WO1989003134A1

WO1989003134A1 - Armature winding arrangement and method for electrical machine

Info

Publication number: WO1989003134A1
Application number: PCT/US1988/003303
Authority: WO
Inventors: William E. Gulbrandson
Original assignee: Onan Corp
Current assignee: Onan Corp
Priority date: 1987-09-30
Filing date: 1988-09-22
Publication date: 1989-04-06
Anticipated expiration: 1990-03-30
Also published as: AU2538388A; CA1303107C

Abstract

The present invention relates to armature windings. Individual coils (100) of a group of coils (105) are disposed in slots (203) of an armature such that a first sub-group of coils (100a) are wound in a first direction and second sub-group of coils (100b) are wound in a second direction opposite the first direction.

Description

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.

Background 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 present 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 placed 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 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 5 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

10 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

15 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

20_. of novelty 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

25 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 Drawings 30 In the Figures, in which corresponding reference numerals and letters indicate corresponding parts throughout;

Figure 1A depicts in diagrammatic linear form a single coil used to wind an armature; 35 Figure IB depicts in diagrammatic linear form multiple coils used to wind an armature; Figure 2A depicts in diagrammatic lineal form the windings on an armature according to the prior art for a two pole electrical machine;

Figure 2B depicts the same prior art as 2A, but is depicted using 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 4A 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 EMF 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 lines 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 electrical machine 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 1A, 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 IB 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 IB. Slots of the armature are represented by reference numeral 203 in Figure 2A and are numbered 1 through 30. When 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 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. 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 necessary 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 I^R 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 I^R losses are decreased. There are 15 slots per pole in the winding shown in Figure 2A. The pitch, defined as the ratio of the 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, 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. 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 100a, 100b 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 100b 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 100a (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 100b 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 the winding according to the prior ar and the I^R 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 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. Figure 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 li 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.

Claims

WHAT IS CLAIMED IS:

1. A method for winding an armature of an electrical machine, the armature comprising a plurality of slots arranged in a circular pattern and aligned with each other, the method comprising the step of winding a plurality of coils in the slots of the armature so as to form a group of coils providing for the flow of electrical current therethrough, a first side of a coil being disposed in a positive slot and a second side of a coil being disposed in a negative slot spaced from the positive slot with end turn portions of the coil interconnecting the first and second side of the coil, winding a first sub-group of said group of coils in a first direction and winding a second sub- group of coils in a second direction opposite the first direction.

2. A method in accordance with claim 1, including winding said second sub-group of coils in two positive and two negative slots.

3. A method in accordance with claim 2, including winding the first sides of the coils in the first sub-group in adjacent positive slots and winding the second sides of the coils in the first sub-group in corresponding adjacent negative slots ten slots removed, winding each of the first sides of the coils in the second sub-group in adjacent positive slots separate from the positive slots of said first sub-group of coils and winding the second sides of the coils in the second sub-group in corresponding adjacent negative slots ten slots removed, winding one of said second sides in said second sub-group in a slot adjacent one of said second sides of said first sub-group of coils and winding one of said first sides of said second sub- group in a slot adjacent one of said first sides of said first sub-group.

4. An armature winding, comprising: a) an armature housing including a plurality of slots arranged in a circular pattern and aligned with one another; and b) at least one group of coils wound in the slots of the armature housing, the group of coils comprising a first sub-group of coils wound in a first direction and a second sub-group of coils wound in an opposite second direction.

5. An armature winding in accordance with claim 4, comprising two groups of coils each having first and second sub-groups of coils wound in opposite directions from one another.

6. An armature winding in accordance with claim 4, wherein said first and second sub-groups comprise one phase belt.

7. An armature winding in accordance with claim , wherein the armature includes thirty slots, each of the coils having first and second sides, the first sides of the coils in the first sub-group of coils being disposed in slots three through ten and the second sides being disposed in slots thirteen through twenty, the first sides of the coils in the second sub-group of coils being- disposed in slots being wound in slots one through two and the second sides being disposed in slots twenty-one through twenty- two so as to have a mechanical span of ten and an effective span of twelve.

8. An armature winding in accordance with claim 4, wherein the group of coils has a mechanical span less than the effective span.

9. An armature winding, comprising: a) an armature housing including a plurality of slots; and b) a group of coils having an effective span greater the mechanical span.