WO2022022768A1

WO2022022768A1 - Stator having winding structures for modular electric machines

Info

Publication number: WO2022022768A1
Application number: PCT/DE2021/100579
Authority: WO
Inventors: Johannes Kolb; Miriam Boxriker
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2020-07-30
Filing date: 2021-07-05
Publication date: 2022-02-03
Also published as: DE102020120117A1

Abstract

The invention relates to a stator (1) for an electric machine, comprising a plurality of submodules (2) which extend separately from one another along the circumference of the stator (1), wherein each submodule (2) has a dedicated winding (3) and a dedicated power module (4) associated with the winding (3) for converting direct current into multi-phase alternating current. The invention also relates to an electric machine and to a method for assembling the stator (1).

Description

Stator with winding structures for modular electric machines

The invention relates to a stator, an electric machine and a method for assembling the stator.

In general, electrical machines are implemented using different winding structures. For example, a winding structure using what is known as hairpin, wave winding and random winding technology is known. There is often a copper fill factor in a slot of approx. 50% (depending on the technology). So there are many cavities and a lot of space for insulation. The voltage and current of the electrical machine are adapted to an energy source provided for the power supply via the respective number of turns, connection of the partial windings within a phase and through a corresponding wire cross-section. A higher voltage level generally requires a higher number of windings or a higher speed of the electrical machine.

DE 10 2014 105642 A1 discloses an electrical machine with a stator and a rotor which is mounted so that it can move. In this case, a stator is provided which comprises a multiplicity of slots for accommodating one or more stator windings. A conductor section of the stator winding is inserted into each of the slots, with the conductor sections being electrically connected to one another at one end, that is to say on one side of the stator, so that they form a short circuit with one another.

DE 10 2014 110299 A1 also discloses an electrical machine with a stator and a rotor which is movably mounted relative to it. The stator includes a plurality of slots for receiving a stator winding. A conductor section of the stator winding is inserted into each slot. On one side of the stator, the conductor sections are electrically shorted together in a shorting means. The short-circuiting means comprises a cooling device. DE 10 2014 113489 A1 also discloses an electrical machine with a stator. The stator includes a plurality of slots formed between adjacent teeth of the stator. The slots serve to accommodate a stator winding. A conductor section of the stator winding is inserted into each slot. The conductor sections of at least one pole pair are shorted together on a first side of the stator. On a second side of the stator, opposite the first side, the free ends of the conductor sections are connected to a connection of a power supply unit. The power supply unit comprises two ring-shaped electrical conductors between which at least one electronic power component is arranged.

DE 10 2014 114615 A1 discloses a winding system for a stator and/or a rotor of an electrical machine comprising a plurality of conductor sections which are arranged essentially between opposite sides of the winding system. Two ring-shaped conductors are provided on a first side of the winding system, with which the conductor sections are coupled via half bridges. At least one half-bridge is provided on the opposite side of the winding system, to which at least one conductor section is connected.

DE 10 2014 118356 A1 relates to a power supply unit which is designed to feed multiple conductor sections of a stator winding of an electrical machine. The conductor sections are inserted into respective slots in the stator of the electrical machine's. The power supply unit in turn feeds a first of the conductor sections and a second of the conductor sections with at least one different operating parameter of a respective current function. Alternatively or additionally, the power supply unit is set up to feed a conductor section with at least two superimposed current functions, each of which has at least one different operating parameter.

DE 10 2016 107937 A1 discloses a circuit arrangement for feeding a drive motor designed as a multi-phase electrical machine. The circuit arrangement can be comprised by the drive device. DE 10 2016 118634 A1 discloses a circuit arrangement for driving a stator winding of a stator of an electrical machine. The stator winding has at least four electrical phases, which are designed to be fed with a respective separate phase current. The stator winding can therefore be connected to power electronics, for example, which supplies each of the electrical phases with its own phase current. The electrical phases can be formed, for example, by electrically conductive rods in slots in one or more stator laminations of the stator.

DE 10 2017 116 145 B3 discloses a winding system for a stator of an electrical machine and an electrical machine. The winding system comprises at least two first conductor sections and at least two second conductor sections. The first and second conductor sections may comprise an electrically conductive material, such as copper or aluminum. The stator can have slots, for example, in each of which there is a conductor section. The stator can include one or more stator laminations, in which the slots are introduced. The stator preferably has a large number of slots. For example, the first and second conductor portions may be electrically conductive rods.

It is the object of the invention to avoid or at least alleviate the disadvantages of the known prior art. In particular, the modularization of an electrical machine is to be promoted.

In the case of a generic device, this object is achieved according to the invention in that a stator for an electrical machine is provided. The stator includes a plurality of sub-modules, which extend separately from one another over the circumference of the stator. Each submodule has its own winding and its own power module assigned to the winding for converting direct current into alternating current, for example three-phase current. A winding is understood to mean the presence of at least one conductor in a slot. Based on this, there can be several conductor pieces per winding and also several conductor pieces in one slot. These can be connected in any way. Conductor sections can be connected in different slots and some slots can be skipped. A connection of only zuei nander adjacent conductor sections is not mandatory. The conductor pieces are made of electrically conductive material such as copper.

One idea of the present invention is that a modularization of components or subsystems in the sense of a structure consisting of several identical parts is important for production, since scaling for different power ratings is only possible via the number of components and no new production is set up must become. However, if the axial length and/or the diameter of certain components has to be changed, for example to adapt to the size of the power, then different components can be used for the said identical parts. These components can again be identical parts to each other. The submodules can also be referred to as stator submodules.

An electric drive system comprising an electric machine and power electronics based on three or more phases is implemented. Disadvantages known from the prior art are avoided. These disadvantages are listed below:

• A power electronics unit, which in turn is connected to a high-voltage intermediate circuit and, for example, a high-voltage battery, only has limited modularization options due to large individual structures.

• A distribution of the windings per phase over the entire circumference of the electrical machine leads to long connection paths with high ohmic resistances in the winding overhangs as well as high material consumption and space requirements. Two or more integrated sub-motors with operating point-optimized designs are now possible.

In the case of the invention, there is also sufficient modularization of the power electronics for space-saving construction (while a typical 3-phase construction with a direct connection to a central intermediate circuit capacitor cannot be further divided or modularized). In the invention, the copper filling factor is now improved in the grooves of the electrical machines.

Advantageous embodiments are claimed in the dependent claims and who explained in more detail below.

Each submodule may have multiple windings of its own and the AC power may be polyphase AC.

Each power module can have its own DC+ and DC- connection and three phase connections for charging the windings with the polyphase alternating current, for example three-phase current. This makes it easy to allocate and operate a common power supply. The invention is not limited to three phases. More than three phases are also possible, e.g. five, six, seven, nine, ten, eleven, twelve, etc. phases, in which case each power module has a number of phase connections corresponding to the phases.

All power modules can be connected in series by connecting the DC+ connection of the power module to the DC- connection of the power module directly adjacent to the corresponding power module. As a result, the power modules can be easily adapted to the voltage of the energy source to be connected or dimensioned accordingly. There are of course other types of connection that can also be used, such as parallel and combined types of connection. Each power module of the submodules can contain its own component from the group consisting of the intermediate circuit capacitor, half-bridge, transistor and diode. Here we ter a half-bridge understood such a component that at least two Transisto ren uses. In this case, diodes can also be used. This means that tried and tested components can be used and there is sufficient failsafety. This refers both to the use of proven components and to a higher number of independently operating components.

Each power module can have its own intermediate circuit capacitor. It is advantageous if the capacitor is connected to the DC+ and DC- terminals and to the 2 connections of each half-bridge in the submodule. The corresponding control of the half-bridges then ensures that the windings are energized, which in turn generate the circulating magnetic field. As a result, the magnetic field required for even concentricity can be generated efficiently.

At least one of the submodules or all submodules can have a housing that allows the submodules to be handled. It is then made easier for a fitter to assemble the individual submodules into the stator of the electrical machine. The submodules can therefore only include the stator winding or also the sheet metal section. Windings can be used that can be formed as follows: single-layer windings, in which case one phase is in a slot and includes at least one conductor in the slot, or two-layer windings, in which at least two conductors are in a slot and belong to the same phase or belong to different phases. At least three conductors form at least three phases that are interconnected to form a star point. The neutral points can be arranged on the same side as the power electronics modules or on the opposite side. This results in a phase number of turns of 0.5 per submodule if one phase conductor is connected to a neutral point. If two conductors from different slots of the same phase are connected in series, the number of windings is 1, with three conductors 1.5, etc. However, the windings can also consist of several parallel-connected conductors per slot; this does not change the number of turns. The enclosure may be provided or formed in the manner of a paper or foil or sheath or covering or solid housing. The term "handling" can be understood as a handle.

Each power module can be arranged on a first end face of the winding, or the power modules can always be arranged alternately, viewed over the circumference, from one submodule to the adjacent submodule, viewed over the circumference, on the first end face and second end face. The installation space can then be used efficiently.

On the one hand, each winding can be of the same design and, on the other hand, the windings of at least two of the submodules can be of different designs.

Furthermore, the winding of each sub-module can be implemented using a formation law as described below. At least one of the following variables can be included in the formation law for a winding scheme of the respective winding: number of slots, number of pole pairs, number of layers and number of phases.

Viewed over the axial length, each submodule can take up an installation space that is consistently wide (viewed in the circumferential direction), or the installation space can be larger at one end face than in an inner area spaced apart from it. An embodiment can thus be created which has a winding in the axial extension of which the power module is arranged. Alternatively, however, an arrangement according to a radial extension in another embodiment may be desired. Both variants can be designed on one or two sides. The latter variant of a two-sided radial extension has advantages if the power modules should/must take up more space. This advantage also applies to a one-sided extension.

For axial flow machines, depending on the design of the motor, eg double stator one rotor, one stator-two rotors, one stator-one rotor, etc., the power modules can be in a radial extension of the stator to the outside or in an axial extension on one Front side facing away from the rotor, be attached. In the radial direction, attachment radially inwards or attachment both radially inwards and outwards is also possible. The power modules can be arranged alternately.

All submodules together can form a block that is joined together in terms of scope, which is conducive to good handling. There are then no gaps between the individual submodules.

Furthermore, the function of a DC-DC converter for the controllable adjustment of the DC voltages in the power modules can be implemented independently of the magnitude of the voltage of the energy source in the overall interconnection.

In a first variant, at least one additional half-bridge is added to each power module. The power modules are then connected via the center taps of these additional half-bridges and also via the DC+ or alternatively DC- connection. For this variant to function, at least one choke is required at any point in the current path between the energy source and the interconnection of the submodules in each series-connected string of submodules. The half-bridges and the choke together form an integral DC-DC converter or a step-up converter.

In a second variant, a DC-DC converter consisting of at least one half-bridge, at least one inductor and possibly at least one capacitor is additionally installed in each power module. As shown, these DC-DC converters can be implemented as step-up converters. Alternatively, step-down converters can also be implemented using the same components. In both cases there are two connection options, namely via the corresponding tap of the DC-DC converter and additionally via the DC+ or alternatively DC- connection.

The above object is also achieved in that an electrical machine with a stator as described above and a rotor is provided. The above object is further achieved in that a method for assembling a stator, preferably as described above, for an electrical machine, preferably as described above, is provided. The method includes providing a large number of submodules, each submodule having its own power module with a winding connected to it. The method also includes assembling the submodules into the stator. Such a method thus relates to an assembly method, the creation of the physical structure or the assembly of the stator. This includes steps of forming and forming the sub-assembly.

It is also advantageous if each submodule occupies a consistently wide installation space over the axial length, or if the installation space on one end face is larger than in an inner region spaced apart from it.

It is also advantageous if all the submodules together form a block that is joined together over the circumference.

In other words, the invention relates to an electrical machine, in particular a stator thereof. A winding structure in the stator of the electrical machine is segmented around a periphery of the electrical machine. The respective connections of the winding structure are connected to the power module as directly as possible (by the shortest route or in the smallest possible space). The smallest identical units or segments (submodules) consist of a stator segment with a local winding structure and an associated power module. Internally, the power module and the winding structure of a respective submodule are electrically connected via at least three connections. Externally, each submodule consists of two connections.

The invention sometimes enables the modular design of an electrical machine with integrated power electronics. The following advantages can be at least partially achieved through one or more aspects: True modularization and integration of the phase and power electronics structure through segmentation over the circumference and the associated high packing density and high power density of the overall system;

Highest possible copper fill factor in the slot (close to 100%, minimum of ohmic resistances or, conversely, a minimum of space required).

Low winding overhang (minimization of the ohmic resistance and minimization of the contact points);

Shortest cable lengths between motor and power electronics (minimization of ohmic resistance and minimization of material costs for cables and connecting elements);

Solving the conflict of objectives between low induced voltage of the electrical machine on the one hand and high voltage level of the energy source at high power (use of high-voltage (HV) battery / 800V voltage class) on the other;

Compatibility with other technologies, e.g. B. partial motor concepts, direct conductor cooling, current/torque control, sensorless control, etc.;

No motor-related disadvantages in relation to the respective mode of operation (e.g. torque ripples, losses);

Simpler structure and manufacture (simple assembly and connection processes of the windings, etc.); and

No disadvantages in terms of power electronics (low-frequency pulsating power, complicated circuit topologies, special electronic components). Furthermore, the invention can also provide suitable winding systems for the electrical machine or the stator. The optimization goals for these windings and their special properties include a very high copper fill factor, short cable lengths per phase or short connections between the individual conductors in the slot and to the connections of the power modules, as well as simple manufacture and assembly.

The following exemplary core ideas of the invention are sometimes included here, which can lead to corresponding advantages/effects: -> segmented winding with a small extent over the circumference of the stator, and

-> as few windings or conductor sections as possible in a slot and in the end winding,

-> Highest copper fill factor for low ohmic resistances, since little area in the slot cross-section is required for insulation,

-> fewer and shorter connectors in the end winding reduce ohmic resistance due to shorter cable lengths,

-> Compact design due to few crossings of conductors in the end winding, only a star point connection instead of interconnecting the pole pairs, -> Simple production of the conductor sections or partial windings (e.g. due to their simple shape comparable to I-pin or hairpin or even through a casting process ),

-> fewer contact stalls when connecting the windings leads to a lower probability of failure and less manufacturing effort, -> Any shape of the conductor sections or different shape of the conductor in the slot and winding head area for compact design and possible integration of slot cooling or direct conductor cooling by forming a cooling channel.

In addition to the variant that all winding structures of the submodules for an electric machine are identical, the individual winding structures can also be implemented differently (but still individually in accordance with the Education Act).

The use of this winding scheme is not limited to radial flux machines in which the windings are arranged over the circumference of the machine in accordance with a lateral surface of a cylinder. This can also be used for axial flow machines. In this case, the windings lie in one plane, which is always arranged orthogonally to the axis of rotation of the rotor of the machine. The stator with these windings thus forms one or possibly several discs of an axial flux machine.

The starting point is the formation law for the variants of the winding scheme. This law of formation is reproduced in the description of the figures.

Instead of copper, other electrically conductive materials can also be used in principle, e.g. e.g. aluminium.

Even if some of the aspects described above/below have been described in relation to the method, these aspects can also apply to the stator and the electric machine. Likewise, the aspects described above/below in relation to the stator and the electrical machine can apply to the method in a corresponding manner. It should also be understood that the terms used herein are for the purpose of describing particular embodiments only and are not intended to be limiting. Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by those skilled in the art relevant to the present disclosure; they are neither too broad nor too narrow. If technical terms are used incorrectly in the present case and thus do not express the technical idea of the present disclosure, they are to be replaced by technical terms that convey a correct understanding to the person skilled in the art. The general terms used here are to be interpreted on the basis of the definition in the lexicon or in accordance with the context; in this case, an overly narrow interpretation is to be avoided.

Other objectives, features, advantages and possible uses result from the following description of non-limiting embodiments with reference to the accompanying drawings. In describing the present disclosure, detailed explanations of well-known related functions or constructions will be omitted insofar as they unnecessarily distract from the spirit of the present disclosure. All of the features described and/or illustrated show the subject matter disclosed here, either individually or in any combination, regardless of how they are grouped in the claims or their dependencies. The dimensions and proportions of the components shown in the figures are not necessarily to scale; they may deviate from what is illustrated here in embodiments to be implemented. In particular, in the figures, the thickness of the lines, layers, and/or regions may be exaggerated or understated for clarity.

The invention is explained below with the aid of drawings. Show it:

FIG. 1 shows a schematic representation of a submodule of a stator; FIG. 2 shows a schematic representation of a stator with an axial extension away from a first end face, ie on one side;

FIG. 3 shows a schematic representation of a stator with a radial extension, on one side;

Figure 4 is a schematic representation of a stator with axial extension away from both ends, i.e. on both sides; FIG. 5 shows a schematic representation of a stator with radial extension, two-sided;

FIG. 6 shows a schematic representation of a DC-side series connection of the submodules;

FIG. 7 shows a schematic representation of a power module;

FIG. 8 shows a schematic representation of a parallel interconnection of the submodules;

FIG. 9 shows a schematic representation of a serial-parallel connection of the submodules;

FIG. 10 shows a schematic representation of a first variant of an integral DC-DC converter;

FIG. 11 shows a schematic representation of a second variant of an integral DC-DC converter; FIG. 12 shows a schematic representation of a first variant with an integrated DC-DC converter in the submodules; FIG. 13 shows a schematic representation of a second variant with an integrated DC-DC converter in the submodules;

FIG. 14 shows a schematic representation of a distributed single-layer winding with a one-sided arrangement of the power modules;

FIG. 15 shows a schematic representation of a distributed single-layer winding with a two-sided arrangement of the power modules; FIG. 16 shows a schematic representation of a distributed single-layer winding with a larger coil width and a higher number of turns;

FIG. 17 shows a schematic representation of a distributed single-layer winding with higher overlap as a combination form;

FIG. 18 shows a schematic representation of a two-layer winding with overlap;

FIG. 19 shows a schematic representation of a two-layer winding without overlap;

FIG. 20 shows a schematic representation of a two-layer winding without overlap; Figure 21 is a schematic representation of a 5/6 pitch distributed two layer winding without overlap; and

Figure 22 is a schematic representation of a 5/6 pitch distributed two layer winding with overlap; The figures are only of a schematic nature and serve exclusively for understanding the invention. The same elements are given the same reference numbers. The features of the individual embodiments can be interchanged.

A stator 1 of the electrical machine will now be described using embodiments.

The inventive solution consists of a segmented winding structure in the stator 1 over the circumference of an electrical machine, the respective connections of which are connected as directly as possible (by the shortest path or in the smallest possible space) to electronic power modules 4 . Thus, the smallest, identical units or segments (= submodules 2) consist of a stator segment with its local winding structure 3 and the associated power module 4, see Fig. 1. Internally, the power module 4 and the winding structure 3 of the stator segment are electrically connected via at least three Connections (S1, S2, S3) are connected and towards the outside the submodule 2 has two connections (DC+ 9 and DC- 10).

This sub-module 2 represents the smallest unit as a sub-system. The zylinderför-shaped arrangement of several identical sub-modules 2 creates a stator 1 of an electrical drive's in a modular manner. This creates a rotating magnetic field in the air gap that is required for operation, so that a torque can be generated on a rotor. The design is independent of the operating principle of the motor and can therefore in principle be used universally for all types of electrical machines (permanent magnet excited synchronous machine, reluctance machine, separately excited synchronous machine, asynchronous machine and corresponding combinations).

The respective power module 4 can be placed directly next to the associated motor segment using different variants, taking into account the shortest possible connections to the motor segment. The motor segment refers to the stator segment with winding structure 3. If the power modules 4 are only arranged on one side:

- at the end in axial extension to the motor segment (see Fig. 2); and

- outwards in a radial extension to the motor segment (see Fig. 3).

In the case of two-sided arrangement, for example as two groups arranged rotated relative to one another, especially if motor segments overlap spatially due to the winding structure:

- Front side in axial extension to the motor segment (Fig. 4); and

- outwards in a radial extension to the motor segment (Fig. 5).

The dimensions of the power modules 4 and stator segments can vary here; the explained arrangements with contacting surfaces are more important, so that the lengths of internal electrical connections are kept to a minimum.

In each stator segment of a submodule 2, windings 3 are implemented with a very low number of turns and a large conductor cross section or high copper fill factor, in order to achieve a minimum of ohmic losses. The production-related implementation can be done here by individual rods in the slots (compare I-Pin, number of coil turns 0.5) or at least a minimum number of turns per slot, which z. B. U-shaped can be introduced comparable to hairpin windings.

The procedure or formation law for describing the structure and generating all possible winding structures is described below. This procedure generally describes the formation of all possible winding systems which meet the required character of a segmentation over the circumference of the stator of the electrical machine. The procedure includes determining the number of slots (N), the number of pole pairs (p) and the number of phases (m) and the number of layers (single-layer or two-layer) depending on the winding factor (x) and harmonic scattering (s ₀ ).

It is divided between odd phase numbers (mmod 2 0), even phase numbers with an odd divisor (— mod 2 0,x e N\{0}), and even phase numbers

Phase numbers only differentiated with even-numbered dividers (m = 2 ^x ,xe N\{0}). The approach applies to m > 2, whereby a lower voltage level is achieved for each submodule by distributing the DC link voltage across the various submodules. This makes it possible to use semiconductor components with a lower voltage level, for example silicon MOSFETs, the lowest number of conductors in a slot, for example one, and the lowest number of turns, for example 0.5.

The degree of segmentation results from the DC link voltage, the desired voltage level for the semiconductor components and the selection of the useful number, number of phases, number of layers and number of pole pairs and the respective connection options listed below.

The minimum number of conductors in a slot is one for a single-layer winding and two conductors for a two-layer winding.

A conductor can be made of any electrically conductive material, in particular copper or aluminum.

If one or more conductors are in a slot and the same current (amplitude, frequency, phase position) should flow through them, they can be connected in parallel or in series and are referred to as the coil side in the following. However, one or two conductors per slot or a parallel connection of several conductors is particularly suitable for the idea according to the invention.

Two forms are possible for the different numbers of phases. Either coil sides of different phase angles are directly connected to one another Connected to the star point or several coil sides are connected in series (hereinafter referred to as coil side rows) and several coil side rows with a different overall phase position are connected to a star point. Depending on the pre-selection of the number of phases, the conditions for an interconnection result. These should now be listed below:

For connecting coil sides with different phase positions to a star point:

• For odd phase numbers m (m mod 2 0) o Connection of m coil sides in a star point through the following conditions

^■ Offset of the induction voltage by — the m coil sides to each other

^■ Coil sides should be as close together as possible o Connection of m _T coil sides in a star point and thus obtaining more star points than in the first point through the following conditions

^■ 3 < m _T < m and m mod m _T = 0

^■

offset of the induction voltage by — TU f the m _T coil sides to each other; between the systems, each with its own star point, there is a phase offset of - m

^■ Coil sides should be as close together as possible

• For even phase numbers with at least one odd divisor mod 2 0,x EN\{0}) Connection of m coil sides in a star point through the following conditions

^■ Offset of the induction voltage at ^ coil sides by ^ · 2 ^X to each other and between the 2 ^X systems (with the 2 ^X - offset) an offset of the systems of

^■ Coil sides should be as close together as possible Connection of

Coil sides in a star point and thus obtaining more star points than in the first point through the following conditions

^■ Variant 1 : For 2 ^X it applies that ^ mod 2 0,x EN\{0} · offset of the induction voltage of the

coil sides of

· 2 ^X to each other; between the systems, each with its own star point, there is a phase shift of

• Coil sides should be as close together as possible

^■ Variant 2: For 2 ^X it holds that ^ mod 2 = 0,xe N\{0} and mod 2

Y 0,ye N\{0} and y > x

• Offset of the induction voltage

coil sides of

· 2 ^y to each other and between the ( 2 ^y~x ) systems (with

the — m · 2 ^y - offset) an offset of the systems of — m ·

2 ^X between the systems, each with its own star point, there is a phase offset of

Coil sides should be as close together as possible o Connection of m _T coil sides in a star point if there are several odd-numbered divisors of m, and thus obtaining more star points than in the first point through the following conditions

^■ 3 < m _T < m and m mod m _T = 0 and m _T mod 2 0

3 < m _T2 < m and m mod m _T2 = 0 and m _T2 mod 2 0 and

^■

offset of the induction voltage by — the m _T coil sides to each other; between the individual m _T2 star point systems there must be a phase shift of — — — and between 2 ^X systems

phase shift from —

^■ Coil sides should be as close together as possible

• For an even number of phases, where the number of phases is a power of two (m = 2 ^x ,xe N\{0} ) o This star point connection always requires an additional connection of each star point to the power electronics of the respective submodule, which means that, in order to ensure short conductor lengths, the star point and the power electronics of the submodule should be close together. This can be achieved, for example, by locating the power electronics on the same side as the star point of the submodule. The star points can be connected via a center tap between two capacitors which, when connected in series, form the intermediate circuit capacitance of the power module. Alternatively, the neutral points can be connected to the power module via the phase connection of one or more additional half-bridges, which are connected to the intermediate circuit voltage. o Connection of m coil sides in a star point through the following conditions

^■ Displacement of the induction voltage with 2 coil sides

to each other, resulting in — subsystems; at — the subsystems is the phase shift from subsystem to subsystem

and

771 between the two —subsystems — so that the smallest neutral point load can be guaranteed

^■ Coil sides should be as close together as possible o Connection of 2 coil sides in one star point (star point load is higher than in the first option) and this means that more star points are obtained than in the first point due to the following conditions

^■ Displacement of the induction voltage with 2 coil sides

to each other, resulting in g systems with their own star point and their own submodule connection; at

of the systems is the phase shift from subsystem to subsystem

and between the two —subsystems—

^■ Coil sides should be as close together as possible

For the interconnection of coil side rows of different phase positions in a star point:

• There are k e N\{0} coil sides connected in series, which is referred to here as the coil side series; these coil sides can have any phase offset to one another.

The conditions described above for the connection of coil sides in a star point can be used for the formation law. Instead of coil side, however, coil side rows are to be used and the Phase offset between coil sides becomes the total phase offset between rows of coil sides

According to the Education Act, various variants resulting from the Education Act are listed below. The starting point of the considerations is the slot voltage star spanned by the number of slots, number of pole pairs, number of layers and number of phases.

According to the Education Act, 3 conductors are connected to a star point in the smallest possible version. Since phase numbers that are powers of two require an additional star point connection that is more heavily loaded than the phase connections, three direct phase connections are assumed in the smallest possible version. The highest fill factor is achieved with a conductor that completely fills the slot. If the conductor is to be understood as a conductor bundle, i.e. made up of several parallel conductor sections, the fill factor is lower because the insulation is applied to a larger surface and its proportion in comparison to the total volume is therefore higher. A conductor or bundle of conductors can be completely adapted to the shape of the slot so that there are no free spaces in the slot.

For the sake of clarity and in order to keep the explanations concise, the variants are not presented and are described below only as examples without figures.

1st variant

Three conductors (or bundles of conductors), one conductor per slot, number of windings 0.5; based on a distributed winding: shortest segments, ie 6 slots per pair of poles (2 submodules per pair of poles) each Weil one-sided or two-sided arrangement segments with increasing number of slots per pair of poles • either through a higher number of basic phases m and dividing into m _T = 3 o with m = 6 and m _T = 3 results in 12 slots per pair of poles with one-sided arrangement and with two-sided arrangement o with m = 9 and m _T = 3 results in 18 slots per pair of poles o Etc.

• or with the same number of basic phases m=3 and with an increasing number of holes q>1 o with m=3 and q=2 results in 12 slots per pair of poles with one-sided arrangement and with two-sided arrangement o with m=3 and q=3 results in 18 slots per pair of poles o Etc.

The modules can also be nested differently; this is also correspondingly possible for the other examples.

2nd variant

Three conductors (or bundles of conductors), one conductor per slot, number of windings 0.5; based on a toothed coil winding or pitched winding: shortest segments, i.e. 6 slots per 2 pairs of poles (2 submodules per 2 pairs of poles) each one-sided or two-sided arrangement,

Segments with an increasing number of pole pairs (the number of slots required per segment also increases) -> different numbers of pole pairs per number of slots per segment possible; through different phase control/sequence and shorter or longer star point network,

• higher number of basic phases m and division into m_T=3 o m=6, N= 12, p=5, m_T=3 o m=9, N= 18, p=8, m_T=3

• same number of basic phases m=3 and longer connecting segment om=3, N= 12, p=5 om=3, N=18, p=8 3rd variant

Three conductors (or bundles of conductors), one conductor per slot, number of windings greater than 0.5; based on a distributed winding:

Number of windings equal to 1

- shortest segments, i.e. 6 slots per pair of poles (1 submodule per pair of poles)

- each one-sided or two-sided arrangement

- Segments with an increasing number of slots per pair of poles

• either through a higher number of basic phases m and division into m_T=3 o with m=6 and m_T=3 results in 12 slots per pair of poles in a one-sided arrangement and in a two-sided arrangement

• same number of basic phases m=3 and longer connecting segment o with m=3 and q=2 results in 12 slots per pair of poles with one-sided arrangement and with two-sided arrangement

Number of turns equal to 1.5

- shortest segments, i.e. 6 slots per pair of poles (2 submodules per 3 pair of poles)

- each one-sided or two-sided arrangement

- Segments with an increasing number of slots per pair of poles

• either through a higher number of basic phases m and division into m_T=3 o with m=6 and m_T=3 results in 12 slots per pole pair of one-sided arrangement

• same number of basic phases m=3 and longer connection segment o with m=3 and q=2 results in 12 slots per pair of poles

Number of windings equal to 2

- shortest segments and number of windings equal to 2, i.e. 12 slots per pair of poles (1 submodule per 2 pairs of poles)

- each one-sided or two-sided arrangement

- Segments with an increasing number of slots per pair of poles • either through a higher number of basic phases m and division into m_T=3 o with m=6 and m_T=3 results in 12 slots per pole pair with one-sided arrangement and with two-sided arrangement

4th variant

Three conductors (or bundles of conductors), one conductor per slot, number of turns greater than 0.5; starting from a toothed coil winding or long-pitched winding

Number of windings equal to 1, 3 slots per pair of poles (1 submodule per pair of poles) increasing number of windings/higher number of basic phases m/longer connecting pieces

5th variant

Five conductors (or bundles of conductors), one conductor per slot or two conductors per slot, number of windings equal to or greater than 0.5, etc. one conductor per slot

• Number of windings 0.5 o 10 slots per pair of poles (2 submodules per pair of poles) o 10 slots per 4 pairs of poles (1 submodule per 2 pairs of poles)

• Number of windings 1 and one conductor per slot o 10 slots per pair of poles (1 submodule per pair of poles) o 10 slots per 4 pairs of poles (1 submodule per 4 pairs of poles) two conductors per slot

• Number of windings 0.5 or 5 slots per 2 pairs of poles (1 submodule per pair of poles) 6th variant

Three conductors (or bundles of conductors), two conductors per slot, number of windings equal to or greater than 0.5 shortest segments, i.e. 3 slots per pole pair (2 submodules per pole pair), e.g. (N=18, p=6, m=3)

Number of windings 1

• 3 slots per pair of poles (1 submodule per pair of poles)

Number of windings 2

• 5 poles per 6 slots (1 submodule per 6 slots), e.g. (N=12, p=5, m=3)

• 1 pair of poles per 12 slots (2 submodules per pair of poles), 5/6 pitch, distributed winding, two-sided arrangement, overlapping

Number of windings 3

• 8 poles per 9 slots (1 submodule per 4 pole pairs), e.g. (N=18, p=8, m=3) number of windings 4

• 1 pair of poles per 12 slots (1 submodule per pair of poles), 5/6 pitch, distributed winding, one-sided arrangement, non-overlapping

The variants mentioned above are examples within the meaning of the Education Act.

Depending on the winding approach and the degree of segmentation, a different number of submodules 2, which form the entire stator 1, can thus be constructed. The maximum modularity in terms of the maximum number of segments that can be realized over the circumference is determined by the number of layers (one or two-layer winding), the number of slots N and the number of phases m. The number of phases three represents an advantageous solution due to the minimum required for the generation of a rotating field or, in relation to the motor segment, a traveling field. With a number of phases three, a constant power and also three symmetrically loaded phases. However, the formation law is not limited to this and describes the realization for any number of phases. In addition, higher motor phase numbers can also be generated with submodules 2 with a lower phase number if the lower phase number is a factor of the higher one. All further descriptions are therefore limited to three-phase variants, without the invention being limited thereto.

The conflict of objectives between low winding voltage due to the small number of turns of the coils in a motor segment and high voltage of the energy source due to the high power to be transmitted is eliminated by connecting the modules on the DC voltage or DC side, preferably comparable to the principle of the "Modular high-frequency converter" or "stacked polyphase bridges converter" solved by a series connection, see Fig. 6.

The following forms of implementation are conceivable under the term "conductor" without further restrictions: solid rod, separate realization by several rods or profile wires (guided in parallel and connected), (high-frequency) stranded wire (possibly with insulated individual conductors).

The power module 4 within the submodule 2 (see Fig. 7) contains a power electronic circuit based on power semiconductors such as transistors 7 and diodes 8 and a local intermediate circuit capacitor 5. An advantageous conversion is carried out by the three-phase bridge circuit with three half-bridges 6 corresponding to the three phases the winding structure in the stator segment. Each half-bridge 6 consists of two transistors 7 in series and, for example, an antiparallel geschal ended freewheeling diode 8. The transistors 7 different types, such. B. IGBTs, MOSFETs, HEMTs, bipolar transistors, GTOs are used. Both the diodes 8 and transistors 7 can be based on typical semiconductor materials such as silicon, silicon carbide, gallium nitride or other suitable materials in the future. Typical modulation methods or pulse width modulation are used to generate a three-phase voltage system whose amplitude and frequency are variable according to the operating point of the entire electrical drive. In addition, each power module 4 contains a control and regulation unit, which controls the transistors 7, detects electrical quantities such as the local intermediate circuit voltage and phase currents, and has interfaces for communication with the neighboring submodules 2 or with a central control unit (not shown in the figures). shown).

The DC-side interconnection of the submodules 2 via their respective two connections DC+ and DC- can be implemented differently depending on the required voltage adjustment between the energy source and the modules: all in series (see Fig. 6), all in parallel (see Fig. 8) or in groups mixed parallel and serial (see Fig. 9).

For example, a DC-DC converter for voltage adjustment during operation can be integrated into the overall system or into each power module 4 . Various variants can be provided for this purpose. 10 shows a first variant and FIG. 11 shows a second variant with a central choke 11. Mixed forms are also possible with regard to the DC-side connection to the associated half-bridge 6 of the DC-DC converter Comparable to modular high-frequency converters. FIG. 12 shows a third variant and FIG. 13 shows a fourth variant with an integrated choke and, for example, an additional capacitor, a DC-DC converter being integrated in each submodule 2 .

Coming back to FIG. 3, it should be added that there the radial direction is marked with the reference number 12, the axial direction with the reference number 13 and the circumferential direction with the reference number 14. From a qualitative point of view, the following variants represent advantageous solutions with regard to the copper fill factor or low number of turns, with regard to strict modularization or also with regard to the shortest possible segmentation using a few slots along the circumference.

In the case of the winding structures 3 and thus the stator segments, there are basically two forms to be distinguished with regard to the so-called “overlap”. In the first case, adjacent winding assemblies 3 can be spatially separated from one another and thus not overlapping. In the second case, this spatial separation no longer applies and, due to the winding principle, two or more winding structures 3 from adjacent submodules 2 spatially overlap. Even if the winding structures 3 and thus the stator segments share a certain volume here, the power modules 4 remain of the adjacent submodules 2 continue to be spatially separated from each other.

The following variants are available for implementing the winding structure with one conductor per slot (in a single-layer winding), which corresponds to a maximum achievable copper fill factor.

14 and 15 represent a winding structure in which the submodules 2 spatially overlap in the region of the winding structures 3. FIG. This is due to the phase sequence shown in the slots and the easiest way to connect the three conductors according to the three phases. These three conductors are contacted on one side with a so-called star point connection and on the other side are connected to the power module 4 via the three connections.

Due to the overlap, a two-sided arrangement (see FIG. 15) of the power modules on the overlapping motor segments is advantageous here compared to a one-sided arrangement (see FIG. 14).

FIG. 16 shows a variant in which one conductor is also introduced per slot. According to FIG. 16, each phase is realized with the aid of two windings four cable sections occupy two adjacent slots twice. As before, the first ends of the windings of the individual phases are contacted with a star point connection and the second ends are connected to the power module. Since there is no spatial overlapping of the motor segments in this variant, the power modules 4 can be advantageously arranged on one side.

If the above features are combined, ie one conductor per slot, which at the same time forms a phase (see FIG. 17), the result is a winding structure with the lowest number of turns and a comparatively large overlap.

Winding structures with two conductors per slot (two-layer winding with toothed coil winding or pitched distributed winding) can be used to implement further advantageous variants with regard to the shortest possible segmentation.

FIG. 18 shows a structure in which each phase consists of only one line in a slot and is connected in a manner comparable to FIGS. 13 and 14. FIG. Two conductors of different phases are inserted per slot. This form represents the shortest segmentation, in which a stator segment comprises only three adjacent slots. Due to the overlapping of the motor segments, implementation using a two-sided arrangement is advantageous.

19 shows a variant in which two conductors of the same phase and then two conductors of different phases are inserted alternately. This results in two windings per phase, with the resulting motor segments not overlapping, as a result of which the power modules 4 can be arranged on one side. Furthermore, there is a neutral point connection between the one ends of the phases and the three connections to the power module 4 .

FIG. 20 continues the previous aspect so that one phase occupies four adjacent slots and furthermore two conductors are introduced per slot. The direction of winding reverses in a phase from one turn to the next. This variant also avoids an overlapping of the motor segments, so that a one-sided attachment can also be implemented advantageously here.

A two-layer winding can also be provided as a pitched distributed winding. For this purpose, FIG. 21 shows the variant with two conductors per slot with a distributed winding. It has four windings per phase and can be implemented without overlapping. Furthermore, FIG. 22, based on FIG. 20, shows the variant with a halved number of turns and double the number of submodules 2. Here, the two-sided arrangement of the power modules 4 is advantageous due to the overlapping motor segments. In principle, the present invention can be used in all types of electric drive systems in the field of e-mobility, e.g. B. e-axles, hybrid modules, DHT (= Dedicated Hybrid Transmission) systems, wheel hub drives. A set in electric drives for industrial purposes is also possible. The aspects and features mentioned and described together with one or more of the examples and figures detailed above may be further combined with one or more of the other examples to replace a similar feature of the other example or to Remember to add it to the other example.

The invention is not in any way limited to the forms of embodiment described above. On the contrary, many possibilities for modifications thereto will become apparent to a person skilled in the art, without departing from the underlying idea of the invention as defined in the appended claims.

List of reference symbols Stator Submodule Winding Power module Intermediate circuit capacitor Half-bridge Transistor Diode DC ⁺ (connection) DC (connection) Choke Radial direction Axial direction Circumferential direction Three-phase connection 1 Three-phase connection 2 Three-phase connection 3

Claims

patent claims

1. Stator (1) for an electrical machine, comprising a plurality of submodules (2) that stretch separately from one another over the circumference of the stator (1), each submodule (2) having its own winding (3) and has its own power module (4) associated with the winding (3) for converting direct current into alternating current.

2. Stator (1) according to claim 1, characterized in that each submodule (2) has a plurality of windings (3) of its own and the alternating current is a multi-phase alternating current and/or each winding (3) is of the same design and/or each power module ( 4) has its own DC+ (9) and DC- (10) connection and three phase connections for applying the multi-phase alternating current to the windings (3) and in particular all power modules (4) are connected in series, in which the DC+ (9) connection each the power modules (4) are connected to the DC (10) connection of the power module (4) directly adjacent to the corresponding power module (4).

3. Stator (1) according to claim 1 or 2, characterized in that the windings (3) of at least two of the submodules (2) are designed differently.

4. Stator (1) according to one of Claims 1 to 3, characterized in that the winding (3) of each submodule (2) is based on a formation law, with at least one of the following variables for a winding scheme of the respective winding (3 ) flows into the formation law: number of slots, number of pole pairs, number of layers and number of phases.

5. Electrical machine with a stator (1) according to any one of claims 1 to 4 and a rotor.

6. Method for assembling a stator (1), preferably according to one of claims 1 to 4, for an electrical machine, preferably according to claim 5, comprising:

Providing a multiplicity of sub-modules (2), each sub-module (2) having its own power module (4) with a winding (3) connected thereto; and assembling the submodules to form the stator (1).