阅读说明：本技术 用于旋转电机的绕组以及用于设计这种绕组的方法 (Winding for a rotating electrical machine and method for designing such a winding ) 是由 布鲁诺·笛赫兹 弗朗索瓦·博达尔 于 2014-06-27 设计创作，主要内容包括：本发明提供了用于旋转电机(1)的绕组(40)以及用于设计这种绕组的方法,该绕组包括柔性PCB(45),该柔性PCB具有在第一表面上的多个导体(60)以及在第二表面上的多个导体(60),所述多个导体具有优化该电机的性能的形状。(The present invention provides a winding (40) for a rotating electrical machine (1) and a method for designing such a winding, the winding comprising a flexible PCB (45) having a plurality of conductors (60) on a first surface and a plurality of conductors (60) on a second surface, the plurality of conductors having a shape that optimizes the performance of the machine.)

1. Winding (40) for a rotating electrical machine (1), said electrical machine comprising an inductor (20), a core (50) and an air gap (30) therebetween, said winding (40) comprising a flexible PCB (45) having conductors (60) on a first surface of a substrate and conductors (61) on a second surface of the substrate, said conductors (60, 61) being traces printed on said PCB (45), each of said conductors (60, 61) having a shape extending in an axial direction from a bottom height of said PCB (45) to a top height of said PCB (45), each conductor (60) of the first surface being connected to a conductor (61) of the second surface by a via (43) to form a turn (41), 42) said PCB (45) having a height and a length when said PCB is in a flat configuration such that when rolled one or more times along the length into one or more layers, the PCB is adapted for insertion into said air gap (30) in one axial direction,

it is characterized in that the preparation method is characterized in that,

a conductor (60) of said plurality of conductors on the first surface has a shape extending in an axial direction along a continuous curve or n straight line segments from said bottom height of said PCB (45) to said top height of said PCB (45) when said PCB is in a flat configuration, n being greater than 3.

2. A winding (40) according to claim 1, wherein said conductors have a variable width such that the gap between one conductor (60, 61) and an adjacent conductor (60, 61) is equal to a predetermined constant along the length of said conductor (60, 61).

3. Winding (40) according to claim 1 or 2, wherein the conductors (60, 61) extend along n rectilinear segments, n being greater than 6 and less than or equal to 100.

4. A winding (40) according to any of claims 1-3, characterized in that said plurality of conductors (60, 61) has a line symmetric shape, the symmetry axis being a line along the length of the PCB (45) at the middle height of the PCB (45).

5. A winding according to claim 4, wherein a plurality of turns are connected in series to form a coil.

6. A winding according to claim 5, characterized in that a conductor (60) on the first surface of a turn extends along its length and is connected by a via (43) to a conductor (61) on the second surface having a corresponding extension, so as to form a connection between two successive turns of said coil, which are at a distance from each other in the length direction.

7. A winding according to claim 5, characterized in that when the PCB is in a flat configuration, the turns are t turns, the conductors (60) of the first surface are numbered from 1 to t in the length direction, the conductors (61) of the second surface are also numbered from 1 to t in the length direction, and for i-1 to i-t-1, conductor i on the first surface is connected at the upper end of the PCB (45) to conductor t-i of the second surface by a trace (65) extending at decreasing heights along the length direction of the PCB;

and for i-1 to i-t, the conductor i on the first surface is connected at the lower end of the PCB to the conductor t-i +1 of the second surface by a trace (65) extending over increasing heights along the length of the PCB.

8. A winding according to any of claims 1 to 3, characterized in that said conductors have a point-symmetrical shape, the reflection point being at the mid-height of the PCB (45).

9. A winding according to claim 8, wherein a plurality of turns are connected in series and form one turn in series.

10. A winding according to claim 9, characterized in that when said PCB is in a flat configuration, turns of the series are arranged at a distance one after another in the length direction, a conductor on the first surface of a turn of a series extending along its length and being connected by a via (44) to a conductor with a corresponding extension in a successive series on the second surface, so as to form a connection between two successive series which are at a distance one after another in the length direction.

11. Winding according to claim 9, characterized in that when said PCB is in a flat configuration, turns of the series are arranged successively at a distance in the length direction, said series are t series, adjacent conductors are numbered from 1 to t on both the first and the second surface, and conductors 1 to t on the first surface are connected at the upper end of the PCB to conductors t to 1 respectively on the second surface by t tracks (65) extending over decreasing heights along the length direction of the PCB, and conductors 1 to t on the second surface are connected at the lower end of the PCB to conductors t to 1 of the first surface by a track (65) extending over increasing heights along the length direction of the PCB, except for one series of said series being in the series, the conductors 1 to t-1 on the first surface are connected to terminals at the upper end of the PCB by t-1 traces (65) extending at decreasing heights along the length of the PCB, and the conductors t of the first and second surfaces are connected to conductors t-1 to 1 on the second surface.

12. A winding according to claim 7 or 11, wherein the plurality of traces extending along the length of the PCB are located on both the first and second surfaces of the PCB.

13. A winding according to claim 12, characterized in that a plurality of vias (43) connect said respective tracks on the first and second surfaces of the PCB.

14. Winding according to any of claims 1-13, wherein the shape is designed to optimize the torque constant k of the winding_TDivided by the phase resistance R_phRatio of square root of (a) k_p，

15. Method for designing a winding (40) for a rotating electrical machine (1), said machine comprising an inductor (20), a core (50) and an air gap (30) therebetween, said winding (40) comprising a flexible PCB (45) having conductors (60) on a first surface and conductors (61) on a second surface, said conductors (60, 61) being traces printed on said PCB, each of said conductors (60, 61) having a shape extending in an axial direction from a bottom height of said PCB (45) to a top height of said PCB (45), each conductor (60) of the first surface being connected to a conductor (61) of the second surface by a via (43) to form a turn, when said PCB is in a flat configuration, said PCB having a height and a length such that, when rolled one or more times along the length, into one or more layers, the PCB is adapted for insertion into said air gap in one axial direction,

wherein a conductor (60) on the first surface extends in an axial direction along a continuous curve or n straight sections from said bottom height of said PCB to said top height of said PCB when said PCB is in a flat configuration, wherein n is greater than 3, and the conductor has a variable width such that the gap between one conductor (60, 61) and an adjacent conductor (60, 61) is equal to a predetermined constant along the length of said conductor,

the method comprises the following steps:

a) determining the torque constant k of the rotating electrical machine from those geometric parameters of the shape of the conductor_T；

b) Determining the phase resistance R of the winding from these geometrical parameters of the shape of the conductor_ph；

c) These shape parameters are varied to optimize the objective function:

thereby obtaining an optimal shape of the plurality of conductors.

Technical Field

The present invention relates to a winding for a rotating electrical machine, the electrical machine comprising an inductor, a core and an air gap therebetween, the winding comprising a flexible PCB having a plurality of conductors on a first surface of a substrate and a plurality of conductors on a second surface of the substrate, the plurality of conductors being traces printed on the PCB, the conductors of the first surface being connected to the conductors of the second surface by vias to form turns, such that the flexible PCB is adapted for insertion in the air gap in an axial direction when rolled up one or more times along a length. The invention also relates to a method for designing such a winding.

Description of the prior art

Conventional windings made of copper wire are known and used to produce electric motors, such as brushless direct current motors (BLDC motors). Windings printed on flexible circuit boards (Flex-PCBs) have also been used to produce such motors, providing an opportunity to improve the performance of these BLDC motors, as they are easier to produce, less expensive and give more flexibility in shape and design than windings made of copper wire.

Document FR76288 discloses a planar direct current motor in which the useful magnetic field of the magnets is axial, the windings of which are printed on a rigid planar PCB having conductors on a first surface of the PCB and circuits on a second surface of the PCB connected by vias. This document discloses the use of windings with multiple curved shaped conductors. It is well known to use windings having a curved shape in planar motors to improve the performance of the motor. However, despite the fact that winding in curved shape is well known in planar motors, these windings are not believed to improve the performance of brushless direct current motors (BLDC motors) in which the useful field of the magnets is radial.

Documents US20090072651 and FR2262880 both disclose slotless windings for rotating electrical machines and methods for their manufacture. These documents disclose the use of a flexible PCB having conductors on a first surface of the PCB and conductors on a second surface of the PCB connected by vias. However, these documents do not solve the problem of optimizing performance, limited to the fact that the plurality of conductors on each PCB surface are windings made of two or three straight sections, and do not describe how to achieve the connection between the plurality of conductors on the first and second surfaces.

Document US 3,324,323 discloses providing a winding member on a flat elongated insulating carrier such that the circuit of the winding is closed on said carrier. The flat insulating carrier comprises two parallel strips along its length, a first set of conductors distributed in one of said strips for constituting thereon a first part of a series wave winding interacting with a first arrangement of permanent magnets, and a second set of conductors distributed in the other of said strips for constituting a second part of the series wave winding interacting with a second arrangement of permanent magnets. This particular configuration allows to more easily close or at least substantially close the series path of the two series wave windings by connecting the series path of the two series wave windings in a series relationship between the ends of the winding portions. This document does not attempt to improve the performance of the motor by increasing the torque constant and/or by reducing the phase resistance.

A flexible PCB slotless winding for a BLDC motor is known from "Analysis and comparison of classic slotless winding and flexible PCB slotless winding in BLDC motor in b.cartesian (b.dehez), m.markovich (m.markovic), y.perrierd (Analysis and compliance of classification and flex-PCB slots windings)" motor and system (ICEMS), pages 1-6, 21-24, international conference 15, 2012, month 10 ". This document (hereinafter referred to as reference 1) describes a general structure of a BLDC motor. An analytical expression is given for two parameters characterizing the winding, namely the torque constant and the resistance. A comparison between a classic copper wire winding and a flexible PCB winding with a simple shape (the conductor on one side of the PCB has three sections from the bottom of the PCB to the top of the PCB, forming a skew winding or a diamond winding as shown on fig. 2 and 3 respectively of this document) shows that the flexible PCB winding has a potential improvement in power density of 30% compared to the classic copper wire winding. However, no attempt has been made to find a design with optimal performance. No details are given as to how the conductors on the first surface are arranged together with the conductors on the second surface to form a series of coils or turns.

Disclosure of Invention

It is an object of the present invention to provide a winding for a rotating electric machine with improved performance, i.e. an improved torque constant k of said winding_TDivided by the phase resistance R_phRatio of square root of (a) k_pAnd a method for designing such a winding.

The invention is defined by the independent claims. The dependent claims define advantageous embodiments.

According to a first aspect of the present invention there is provided a winding for a rotary electric machine, the machine comprising an inductor, a core and an air gap therebetween, the winding comprising a flexible PCB having a plurality of conductors on a first surface of a substrate and a plurality of conductors on a second surface of the substrate, the conductors being traces printed on the PCB, a conductor of the first surface being connected to a conductor of the second surface by a via to form a turn, the PCB having a height and length such that when rolled up one or more times along the length into one or more layers, the PCB is adapted for insertion into the air gap in an axial direction. According to the invention, the conductor has a shape extending in axial direction along one continuous curve or n straight sections from the bottom height of the flexible PCB to the top height of the PCB, n being greater than 3. The applicant has found that by giving the conductors a more complex shape (i.e. a continuous curve or more than three straight sections) unexpectedly good results can be obtained with respect to improving the performance of the machine.

Preferably, the shape has a variable width such that the gap between a conductor and an adjacent conductor is equal to a predetermined constant along the length of the conductor. The predetermined constant distance is selected so as to achieve good electrical insulation between two adjacent conductors located on the same side of the PCB. In other words, the conductors have a variable width.

When the shape of the conductors is such that it extends along n rectilinear segments, n is advantageously greater than 6 and less than or equal to 100. The applicant has found that 6 or more segments still improve performance, while no more significant improvement can be obtained by using more than 100 segments.

According to a first preferred embodiment, the conductors have a line-symmetrical shape, the symmetry axis being a line along the length of the PCB at the mid-height of the PCB. Such windings are known in the art as lap windings.

Preferably, a plurality of turns are connected in series to form one coil.

In a first connection mode, the conductor on the first surface of one turn extends along its length and is connected by a via to a conductor having a corresponding extension on the second surface so as to form a connection between two successive turns of the coil, which are at a distance from each other in the length direction.

In a second connection, the plurality of turns are t turns, the plurality of conductors of the first surface being numbered lengthwise from 1 to t, the plurality of conductors of the second surface also being numbered lengthwise from 1 to t, for i-1 to i-t-1, the conductor i on the first surface being connected at the upper end of the PCB to the conductor t-i on the second surface by a trace extending at decreasing height along the lengthwise direction of the PCB;

and for i-1 to i-t, the conductor i on the first surface is connected at the lower end of the PCB to the conductor t-i +1 on the second surface by one track extending over an increasing height along the length of the PCB.

The conductors numbered t of the first and second surfaces are connected to the terminals. By using this second connection, the same torque as in the first connection is obtained. However, as the total length of these conductors is shortened, the resistance decreases and the performance improves.

According to a second preferred embodiment, the plurality of conductors have a point-symmetrical shape, the reflection point being at an intermediate height of the PCB. Such windings are known in the art as wave windings.

Preferably, the plurality of turns are connected in series and thus form a series of turns.

In a first connection mode, a number of adjacent series of turns are arranged at a distance in the length direction, the conductor on the first surface of one turn in a series extending along its length and being connected by vias to the conductor with a corresponding extension in a successive series on the second surface so as to form a connection between two successive series which are at a distance in the length direction.

In a second connection, adjacent turns in series are arranged consecutively at a distance in the length direction, said series being t series, adjacent conductors being numbered from 1 to t on both the first and second surfaces, and conductors 1 to t on the first surface being connected at the upper end of the PCB to conductors t to 1 on the second surface, respectively, by t tracks extending at decreasing heights along the length direction of the PCB, and conductors 1 to t on the second surface being connected at the lower end of the PCB to conductors t to 1 of the first surface by a track extending at increasing heights along the length direction of the PCB. For a series of adjacent turns of said series, the conductors 1 to t-1 on the first surface are connected to the conductors t-1 to 1 on the second surface at the upper end of the PCB by t-1 tracks extending at decreasing heights along the length of the PCB. The conductors numbered t of the first and second surfaces are connected to the terminals. By using this second connection, the same torque as in the first connection is obtained. However, as the total length of these conductors is shortened, the resistance decreases and the performance improves.

In the first and second embodiments, the traces of the second connection means may advantageously be located on both the first and second surfaces of the PCB. This will further reduce the resistance of the windings and improve the performance of the machine.

In this case, the traces on both sides of the PCB may be connected by vias.

The shape of the winding/conductor can advantageously be designed to optimize the torque constant k of the winding_TDivided by the phase resistance R_phRatio of square root of (a) k_p：

Other objective functions to be optimized may be selected: the efficiency (i.e., the ratio of power output to power input) or the power density or size of the motor.

According to a second aspect of the present invention there is provided a method for designing a winding for a rotating electrical machine, the machine comprising an inductor, a core and an air gap therebetween, the winding comprising a flexible PCB having a plurality of conductors on a first surface and a plurality of conductors on a second surface, the conductors being traces printed on the PCB, the conductors of the first surface being connected to the conductors of the second surface by vias to form turns, the PCB having a height and length such that when rolled one or more times along the length into one or more layers, the PCB is adapted for insertion in an axial direction into the air gap. A conductor extends in an axial direction along a continuous curve or n straight sections from a bottom height of the flexible PCB to a top height of the PCB, n being greater than 3, and the conductor has a variable width such that a gap between the conductor and an adjacent conductor is equal to a predetermined constant along a length of said conductor. According to the invention, the method comprises the following steps:

a) determining the torque constant k of the rotating electrical machine from those geometric parameters of the shape of the conductor_T；

b) Determining the phase resistance R of the winding from these geometrical parameters of the shape of the conductor_ph；

c) These shape parameters are varied to optimize the objective function:

thereby obtaining an optimal shape of the plurality of conductors.

Other objective functions described above may also be selected.

The optimization may advantageously be performed using a genetic algorithm.