Fluid-cooled, multi-phase permanently excited synchronous machine

Abstract

The invention relates to a fluid-cooled, multi-phase permanently excited synchronous machine, having a stator and a rotor in an outer-rotor or inner-rotor configuration. Here, the stator has field coils to be energised, and the rotor has permanent-magnet elements. The stator is spaced apart from the rotor radially, thus forming an air gap. The rotor is divided axially into two or more rotor discs sitting on a rotor shaft. Each rotor disc comprises two or more at least practically unmagnetic, preferably paramagnetic carrier plates supporting the permanent-magnet elements and soft-magnetic rotor tooth elements. A heat-conductive layer reaching from the permanent-magnet elements at least as far as close to the rotor shaft is received between the carrier plates. The rotor, close to the rotor shaft, has cooling fluid channels penetrating the carrier plates of the rotor lamination radially and axially. The rotor shaft has cooling fluid feed lines and / or discharge lines connected to the cooling fluid channels of the rotor.

Description

[0001] Fluid-cooled, multiphase permanent magnet synchronous machine

[0002] Description

[0003] background

[0004] A fluid-cooled, multiphase permanent magnet synchronous machine (PMSM) is disclosed here. This machine can also be used as an electric aircraft propulsion system. Such an aircraft propulsion system is part of an aircraft drive train and comprises such a fluid-cooled, multiphase permanent magnet synchronous machine. Further components of the aircraft drive train are an electrical energy source, which can be configured as a battery, photovoltaic array, and / or a fuel cell unit, and which supplies the electric aircraft propulsion system with electrical energy, as well as optionally a (reduction) gear coupled between the electric aircraft propulsion system and an airscrew, propeller, turbine, or similar device. Details are defined in the claims; however, the description also contains relevant information on the structure and mode of operation, as well as on variants of the machine.Machines of the type disclosed here are to be implemented as high-performance drives with a power-to-weight ratio of 10kW / kg - 25kW / kg.

[0005] Electrical machines are understood here to include both motor- and generator-operated machines, as well as machines that operate alternately between these two modes of operation.

[0006] Electrical machines have a stator and a rotor. The rotor is driven by magnetic interaction with the stator. The alternating magnetic fields generated in the machine components during operation lead to the generation of eddy currents. These eddy currents generate heat in the stator and rotor. Hysteresis and remagnetization losses lead to heat generation in the laminations of the stator and rotor. If the heat generation is too high, it can damage machine components. In particular, in permanent magnet electrical machines, the operating temperature must be limited to maintain magnetization and reduce or prevent demagnetization.

[0007] To date, cooling of small electrical machines, such as drive motors for vehicle propulsion, has typically involved stator shell cooling with cooling water or oil as the cooling medium, and optionally rotor cooling with air or oil as the cooling medium. Previous cooling systems conduct a cooling medium through the electrical machine to absorb operating heat. The heated cooling medium is then removed from the electrical machine, where it is cooled passively or actively, and then fed back into the electrical machine.

[0008] An electric machine with cooling is known from DE 10 2014 216 241 A1. Here, a rotor arrangement of the machine has a refrigerant line with a cross-sectional expansion to effect a phase transition of a refrigerant flowing through it. The rotor arrangement has a permanent magnet, to which an evaporation channel of the refrigerant line is arranged. The cross-sectional expansion is achieved by dividing the refrigerant line or by expanding the refrigerant line. Liquid refrigerant is supplied to the refrigerant line. The refrigerant line opens into the interior of the housing, which is provided with a discharge line to discharge expanded refrigerant from the housing. The refrigerant line has a supply channel running axially along the rotor shaft, and several radial distribution channels and several evaporation channels.

[0009] WO 2007 / 119952 A1 describes receiving elements for receiving preferably trapezoidal permanent magnets, which can be inserted into corresponding dovetail slots of a rotor element with a positive fit. However, this results in the problem that the force exerted by the magnets on the receiving elements or the side edges of the dovetail slots caused by the rotor's rotation can only be inadequately compensated, which can lead to the permanent magnets breaking after some time of operation.

[0010] DE 10 2008 023 999 A1 discloses a device for holding magnets in a moving component, in particular in a laminated core of a rotor of an electric motor, comprising a holding pocket into which a magnet is inserted and secured by means of an adhesive. The adhesive expands to a predetermined extent upon curing and contains propellant for foaming an adhesive. A disadvantage of this device is that the permanent magnets are enclosed in the holding pockets, which are firmly integrated into the rotor core and produced by stamping. This results, on the one hand, in limited flexibility when assembling a corresponding rotor. On the other hand, stresses resulting from centrifugal forces and different thermal expansion coefficients of the magnets and the rotor core can only be compensated to a limited extent by the adhesive.

[0011] Underlying problem

[0012] The present solution is based on the problem of providing a highly efficient electric machine with a very good power-to-weight ratio (useful power / weight) and minimal installation space.

[0013] This object is achieved by an electrical machine according to claim 1.

[0014] In particular, a fluid-cooled, multi-phase permanent magnet synchronous machine is specified here, with a stator and a rotor in internal or external rotor configuration.

[0015] The stator has field coils to be energized, and the rotor has permanent magnet elements. The stator is radially spaced from the rotor, forming an air gap. The rotor has at least one, at least virtually non-magnetic support that carries the permanent magnet elements and soft-magnetic rotor tooth elements. At least one heat-conducting layer extends from the side of the permanent magnet elements and / or the rotor tooth elements remote from the air gap to close to the rotor shaft.

[0016] In some variants, the rotor has cooling fluid channels penetrating it near the rotor shaft. The rotor shaft has cooling fluid supply and / or discharge lines connected to the rotor's cooling fluid channels.

[0017] The arrangement of the thermally conductive layer as a transport medium for the thermal energy from the radially outer permanent magnet elements to the radially inner region of the rotor, where heat exchange / cooling takes place with the fluid cooling circuit guided through the central support shaft, can be implemented in both an internal and external rotor configuration of the machine. This external rotor variant is particularly advantageous for compact configurations.

[0018] Further embodiments are specified in the dependent claims.

[0019] In one variant of an internal rotor configuration, the support is designed as at least one support plate that is non-rotatably held on the rotor shaft, for example, as a support plate. In an external rotor configuration, the support is designed as at least one support tube or similar that is non-rotatably held on the rotor shaft.

[0020] In one variant of an internal rotor configuration, the heat-conducting layer is in thermal contact with at least one carrier plate, and the cooling fluid channels penetrate the at least one carrier plate to dissipate heat from the heat-conducting layer. In one variant of an external rotor configuration, the heat-conducting layer is in thermal contact with at least one annular collar, and the cooling fluid channels penetrate the at least one annular collar to dissipate heat from the heat-conducting layer. The cooling fluid channels preferably penetrate the rotor in a radial and / or axial direction. In one variant, the machine has a permanent magnet rotor and windings on the stator. The stator windings generate a sinusoidal magnetic flux density in the air gap of the machine, which fluctuates depending on the operating mode. Due to the permanent magnet excitation, the PMSM can also start up from a standstill under load.A digital pulse-width modulation inverter supplies the required electrical power in the appropriate phase position. The machine can be operated in various versions, either with speed control or torque control.

[0021] One criterion for dimensioning the permanent magnets in an electrical machine is their demagnetization resistance. This resistance depends significantly on the temperature to which the permanent magnets are exposed during operation. The demagnetization of the permanent magnets occurs due to opposing magnetic fields generated by the stator coils in electronically commutated electrical machines. The measure of the demagnetization resistance is defined by the coercive field strength, which is highly temperature-dependent and decreases with increasing temperature. To increase the coercive field strength, the permanent magnets contain rare earth elements.

[0022] In one variant, the rotor is constructed from components that are at least virtually ineffective magnetically and are magnetically inductive. This results in twice the surface thrust compared to conventional electrical machine designs. The internal rotor machine does not require a magnetic induction loop and has only a small amount of laminated, poorly electrically conductive material between the rotor shaft and the radially outer rotor tooth elements and the permanent magnet elements.

[0023] In a variant of the internal rotor machine, a sealing plate for sealing the cooling fluid channels is arranged between each carrier plate and the adjacent heat-conducting layer in the region near the rotor shaft, wherein in particular a first region containing the cooling fluid channels in the carrier plate comprises approximately 10% to approximately 60% of the radial extent of the carrier plate against which the sealing plate rests.

[0024] In a variant of the internal rotor machine, radially outward-pointing spokes are provided in a second region of the carrier plate adjacent to the first region, which spokes can preferably each have a receptacle for the rotor tooth elements at their free end.

[0025] In one variant, each permanent magnet element has a cross-sectional shape approximately shaped like a circular ring segment or trapezoid, with its shorter concentric or parallel side oriented toward the air gap, and its two inclined sides oriented toward oppositely oriented inclined sides of two adjacent rotor tooth elements. In one variant, each of the permanent magnet elements is magnetically oriented essentially tangentially, and two adjacent permanent magnet elements are magnetically oppositely oriented. In one variant, two adjacent rotor tooth elements project beyond the permanent magnet element accommodated between them in the radial direction toward the air gap, and preferably also in the circumferential direction.

[0026] In one variant of the internal rotor machine, the rotor tooth element is held in place by a positive fit on the holder. In one variant, the rotor tooth element and the holder have hooks that engage in a pocket in which they are secured, for example, with locking rods.

[0027] In one variant of the internal rotor machine, the slanted sides of the permanent magnet element and the oppositely slanted sides of two adjacent rotor tooth elements have a radial angle which, depending on the material, is dimensioned such that self-locking of the permanent magnet element and its adjacent rotor tooth elements is achieved in the radial direction. The wedge-shaped design of the rotor tooth elements and the permanent magnet element can cause preload of the rotor through self-locking. Accelerating the rotor to a centrifugal speed of, for example, 20,000 rpm during machine assembly can drive the permanent magnet element radially outward between the adjacent rotor tooth elements. Due to the self-locking, the permanent magnet element can then remain in operation at rated speed, whereby the following applies: centrifugal speed > rated speed.Since the magnets assume their radially outermost position at the spin speed, no pulsating loads or diameter changes due to changing centrifugal forces occur during subsequent normal operation.

[0028] In one variant, the thermally conductive layer forms a thermal connection between the permanent magnet element and the cooling fluid channels, and the thermally conductive layer has a contact area that is in contact with a radially inner side of the permanent magnet element. In one variant, the thermally conductive layer has several thermally conductive graphite foils to reduce the coolant diameter. In one variant, a mixture of water and glycol of approximately 20 / 80 to approximately 80 / 20, preferably 50 / 50, is to be pumped through the cooling fluid channels.

[0029] In a variant of the internal rotor machine, the heat conducting layer forms approximately Vs to 2 / s, especially about 1 / 2 of the volume of the rotor in the axial direction.

[0030] In one variant, the permanent magnet element is formed by mutually insulated discs with a strip-shaped, circular-ring-segment-shaped, or trapezoidal cross-section. In one variant, each rotor tooth element is made of laminated and mutually insulated sheet material containing a nickel-iron, silicon-iron, or cobalt-iron alloy with sheet thicknesses between 0.025 and 0.5 mm, and / or a coercive field strength of < 1.6 ± 1 A / cm, and / or a specific resistance of approximately 0.4 ± 0.25 Ω mm. 2 / m formed.

[0031] In one variant, the rotor shaft has a first end with an end face that has a central connection for a cooling fluid supply or discharge line that penetrates the rotor shaft centrally and lengthwise. This cooling fluid supply or discharge line opens into a radially projecting first annular collar with several axially oriented openings in the region of a second end of the rotor shaft. The openings communicate with the cooling fluid channels of the carrier plates. In one variant, the first annular collar is formed integrally with the rotor shaft or is held captive thereon in the longitudinal and / or circumferential direction. In one variant, the rotor shaft has a connection on its circumference in the region of the first end for a cooling fluid supply or discharge line that penetrates the rotor shaft in the shape of a hollow ring. This cooling fluid supply or discharge line opens into one or more radially oriented openings that communicate with the cooling fluid channels of the carrier plates.In one variant, this cooling fluid supply or discharge line opens into a radially projecting second annular collar with several axially oriented openings near the first end of the rotor shaft. The openings communicate with the cooling fluid channels of the support plates. In one variant, the second annular collar is formed integrally with the rotor shaft or is held captively on it in the longitudinal and / or circumferential direction.

[0032] In one variant of the internal rotor machine, rotor disks mounted on the rotor shaft are offset from each other by a circumferential angle. This creates a groove chamfer effect for the electric machine.

[0033] In one variant, permanent magnets serve as the field excitation source, particularly rare-earth magnets in the form of neodymium-iron-boron (Nd 2 Fe 14 B), samarium-cobalt (SmCo 5 and Sm 2 Co 17), samarium-iron-nitrogen (Sm 2 Fe 18 N 3), cerium-cobalt (Ce Co 5), iron-germanium (Fe 3 Ge), barium or strontium ferrite (Ba Fe 12 O 19; Fe 12 O 19 Sr), or magnets containing an AINi or AINiCo alloy. The permanent magnet elements can also be pressed, cast, or cut parts made of these materials.

[0034] The rotor discs of the internal rotor machine, which are located on the rotor shaft, are held against each other on the rotor shaft.

[0035] In one variant, the rotor shaft is preferably made of sintered metal. Alternatively or additionally, the rotor shaft has a stiffening structure between its central cooling fluid supply or discharge line and the outer surface of the rotor shaft. Alternatively or additionally, the rotor shaft is formed as an additive component, preferably from a titanium-containing metal, such as Ti-6AI-4V (also known as Ti64), which is a high-strength titanium alloy containing titanium, 6 mass percent aluminum, and 4 mass percent vanadium.

[0036] Short description of the characters

[0037] Further features, properties, advantages, and advantages of the devices and methods can be found in the following description in conjunction with the drawings. Possible modifications will also become clear to a person skilled in the art from the following description, which refers to the accompanying drawings. The figures schematically show the devices discussed here.

[0038] Here we show:

[0039] Fig. 1 shows a schematic representation of a fluid-cooled, multi-phase permanent magnet synchronous machine as an application in an aircraft drive train;

[0040] Fig. 2 shows a schematic longitudinal section of the fluid-cooled, multi-phase permanent magnet synchronous machine with a stator and a rotor in internal rotor configuration; and

[0041] Fig. 2a shows a schematic longitudinal section of the fluid-cooled, multi-phase permanent magnet synchronous machine with a stator and a rotor in external rotor configuration; and

[0042] Fig. 3 shows a schematic partial cross-sectional view of the fluid-cooled, multi-phase permanent magnet synchronous machine from Fig. 2.

[0043] Detailed description of variants of devices and procedures

[0044] Fig. 1 illustrates an aircraft drive train in which an electric aircraft propulsion system is implemented. This aircraft propulsion system is part of an aircraft drive train and comprises a fluid-cooled, permanent magnet synchronous machine 10, also disclosed here. Further components of the aircraft drive train include an electrical energy source 2, which can be designed, for example, as shown here, as a hydrogen, methane, or methyl alcohol-powered fuel cell unit with water and / or carbon dioxide as exhaust gas. Alternatively, an accumulator or solar-powered ultracaps can also be provided to supply the electric aircraft propulsion system with electrical energy. A multi-phase 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, with the fluid being circulated through a heat exchanger (not further illustrated).Optionally, a (reduction) gear 4 is coupled between the electric aircraft drive and a propeller, a propeller, or a turbine 8. Depending on the speed / torque design of the synchronous machine 10, the gear 4 may also be omitted.

[0045] Fig. 2 illustrates the fluid-cooled, multi-phase permanent magnet synchronous machine 10, with a stator 12 and a rotor 14 in an internal rotor configuration. Such a PMSM can be used, for example, in the drive train 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 is axially divided, for example, into three rotor disks 14a seated on a rotor shaft 22. Each rotor disk 14a comprises a stack of carrier plates 24, which carry a plurality of permanent magnet elements 18 and soft-magnetic rotor tooth elements 26 along their outer circumference. The carrier plates 24 are at least almost non-magnetic, more precisely, paramagnetic.

[0046] A heat-conducting layer 28 extending from the permanent magnet elements 18 at least close to the rotor shaft 22 is accommodated between each two adjacent support plates 24. The rotor 14 has cooling fluid channels 30 penetrating the support plates 24 of the rotor disk 14a radially and axially near the rotor shaft 22. The rotor shaft 22 has cooling fluid supply and / or discharge lines 32, 34 connected to the cooling fluid channels 30 of the rotor 14.

[0047] In one variant, the support plates 24 of the rotor 14 are made of a titanium-containing alloy, such as Ti-6AI-4V. Instead of a titanium alloy, another lightweight metal can also be used. The thermally conductive layer 28 is formed here from several thermally conductive graphite foils. Thus, the rotor is constructed from components that are at least virtually ineffective magnetically and are magnetically inductive. A sealing plate 24a is arranged between each support plate 24 and the adjacent thermally conductive layer 28 in the area near the rotor shaft 22.

[0048] A first region 24' containing the cooling fluid channels 30 in the carrier plate 24 extends approximately 10% to approximately 60% of the radial extent of the carrier plate 24. The sealing plate 24a rests against this region. In a second region 24" of the carrier plate 24 adjacent to the first region 24', radially outward-facing spokes 24c are provided. These spokes 24c each have a fork-shaped receptacle 24d for the rotor tooth elements 26 at their free end.

[0049] Each permanent magnet element 18 has a cross-sectional shape approximately shaped like a circular ring segment or trapezoid, with its shorter concentric or parallel side 18a oriented toward the air gap 20. The two oblique sides 18b of the permanent magnet element 18 are oriented toward respective opposite oblique sides 26a of two adjacent rotor tooth elements 26. Each of the permanent magnet elements 18 is magnetically oriented essentially tangentially, with two adjacent permanent magnet elements 18 being magnetically oppositely oriented, as indicated by the directional arrows in the permanent magnet elements 18. The rotor tooth elements 26 alternate with the permanent magnet elements 18 in the circumferential direction. One of the rotor tooth elements 26 is received in the fork-shaped receptacle 24d of each of the spokes 24c.Each pair of adjacent rotor tooth elements 26 extends beyond the permanent magnet element 18 accommodated between them in the radial direction toward the air gap 20. Furthermore, two adjacent rotor tooth elements 26 have projections 26a that also extend beyond the permanent magnet element 18 accommodated between them in the circumferential direction and limit its movement in the radial direction.

[0050] The rotor tooth element 26 is held in a form-fitting manner on the receptacle 24d. For this purpose, the rotor tooth element 26 and the receptacle 24d have two hooks 26a', 26a" that engage in a pocket 24e, in which they are secured by locking pins 24f, here made of a stable, suitable ceramic.

[0051] The inclined sides 18b of the permanent magnet element 18 and the oppositely inclined sides 26b of two adjacent rotor tooth elements 26 have a radial angle that causes the permanent magnet element 18 and its adjacent rotor tooth elements 26 to self-lock in the radial direction. The wedge-shaped design of the rotor tooth elements and the permanent magnet element causes the rotor to be preloaded by self-locking. This is particularly true after the synchronous machine 10 is brought to a spin speed > nominal speed, for example, 20-30% higher than the spin speed during assembly of the machine. Centrifugal force drives the permanent magnet element 18 between the adjacent rotor tooth elements 26 radially outward against the projections 26a of the rotor tooth elements 26. Due to the self-locking, the permanent magnet element 18 then remains there even at nominal speed during operation of the synchronous machine 10.

[0052] The heat-conducting layer 28 forms a thermal connection between the permanent magnet elements 18 arranged on the circumference of the rotor – and the rotor tooth elements 26 – and the cooling fluid channels 28 near the rotor shaft 22. The heat-conducting layer 28 has a contact area 28a angled in the axial direction, which is in contact with a radially inner side 18c of the permanent magnet element 18. The heat-conducting layer 28 is preferably formed from several heat-conducting graphite foils to reduce the coolant diameter. This means that the specifically heavier cooling fluid is guided radially further inward, which has a positive effect on the lower pressure load on the cooling fluid lines at high rated speeds. In the axial direction, the heat-conducting layer 28 forms approximately half the axial length of the rotor core in the area of ​​the spokes 24c of the rotor.As a cooling fluid, a coolant adapted to the application with a suitable throughput is pumped through the cooling fluid channels 28 by a pump (not further illustrated).

[0053] Each permanent magnet element 18 is formed by mutually electrically insulated discs of a few mm axial length with a circular ring-segment-shaped or trapezoidal cross-section. The permanent magnet elements 18 are rare earth magnets in the form of neodymium-iron-boron (Nd 2 Fe 14 B), samarium-cobalt (SmCo 5 and Sm 2 Co 17), samarium-iron-nitrogen (Sm 2 Fe 18 N 3), cerium-cobalt (Ce Co 5), or iron-germanium (Fe 3 Ge), or the like, or an AINi or AINiCo alloy, or barium or strontium ferrite (Ba Fe 12 O 19; Fe 12 O 19 Sr).

[0054] Each rotor tooth element 26 is made of laminated and mutually insulated sheet material containing a nickel-iron, silicon-iron or cobalt-iron alloy with sheet thicknesses between, for example, 0.025 and 0.5 mm, and / or a coercive field strength of, for example, approximately < 1.6 ± 1 A / cm, and / or a specific resistance of, for example, approximately 0.4 ± 0.25 Ω mm 2 / m formed.

[0055] The rotor shaft 22 has a first end with an end face 22a, which has a central connection 22b for a cooling fluid supply or discharge line 32 penetrating the rotor shaft 22 centrally and lengthwise. This cooling fluid supply or discharge line 32 opens in the region of a second end of the rotor shaft 22 into a radially projecting first annular collar 38 with a plurality of axially oriented openings 38a. The second end 22b of the rotor shaft 22 is the output-side end of the electric machine 10. The first annular collar 38 is formed integrally with the rotor shaft 22. Alternatively, it is held captive in the longitudinal and / or circumferential direction. The axially oriented openings 38a are arranged radially close to the rotor shaft 22, evenly distributed in the circumferential direction of the first annular collar 38. The openings 38a communicate with the cooling fluid channels 28 of the support plates 24.

[0056] The rotor shaft 22 has a connection on its circumference in the region of the first end for a cooling fluid supply or discharge line 34 penetrating the rotor shaft 22 in the shape of a hollow ring. This cooling fluid supply or discharge line 34 leads in the region of the first end of the rotor shaft 22 into a radially projecting second annular collar 48 with a plurality of axially oriented openings 48a. These openings 48a communicate with the cooling fluid channels 28 of the support plates 24. The cooling fluid supply or discharge line 34 opens into the plurality of radially oriented openings 38b, which communicate with the cooling fluid channels 28 of the support plates 24. The rotor disks 14a seated on the rotor shaft 22 are held on the rotor shaft 22 in a clamped manner against one another. For this purpose, the second annular collar 48 is held captively in the longitudinal and / or circumferential direction on the rotor shaft 22 by means of tension rods (not further illustrated) which extend through the support plates 24 to the first annular collar 38.Furthermore, the second annular collar 48 is held in a rotationally fixed manner on the rotor shaft 22 by means of anti-rotation devices (not further illustrated). The rotor disks 14a seated on the rotor shaft 22 are offset from one another by a circumferential angle. This has the effect of a groove bevel.

[0057] The rotor shaft 22 is preferably 3D-printed from sintered metal and has a stiffening structure 50 between the cooling fluid supply or discharge line 32, 34 and the outer surface of the rotor shaft 22. For this purpose, the rotor shaft with the stiffening structure is formed as an additive component, here, for example, from a metal containing titanium, Ti-6AI-4V. This stiffening structure 50, in addition to the choice of material, serves to reduce weight and increase the stability of the overall assembly. The rotor shaft 22 has (angular contact) bearings (not illustrated here) at both ends of the machine 10.

[0058] The field coils 16 are to be energized from the inverter 6 at a nominal speed of, for example, approximately 14,000 - 16,000 rpm with a pole alternating frequency of, for example, approximately 3,600 - 4,200. The inverter 6 has power electronics that are mounted on a bearing flange (shield B) of the machine in a swinging manner and are thus vibration-decoupled.

[0059] This design allows, for example, a machine 10 with a torque of more than approximately 380 Nm, which has a total length of approximately 450 mm including the inverter 6 and a maximum diameter of approximately 300 mm. The output power in continuous operation of the machine is, for example, approximately 500–800 kW at a rated speed of approximately 12,000 rpm to approximately 18,000 rpm, with the total mass of the machine and inverter 6 being approximately 35–50 kg. The overall efficiency of the machine 10 and inverter 6 can be, for example, approximately 96%, which represents a highly efficient machine with a very good power-to-weight ratio and minimal installation space.

[0060] Fig. 2a illustrates a fluid-cooled, multi-phase permanent-magnet synchronous machine 10 with a stator 12 and a rotor 14 in an external rotor configuration. Such a machine can also be used, for example, in the drive train of Fig. 1. The inner stator 12 of the synchronous machine 10 has field coils 16 to be energized, and the outer 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 is rotationally fixedly connected to the rotor shaft 22. The rotor 14 has at least one at least virtually non-magnetic support tube 14r. The support tube 14r carries a plurality of permanent magnet elements 18 and soft-magnetic rotor tooth elements (not shown in the figure) along its inner wall. The rotor tooth elements alternate with the permanent magnet elements 18 in the circumferential direction.

[0061] The rotor shaft 22 has a first end with an end face 22a, which has a central connection 22b for a cooling fluid supply or discharge line 32 penetrating the rotor shaft 22 centrally and lengthwise. This cooling fluid supply or discharge line 32 opens in the region of a second end of the rotor shaft 22 into a radially projecting first annular collar 38 with a plurality of axially oriented openings 38a. The axially oriented openings 38a are arranged radially close to the rotor shaft 22, evenly distributed in the circumferential direction of the first annular collar 38. The second end of the rotor shaft 22 is the output-side end of the electric machine 10. The first annular collar 38 is formed integrally with the rotor shaft 22. Alternatively, the first annular collar 38 is held captive on the rotor shaft 22 in the longitudinal and / or circumferential direction thereof.A radially projecting second annular collar 48 is held displaceably on the rotor shaft 22 at a short distance from the first annular collar 38 in the longitudinal direction of the rotor shaft 22. The second annular collar 48 is provided with a plurality of axially oriented openings 48a. A heat-conducting layer 28 extending from the permanent magnet elements 18 at least close to the rotor shaft 22 is accommodated between the first annular collar 38 and the second annular collar 48. Through recesses in the heat-conducting layer 28, the openings 48a of the second annular collar 48 are in fluid communication with the openings 38a of the first annular collar 38. Cooling fluid channels 30 thus penetrate the rotor 14 near the rotor shaft 22 in the radial and axial directions. These cooling fluid channels 30 of the rotor 14 are connected to the cooling fluid supply and / or discharge lines 32, 34.

[0062] Each permanent magnet element 18 has a cross-sectional shape approximately shaped like a circular ring segment or trapezoid, with its shorter concentric or parallel side oriented toward the air gap 20. The two oblique sides of the permanent magnet element 18 are oriented toward respective opposite oblique sides of two adjacent rotor tooth elements. Each of the permanent magnet elements 18 is magnetically oriented essentially tangentially to the inner circumference of the support tube 14r, with two adjacent permanent magnet elements 18 being magnetically oppositely oriented. Each two adjacent rotor tooth elements 26 project beyond the permanent magnet element 18 accommodated between them in the radial direction toward the air gap 20.

[0063] The heat-conducting layer 28 forms a thermal connection between the permanent magnet elements 18 arranged on the inner circumference of the support tube 14r of the rotor 14 – and the rotor tooth elements 26 – and the cooling fluid channels 28 near the rotor shaft 22. The heat-conducting layer 28 has an axially angled contact area 28a, which is in contact with a radially inner side 18c of the permanent magnet element 18. The heat-conducting layer 28 is preferably formed from several heat-conducting graphite foils to reduce the coolant diameter. This means that the cooling fluid, which is heavier than the heat-conducting layer 28, is guided radially further inward, while the heat-conducting layer 28 extends radially outward to the permanent magnet elements 18. This has a positive effect on the lower pressure load on the cooling fluid lines at high rated speeds.A pump (not further illustrated) delivers a coolant adapted to the application with a suitable throughput through the cooling fluid channels 28.

[0064] Each permanent magnet element 18 is formed by mutually electrically insulated discs of a few mm axial length with a circular ring-segment-shaped or trapezoidal cross-section. The permanent magnet elements 18 are rare earth magnets in the form of neodymium-iron-boron (Nd 2 Fe 14 B), samarium-cobalt (SmCo 5 and Sm 2 Co 17), samarium-iron-nitrogen (Sm 2 Fe 18 N 3), cerium-cobalt (Ce Co 5), or iron-germanium (Fe 3 Ge), or the like, or an AINi or AINiCo alloy, or barium or strontium ferrite (Ba Fe 12 O 19; Fe 12 O 19 Sr).

[0065] Each rotor tooth element is made of laminated and mutually insulated sheet material containing a nickel-iron, silicon-iron or cobalt-iron alloy with sheet thicknesses between, for example, 0.025 and 0.5 mm, and / or a coercive field strength of, for example, approximately < 1.6 ± 1 A / cm, and / or a specific resistance of, for example, approximately 0.4 ± 0.25 Ω mm 2 / m formed.

[0066] The rotor shaft 22 is preferably 3D-printed from sintered metal and has a stiffening structure (not further illustrated in Fig. 22a) analogous to the stiffening structure 50 in Fig. 2 between the cooling fluid supply or discharge line 32, 34 and the outer surface of the rotor shaft 22. For this purpose, the rotor shaft with the stiffening structure is formed as an additive component, here from a metal containing titanium, Ti-6AI-4V. This stiffening structure, in addition to the choice of material, serves to reduce weight and increase the stability of the overall assembly. The rotor shaft 22 has (angular contact) bearings (not further illustrated here) at both ends of the machine 10.

[0067] The stator 12 is fixedly mounted on the housing 10a, which is only partially shown in Fig. 2a. Furthermore, the stator 12 is rotatably mounted relative to the rotor shaft 22 by means of two rolling bearings 12w, so that the rotor shaft 22 can rotate with the rotor relative to the stator 12. The stator 12 is designed, at least in its radially outer region 12a, as a laminated core and carries field coils 16.

[0068] The field coils 16 are to be energized from the inverter 6 at a nominal speed of, for example, approximately 14,000 - 16,000 rpm with a pole change frequency of, for example, approximately 3,600 - 4,200 Hz. The inverter 6 has power electronics that are mounted on a bearing flange (shield B) of the machine in a vibration-free manner and are thus vibration-decoupled.

[0069] The variants of the device described above, as well as their construction and operating aspects, serve merely to better understand the structure, functionality, and properties; they do not limit the disclosure to the exemplary embodiments. The figures are partly schematic, with essential properties and effects sometimes shown significantly enlarged to clarify the functions, operating principles, technical configurations, and features. Each functionality, principle, technical configuration, and feature 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 functionality, principles, technical configurations, and features contained in or resulting from this disclosure, so that all conceivable combinations can be assigned to the described procedure.This also includes combinations between all individual embodiments in the text, i.e., in every section of the description, in the claims, as well as combinations between different variants in the text, in the claims, and in the figures. The claims also do not limit the disclosure and thus the possible combinations of all the features shown with each other. All disclosed features are explicitly disclosed here, both individually and in combination with all other features.

Claims

Patent claims 1. A fluid-cooled, multiphase permanent magnet synchronous machine (10), with a stator (12) and a rotor (14) in an external or internal rotor configuration; wherein - the stator (12) has field coils (16) to be energized, and the rotor (14) has permanent magnet elements (18), and the stator (12) is radially spaced from the rotor (14) forming an air gap (20); - the rotor (14) comprises at least one support, at least nearly non-magnetic, which carries the permanent magnet elements (18) and soft magnetic rotor tooth elements (26); and - a heat-conducting layer (28) extends from the side of the permanent magnet elements (18) and / or the rotor tooth elements (26) away from the air gap (20) to near the rotor shaft (22).

2. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to claim 1, wherein - near the runner shaft (22) the runner (14) has cooling fluid channels (30) penetrating it; and - the rotor shaft (22) has cooling fluid supply and / or discharge lines (32, 34) connected to the cooling fluid channels (30) of the rotor (14), and / or wherein - the carrier - in an internal rotor configuration as at least one support plate (24) which is fixed to the rotor shaft (22) without rotation; or - is designed in an external rotor configuration as at least one support tube (14r) which is held non-rotatably on the rotor shaft (22); wherein preferably - in an internal rotor configuration, the heat-conducting layer (28) is in thermal contact with the at least one support plate (24), and the cooling fluid channels (30) penetrate the at least one support plate (24) to dissipate heat from the heat-conducting layer (28); or preferably - in an external rotor configuration the heat conducting layer (28) is in thermal contact with at least one ring collar, and the cooling fluid channels (30) penetrate the at least one ring collar to dissipate heat from the heat conducting layer (28).

3. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to any one of the preceding claims, wherein - the runner is made of components that are at least almost magnetically ineffective and is designed to be magnetically non-reverse; and / or - the rotor (14) is axially divided into two or more rotor disks (14a) mounted on a rotor shaft (22); and / or - a sealing plate (24a) is arranged between each support plate (24) and the adjacent heat-conducting layer (28) in the area near the rotor shaft (22); and / or - a first region (24') containing the cooling fluid channels (30) in the support plate (24) comprises approximately 10% to approximately 60% of the radial extent of the support plate (24) against which the sealing plate (24a) abuts; and / or - in a second area (24") adjacent to the first area (24') of the carrier plate (24) radially outwardly pointing spokes (24c) are provided, each of which has a receptacle (24d) for the runner tooth elements (26) at its free end.

4. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to one of the preceding claims, wherein - each permanent magnet element (18) has a cross-sectional shape approximately annular segment-shaped or trapezoidal, the shorter concentric or parallel side (18a) of which is oriented towards the air gap (20), and the two inclined sides (18b) of which are oriented towards the respective opposite inclined sides (26a) of two adjacent rotor tooth elements (26); - wherein each of the permanent magnet elements (18) is magnetically oriented substantially tangentially, and two adjacent permanent magnet elements (18) are magnetically oriented in opposite directions; and / or - two adjacent rotor tooth elements (26) project beyond the permanent magnet element (18) held between them in a radial direction towards the air gap (20), and preferably also in a circumferential direction; and / or in the preferably - the runner tooth element (26) is positively locked to the receptacle (24d), in particular the runner tooth element (26) and the receptacle (24d) have hooks (26a', 26a") which engage in a pocket (24e) in which they are secured by locking rods (24f); and / or preferably - the inclined sides (18b) of the permanent magnet element (18) and the opposite inclined sides (26b) of two adjacent rotor tooth elements (26) have a radial angle that causes self-locking of the permanent magnet element (18) and its adjacent rotor tooth elements (26) in the radial direction, and / or - the wedge-shaped design of the rotor tooth elements and the permanent magnet element causes a preload of the rotor through self-locking. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to one of the preceding claims, wherein - the thermal conducting layer (28) forms a thermal connection from the permanent magnet element (18) to the cooling fluid channels (30), and the thermal conducting layer (28) has a contact area (28a) that is in contact with a radially inner side (18c) of the permanent magnet element (18), and / or - the heat-conducting layer (28) preferably comprises several heat-conducting graphite foils to reduce the coolant diameter, and / or - the thermal conductivity layer (28) in the axial direction approximately Vs to 2 / s, especially 1 / 2 of the axial extent of the rotor is fulfilled. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to one of the preceding claims, wherein - that or each permanent magnet element (18) is formed by disks insulated from each other, and / or - each rotor tooth element (26) made of laminated and mutually insulated sheet material containing a nickel-iron, silicon-iron or cobalt-iron alloy with sheet thicknesses between 0.025 and 0.5 mm, and / or a coercive field strength < 1.6 ± 1 A / cm, and / or a resistivity of about 0.4 ± 0.25 Q mm 2 / m is formed, and / or - the permanent magnet elements (18) are rare-earth magnets in the form of neodymium-iron-boron (Nd₂Fe₁₄B), samarium-cobalt (SmCo₅ and Sm₂Co₁₇), samarium-iron-nitrogen (Sm₂Fe₁₈N₃), cerium-cobalt (CeCo₅), iron-germanium (Fe₃Ge), barium or strontium ferrite (BaFe₁₂O₁₉; Fe₁₂O₁₉Sr), or containing an AINi or AINiCo alloy. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to one of the preceding claims, wherein - the rotor shaft (22) has a first end with a front face (22a) which has a central connection for a cooling fluid supply or discharge line (32, 34) that penetrates the rotor shaft (22) centrally and lengthwise, wherein - this cooling fluid supply or discharge line (32, 34) opens in the area of ​​a second end of the rotor shaft (22) into a radially projecting first annular collar (38) with several axially oriented openings (38a), - the openings (38a) communicate with the cooling fluid channels (30) of the support plates (24), and - the first ring assembly (38) is formed in one piece with the runner shaft (22) or is held captive in the longitudinal and / or circumferential direction.

8. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to one of the preceding claims, wherein - the rotor shaft (22) has a connection on its circumference in the region of the first end for a cooling fluid supply or discharge line (32, 34) penetrating the rotor shaft (22) in a hollow ring shape, wherein - this cooling fluid supply or discharge line (32, 34) opens into one or more radially oriented openings (38b) which communicate with the cooling fluid channels (30) of the support plates (24), - this cooling fluid supply or discharge line (32, 34) opens in the area of ​​the first end of the rotor shaft (22) into a radially projecting second annular collar (48) with several axially oriented openings (48a), - the openings (48a) communicate with the cooling fluid channels (30) of the support plates (24), and - the second ring assembly (48) is formed in one piece with the runner shaft (22) or is held captive in the longitudinal and / or circumferential direction.

9. The fluid-cooled, multiphase permanent magnet synchronous machine (10) according to one of the preceding claims, wherein - the rotor discs (14a) mounted on the rotor shaft (22) are offset from each other by a circumferential angle on the rotor shaft (22), to create a groove chamfer, and / or the rotor discs (14a) mounted on the rotor shaft (22) are clamped against each other on the rotor shaft (22), and / or - the rotor shaft (22) made of preferably sintered metal has a stiffening structure (50) between the cooling fluid supply or discharge line (32, 34) and the outer surface of the rotor shaft (22), and / or is formed as an additive component, preferably made of titanium-containing metal, such as Ti-6Al-4V.

10. Electric aircraft propulsion system comprising a fluid-cooled, multi-phase permanent magnet excited synchronous machine according to any of the preceding claims.