Multiphase permanent magnet synchronous machine
Patent Information
- Application Number
- DE102023127329
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-10-06
- Publication Date
- 2025-04-10
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
Object ArticleA polyphase permanent magnet excited synchronous machine (PMSM) is disclosed herein. This can also be used in an application as an electric aircraft drive. Such an aircraft drive is part of an aircraft drive train and comprises such a polyphase, permanently excited synchronous machine. Further assemblies of the aircraft drive train are an electrical energy source, which can be designed as a rechargeable battery, photovoltaic arrangement and / or as a fuel cell assembly, and which feeds the electrical aircraft drive with electrical energy, and optionally a (reduction) gear, which is coupled in between the electrical aircraft drive and an airscrew, a propeller, a turbine or the like. Machines of the type disclosed here can be realized as high-performance drives with a performance weight of 10 kW / kg-25 kW / kg and up to 40 kW / kg or more. Details in this respect are defined in the claims; however, the description also contains relevant details on the structure and on the mode of operation and on variants of the machine.Electric machines are understood here to mean both machines operated by motor and generator, and machines which are operated alternately between these two operating modes.BackgroundElectric machines have a stator and a rotor. The rotor is driven by magnetic interaction with the stator. The alternating magnetic fields generated during operation in the machine components lead to the generation of eddy currents. The eddy currents induce heat in the stator and the rotor. Hysteresis and polarity reversal losses lead to heat development in laminated cores of stator and rotor. If the heat generation is too high, this heat generation can damage components of the machine. In particular, in the case of permanent magnet-excited electrical machines for maintaining the magnetization, the operating temperature must be limited in order to reduce or prevent demagnetization.Prior ArtGerman Patent 2 77 012 C describes the "Robbing" of conductor bars of electric machines. Conductors for electric machines consist of two or more groups of flat partial conductors. Within each stator slot of the electric machine, the subconductors of each group are interlaced with each other by means of bends, all of which may be equal to each other. The subconductor groups are twisted together by being plugged together at the cranked points. Each conductor section has twice as many bends as the number of full twist turns. Thus, each conductor section is guided through all points of the slot cross section and therefore identical electromotive forces are induced in all parallel-connected conductor sections of a stator slot and eddy currents are avoided. For this purpose, the parallel-connected conductors assume identical conductor subpositions in the stator slot. Thus, the voltages induced by the transverse slot fields are the same and consequently no circulating currents occur.DE 195 45 307 describes a robbed stator winding rod with extended field compensation, which is intended to allow suppression of the winding currents and thus flattening of the temperature profile in the conductor rod. For this purpose, the partial conductors have a twist between 60° and 120° in both end bracket sections / winding heads, and either an underrobeling in the active partial section / in the stator groove, i.e. the twist in the active partial section is uniform and less than 360°, or an empty length, i.e. an untwisted section, is provided in the active partial section in the active partial center in the case of a complete 360° twist, while the twist in the active partial section outside this untwisted section is in each case a uniform 180° frobeling.Further technological background can be found in DE 14 88 769 B.Compensation of the so-called current-induced coils in the bars constructed from longitudinally divided and insulated partial conductors from one end of the end bars (winding head) of a Roebel bar to the other end is shown, in which, in addition to the twisting in the straight part embedded in grooves by one revolution, i.e. by 360°, the Roebel bar carries a uniformly distributed twisting by 90° along each end bar. In this case, the twisting direction is the same in each end bow, which in turn is the same or opposite to the twisting direction in the straight part.In the known stator coils making use of a roebeling of the partial conductors, the partial conductors have either half the width or half the height of the stator slot. In the stator slot, two partial conductors are arranged next to one another. These two subconductors arranged side by side require corresponding insulation between them. The insulation reduces the volume of conductor that can be accommodated in the stator slot.Permanently excited operated machines in the high-power segment are limited in their alternating pole frequency by the structure of the stator coils. The stator coil is usually implemented as a copper enameled wire winding or as a so-called hair pin winding. A hair pin winding is designed as a plug-in coil, which are inserted into the slots of the stator laminated core. These plug-in coils, so-called hair pins, are formed from U-shaped painted copper flat wires and resemble hairpins in their geometry. In both types of windings, comparatively high losses occur due to eddy current losses, which result from the thickness of the conductors, which is unfavorable for higher frequencies. Alternatively, the stator coils are also made of HF stranded wire, which likewise leads to increased losses. Although this avoids eddy current losses, the possible copper cross section is reduced because of the poorer packing density. Accordingly, such electric machines are limited with regard to their number of pole pairs or rotational speed. In addition, the copper fill factor is low, especially in the case of a copper enameled wire winding, which leads to increased waste heat.Underlying ProblemThe present solution is based on the problem of providing a highly efficient electric machine with very good power weight (useful power / weight) and minimal installation space.SolutionAn electric machine according to claim 1 solves this problem.In particular, a polyphase permanent-excited synchronous machine is specified here, with a stator and a rotor in an internal or external rotor configuration. The stator has stator coils to be energized. The rotor has permanent magnet elements. The stator is spaced from the rotor to form an air gap. The stator has a plurality of stator teeth spaced apart from each other to form a plurality of stator slots. Each stator coil is accommodated, at least surrounding one of the stator teeth to form two winding heads on short sides of the stator teeth at least once, at least approximately completely, in two stator slots on long sides of the stator teeth. Each of the stator coils has at least two conductor portions. The at least two conductor sections together form in each case at least one winding of the respective stator coil. Each of the at least two conductor sections is respectively divided into at least two subconductors which are at least approximately the same in cross section. At least in the case of the windings lying closer to the air gap, the partial conductors of the respective conductor section have at least two partial conductor sections along the extent of the partial conductor around the respective stator tooth. The conductor sub-sections of one conductor sub-section are alternately connected to the conductor sub-sections of the other conductor sub-section along the extension of the conductor sub-sections.An efficient electric machine with a high number of pole pairs and a high rotational speed is thus possible, the eddy current losses of which in the stator coil are minimized. For this purpose, the coil structure is highly segmented both in the direction of the longitudinal and the height extension of the stator slot and the copper fill factor is maximized by 90% and more compared to conventional coil structures having a copper fill factor of approximately 50%. This is not possible, for example, with hair pin / painted copper wire windings. In one variant, an insulation layer separates the flat, radially thin conductors from one another. The conductors can be adapted to operating current and voltage both by selection of the number of turns and by appropriate parallel and series connection.In the variant disclosed here, the alternating connection of the conductor sub-sections of one conductor sub-sections to the conductor sub-sections of the other conductor sub-sections can take place along the extension of the conductor sub-sections both in the winding heads and in the longitudinal sections of the conductor sub-sections which are arranged in the stator slots. In order to avoid compensation currents, the alternating connection is realized with corresponding through-contacting in the winding head and / or in the regions of the partial conductor sections located in the stator slots.Further embodiments are given in the dependent claims. In the range indications, all intermediate values including the final values of the indicated range are considered to be disclosed herein.In a variant of the synchronous machine, at least in the case of the windings lying closer to the air gap, the partial conductor sections of one conductor section located in the region of the one winding head are alternately connected to the partial conductor sections of another, for example adjacent, conductor section. This achieves a further exchange of the current conduction over the height of the stator slot, as a result of which the eddy current losses decrease further.In a variant of the synchronous machine, at least two mutually adjacent ones of the windings have an even number of conductor sections. The conductor sections of the two adjacent turns are arranged one above the other in the stator slot. In both of the two turns, an upper half of the conductor sections and a lower half of the conductor sections are connected to one another in the region of a winding head. The upper half of the interconnected conductor portions of the upper of the two turns is connected to the lower half of the interconnected conductor portions of the lower of the two turns, and the lower half of the interconnected conductor portions of the upper of the two turns is connected to the upper half of the interconnected conductor portions of the lower of the two turns.This measure extends the exchange of the position of the conductor sections in the stator slot from one winding to two or more windings. The alternate connection defined herein seeks to balance the sums of the transverse voltages to which the individual conductor portions of the turns in the stator slot are subjected.In a variant of the synchronous machine, the conductor sections of the conductors have a transverse dimension at least over substantial parts of their longitudinal extent, which transverse dimension substantially corresponds to a transverse dimension of the stator slots. This is in contrast to the conventional arrangements of stator coils. In these conventional arrangements, the conductor elements take up either half the width or half the height of the stator slot, two conductor elements being arranged next to one another in each case in the stator slot. These two subconductors arranged side by side require a corresponding insulation between them, which reduces the volume of conductor that can be accommodated in the stator slot.In a variant of the synchronous machine, at least two of the windings of the stator coil have a mutually different cross-sectional area. The at least two conductor sections of at least one of the windings of the stator coil having the smaller cross-sectional area are arranged closer to the air gap in the stator slots than the at least two conductor sections of at least one of the windings of the stator coil having the larger cross-sectional area. This is in contrast to the conventional arrangements of stator coils. In these conventional arrangements, the subconductors of the stator coil have identical cross-sectional areas.The synchronous machine disclosed herein is based on one or more of the foregoing principles summarized as follows:the number of conductor sections per winding increases with the height of the winding in the slot;the cross-sectional area of the conductor sections per winding decreases with the height of the winding in the slot;the number of connections to which the partial conductor sections of the different conductor sections of a winding are alternately connected increases with the height of the winding in the slot gap;In the case of windings located higher in the slot gap, the partial conductors of adjacent windings connected to one another in the winding head are connected alternately.These individual measures can also be combined in order to optimize the synchronous machine as a function of the electrical and mechanical requirements (current, voltage, frequency, number of poles, machine length, machine diameter, peak and continuous power, etc.In one variant, the stator of the polyphase permanent-excited synchronous machine is formed from a multiplicity of stator laminations arranged along the central longitudinal axis of the synchronous machine. In one variant, the stator laminations contain soft iron, cobalt, nickel or alloys thereof. The stator laminations may contain NiFe alloys with about 72-about 83% Ni, with about 54-about 68% Ni, with about 45-about 50% Ni, or CoFe alloys with 17-50% Co. The stator laminations may have a thickness of about 10 μm to about 250 μm, for example 200 μm thick.NiFe alloys with 72-83% Ni are magnetically very soft materials with high initial and maximum permeability and low coercive field strength. NiFe alloys with 54-68% Ni can have high initial and maximum permeabilities by means of a preferred direction (magnetic field temperature change) induced by the magnetic field. In the case of NiFe alloys with 45-50% Ni, the hysteresis behavior can be adapted by selecting the rolling steps and intermediate annealing operations. Cobalt-iron alloys have very high saturation polarization at about 2.35 T. They can have a very low coercive field strength (Hc≤0.4 A / cm) with particularly low losses and very good mechanical properties.In one variant, the stator laminations are formed from a grain-oriented iron-silicon alloy-FeSi-with insulation of the individual laminations, for example laminations 50 μm-250 μm thick. Thus, eddy currents and consequently eddy current losses can be kept very low. Although stator laminations made of iron silicon achieve only lower performance data, they do so at significantly lower costs.After each 10th-50thstand sheet of the sheet stack forming the stand, in one variant, for example after each 30thstand sheet, a graphite foil having a thickness of about 10 μm to about 100 μm, for example 50 μm, can be arranged.Instead of a graphite foil, in one variant the stator metal sheets are coated with graphene or DLC-diamond-like carbon. Thus, DLC has a very high thermal conductivity (about 5 times as high as the thermal conductivity of copper).Graphite foils are thermally conductive and contain natural or synthetic graphite and have no electrical insulation. Because of their nature, the thermally conductive graphite foils conform very well to the contact surfaces with the stator sheets above and below. Graphite foils combine a high thermal conductivity with a very low thermal contact resistance. The thermal conductivity of the graphite sheet in the X / Y direction (face) and in the Z direction (surfaces to be contacted) is anisotropic. The anisotropy is reduced in weight in comparison with other thermally active materials and high temperature resistance (-40° C. to 400° C.) of the graphite foils.In the case of the stator laminations against which a graphite foil bears or which are coated with graphene or DLC, the insulation can be dispensed with in order to improve the heat conduction.In a variant of the synchronous machine, each conductor section surrounds one of the stator teeth at least once at least approximately completely.In a variant of the polyphase permanent-excited synchronous machine, the conductor sub-sections are formed as cut-outs from electrically conductive metal plates or metal foils, comprising copper, aluminum or the like. These electrically conductive metal plates or metal foils are electrically insulated from one another and / or from walls of the stator slots and / or of the stator tooth by insulation layers at least on some of their upper, lower or side surfaces.In one variant, the insulation layers have epoxy resin, halogen-free epoxy resin, PTFE, PEEK, polyimide, polyamide, anodically or cathodically applied dip coating material, electrostatic powder coating material, an aluminum layer, ceramic coating made of, for example, Al2O3, Si3N4, glass or the like, which is applied by PVD, CVD or wet-chemically and / or anodized. In a variant, the partial conductor sections have at least some edges, which are rounded at least in sections. In one variant, the conductor sub-sections have an undersize or at least approximately an even dimension with respect to at least some of their insulation layers, in particular in the direction of a lateral wall of the stator slot and / or of the stator tooth.In a variant of the polyphase permanent-excited synchronous machine, the conductor sub-sections and the insulation layers are configured as two- or multilayer coil structures with, for example, a flexible printed circuit board or ceramic plate as a connecting layer in the form of direct copper bonded-DCB substrates, direct bond copper-DBC substrates, copper plated ceramic-CPC substrates as a connecting layer. In one variant, via areas are provided for alternately connecting the partial conductor sections of one partial conductor to the partial conductor sections of the other partial conductor along the extension of the partial conductors. In one variant, the conductor sub-sections of one conductor sub-section are connected to the conductor sub-sections of the other conductor sub-section along the extension of the conductor sub-sections by silver sintering. In a variant, the conductor sections of the stator coil having different cross-sectional areas are connected by, for example, laser-welded or laser-soldered vertical connectors.For connecting the ceramic insulation layer to partial conductor sections made of, for example, copper, an AMB process-active metal brazing-can also be used in a variant, in which a layer made of copper having the required thickness is connected to the ceramic insulation layer using a high-temperature solder.DBC substrates include ceramic substrates of Si3N4 (silicon nitride), Al2O3 (aluminum oxide) or AlN (aluminum nitride). These materials have very good heat conducting properties (Al2O3>30 W / mK, Si3N4>90 W / mK, AlN>170 W / mK) also in the direction of the stator teeth. Silicon nitride is a non-oxide ceramic with very good material properties. These include a high fracture toughness (5-8 MPa / m 2) combined with a very high flexural strength (800-1000 MPa) and a low coefficient of thermal expansion (3.5 ppm / K). The metal coil pieces (sub-conductors, sub-conductor portions) are joinable by sintering, soldering, welding, and wire bonding, as preparation.Direct copper bonded (DCB) substrates and direct bond copper (DBC) substrates have a ceramic insulator made of aluminum oxide or aluminum nitride, on which, for example in a high-temperature melting and diffusion process, or in a plating process, one or more metal layers, for example pure copper, are applied and bonded firmly to the ceramic. The high thermal conductivity of Al2O3(10-30 W / mK, depending on the purity level) and AlN (130 to 180 W / mK) and the high heat capacity and heat spread of the thick metal coating are very advantageous for the electric machine.The mechanical stress load on the coils formed from the metal coating is also low here, since the coefficient of thermal expansion at 7.1 ppm / K for Al2O3and 4.1 ppm / K for AlNis better matched to that of the metal (for example Cu about 15 ppm / K) than that of plastics-based substrates. Overall, such substrates are very well suited for this use because of their high thermal conductivity and temperature resistance, their high insulation voltage, their high heat spread and their matched coefficient of expansion. Ceramic has no leakage current problems and a high CTI value-comparative tracking index. CPC substrates have base materials to which, for example, pure copper is electroplated. The base materials include Al2O3(aluminum oxide) or AlN(aluminum nitride), BeO(beryllium oxide), and a plurality of 100 μm of Cu are electroplated on this substrate according to the structure of the coil. The high thermal conductivity of Al2O3(10-30 W / mK depending on the purity level) and AlN (130 to 180 W / mK) and the high thermal capacity and heat spreading of the thick copper coating offer an efficient use in the present solution. In the case of CPC substrates, it is also possible to realize very well conductive connections from the top side to the underside of the substrate. The holes / vias may be previously formed in the ceramic substrate.The variants of the stator coils disclosed here are very precise to produce geometrically and mechanically. In addition, the variants disclosed here of the insulations of the stator coils are very thin for the required voltage strength and can likewise be produced very precisely. This makes it possible to realize a machine which, on the one hand, has stator coils which, owing to the above-described mutual connection of the conductor elements and / or the conductor sections, and / or the conductors of different thicknesses and / or the number of conductor sections of the individual windings, have a very high current-carrying capacity and lower current heat losses as a function of their height position in the stator slot, and which, on the other hand, can be heat-removed very well, since very good heat transfers from the stator coils into the stator teeth or the walls of the stator slots can be defined and efficiently realized by the very thin and precise insulations of the stator coils which are to be produced.Thus, the solution presented here makes it possible to realize a line fill factor of about 95% (and about 5% insulation) based on the volume of the stator slot instead of a conventional line fill factor of about 50% (and about 50% insulation). As a result, the power loss can decrease by about 1 / 3 or more.In a variant of the polyphase permanent-excited synchronous machine, the conductor sub-sections are formed from structures containing copper or aluminium by punching or cutting, with a ceramic plate, a flexible printed circuit board or a glass plate as insulation layer. In one variant, the conductor sub-sections are diffusion-welded to one another, for example.In a variant, through-contact locations with a raised portion are provided on the partial conductor sections, which are produced in a high-embossing process.In one variant, the partial conductor sections have at least partially rounded edges.In one variant, the partial conductor sections are provided circumferentially with a ceramic layer as insulation layer. The insulation layer has a thickness of about 10-100 μm. In one variant, the partial conductor sections are provided circumferentially with a plastic layer as insulation layer. The insulation layer has a thickness of about 5-50 μm.In one variant, the partial conductor sections have shallow depressions for the through-connection. In a variant, at least some of the subconductors are connected to one or more adjacent subconductors by means of contact pins.In one variant, the conductor sections of the stator coil have, in the outer region of at least one of their end windings, connectors to adjacent conductor sections of a control electronics.In a variant of the polyphase permanent-excited synchronous machine, at least one conductor section formed from an HF stranded wire is provided in at least one winding of the stator coil closer to the air gap, and the HF stranded wire is connected, for example welded, to a conductor section lying further away from the air gap.Moreover, an electric aircraft drive is disclosed here as one of a plurality of possible fields of application, comprising a polyphase permanent magnet-excited synchronous machine having one or more of the preceding features. Such an electric drive-also for other purposes-can be realized with a very high specific mass output of up to 40 kW / kg compared to approximately 6 kW / kg of present-day specific mass output.The electric machine has a permanent magnet rotor and stator coils. The stator coils generate a sinusoidal magnetic flux density in the air gap of the machine, which flux density is produced by the operating alternating current and is angle-dependent depending on the operating mode. Because of the permanent magnet excitation, the electric machine can also start from the stand under load. For operation, a preferably digital pulse width modulation inverter supplies the required electrical power in a corresponding phase position for the individual windings. The electric machine is to be operated under speed control or under torque control in different variants.Brief Description of the FiguresFurther features, properties, advantages, functionalities of the apparatuses and the procedures can be gathered from the following description in conjunction with the drawing. Possible modifications will also become apparent to a person skilled in the art from the following description, in which reference is made to the attached drawings. In this case, the figures schematically show the apparatuses discussed here.The following are shown here: FIG. 1 shows a schematic illustration of a fluid-cooled, polyphase, permanently excited synchronous machine as a use case in an aircraft drive train; FIG. 2 shows a schematic partial cross-sectional illustration of the polyphase permanent-excited synchronous machine, with a stator and a rotor in the internal rotor configuration; FIG. 3 shows a schematic partial cross-sectional illustration of the stator of the permanently excited synchronous machine from FIG. 2 ; FIG. 4 shows a schematic illustration of a stator winding with six turns of a polyphase, permanently excited synchronous machine; FIG. 4 a shows a schematic illustration of a winding of the stator winding from FIG. 4 ; FIG. 5 is a schematic top view illustration of how the conductor sections of the stator coil can be produced in use; FIG. 6 is a schematic, enlarged perspective illustration of how the partial conductor sections of two partial conductors placed one above the other are to be electrically connected; and FIG. 7 shows a schematic partial cross-sectional illustration of the stator coil from FIGS. 2 and 3 with the insulation layers between the individual conductor sub-sections.Detailed Description of Variations of Devices and ProceduresFIG. 1 illustrates, as a possible application of the permanently excited synchronous machine illustrated here, an aircraft drive train in which an electric aircraft drive is realized. This aircraft drive is part of an aircraft drive train and comprises a fluid-cooled, permanent-magnet-excited synchronous machine 10 also disclosed here. Further assemblies of the aircraft drive train are an electrical energy source 2, which can be designed, for example, as shown here as a hydrogen-, methane- or methyl alcohol-fed fuel cell assembly with water and / or carbon dioxide as exhaust gas. Alternatively, a rechargeable battery or solar current-fed ultracaps for supplying the electric aircraft drive with electrical energy can also be provided, for example. A polyphase inverter 6 is connected between the energy source 2 and the synchronous machine 10. The synchronous machine 10 and the inverter 6 are fluid-cooled, wherein the fluid is circulated through a heat exchanger, which is not illustrated in any more detail.Optionally, a (reduction) gear 4 is coupled between the electric aircraft drive and an airscrew, propeller or turbine 8. Depending on the rotational speed / torque design of the synchronous machine 10, the transmission 4 can also be omitted. In the illustrated aircraft drive train, the cooling of the electric machine and, if appropriate, its rotor is realized separately and in parallel with the cooling of the power electronics. It is also possible to use other cooling architectures and / or to design the rotor of the electric machine not to be fluid-cooled.FIG. 2 illustrates the polyphase permanent magnet synchronous machine 10 having a stator 12 and a rotor 14 in internal rotor configuration.Such a PMSM is to be used, for example, in the powertrain of FIG. 1. The stator 12 of the synchronous machine 10 has field coils 16 to be energized, and the rotor 14 has permanent magnet elements 18. the stator 12 is radially spaced from the rotor 14 by an air gap 20. The rotor 14 comprises a stack of rotor laminations. This stack of rotor laminations carries a plurality of permanent magnet elements 18 on its outer circumference between radially outwardly directed webs 14 a. The rotor laminations are at least almost non-magnetic, in particular paramagnetic. In a variant, not illustrated in more detail, flux guide pieces made of sheet-metal material are provided in the region between the permanent magnet elements 18 for guiding and aligning the magnetic flux. The non-magnetic material of the rotor laminations starts here lying radially further inwards in the spokes illustrated in FIG. 2 and extends as far as the center of the rotor laminations.The field coils 16 are to be supplied with current at a nominal rotational speed of, for example, about 14000-about 16500 rpm with a pole alternating frequency of, for example, about 3000-about 5000 Hz from the inverter 6, which is not illustrated in more detail. The inverter 6 has power electronics.This configuration allows, for example, a machine 10 having a torque greater than about 380 Nm, which has an overall length of about 450 mm including the inverter 6 and a maximum diameter of about 300 mm. The outputable power during continuous operation of the machine is, for example, approximately 500-800 kW at a rated rotational speed of approximately 12000 rpm to approximately 18000 rpm, wherein the total mass of machine and inverter 6 is approximately 35-50 kg. The overall efficiency of machine 10 and inverter 6 may be, for example, about 96%, which represents a highly efficient machine with very good power weight and minimal installation space.The stator 12 has, on its inner periphery oriented toward the air gap 20, a plurality of stator teeth 12 a, which are spaced apart from one another to form a plurality of stator slots 12 b. Each stator coil 16 is accommodated in two adjacent stator slots 12b surrounding one of the stator teeth 12a. In FIG. 3, the cross section through the stator coil 16 is shown enlarged. In the variant shown here, each stator coil 16 has three conductor sections 16 a; 16 b; 16 c; more than three conductor sections are also possible, as is illustrated, for example, in FIGS. 4, 4 a. In FIG. 3, each of the three conductor sections is divided into two partial conductors 16 a 1, 16 a 2; 16 b 1, 16 b 2; 16 c 1, 16 c 2 that are approximately the same in cross section and are electrically insulated from one another. At least two of the conductor sections 16 a; 16 b; 16 chave a mutually different cross-sectional area. In the variant shown here, the cross-sectional area decreases the farther the conductor sections 16 a; 16 b; 16 cand their partial conductors 16 a 1, 16 a 2; 16 b 1, 16 b 2; 16 c 1, 16 c 2 are situated away from the slot base 12 cof the stator slot 12 b. In this case, the conductor sections 16 a; 16 b; 16 cand the subconductors 16 a 1, 16 a 2; 16 b 1, 16 b 2; 16 c 1, 16 c 2 thereof practically completely fill the stator slot 12 bin the transverse extent of the stator slot 12 b-apart from an insulation layer, explained in detail further below, towards the two parallel side walls of the stator slot 12 b. Thus, the thickness of the conductor sections 16 a; 16 b; 16 cand their subconductors 16 a 1, 16 a 2; 16 b 1, 16 b 2; 16 c 1, 16 c 2 decreases in the direction of the height of the stator slot 12 btoward the air gap 20.In the variant illustrated here, each stator coil 16 surrounds one of the stator teeth 12a and is accommodated in two stator slots 12b on long sides of the stator teeth 12a, forming two winding heads 16w, 16w' on short sides of the stator teeth 12a.With reference to FIGS. 4 and 4 a, a possible interconnection scheme of the stator coil 16, its windings W1... W 6, the conductor sections 16 a;... 16d, their subconductors 16a1, 16a2;... 16d1, 16d2 and their partial conductor sections 16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d;.. 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d. The individual components of the stator coil 16 are provided with reference numerals in FIG. 4 a. The interconnection scheme is shown as a whole in FIG. 4; for the sake of better clarity, the reference numerals are partly omitted here.FIG. 4 ashows a winding Wnof the stator coil 16. The winding Wn here has four conductor sections 16 a... 16d, together comprising a winding W1,... W 6 of the stator coil 16 from FIG. 4. Each of the four conductor portions 16 a... In this variant, 16 dis formed into two partial conductors 16 a 1, 16 a 2; ... that are identical in cross section. 16d1, 16d2. In the first winding head 16 w(on the left in FIG. 4 a), the partial conductors 16 a 1, 16 a 2; ... 16d1, 16d2 of the four conductor portions 16a... 16d are connected to each other. In addition, the ends of the upper two and the lower two of the four conductor portions 16 a... 16d are connected to each other. These two pairs of the upper two and the lower two of the four conductor portions 16a... 16 dare likewise connected to one another and here form the first terminal A 1 of the winding Wn of the stator coil 16.In the winding Wn of the stator coil 16 illustrated in FIG. 4 a, the partial conductors 16 a 1, 16 a 2... 16 d 1, 16 d 2 of the respective conductor section 16 a... 16 dalong the extension of the partial conductor 16 a 1, 16 a 2... 16 d 1, 16 d 2 around the respective stator tooth 12 a, two partial conductor sections 16 a 1 a, 16 a 1 b, 16 a 1 c, 16 a 1 d; 16 a 2 a; 16 a 2 b, 16 a 2 c, 16 a 2 d... 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d. These sub-conductor portions 16 a 1 a, 16 a 1 b, 16 a 1 c, 16 a 1 d; 16 a 2 a; 16 a 2 b, 16 a 2 c, 16 a 2 d... 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d of the one subconductor 16a1, 16a2... 16 d 1, 16 d 2 are connected to the partial conductor sections 16 a 1 a, 16 a 1 b, 16 a 1 c, 16 a 1 d; 16 a 2 a; 16 a 2 b, 16 a 2 c, 16 a 2 d... 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d of the other subconductor 16a1, 16a2... 16 d 1, 16 d 2 along the extension of the subconductors 16 a 1, 16 a 2... 16d1, 16d2 are alternately connected. Thus, here, the first conductor sub-section 16 a 1 aof the uppermost, first conductor sub-section 16 a 1 is connected to the second conductor sub-section 16 a 2 bof the second conductor sub-section 16 a 2 of the uppermost, first conductor section 16 a, and the first conductor sub-section 16 a 2 aof the second conductor sub-section 16 a 2 is connected to the second conductor sub-section 16 a 1 bof the uppermost conductor sub-section 16 a 1 of the first conductor section 16 a. This results in a mutual crossover U of the line guide through the individual conductor sub-sections of the uppermost conductor sub-16 a. In FIGS. 4, 4 a, the ends of the partial conductor sections at which a connection to another conductor or a plated-through hole is provided are marked with a point.Similarly, the first partial conductor portions 16 b 1 a... 16d1a of the respective upper, first subconductors 16b1... 16d1 of the second to fourth conductor portions 16b... 16 dwith the respective lower second partial conductor sections 16 a 2 b... 16d2b of the second to fourth respective lower, second subconductors 16b1... 16d1 of the second to fourth conductor portions 16b... 16 d, and the first partial conductor portions 16 b 2 a... 16 b 2 dof the respective second subconductors 16 b 2... 16 d 2 with the respective upper second partial conductor sections 16 b 1 b... 16 d 1 bof the second to fourth upper sub-conductors 16 b 1... 16d1of the second to fourth conductor portions 16b... 16d. This results in a mutual crossover U of the line guide through the individual conductor sub-sections of the second to fourth conductor sub-sections 16 b... 16d.In the winding Wn of the stator coil 16 illustrated in FIG. 4 a, the partial conductors 16 a 1, 16 a 2... 16 d 1, 16 d 2 of the respective conductor section 16 a... 16d in the second winding head 16w' (in FIG. 4a in the middle of the winding Wn) are connected in pairs at a mutual crossover U. For this purpose, the partial conductor sections 16a1b, 16a1c, 16a2b, 16a2c;.. located in the region of the winding head 16w'. 16d1b, 16d1c, 16d2b, 16d2c of the one conductor portion 16a... 16 dwith the subconductor sections 16 a 1 b, 16 a 1 c, 16 a 2 b, 16a2c;.. 16d1b, 16d1c, 16d2b, 16d2c of the adjacent conductor portion 16a... 16 din a mutual crossover U. In other words, for example, the uppermost partial conductor sections 16 a 1 blocated in the region of the winding head 16 w' are connected to the second partial conductor section 16 a 2 blocated in the region of the winding head 16 w'; these two partial conductor sections 16 a 1 b, 16 a 2 bare connected to the likewise mutually connected two partial conductor sections 16 b 1 c, 16 b 2 bin the region of the winding head 16 w'. Similarly, the partial conductor sections 16b1b located in the region of the winding head 16w' are connected to the partial conductor section 1622b located in the region of the winding head 16w'; these two partial conductor sections 16b1b, 16b2b are connected to the likewise mutually connected two partial conductor sections 16a1c, 16a2c in the region of the winding head 16w'. This reciprocal crossover U of the line routing through the individual conductor sub-sections of the upper two conductor sub-sections 16 aand 16 breceeds with the reciprocal crossover of the line routing through the individual conductor sub-sections of the lower two conductor sub-sections 16 cand 16 d.This is followed by a crossed line routing as described above by the individual conductor sub-sections within the respective conductor sections 16 a... 16d an.In the region of the winding head 16 won the left in FIG. 4, the ends of the partial conductor sections 16 a 1 dand 16 a 2 dof the partial conductors 16 a 1 and 16 a 2 are each connected to one another, and the ends of the partial conductor sections 16 b 1 dand 16 b 2 dof the partial conductors 16 b 1 and 16 b 2 are each connected to one another. Similarly, the ends of the divided conductor portions 16 c 1 dand 16 c 2 dof the divided conductors 16 c 1 and 16 c 2 are respectively connected to each other, and the ends of the divided conductor portions 16 d 1 dand 16 d 2 dof the divided conductors 16 d 1 and 16 d 2 are respectively connected to each other.As shown in FIG. 4, two of the turns W1... adjacent to each other have. W6 is an even number of conductor portions 16a... 16d. The conductor portions 16 a... 16d of two adjacent windings W1... W6 are arranged one above the other between the groove base 12c and the air gap 20. As described above, in both of the two turns, an upper half of the conductor sections 16 a, 16 band a lower half of the conductor sections 16 c, 16 dare connected in the region of a winding head 16 win a mutual crossover U. The upper half of the interconnected conductor sections 16 a, 16 bof the upper of the two windings is connected to the lower half of the interconnected conductor sections 16 c, 16 dof the lower of the two windings, and the lower half of the interconnected conductor sections 16 c, 16 dof the upper of the two windings is connected at a mutual crossover U to the upper half of the interconnected conductor sections 16 a, 16 bof the lower of the two windings.The reciprocal crossover of the line routing is realized by mutual contacting of the individual conductor sub-sections of the two conductor sub-sections by means of connectors 16 vin the winding head and / or along the long sides of the respective stator tooth 12 a.Overall, the coil structure is realized by layers of individual metal layers and corresponding contacting. For the insulation of the individual layers with respect to one another and the through-connection of the insulation layers, different procedures explained below are provided.As illustrated in FIGS. 2, 3 and 4, different turns of the stator coil 16 have a different cross-sectional area. In this case, the conductor sections 16 a; 16 bof the stator coil 16 with the smaller cross-sectional area, which conductor sections lie higher in the stator slot 12 bin FIG. 3, are arranged closer in the two stator slots 12 bto the air gap 20 than the conductor section 16 cwith the larger cross-sectional area, which conductor section lies lower in the stator slot 12 b. In FIG. 4, the different line strengths of the individual windings W1... W6 denotes the different cross-sectional areas of the partial conductors depending on the height position of the respective winding in the stator slot 12b. In a stator coil 16 with, for example, 6 turns, each turn of the same width in the stator slot has, for example, the following thickness of the metal layer forming a partial conductor, wherein turn 6 is arranged close to the slot base and turn 1 is arranged close to the air gap and each turn is formed from partial conductors arranged one above the other 8 (see, for example, FIG. 4 ):10,01420,05530,12340,21850,34160,491In a variant of the synchronous machine 10, the increase in the thickness of the winding decreases from the 4th winding to zero, i.e. the thickness of the metal layer in the 5th and 6th windings is just as great as that of the 4th winding.The stator 12 is formed from a plurality of stator laminations stacked along the central longitudinal axis M of the synchronous machine 10. The stator laminations of the stator 12 are made of soft iron (Fe), cobalt (Co), nickel (Ni), silicon (Si), or alloys containing these materials. These alloys include NiFe alloys containing about 72-about 83% Ni, about 54-about 68% Ni, about 45-about 50% Ni, or CoFe alloys containing about 17-about 50% Co, or FeSi alloys. The stator laminations of the stator 12 have a thickness of about 10 μm to about 250 μm, for example, 50 μm thickness. After each 10th-50thstand sheet, for example after each 30thstand sheet, a graphite foil having a thickness of about 10 μm to about 100 μm, for example 50 μm thick, is located in the stack of the stand sheets. This graphite foil serves to heat the stator 12, in particular in the direction of an outer circumference. From there, the heat can be dissipated very efficiently with axially extending cooling channels, not illustrated in more detail. Instead of a graphite foil, in one variant all or some of the stator metal sheets are coated with graphene or DLC-diamond-like carbon.In FIGS. 1 to 4, it is illustrated that each conductor section 16 a; 16 b; 16 csurrounds one of the stator teeth 12 aat least once at least approximately completely.In FIG. 4, it is also illustrated in detail how, at least in the case of conductor sections 16 a; 16 btoward the air gap 20, the partial conductors 16 a 1, 16 a 2; 16 b 1, 16 b 2 of the respective conductor section 16 a; 16 balong the extension of the partial conductor 16 a 1, 16 a 2; 16 b 1, 16 b 2 around the respective stator tooth 12 ahave a plurality of partial conductor sections 16 a 1 a, 16 a 1 b, 16 a 1 c, 16 a 1 d; 16 a 2 a; 16 a 2 b, 16 a 2 c, 16 a 2 d; 16 b 1, 16 b 1 a, 16 b 1 b, 16 b 1 c, 16 b 1 d; 16 b 2 a, 16 b 2 b, 16 b 2 c, 16 b 2 d. In order to reduce the skin effect during operation of the machine, the partial conductor sections 16 a 1 a, 16 a 1 b, 16 a 1 c, 16 a 1 d; 16 a 2 a; 16 a 2 b, 16 a 2 c, 16 a 2 dof the one partial conductor 16 a 1; 16 a 2 are alternately connected to the partial conductor sections 16 a 2 b, 16 a 2 c, 16 a 2 d, 16 a 2 a; 16 a 1 b, 16 a 1 c, 16 a 1 d, 16 a 1 aof the other partial conductor 16 a 2; 16 a 1 along the extension of the partial conductors 16 a 1, 16 a 2; 16 b 1, 16 b 2 around the respective stator tooth 12 a.In particular, the connections 16 vof the conductor sub-sections of one conductor sub-section to the conductor sub-sections of the other conductor sub-section are realized such that the current flow along the circumference of the respective stator tooth through the conductor sub-sections of the one conductor sub-section has as many pieces of equal length at the same height of the stator tooth as the conductor sub-sections of the other conductor sub-section of the conductor section.These connections 16 vthat bring about the respective change are provided in the variants illustrated here both in the two winding heads, in FIG. 4 in the drawing on the two short sides of the respective stator tooth 12 a, and on the two long sides of the respective stator tooth 12 a.However, in variants of the machine it is also provided that the connections 16 vthat bring about the respective change are optionally provided only in the two winding heads or only on the two long sides of the respective stator tooth 12 a. In variants of the machine, it is also provided to provide more than one connection 16 vwhich brings about the respective change on the two long sides of the respective stator tooth 12 a. In variants of the machine, it is also provided that lower windings W3... are located in the stator slot 12c. W 6 (in FIG. 4 ) does not provide a cross-switching of the line guide between the line segments in the stator slot 12 c, but instead a cross-switching of the line guide between the line segments only in the region of the end windings. In addition, in variants of the machine, it is also realized that in the two lowermost turns W 5 and W 6 (in FIG. 4 ) located in the stator slot 12 c, only two conductor sections 16 a, 16 bare provided without crosswise changing of the line routing between the partial conductor sections. When metal layers of different thicknesses are used, the crosswise changing of the line guide to the base of the stator groove can be dispensed with, since the losses decrease. In the region of the uppermost winding layers, the crosswise changing of the line guide is advantageous. This type of construction reduces the proportion of the insulation layers and increases the copper proportion in the groove without producing additional losses, which increases the efficiency.The divided conductor portions 16 a 1 a... 16 b 2 dof the partial conductor of a conductor section are formed in one variant as cut-outs from electrically conductive metal plates or metal foils comprising copper (Cu), aluminum (Al) or the like. At least on some of the upper, lower or side surfaces of these cutouts, these are electrically insulated from one another and / or from walls of the stator slots 12 band / or of the stator tooth 12 aby insulation layers 22. At least some of the partial conductor sections can have rounded edges at least in sections. Rounding the edges improves the adhesion of the insulation layers 22 to the conductor sub-sections and counteracts corona discharges.FIG. 7 illustrates that the insulation layers 22 may comprise epoxy resin, halogen-free epoxy resin, PTFE, PEEK, polyimide, polyamide, anodically or cathodically applied dip coating material, electrostatic powder coating material, aluminum layer applied and / or anodized by PVD, CVD or wet-chemically applied, ceramic coating of, for example, Al2O3, AlN, Si3N4, glass or the like. These insulation layers 22 may have a layer thickness in a range of 30 μm to 3 μm, or less than 15 μm. This results in a copper core for the partial conductor sections, on which aluminum layer is vapor-deposited on its outer surfaces, which in turn is anodized. The anodized aluminum layer forms the insulation layer 22, which results in a volume ratio of up to 95% copper conductor to about 5% insulation layer.The conductor sub-sections have an undersize or at least approximately an even dimension compared to at least some, here the horizontal, of their insulation layers 22, in particular in the direction of a lateral wall of the stator slot 12 band / or of the stator tooth 12 a. This ensures that the voltage resistance is ensured in each case. The insulation voltage of the turns relative to one another must be about 100 Vac and the insulation voltage relative to the stator laminated core must be about 1000 Vac. Therefore, an additional heat-conducting insulation (e.g. made of Al2O3) is required towards the stator laminated core.In one variant, the partial conductor sections and the insulation layers 22 are configured as two- or multilayer coil structures having, for example, a flexible printed circuit board, glass plate or ceramic plate as a connection layer in the form of direct copper bonded-DCB substrates, direct bond copper-DBC substrates, copper plated ceramic-CPC substrates as a connection layer. In this case, in one variant, through-contact surfaces are provided for alternately connecting the conductor sub-sections of one conductor sub-section to the conductor sub-sections of the other conductor sub-section along the extent of the conductor sub-sections.In one variant, the conductor sub-sections of one conductor sub-section are connected to the conductor sub-sections of the other conductor sub-section along the extension of the conductor sub-sections by silver sintering.In a variant, the conductor sections 16 a; 16 bof the stator coil 16 having different cross-sectional areas are connected by, for example, laser-welded or laser-soldered vertical connectors. This is illustrated in FIGS. 5 and 6. In FIG. 5, the partial conductor sections of a partial conductor to be formed from, for example, copper or aluminum sheet are shown in use by water jet cutting, laser cutting, milling or otherwise forming. In this case, the upper conductor sections of a conductor section in FIG. 5 are to be placed over the lower conductor sections of the conductor section in FIG. 5. FIG. 6 illustrates, on an enlarged scale, how the partial conductor sections of the two partial conductors which are laid one above the other are to be electrically connected. In this case, end portions 24 aof the individual conductor sub-portions of the one conductor sub-portions project mutually beyond end portions 24 bof the other conductor sub-portions of the other conductor sub-portions in a lateral extent. Vertical connector pins 26 pass through these end portions 24 a, 24 bof the two subconductors, which end portions project beyond one another. These laterally juxtaposed vertical connector pins 26 or contact pins realize the intersecting connections 16v illustrated in Figure 4.In a variant which is not illustrated in more detail, the conductor sub-sections of the conductor sub-sections have shallow depressions for contacting with one another or with connections to control electronics. At least some of the conductor sub-sections of the conductors may be connected in the area of the depressions by means of contact pins or welding points. The conductor sections of the stator coil have connectors A 1, A 2 (see FIG. 4 ) in the outer region of at least one of their end windings to adjacent conductor sections and / or to control electronics.In a variant, the partial conductor sections are formed from structures containing copper or aluminum by punching or cutting, with a ceramic plate, a flexible printed circuit board or a glass plate as insulation layer. In this case, the conductor sub-sections can be diffusion welded to one another. Via locations may be provided with a ridge formed in a high embossing process. The partial conductor sections can have at least partially rounded edges and be provided circumferentially with a ceramic layer or a plastic layer as an insulation layer, wherein the insulation layer has a thickness of 10-100 μm or a thickness of 5-50 μm.The partial conductor sections can also have shallow depressions for the purpose of making contact.At least some of the subconductors are connected to one or more adjacent subconductors by means of contact pins. Furthermore, the conductor sections 16 a; 16 bof the stator coil 16 have connectors A 1, A 2 to adjacent conductor sections and / or to control electronics in the outer region of at least one of their end windings.In a further variant of the machine, the at least one conductor section of the stator coil 16 with the smaller cross-sectional area, which conductor section is nearer or closest to the air gap 20, is provided at least with one winding which is formed from an RF stranded wire. The RF braid is connected to a conductor portion remote from the air gap 20, for example by ultrasonic friction welding.The variants of the device described above and their design and operating aspects serve merely for better understanding of the structure, the mode of operation and the properties; they do not restrict the disclosure, for example, to the exemplary embodiments. The figures are partially schematic, wherein essential properties and effects are in part shown in a clearly enlarged manner in order to clarify the functions, principles of action, technical configurations and features. In this case, each mode of operation, each principle, each technical configuration and each feature which is / are disclosed in the figures or in the text can be freely and arbitrarily combined with all claims, each feature in the text and in the other figures, other modes of operation, principles, technical configurations and features which are contained in this disclosure or result therefrom, with the result that all conceivable combinations are to be associated with the described procedure. Combinations between all individual embodiments in the text, i.e. in each section of the description, in the claims and also combinations between different variants in the text, in the claims and in the figures, are also included here. The claims also do not limit the disclosure and thus the possible combinations of all features shown with one another. All disclosed features are explicitly also disclosed individually and in combination with all other features here.References included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 2 77 012 C
[0004] DE 195 45 307
[0005]
Claims
A polyphase permanent-excited synchronous machine (10) comprising a stator (12) and a rotor (14) in external or internal rotor configuration; wherein - the stator (12) has stator coils (16) to be energized and the rotor (14) has permanent magnet elements (18), and the stator (12) is spaced apart from the rotor (14) to form an air gap (20); - the stator (12) has a plurality of stator teeth (12a) spaced apart from one another to form a plurality of stator slots (12b); each stator coil (16) of at least one of the stator teeth (12a), forming two winding heads (16w, 16w') on short sides of the stator teeth (12a), being received at least once, at least approximately completely, in two stator slots (12b) on long sides of the stator teeth (12a); each of the stator coils (16) of at least two conductor sections (16a;... 16d), wherein the at least two conductor sections (16a;... 16d) together in each case at least one winding (W1,... W6) of the respective stator coil (16); each of the at least two conductor sections (16a;... 16d) each in at least two partial conductors (16a1, 16a2;... which are at least approximately the same in cross section and are electrically insulated from one another. 16d1, 16d2); at least in the windings (W1... located closer to the air gap (20). W5) the subconductors (16a1, 16a2;... 16d1, 16d2) of the respective conductor section (16a;... 16d) along the extension of the partial conductor (16a1, 16a2;... 16d1, 16d2) around the respective stator tooth (12a) at least two conductor sub-sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d;.. 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d); and the subconductor portions (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d;.. 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d) of the one subconductor (16a1, 16a2;... 16d1, 16d2) with the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d;.. 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d) of the other subconductor (16a1, 16a2;... 16d1, 16d2) along the extension of the subconductors (16a1, 16a2;... 16d1, 16d2) are alternately connected.Polyphase permanent-excited synchronous machine (10) according to the preceding claim, wherein - at least in the case of the windings (W1... lying closer to the air gap (20). W5) the partial conductor sections (16a1b, 16a1c, 16a2b, 16a2c;.. located in the region of the one winding head (16w'). 16d1b, 16d1c, 16d2b, 16d2c) of the one conductor section (16a... 16d) with the partial conductor sections (16a1b, 16a1c, 16a2b, 16a2c;.. 16d1b, 16d1c, 16d2b, 16d2c) of another, for example adjacent, conductor section (16a... 16d) are connected alternately.The polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein - at least two of the windings (W1... adjacent to one another. W6) is an even number of conductor sections (16a... 16d); - the conductor sections (16a... 16d) of the two adjacent turns (W1... W6) are arranged one above the other between the slot base (12c) and the air gap (20); - in each of the two windings an upper half of the conductor sections (16a, 16b) and a lower half of the conductor sections (16c, 16d) are connected to one another in the region of a winding head (16w); and - the upper half of the connected conductor sections (16a, 16b) of the upper of the two windings is connected to the lower half of the connected conductor sections (16c, 16d) of the lower of the two windings, and the lower half of the connected conductor sections (16c, 16d) of the upper of the two windings is connected to the upper half of the connected conductor sections (16a, 16b) of the lower of the two windings.The polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein - the conductor sub-sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d;.. 16d1a; 16d1b, 16d1c, 16d1d; 16d2a, 16d2b, 16d2c, 16d2d) of the subconductor (16a1, 16a2;... 16d1, 16d2) have a transverse dimension at least over substantial parts of their longitudinal extent which substantially corresponds to a transverse dimension of the stator slots (12b).The polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein - at least two of the windings of the stator coil (16) have a mutually different cross-sectional area; - the at least two conductor sections (16a; 16b; 16c; 16d) of at least one of the windings of the stator coil (16) having the smaller cross-sectional area are arranged closer to the air gap (20) in the stator slots (12b) than the at least two conductor sections (16a; 16b; 16c; 16d) of at least one of the windings of the stator coil (16) having the larger cross-sectional area.The polyphase permanent-excited synchronous machine (10) according to any one of the preceding claims, wherein - the stator (12) is formed from a plurality of stator laminations arranged along the central longitudinal axis of the synchronous machine (10); and / or - the stator laminations contain soft iron, cobalt, nickel, silicon or alloys thereof, such as NiFe alloys with about 72 - about 83% Ni, with about 54 - about 68% Ni, with about 45 - about 50% Ni, or CoFe alloys with 17 - 50% Co, CoFe alloys or FeSi alloys; and / or - the stator laminations have a thickness of about 10 μm to about 200 μm, for example 50 μm thickness; and / or - after each 10th - 50th stator sheet, for example after each 30th stator sheet, there is a graphite foil with a thickness of about 10 μm to about 100 μm, for example 50 μm thickness; and / or - every nth, wherein 2<=n<=10, of the stator sheets is coated with DLC or graphene with a layer thickness of up to about 1 μm.The polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein - the partial conductor sections (16a1a.. 16b2d) are formed as cut-outs from electrically conductive metal plates or metal foils comprising copper, aluminium or the like which are electrically insulated from one another and / or from walls of the stator slots (12b) and / or of the stator tooth (12a) by insulation layers (22) at least on some of their upper, lower or side surfaces; and / or - the insulation layers (22) comprise epoxy resin, halogen-free epoxy resin, polyimide, polyamide PTFE, PEEK, anodically or cathodically applied dip coating material, electrostatic powder coating material, aluminum layer, ceramic coating made of, for example, Al2O3, AlN, Si3N4, glass or the like, applied chemically by PVD, CVD or wet-chemically applied and / or anodized; and / or - the insulation layers (22) have a layer thickness in a range from 30 μm to 3 μm, or less than 15 μm; and / or the conductor sub-sections (16a1a.. 16b2d) have rounded edges; and / or - the partial conductor sections (16a1a.. 16b2d) have undersize or at least approximately uniform size with respect to at least some of their insulation layers (22), in particular in the direction of a lateral wall of the stator slot (12b) and / or of the stator tooth (12a).The polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein the conductor sub-sections (16a1a.. 16b2d) and the insulation layers () as two- or multi-layer coil structures with, for example, flexible printed circuit board, glass plate or ceramic plate as connecting layer in the form of direct copper bonded-DCB substrates, direct bond copper-DBC substrates, copper plated ceramic-CPC substrates as connecting layer; and / or through-contact areas for alternately connecting the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d) of the one partial conductor (16a1; 16 a2) with the conductor sub-sections (16 a2b, 16 a2c, 16 a2d, 16 a2a; 16 a1b, 16 a1c, 16 a1d, 16 a1a) of the other conductor sub-section (16 a2; 16 a1) along the extension of the conductor sub-sections (16 a1, 16 a2; 16 b1, 16 b2); and / or - the conductor sub-sections (16 a1a, 16 a1b, 16 a1c, 16 a1d; 16 a2a; 16 a2b, 16 a2c, 16 a2d) of the one conductor sub-section (16 a1; 16 a2) with the conductor sub-sections (16 a2b, 16 a2c, 16 a2d, 16 a2a; 16a1b, 16a1c, 16a1d, 16a1a) of the other conductor element (16a2; 16a1) are connected along the extension of the conductor elements (16a1, 16a2; 16b1, 16b2) by silver sintering; and / or - the conductor sections (16a; 16b) of the stator coil (16) with different cross-sectional area are connected by, for example, laser-welded or laser-soldered vertical connectors (); and / or the conductor element sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d) of the conductor elements (16a1; 16a2) have shallow depressions for contacting with one another or with terminals to drive electronics; and / or - at least some of the conductor sub-sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d) of the conductor sub-sections (16a1; 16a2) are connected by means of contact pins; and / or - at least some of the conductor sub-sections (16a1; 16a2) are connected to one or more adjacent conductor sub-sections (16a1; 16a2) by means of contact pins; and / or - the conductor sections (16a; 16b) of the stator coil (16) in the outer region of at least one of its end windings (16w) have connectors to adjacent conductor sections (16a; 16b) and / or to control electronics.The polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein - the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d; 16b1, 16b1a, 16b1b, 16b1c, 16b1d; 16b2a, 16b2b, 16b2c, 16b2d) are formed from structures containing copper or aluminium by punching or cutting, with a ceramic plate, a flexible printed circuit board or a glass plate as insulation layer (22), and / or wherein the partial conductor sections are diffusion welded to one another; and / or - via locations with a ridge created in a high-embossing process; and / or - the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d; 16b1, 16b1a, 16b1b, 16b1c, 16b1d; 16b2a, 16b2b, 16b2c, 16b2d) have at least partially rounded edges; and / or - the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d; 16b1, 16b1a, 16b1b, 16b1c, 16b1d; 16b2a, 16b2b, 16b2c, 16b2d) are provided circumferentially with a ceramic layer as insulation layer (22), wherein the insulation layer (22) has a thickness of 10-100 μm; and / or - the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d; 16b1, 16b1a, 16b1b, 16b1c, 16b1d; 16b2a, 16b2b, 16b2c, 16b2d) are provided circumferentially with a plastic layer as insulation layer (22), wherein the insulation layer (22) has a thickness of 5-50 μm; - the partial conductor sections (16a1a, 16a1b, 16a1c, 16a1d; 16a2a; 16a2b, 16a2c, 16a2d; 16b1, 16b1a, 16b1b, 16b1c, 16b1d; 16b2a, 16b2b, 16b2c, 16b2d) have shallow depressions for the plated-through hole; - at least some of the partial conductors (16a1; 16a2) have one or more adjacent partial conductors (16a1; 16a2) by means of contact pins; and / or - the conductor sections (16a; 16b) of the stator coil (16) have, in the outer region of at least one of their end windings (), connectors to adjacent conductor sections (16a; 16b) and / or a control electronics.Polyphase permanent-excited synchronous machine (10) according to one of the preceding claims, wherein - in the case of at least one winding (Wn) of the stator coil (16) which is closer to the air gap (20), conductor sections are provided which is formed from an RF stranded wire, and the RF stranded wire is connected, for example welded, to a conductor section (16a; 16b; 16c) which lies further away from the air gap (20).An aircraft electric drive or drive having a specific mass output of up to about 40 kW / kg, comprising a polyphase permanent magnet excited synchronous machine according to any preceding claim.