Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1303107
ARMATURE WINDING ARRANGEMENT AND METHOD
FOR ELECTRICAL MACHINE
Field of the Invention
Electrical machines are commonly designed to use
electrical conductors, herein referred to as wires, wrapped
in the slots of an armature in such a way as to obtain a
desired voltage, current, flux concentration and waveform.
The present invention is directed to the arrangement and
configuration in which the wires are wrapped in the slots
of the armature.
Backqround of the Invention
Typically, an armature winding contains one or
more coil groups such that the shortest distance from the
positive slot for a given coil, and the negative slot for a
given coil, is in the same direction for every coil of a
group. The present invention is directed to reversing a
number of the coils, thereby changing the direction of the
shortest distance from the positive to the negative slot.
This provides for greater efficiency and reduced material
requirements. The pxesent invention solves many problems
associated with existing armature windings.
Summary of the Invention
The present invention is directed to the
positioning of coils on an armature for an electrical
machine. The invention utilizes the fact that the sections
of windings outside of the slots do not substantially
affect the magnetic field, nor does the order in which the
coils are plac~d in the slots substantially affect the
magnetic field. The invention includes reversing the
direction that one or more coils are wound within a group
of coils. This results in decreasing the mechanical span
(the distance from the positive to the negative slot for a
coil), but maintaining the same effective span, which in
turn reduces the amount of wire necessary to wind the
armature. For purposes of this application, the effective
span is defined as the distance from the first slot of a
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series of sequentially occurring positive slots in a coil
group, across the slots of that series to the first slot of
a series of sequentially occurring negative slots in the
same coil group. Other important effects are that the
armature resistance is reduced and that there is less loss
in the winding. The overall effect is that the machine is
more efficient, and fewer raw materials are required to
produce the electrical machine.
This invention will be explained with reference
to one phase alternating current machines having two poles.
However, those skilled in the art will recognize that this
invention applies equally to direct current and polyphase
alternating current electrical machines having two or more
poles. The invention also applies to electrical machines
that use bars or multi-layered coils. Furthermore, the
invention may be applied to all types of windings; some of
the common types of winding being lap windings, wave
winding and concentric windings.
These and various other advantages and features
of novelt~ which characterize the present invention are
pointed out with particularity in the claims annexed hereto
and forming a part hereof. However, for a better
understanding of the invention, its advantages and objects
attained by its use, reference should be had to the
drawings which form a further part hereof and to the
accompanying descriptive matter in which there is
illustrated and described an embodiment of the invention.
Brief Description of the Drawinqs
In the Figures, in which corresponding reference
numerals and letters indicate corresponding parts
throughout,
Figure lA depicts in diagrammatic linear form a
single coil used to wind an armature;
Figure lB depicts in diagrammatic linear form
multiple coils used to wind an armature;
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Figure 2A depicts in diagrammatic linear form the
windings on an armature according to the prior art for a
two pole electrical machi.ne;
Figure 2B depicts the same prior art as 2A, but
is depicted usins a circular representation rather than a
linear representation;
Figure 3A depicts in diagrammatic linear form the
windings on an armature according to the prior art for a
four pole electrical machine;
Figure 3B depicts the same prior art as Figure
3A, but is depicted using a circular representation rather
than a linear representation;
Figure 4~ depicts in diagrammatic linear form an
armature winding that provides the same voltage and EMF as
that of Figures 2A and 2B, but is wound according to the
present invention
Figure 4B depicts the same winding as Figure 4A,
but is depicted using a circular representation rather than
a linear representation;
Figure 5A depicts in diagrammatic linear form an
armature winding that provides the same voltage and ENF as
that of Figures 3A and 3B but is wound according to the
present invention;
Figure 5B depicts the same winding as Figure 5A
but is depicted using a circular representation rather than
a linear representation;
Figure 6 is a fragmentary partial view of an
electrical machine made according to the prior art from a
top perspective;
Figure 7 is a top view of the electrical machine
shown in Figure 6;
Figure 8 is a sectional view taken along lLnes
8-8 of Figure 7;
Figure 9 is a fragmentary partial view of an
electrical machine made according to the present invention;
Figure 10 is a top view of the electxical machine
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shown in Figure 9; and
Figure 11 is a sectional view taken along line
11-11 of Figure 10.
Detailed Description of the Preferred Embodiment
Referring now to the drawings, wherein like
reference numerals refer to identical or corresponding
components throughout the several views, and more
particularly to Figure 1, a coil 100 used in an armature
winding is depicted. For the purposes of this discussion,
a coil shall be treated as one loop through two slots of
the armature. However, those skilled in the art will
realize that a coil may consist of numerous loops, a single
bar, or any other device used in armature winding and still
fall within the scope of the present invention.
In Figure lA, when a positive voltage is applied
to terminal 101 a current flows up the left side of the
coil 100 and down the right side of the coil 100 to
terminal 102. If the coil would consist of more than one
loop, the current would flow up the left side of each loop,
and down the right side.
Figure lB represents several coils 100. The
coils 100 are collectively referred to as a group of coils
105. Each loop of each coil is connected such that when a
positive voltage is applied to terminal 103, current flows
up the left side of each coil 100 (and each loop of each
coil) and down the right side to terminal 104.
In Figure 2A, a typical armature winding
according to the prior art is shown. The winding comprises
a group of coils 105 comprising the coils 100, similar to
the coils 100 shown in Figure lB. Slots of the armature
are represented by reference numeral 203 in Figure 2A and
are numbered 1 through 30. ~hen a positive voltage is
applied to terminal 201, the current flows up a first side
of each of the coils 100 placed in slots 1-10, and down a
second side of each of the coils 100 placed in slots 13-22
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to terminal 202. For the purposes of this discussion, the
slots are defined such that when a positive voltage is
placed at the positive terminal 201, the current flows
through a positive slot first, and then through a negative
slot. Thus, each coil 100 has a first side placed in one
positive slot, and a second side placed in one negative
slot. In Figure 2A, slots 1-10 are positive slots and
slots 13-22 are negative slots. The negative and positive
slots together form one phase belt. Those skilled in the
art realize that in actual practice an alternating current
supply may be used and that the current reverses direction.
However, at any one time the current is flowing in the same
direction in all positive slots and in the opposite
direction in all negative slots. The current path for the
winding shown in Figure 2A is 201, 1, 13, 2, 14, 3, 15, 4,
16, 5, 17, 6, 18, 7, 19, 8, 20, 9, 21, 10, 22, 202.
Figure 2B represents the same winding shown in
Figure 2A, however in this view, end turns of the coils 100
cannot be seen. When a positive voltage is applied to
terminal 201, current flows from each coil's positive slot
to each coil's negative slot to terminal 202.
The armature shown in Figures 2A and 2B is a two
pole armature, also referred to as a bipolar armature.
Each coil has a mechanical and effective span associated
with it. The mechanical span of a coil is the number of
slots between its corresponding positive slot and negative
slot. Thus, the mechanical span of the coils 100 in
Figures 2A and 2B is twelve (12). The effective span is
defined as the number of slots from the first positive slot
of the series of sequentially occurring positive slots in
the coil group, across the series of positive slots to the
first negative slot of the series of sequentially occurring
negative slots of that same coil group. In Figures 2A and
2B, the effective span is twelve ~12).
The prior art shown uses electrical machines
having the mechanical span equal to the effective span.
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The present invention alters the mechanical span without
changing the effective span. This has little or no effect
on the machine except to increase or decrease the amount of
wire necessar~r to construct the machine.
The current in the portion of the coil that is
not in the slot, that is the portion of the coil on the
armature connecting the positive and negative slots, also
referred to as the end turn, does not substantially affect
the flux, and therefore the output voltage is not affected.
The I2R losses are proportional to the length of the wire
used, often copper, and therefore are dependent on the
mechanical span. From the standpoint of the flux created,
the wiring external to the slots does not matter, so long
as each slot remains the same polarity. Therefore,
changing the mechanical pitch and holding the electrical
pitch constant results in a machine whose electrical
characteristics do not change, but the amount of wire used
is decreased, and the I2R losses are decreased. There are
15 slots per pole in the winding shown in Figure 2A. The
pitch, defined as the ratio of ~he effective span to the
slots per pole, is equal to 4/5. The pitch and
distribution of a winding affects the magnitude of
undesirable harmonics, thus it is desirable to maintain the
pitch and the slot's polarity.
Another example of prior art is shown in Figures
3A and 3B. There are two groups of coils 105a,b present.
This is a four-pole winding using a 48 slot armature.
Slots 51-58 and 75-82 are positive slots, while slots 61-68
and 85-92 are negative slots. Slots 51-68 comprise one
phase belt and slots 75-92 comprise a second phase belt.
The mechanical and effective span is 10, and the pitch is
5/6. Figure 3A uses a linear representation and Figure 3B
uses a circular representation. There are two current
paths. They are: 301, 51, 61, 52, 62, 53, 63, 54, 64, 55,
~5 65, 56, 66, 57, 67, 58, 68, 302; and 303, 75, 85, 76, 86,
77, 87, 78, 88, 79, 89, 80, 90, 81, 91, 82, 92, 304.
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In Figures 4A and 4B, the winding of Figures 2A
and 2B is made according to the present invention. The
group of coils 105 comprises two different sets of coils
lOOa, lOOb which are wound in different directions. The
positive slots in Figure 4A and 1-10, and the negative
slots are 13-22, just as in the winding of Figure 2A. In
this design, the mechanical span is reduced to 10 while the
effective span is held at 12. The electrical pitch and
distribution of positive/negative slots is the same as
figures 2A and 2B. Since the mechanical span is less than
that of Figures 2A and 2B, less wire is necessary to wind
the armature. Decreasing the mechanical span is
accomplished by reversing the direction the last two coils
lOOb are wound. In Figures 2A and 2B, the direction from
the positive slot to the negative slot for all coils is the
same (to the right in Figure 2A and clockwise in Figure
2B). This invention uses the novel technique of reversing
the direction for two coils. For the eight coils lOOa
(those in positive slots 3-10) the direction from the
positive slot to the negative slot is to the right in
Figure 4A (clockwise in Figure 4B) and for the remaining
two coils lOOb in positive slots 1 and 2 the direction from
the positive slot to the negative slot is left in Figure 4A
(counterclockwise in 4B).
This "flipping" of two coils reduces the
mechanical span and results in using less wire, reducing
losses, and increasing efficiency. At the same time, it is
possible to maintain each slot as a positive or negative
slot as in Figure 2A. An armature wound according to the
present invention uses less wire than th~ winding according
to the prior art and the I2R losses are also reduced.
Figures 5A and 5B represent the same winding as
that of Figures 3A and 3B, except made according to the
present invention. The direction from the positive slot to
the negative is to the right (or clockwise) except for two
coils in each group of coils. The slots are maintained at
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the polarity of Figures 3A and 3B, but the mechanical span
is reduced to 8, as opposed to a mechanical span of 10 in
Figures 3A and 3B.
Figure 6 is an exploded perspective of an
electrical machine armature (602) made according to the
prior art such as shown in Figures 2A and 2B. The slots in
which the coils are placed are referred to by 601. The
portion of the coil in the slots is the portion that
contributes to the magnetic flux. The end portions, also
referred to as end turns, of the coils are referred to by
603 and do not substantially contribute to the magnetic
flux. Fi~ure 7 shows a top view of the machine in Figure
6. It is possible to see that every coil is wound in the
same direction. It may be seen that the mechanical span
and the effective span are 12. Figure 8 shows a section
along line 8-8 of Figure 7.
Figure 9 is an exploded perspective of an
electrical machine armature wound according to the present
invention. Figure 10 is a top view of the machine in
Figure 9. It may be seen that two coils are wound in the
direction opposite the others, and that the mechanical span
is 10. The effective span is equal to 12, just as in
Figure 7. Figure 11 shows a section along line 11-11 of
Figure 8.
It is to be understood that even though numerous
characteristics and advantages of various embodiments of
the present invention have been set forth in the foregoing
description, together with details of the structure and
function of various embodiments of the invention, this
disclosure is illustrative only and changes may be made in
detail, especially in matters of shape, size and
arrangement of parts, within the principles of the present
invention, to the full extent indicated by the broad
general meaning of the terms in which the appended claims
are expressed.
