 134 of the rotor 120. 10
[033]
The odd numbered poles 122A, 122C, 122E and so on, may further have two flux barriers 130A,130B, wherein a first end 130A’,130B’ of each of the flux barriers 130A,130B is positioned at a third angle ?3 from each end 128A’,128A” of the third set 128 of one magnet 128A, and a second end 130A”,130B” of each of the flux barriers 130A,130B may be positioned adjacent to the outer periphery 134 of the 15 rotor 120.
[034]
Figure 4 illustrates an exemplary even numbered (n= {2K, K=1}) pole 122B of the rotor 120. As illustrated in Figures 3 and 4, in poles numbered n= {2K, K=1} 122B,122D,122F, i.e. poles numbered 2, 4, 6 and so on, the first set 124 of two magnets 124A,124B are arranged in a substantially V-shaped configuration 20 symmetrically along a central axis B-B’ of the even numbered pole 122B, and the second set 128 of one magnet 128A is arranged between the first set 124 and the
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outer periphery
134 of the rotor 120. The even numbered poles 122B,122D,122F and so on, further have two flux barriers 126A,126B, wherein the first end 126A’,126B’ of each of the flux barriers 126A,126B is positioned at a second angle ?2 from the second end 124A”,124B” of each magnet 124A,124B of the first set 124, and the second end 126A”,126B” of each of the flux barriers 126A,126B is positioned 5 adjacent to the outer periphery 134 of the rotor 120. The first end 126A’,126B’ of the flux barriers 126A,126B is curved so as to align with the magnets 124A,124B of the first set 124, that they are attached to.
[035]
The even numbered poles 122B,122D,122F and so on, further have two flux barriers 130A,130B, wherein the first end 130A’,130B’ of each of the flux barriers 10 130A,130B is positioned at a fourth angle ?4 from each end 128A’,128A” of the second set 128 of one magnet 128A, and a second end 130A”,130B” of each of the flux barriers 130A,130B is positioned adjacent to the outer periphery 134 of the rotor 120.
[036]
In an embodiment of the invention as referenced in Figure 3, 4 and 5, the first 15 angle ?1 is greater than the second angle ?2, i.e. the angle formed between the first end 126A’,126B’ of each of the flux barriers 126A,126B from the second end 124A”,124B” of each magnet 124A,124B of the first set 124 in odd numbered poles 122A,122B,122E is greater than the angle formed between the first end 126A’,126B’ of each of the flux barriers 126A,126B from the second end 124A”,124B” of each 20 magnet 124A,124B of the first set 124 in even numbered poles 122B,122D,122F. Further, the third angle ?3 is greater than the fourth angle ?4, i.e. the angle formed
13
b
etween the first end 130A’,130B’ of each of the flux barriers 130A,130B from each end 128A’,128A” of the second set 128 of one magnet 128A in odd numbered poles 122A,122C,122E is greater than the angle formed between the first end 130A’,130B’ of each of the flux barriers 130A,130B from each end 128A’,128A” of the second set 128 of one magnet 128A in even numbered poles 122B,122D,122F. 5
[037]
Such an alternating arrangement of magnets 124,132 and 128 and flux barriers 126,136, 130 in adjacent odd and even numbered poles 122 of the rotor 120 improves the reluctance difference between the rotor 120 and the stator 110 around the outer periphery 134 of the rotor 120, reducing the saliency and hence improving the usage of the magnets over a long period of time in operation. Further, the alternating 10 arrangement of magnets 124,128 and flux barriers 126,136,130 in the adjacent poles 122 of the rotor 120 reduces the distortion in the back EMF waveform, resultantly reducing the harmonics in the waveform and giving rise to a more sinusoidal voltage waveform and reducing torque ripple.
[038]
Further, in an embodiment, the arrangement of magnets 124,132,128 and flux 15 barriers 126,136,130 in the poles 122 of the rotor 120 are, in a manner that the flux barriers 126,136,130 have curved profile at their respective first ends 126A’,126B’,136A’, 136B’ 130A’,130B’ and the first ends 126A’,126B’,130A’,130B’ and second ends 126A”,126B”,130A’”,130B” of all the flux barriers 126,136,130 have curved edges, instead of the conventional sharp edges, 20 reducing the chances of flux concentration at the sharp edges and hence reduce the possibility of core saturation.
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[039]
As further illustrated in Figure 3, similar magnets have been used in the first set 124 of two magnets 124A,124B; the second set 132A, 132B and the third set 128 of one magnet 128A across the odd numbered and even numbered poles 122, hence eliminating the need of separate manufacturing of magnets for the first set 124 and the second set 128. 5
[040]
Advantageously, the configuration of the magnets and the flux barriers in the poles of the rotor give rise to a closely sinusoidal back-emf curve, reducing the harmonics and the resultant heat generation, hence allowing for a delta connection to be used in the winding on the stator. A merit of using the delta connection in winding is higher reliability. If one of the three primary windings fails, the secondary will still 10 produce full voltage on all three phases. The only requirement is that the remaining two phases must be able to carry the load.
[041]
Further, the cogging torque in the present invention is reduced along with the reduction in saliency, thereby reducing the torque ripple, which contributes towards a more sinusoidal back-emf waveform. 15
[042]
Further, due to similar magnets being used in the first set, the second set and the third set in the poles, the requirement of manufacturing separate permanent magnets is eliminated, hence reducing the manufacturing and assembly cost. Also, the use of similar magnets in the rotor leads to lamination sheets of the rotor having rotational symmetry, which eases the rotor stacking process as in cases of asymmetric 20 lamination sheet geometry the lamination sheets can be stacked in only one way.
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[043]
The concept of arranging sets of magnets eliminate the requirement for manufacturing the permanent magnets separately. This specific concept adds practical utility to the invention, as it addresses the need for adaptable and personalized control interfaces. The overall design and functionality of the claimed invention are geared toward addressing practical challenges in manufacturing and performance of the 5 rotary electrical machine. Thus, the invention provides a technical solution with tangible applications in the automotive industry.
[044]
In summary, the claimed invention provides a specific, tangible, and practical solution to challenges in vehicle control interfaces.
[045]
While the present invention has been described with respect to certain 10 embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims. , Claims:WE CLAIM:
1.
A rotary electrical machine (100), comprising:
a stator (110) having a plurality of slots (112) for winding; and
a rotor (120) having an even number of magnetic poles (122) and rotatably engaged with the stator (110), each of the magnetic poles (122) comprising: at 5 least five magnets, wherein
a first set (124) of at least two magnets are arranged in a substantially V-shaped configuration;
a second set (132) of at least two magnets are arranged in a substantially V-shaped configuration; and, 10
a third set (128) of at least one magnet is arranged between the first set (124) of magnets and an outer periphery (134) of the rotor (120); at least one flux barrier (126) positioned between the first set (124) of magnets and the outer periphery (134) of the rotor (120);
at least one flux barrier (136) positioned between the first set 15 (124) of magnets and the outer periphery (134) of the rotor (120);
at least one flux barrier (126) positioned between the second set (132) of magnets and the outer periphery (134) of the rotor (120); and,
at least one flux barrier (130) positioned between the third set 20 (128) of magnets and the outer periphery (134) of the rotor (120).
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2.
The rotary electrical machine (100) as claimed in claim 1, wherein each magnet in the first set (124) of two magnets (124A,124B) comprises: a first end (124A’,124B’) and a second end (124A”,124B”) wherein the first end (124A’,124B’) of each of the magnets (124A,124B) in the first set (124) are adjacent to each other with a second angle ?2 subtended between the first end 5 (124A’) and the first end (124B’) of the first set (124) of two magnets (124A, 124B).
3.
The rotary electrical machine (100) as claimed in claim 1, wherein each magnet in the second set (132) of two magnets (132A,132B) comprises: a first end 10 (132A’,132B’) and a second end (132A”,132B”) wherein the first end (132A’,132B’) of each of the magnets (132A,132B) in the second set (132) are adjacent to each other with a fourth angle ?4 subtended between the first end (132A’) and the first end (132B’) of the second set (132) of two magnets (132A, 132B). 15
4.
The rotary electrical machine (100) as claimed in claim 1, wherein the first end 128A’’ and the second end 128A’’ of the third set (128A) of the at least one magnet (128) subtend a third angle ?3 between the first end (128A) and the second end (128B) of the third set (128) and the flux barrier (130A, 130B). 20
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5.
The rotary electrical machine (100) as claimed in claim 1, wherein poles (122) numbered n= {2k+1, K=0} comprise the first set (124) of two magnets (124A,124B) and the second set of two magnets (132A, 132B) arranged in a substantially V-shaped configuration symmetrically along a central axis (A-A’) of the pole (122), the first set of magnets (124A, 124B) and the second set of 5 magnets (132A, 132B) separated by a pre-defined distance along the central axis (A-A’) and the third set (128) of one magnet (128A) arranged between the first set (124) and the outer periphery (134) of the rotor (120).
6.
The rotary electrical machine (100) as claimed in claims 2 and 3, comprising two 10 sets of flux barriers (126A,126B) (136A, 136B), wherein a first end (126A’,126B’) (136A’,136B’) of each of the flux barriers (126A,126B) (136A, 136B) is positioned at a first angle (?1) from the second end (124A”,124B”) (132A’’,132B’’) of each magnet (124A,124B)(132A,132B) of the first set (124) and the second set (132), and a second end (126A”,126B”)(136A’’,136B’’) of 15 each of the flux barriers (126,126B) is positioned adjacent to the outer periphery (134) of the rotor (120).
7.
The rotary electrical machine as claimed in claim 1, wherein poles (122) numbered n= {2K, K=1}, comprise the first set (124) of two magnets 20 (124A,124B), the second set of two magnets (132A, 132B) arranged in a substantially V-shaped configuration symmetrically along a central axis (A-A’) of
19
the pole
(122) and the third set (128) of one magnet (128A) arranged between the first set (124) and the outer periphery (134) of the rotor (120).
8.
The rotary electrical machine (100) as claimed in claims 3 and 8, comprising twoflux barriers (126A,126B), wherein the first end (126A’,126B’) of each of the5 flux barriers (126A,126B) is positioned at a second angle (?2) from the secondend (124A”,124B”) of each magnet (124A,124B) of the first set (124).
9.
The rotary electrical machine (100) as claimed in claims 5 and 7, wherein thesecond angle ?2 is greater than the fourth angle ?4.10
10.
The rotary electrical machine (100) as claimed in claims 5 and 8, wherein the firstset (124) of two magnets (124A,124B) and the second set of two magnets (132A,132B) arranged in V-shaped configuration together with the third set (128) of onemagnet (128A) forming a delta shape.15
11.
The rotary electrical machine (100) as claimed in claim 1, wherein the number ofmagnetic poles (122) is six and the number of slots (112) for winding is thirty-six.