Three-phase stator winding for electric machine with axial magnetic flux, made on printed base

Abstract

FIELD: electrical engineering.SUBSTANCE: design of stator windings of electric machines with axial magnetic flux. A three-phase stator winding for an electric machine with axial magnetic flux is made on a printed base containing a dielectric base and conductive tracks grouped into coils that form phase windings. A distinctive feature of the invention is that on one active layer of the printed base, conductive tracks of all three phases are simultaneously located, forming a symmetrical three-phase distributed winding. In this case, the geometry of the conductive paths is made wavy with the possibility of the transition of paths of one phase to different active layers through metallized holes and their passage within one layer without intersecting with the conductive paths of other phases.EFFECT: reduction in the thickness of the stator winding package, a reduction in the number of layers of the printed circuit board, a simplification of the winding design, as well as ensuring high accuracy and repeatability of the winding geometry, the elimination of tooth torque pulsations and the possibility of integrating control system elements directly on the board with the winding.1 cl, 7 dwg

Description

[0001] FIELD OF TECHNOLOGY

[0002] The present invention relates to electrical engineering, in particular to the design of stator windings of electric machines with axial magnetic flux, and can be used in the design and production of rotating and linear three-phase synchronous and asynchronous motors and generators built into household appliances, instrument making, mechanical engineering, as well as compact electric drives for various purposes.

[0003] STATE OF THE ART

[0004] In modern electrical engineering, technical solutions are known for creating flat stator windings for axial electric machines using printed circuit board technology. The main advantage of this approach is the ability to produce windings with high geometric accuracy, repeatability of parameters, and reduced weight and dimensions.

[0005] A multiphase stator winding on a printed circuit board is known from the prior art, disclosed in patent RU 2814208 C2. This winding is implemented as a multilayer printed circuit board, with each phase winding placed on two separate layers—the primary and secondary layers. The coils of each phase are grouped according to the number of poles of the electric machine and connected in opposite series. A disadvantage of this solution is that at least six active layers (two layers per phase) are required to accommodate all three phases, which increases the thickness of the winding stack, complicates interlayer switching, and increases manufacturing costs. Furthermore, the coils of each phase are spatially distributed across different layers, preventing the creation of a three-phase distributed winding using the minimum possible number of layers.

[0006] A stator winding for an axial electric machine with an adaptive concentric coil topology is also known, as described in patent RU 2823259 C1. In this solution, the coils are segmented, tapering toward the axis of rotation, with the active zone optimized to increase EMF and torque. However, this winding is focused on optimizing the topology of a single coil or a single phase and does not disclose the principle of simultaneously forming a symmetrical three-phase distributed winding on a single active layer without crossing the conductive paths of different phases.

[0007] A stator winding for an axial electric machine, disclosed in patent RU 2784009 C1, is known. In this winding, only a single phase is placed on a single unified active layer, while a three-phase system is formed by mechanically shifting the layers and then switching them with jumpers. A disadvantage of this solution is the inability to accommodate all three phases within a single rigid printed circuit board assembly without additional shifting and switching operations, which limits the minimum winding thickness and increases assembly labor.

[0008] The closest analog (prototype) to the claimed invention is a stator winding for an axial electric machine, described in patent US 2020 / 0220406 A1. In this solution, the phase windings are implemented on printed circuit boards, with each phase occupying a separate layer or group of layers, and each active layer containing tracks for only one phase. This limits the possibility of further reducing the winding thickness and increasing the fill factor of the printed circuit board.

[0009] Therefore, there is a need to create a three-phase stator winding for electric machines with axial magnetic flux, made on a printed base, which would allow placing a full-fledged symmetrical three-phase distributed winding on a smaller number of active layers (in the limit - on two layers) without using a mechanical shift of layers and ensuring electromagnetic symmetry of the phases.

[0010] DISCLOSURE OF THE INVENTION

[0011] The objective of the present invention is to develop a three-phase stator winding for an electric machine with axial magnetic flux, made on a printed base, in which the three-phase distributed winding is formed on the minimum possible number of active layers by placing the conductive tracks of all three phases on one active layer of the printed base.

[0012] The technical result achieved by implementing the invention consists in reducing the thickness of the stator winding package, reducing the number of printed circuit board layers required to form a three-phase system, simplifying the winding design, reducing manufacturing costs, as well as ensuring high accuracy and repeatability of the winding geometry, eliminating tooth torque pulsations and the ability to integrate control system elements directly on the board with the winding.

[0013] The stated technical result is achieved by a three-phase stator winding for an electric machine with axial magnetic flux, implemented on a printed circuit board. It comprises a dielectric base, formed as a round or rectangular printed circuit board, and conductive tracks forming the phase windings. Several symmetrically distributed winding coils in the form of teeth are located on the board. The windings are formed by copper conductive tracks applied to the printed circuit board. Each winding forms a closed circuit, which is wound on a corresponding stator tooth. The winding circuits are interconnected, forming three different phase circuits according to a three-phase connection scheme. Contact pads and winding terminals for connection to an external circuit are located on the outer edge of the printed circuit board. The winding geometry and their arrangement are designed to generate axial magnetic flux.

[0014] The geometry of the stator winding on the printed circuit board is as follows. The winding consists of a set of curved copper tracks, evenly spaced around the stator circumference. Each winding coil is formed by two parallel tracks that extend from one contact pad, pass along a stator tooth, then fold back and return to the other contact pad, forming a closed loop. The stator teeth are expressed as protruding segments containing the winding tracks, with gaps between them allowing the passage of magnetic flux. The copper tracks are narrow and uniform in thickness, typical of printed circuit boards, and follow a wave-like trajectory optimized for uniform current distribution. The ends of the windings are connected to contact pads, which are evenly distributed around the outer ring of the stator for convenient connection of three-phase circuits.The coils and tracks are arranged symmetrically around the stator's center, ensuring a balanced magnetic field and reducing vibration during operation. The central hole allows the rotor to be installed, with the magnetic flux directed axially, perpendicular to the plane of the printed circuit board.

[0015] The key difference between the claimed invention and its closest analogues is that the conductive tracks of all three phases are simultaneously located on a single active layer of the printed circuit board, forming a symmetrical three-phase distributed winding. Moreover, the geometry of the conductive tracks is wavy, allowing tracks from one phase to transition to different active layers through metallized holes and to pass within a single layer without intersecting with the conductive tracks of other phases.

[0016] In specific embodiments of the invention, the dielectric base may be made of fiberglass or another material used for printed circuit board production. The number of active layers may be any even multiple of two, allowing for increasing the power of the electric machine by connecting additional layers in parallel or series. The phase windings may be connected using a star or delta configuration directly on the printed circuit board. Contact pads for connection to the power source or receiver may be located on the outer or inner perimeter of the board, although their presence is not mandatory, as connection can be achieved by other means.

[0017] The cause-and-effect relationship between the set of essential features and the achieved technical result is as follows.

[0018] Placing the conductive tracks of all three phases on a single active layer reduces the total number of layers required to form a three-phase winding to two (with double-sided metallization) or to any even multiple of two if an increase in the conductor cross-section or number of turns is required. This directly reduces the thickness of the winding package and, consequently, the weight and dimensions of the final product.

[0019] The coils are constructed as closed loops of two parallel tracks encircling dielectric teeth, creating clearly defined magnetic poles and directing the axial magnetic flux. The gaps between the teeth create directed paths for the magnetic flux, increasing the efficiency of electromagnetic interaction with the rotor.

[0020] The implementation of wave-shaped track geometry with transitions between layers allows for the tracks of one phase to "bypass" those of another phase without electrical contact. This allows for a single-layer topology in which all three phases are electromagnetically independent but geometrically integrated into a single printed circuit. This allows for a symmetrical three-phase distributed winding with uniform phase zones around the circumference.

[0021] The symmetrical arrangement of the coils and tracks relative to the center of the stator ensures a balance of magnetic fields, eliminates parasitic vibrations and promotes uniform distribution of current loads.

[0022] The winding is manufactured using printed circuit board technology with high-precision photolithography, ensuring high repeatability of parameters from product to product and the complete elimination of cogging torque pulsations typical of windings laid in slots of a ferromagnetic core. Furthermore, the cogging teeth themselves, made of the dielectric material of the printed circuit board, do not generate the cogging pulsations typical of ferromagnetic cogging.

[0023] The ability to place control system elements (Hall sensors, drivers, passive components) on the same dielectric base allows the electronics to be integrated directly into the winding board, which further simplifies the overall design of the electric drive.

[0024] Thus, each of the essential features influences the achievement of the technical result, and their combination allows us to obtain a new, previously unachievable effect - the creation of an ultra-flat three-phase distributed winding on a printed circuit board with a minimum number of layers.

[0025] BRIEF DESCRIPTION OF DRAWINGS

[0026] The invention is illustrated by the drawings shown in Fig. 1-7.

[0027] Fig. 1 - general view of a three-phase stator winding from above, diagram of the arrangement of conductive paths of three phases on one active layer (special case 2p = 12, number of conductors per pole and phase - 1);

[0028] Fig. 2 - a fragment of the winding with an enlarged scale, illustrating the wave-like trajectory of the tracks and interlayer transitions;

[0029] Fig. 3 - an example of a three-phase winding on a two-layer printed circuit board, view of the first layer (special case 2p = 12, number of conductors per pole and phase - 1);

[0030] Fig. 4 - an example of a three-phase winding on a two-layer printed circuit board, view of the second layer (special case 2p = 12, number of conductors per pole and phase - 1);

[0031] Fig. 5 - diagram of the connection of phase windings in a star (special case 2p = 4, the number of conductors per pole and phase is 2);

[0032] Fig. 6 - diagram of the connection of phase windings in a triangle (special case 2p = 4, number of conductors per pole and phase - 1);

[0033] Fig. 7 - cross-section of the winding in the interlayer transition zone.

[0034] The following designations are used in the drawings:

[0035] 1 - dielectric base (printed circuit board);

[0036] 2 - conductive paths of phase A;

[0037] 3 - phase B conductive tracks;

[0038] 4 - phase C conductive tracks;

[0039] 5 - through plated hole (transition between layers);

[0040] 6 - contact pad;

[0041] 7 - central hole for rotor (if necessary);

[0042] 8 - mounting hole;

[0043] 9 - conditional boundary of pole division;

[0044] 10 - control system element (optional).

[0045] IMPLEMENTATION OF THE INVENTION

[0046] The claimed three-phase stator winding is made in the form of a circular, ring-shaped, or rectangular printed circuit board. The magnetic flux during operation is directed axially, perpendicular to the plane of the printed circuit board.

[0047] The dielectric base is made of FR-4 fiberglass with a thickness corresponding to the selected number of layers. Other materials with the required dielectric and mechanical properties can be used.

[0048] The conductive pattern is formed by selective etching of copper foil or mechanical milling. The conductive tracks are made of copper and have a uniform thickness determined by the thickness of the original foil, and a width calculated based on the permissible current density and the manufacturing standards of the printed circuit boards. The tracks are narrow and uniform in thickness, typical of printed circuit boards, and follow a wave-like trajectory optimized for uniform current distribution.

[0049] On a single active layer (e.g., the top layer of a double-sided printed circuit board), conductive tracks for all three phases are formed. Several symmetrically distributed winding coils, shaped like teeth, are located on the board. Each winding forms a closed loop, which is wound onto a corresponding stator tooth. Each winding coil is formed by two parallel copper tracks that extend from one contact pad, run along a stator tooth, then wrap around and return to the other contact pad, forming a closed loop. The winding circuits are interconnected, forming three different phase circuits according to a three-phase connection scheme.

[0050] The stator teeth are expressed in the form of protruding segments of the dielectric base with locations for the winding tracks, between which gaps are formed, ensuring the directed passage of the axial magnetic flux.

[0051] The number of coils in each phase corresponds to the number of pole pairs of the electric machine and can vary depending on the required electromagnetic parameters.

[0052] The trace topology is designed to prevent conductors from crossing different phases within a single layer. To achieve this, the trace path of one or more phases is wavy: in areas where crossing with traces of another phase is unavoidable, the trace extends to the adjacent layer through a metallized hole, bends around the obstacle, and returns to the original layer. This maintains the continuity of the phase winding and the correct polarity of the coils.

[0053] The winding ends are connected to contact pads, which are evenly distributed across the stator's outer ring for convenient connection of three-phase circuits. In the preferred embodiment, the winding is implemented on a two-layer printed circuit board. The first layer contains the main sections of the windings for all three phases. The second layer contains additional sections connected to the first layer via plated holes. This design allows for a complete three-phase winding on a board of minimal thickness.

[0054] The contact pads are located on the outer edge of the printed circuit board and are used to connect to a three-phase power source or a three-phase receiver. Alternatively, the contact pads may be located on the inner perimeter of the board or may be absent if the connection is made by other means.

[0055] The switching of phase windings can be performed using the star or delta scheme directly on the printed circuit board by connecting the corresponding contact pads with printed conductors or external jumpers.

[0056] Mounting holes are used to mechanically secure the winding in the stator housing or directly in the electric machine housing. In some cases, mounting holes may be absent if securing is accomplished by other means.

[0057] When three-phase voltage is applied to the contact pads, a rotating magnetic field is generated in the winding with an axial magnetic induction vector perpendicular to the plane of the printed circuit board. In generator mode, the rotation of the rotor induces an EMF in the winding, which is removed from the contact pads and applied to the load.

[0058] The arrangement of the coils and tracks is symmetrical relative to the center of the stator, which ensures the balance of magnetic fields, reduces vibration during operation and promotes uniform distribution of currents.

[0059] Because the windings of all three phases are already formed on the first two layers, the winding stack thickness is minimal. The teeth are made of the printed circuit board's dielectric material and the absence of a ferromagnetic core completely eliminates the cogging torque pulsation typical of traditional stators with ferromagnetic teeth, which is especially important for low-noise and precision electric drives. The high precision of the printed circuit technology ensures identical winding parameters in serial production and, if necessary, allows for the integration of control system components, such as rotor position sensors, thermistors, or integrated drivers, into the winding board.

[0060] Thus, the claimed invention ensures the achievement of a technical result in all cases to which the requested scope of legal protection applies.

Claims

A three-phase stator winding for an electric machine with an axial magnetic flux, made on a printed base, containing a dielectric base and conductive tracks grouped into coils that form phase windings, characterized in that on one active layer of the printed base, conductive tracks of all three phases are simultaneously located, forming a symmetrical three-phase distributed winding, wherein the geometry of the conductive tracks is made wavy with the possibility of transition of tracks of one phase to different active layers through metallized holes and their passage within one layer without intersection with conductive tracks of other phases.

Images