Electric motor

Abstract

The invention relates to an electric motor having a field conductor designed as a rod in the stator, comprising a plurality of inverters for control rods, the power parts of the inverters being arranged on one or more circuit boards, the circuit boards being arranged on at least one cooling plate, the cooling plate being fixed directly to the rod or to a rod-like current conductor fixed thereto. The rod has an internal cooling channel or heat pipe for dissipating heat such that the rod dissipates heat in the region of the cooling plate.

Description

Technical Field

[0001] The invention relates to an electric motor having a field conductor designed as a rod on the stator side. Background Art

[0002] The electric motor can be designed such that the stator has a series of bars instead of wound wire conductors as field conductors. Compared with conventional windings, the bars have a low inductance. Therefore, a relatively large current is required to generate a predetermined magnetic field.

[0003] However, due to the low inductance of the rod, such a high current requires only a relatively low voltage of, for example, 12 V. The low voltage enables the components of the inverter for controlling the rod to be arranged at a small distance from one another. Thus, for example, the components of the power electronics can be arranged on one or more circuit boards arranged close to the electric motor. In this case, the rod can be used directly as a mechanical carrier for the circuit board or via an electrically conductive rod-shaped connecting element.

[0004] That is, in such an electric motor, the high packing density of the electrical and electronic components leads to high heat losses of the electrical and electronic components due to the high current intensity. The direct connection of the electrical and electronic components to the stator / rotor block via the rod ensures additional heat input from the stator / rotor block. This disadvantageously leads to considerable cooling costs for the electrical and electronic components on the circuit board. Summary of the invention

[0005] The object of the present invention is to specify an electric motor which reduces the disadvantages mentioned at the outset.

[0006] This object is achieved by an electric motor having the features specified in claim 1 .

[0007] The electric motor according to the invention comprises a stator having a plurality of field conductors designed as rods, and an inverter having one or more parallel-connected power sections for each field conductor for controlling the field conductors, wherein the inverter comprises a controller for generating control signals for the power sections.

[0008] Here, the output stages of the inverter are arranged on a plurality of circuit boards, and the circuit boards are arranged on at least one cooling plate, wherein the cooling plate is arranged such that the field conductor or a current conductor arranged on the field conductor extending the field conductor in the axial direction is mechanically operatively connected to the cooling plate.

[0009] Finally, there is at least one cooling device which comprises a fluid line which is guided at least in sections within one of the field conductors and / or the current conductors.

[0010] The electric motor according to the invention advantageously has an improved heat dissipation for the field conductors by means of the cooling device. As a result, a smaller heat flow reaches the cooling plate and the electronic devices arranged on the cooling plate, in particular the inverter. This in turn reduces the cooling costs in the area of ​​the cooling plate and the electronic devices.

[0011] The field conductor or current conductor preferably serves as a mechanical carrier for the cooling plate and is thus mechanically operatively connected to the cooling plate. The field conductor or current conductor can pass through the cooling plate and the printed circuit board.

[0012] Advantageous embodiments of the electric motor according to the invention are obtained from the dependent claims. Here, the embodiments of the independent claim can be combined with the features of one of the dependent claims or preferably also with the features of several dependent claims. Thus, the following features can also be provided in addition:

[0013] The fluid line may be a water line. Water is a standard coolant and may be provided, for example, in a mechanism external to the electric motor, so a line suitable for water is appropriate.

[0014] The electric motor may be designed to use an electrically conductive fluid as a cooling fluid, wherein the specific conductivity is at least 10 -2 S / m, in particular at least 1 S / m. If the cooling fluid is electrically conductive, an additional current path is thereby provided in the fluid line which would not otherwise be provided. As a result, for a given current flow through the field conductor or current conductor, the cross section of the metal conductor (e.g. copper) which must be provided for the current is reduced, thus saving material and weight.

[0015] The electric motor can be designed to use air as a cooling fluid. Air has the advantage of being less demanding in construction than other media, since the air does not need to be included and does not need to be enclosed relative to the structure to be cooled. Instead, the air can be guided in open cooling channels and provided at will.

[0016] The electric motor can have a pump for the cooling fluid. If the cooling fluid is not fed from the outside, it is advantageous if the electric motor is designed to be able to generate a fluid circulation which ensures heat dissipation by material movement. If the electric machine has a large number of field conductors, for example more than 50 or even more than 100 field conductors, a plurality of pumps can also be present.

[0017] The electric motor can be designed such that a fluid line is present for each of the field conductors and / or current conductors and the fluid line is guided at least in sections within the field conductors and / or current conductors. It is expedient to provide heat dissipation for each of the field conductors or current conductors, since during operation of the electric motor, the field conductors or current conductors are also subjected to thermal loads, so that each of the field conductors or current conductors contributes approximately the same amount to the heat transport to the cooling plate.

[0018] The region in which the fluid lines are guided in the field conductors and / or current conductors is advantageously located axially between the cooling plate and the axial start of the rotor. It is also advantageous if heat is dissipated in this region in order to reduce the heat input from the rotor region, i.e. from the drive system into the electronics, i.e. from the region of the cooling plate and the printed circuit board.

[0019] If a current conductor is present, it is expediently connected to the field conductor by means of a "ferrule", wherein the fluid lines can also be guided in the "ferrule". The ferrule serves for a fixed connection between the field conductor and the current conductor, wherein the field conductor belongs to the drive side of the electric motor, and the current conductor contacts the electronics on the printed circuit board and carries the cooling plate and the printed circuit board.

[0020] The electric motor can have a short-circuit ring for the electrical connection of the field conductors. The fluid lines for at least two of the field conductors can be connected to one another in the short-circuit ring. Advantageously, the fluid lines are connected in series on one side of the electric motor, so that the inlet and outlet are located on one side of the electric motor. It is expedient for the fluid lines to be connected together in pairs in the short-circuit ring.

[0021] If the fluid lines are connected together in pairs in short-circuit rings on the end face of the electric motor, it may be advantageous to also connect a part of the fluid lines on the back side of the electric motor. In this case, the fluid lines are advantageously connected in blocks of at least two fluid lines, so that the resulting connected fluid lines extend in a meandering manner through the stator. The number of inlets and outlets is thereby reduced, thereby simplifying the construction of the electric motor. In principle, the number of inlets and outlets can be reduced to one by connecting all fluid lines in series. In a specific design of the electric motor, it may be advantageous to use more than one outlet and inlet, that is, to connect the fluid lines in series only in blocks.

[0022] The fluid lines connected together can be spaced apart from each other so that they do not belong to adjacent conductor bars. For example, the fluid lines of every n-th conductor bar can be connected in series, wherein n is at least two. That is, in the case of n=2, the fluid line of the first conductor bar is connected to the fluid line of the next (third) conductor bar. Thus, for example, there can be n fluid channel paths that are separate from each other, which are composed of the fluid lines connected together. This advantageously achieves that in the event of a failure in one of the fluid channel paths, the lack of cooling does not affect the continuous block of conductor bars, but is evenly distributed over the circumference of the motor.

[0023] The fluid line can be formed at least partially by a cavity or hole in the field conductor and / or the current conductor. In principle, the fluid line then has no material of its own, since it is not a separate component. Alternatively, the fluid line can also be a separate component. In this case, the fluid line can have a metallic material, in particular can be metallic. Thus, advantageously the fluid line itself, and possibly also the cooling fluid, can be used as an electrical conductor.

[0024] The fluid line can also include a ceramic material, in particular be made of a ceramic material. Ceramic materials are heat-resistant, chemical-resistant and electrically insulating and are therefore advantageous in certain designs of electric motors.

[0025] The fluid line can be a heat pipe or a thermosiphon. It is therefore preferred that the fluid line is completely arranged in one of the field conductors and / or current conductors. Due to the extremely high thermal conductivity of the heat pipe, a strong heat dissipation of the field conductor or current conductor is achieved in the area of ​​the evaporator side of the heat pipe. The evaporator side of the heat pipe is preferably arranged in the area of ​​the cooling plate and the circuit board, or between the cooling plate and the circuit board and the stator / rotor block. As a result, in particular, it is prevented or reduced that the waste heat from the stator / rotor block additionally heats the cooling plate and the circuit board through the field conductor. On the one hand, the condenser side of the heat pipe can be arranged at a position away from the stator / rotor block and on the other side of the cooling plate. Alternatively, the condenser end can also be arranged in the area of ​​the short-circuit ring of the motor. Here, the heat pipe can also extend into the short-circuit ring.

[0026] In the region of the condenser end of the heat pipe, it is expedient to enable good heat dissipation, for example by the presence of cooling fins. If the condenser end of the heat pipe is located in the region of the short-circuit ring, the short-circuit ring can be constructed, for example, in the form of a laminate, wherein the individual laminates can be spaced apart. The short-circuit ring thus has a larger surface, thus enabling effective heat dissipation. This can be assisted by a forced air movement, for example by an internal or external fan.

[0027] The electric motor can have several circuit boards. In particular, several individual circuit boards can be arranged on a cooling plate. By distributing the components on several circuit boards, the power electronics used can be modularized. Thus, a plurality of circuit boards of the same type can be used to provide a large number of converters, whereby the manufacturing efficiency is improved with regard to scrap.

[0028] The circuit board can be designed to be a circular sector or an annular sector. Thus, the circuit board can be arranged in a circle or a ring around the axis of the motor. Circuit boards with this shape can be combined into a circle or a ring, thereby being arranged at the axial end of the motor in a manner that best matches the shape of the motor, wherein a high degree of modularity is achieved at the same time. Thus, the circuit board can be arranged axially displaced relative to the stator and the rotor in a space-saving manner and form an integral part of the motor. In this way, multiple cooling plates and circuit boards can also be arranged axially displaced relative to each other, so that, for example, they are connected in parallel with inverters arranged in the same azimuth position.

[0029] The cooling plate is preferably arranged perpendicularly to the axis of the electric motor. In this way, the cooling plate with the circuit board can be arranged in a space-saving manner at the axial end of the electric motor. It is also possible to arrange a plurality of cooling plates axially displaced and close to one another. In addition, in this arrangement, a uniform spacing is provided between the cooling plate and the power electronics and the rods forming the field conductors, whereby contacting the rods is simplified.

[0030] It is particularly advantageous to control each field conductor with a separate phase. A phase is to be understood as an AC voltage supply which is phase-shifted by an angle different from zero compared to all other phases used in the electric motor. In this case, it is expedient for each field conductor to have its own inverter which controls only this field conductor.

[0031] The inverter can be designed to generate an AC voltage with an amplitude of 200 V or less, in particular 150 V or less, in particular 50 V or less. The voltage generated in this way is the voltage applied to the field conductors, i.e. the stator bars. Due to this relatively low voltage, the components of the inverter can be arranged very close to each other. Distances of about 2 mm between components such as power semiconductor switches can be used, resulting in a high packaging density of electronic components and the ability to arrange a plurality of inverters in a relatively small space. As a result, a large number of phases can be used with a small space requirement, in particular a number of phases corresponding to the number of stator bars. Thus, with a correspondingly large number of stator bars, 48, 72 or even 120 phases can be used.

[0032] Herein, the terms "axial", "radial" and "azimuth" relate to the axis of the rotor and thus to the corresponding axis of symmetry of the stator. Herein, "axial" describes a direction parallel to the axis, "radial" describes a direction orthogonal to, towards or away from the axis, and "azimuth" is a direction oriented to maintain a constant radial distance from the axis and to maintain a constant axial position in a circle around the axis.

[0033] If the terms "axial", "radial" and "tangential" are used with respect to a surface, such as a cross section, these terms describe the orientation of the normal vector to that surface, ie the orientation of the vector perpendicular to the relevant surface.

[0034] Such electric motors can advantageously be used in applications in which a high power of 10 kW or more, in particular 100 kW or more, in special designs 1 MW or more, adjustable over a wide torque and power range is required. Furthermore, such electric motors are advantageous when a compact design is required. Examples of advantageous fields of application are ship drives from small boats to large ships, motor vehicles, pumps, fans, centrifuges in the industrial sector; transport and the food industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be described and explained in detail below with the aid of the embodiments shown in the accompanying drawings. In the accompanying drawings:

[0036] Figure 1 An oblique view shows an electric motor having a power section arranged on circuit boards which are carried by a cooling plate.

[0037] Figure 2 The circuit board arranged on the cooling plate is shown in a front view,

[0038] Figure 3 A detail of an electric motor is shown in an oblique view, the detail having a cooling plate with a printed circuit board.

[0039] Figure 4 shows a sectional view of a conductor bar with an inserted cooling plate and with fluid channels and hose connections,

[0040] Figure 5 shows a sectional view of a conductor bar with three inserted cooling plates and with fluid channels and hose connections,

[0041] Figure 6 shows the fluid channels leading to the front and back of the motor,

[0042] Figure 7 A cross-sectional view of a motor with a heat pipe as a fluid channel is shown,

[0043] Figure 8 A detail of an end face of an electric motor with a short-circuit ring in the form of a lamination stack is shown. DETAILED DESCRIPTION

[0044] Figure 1 FIG. 1 shows an isometric view of an electric motor 10 as one embodiment of the present invention. The electric motor 10 includes a stator 11 and a rotor substantially arranged in the stator 11. Figure 1 The rotor is connected to the shaft in a rotationally fixed manner, which is also Figure 1 The rotor is rotated around the axis 9 by electromagnetic interaction between the rotor and the energized stator 11. Here, the rotor is isolated from the stator 11 by an air gap. In other embodiments, the motor 10 may also be an outer rotor motor or a bell armature motor.

[0045] The stator 11 includes a plurality of rigid straight conductor bars 12 as field conductors. Figure 1 The conductor bars 12 are connected to each other through short-circuit rings 38 on the end faces 13 that are far away from each other. On the back side 14 of the motor 10, the conductor bars 12 are fed separately through the corresponding inverter modules. Because the motor 10 is a motor 10 that operates at a low voltage due to the conductor bars 12, the inverter module can be arranged relatively closely together with other components of the electronic device (DC voltage converter, rectifier) ​​on the circuit board 15. Here, in this example, the circuit board 15 is annular sector-shaped, and many individual circuit boards 15 together form an annular circuit board structure.

[0046] Although it is assumed in this example that the circuit board 15 carries at least the power part of the inverter, a part of the circuit board 15 may also carry a rectifier and a DC / DC converter.

[0047] Figure 2 Here, for greater clarity, the plan view of the circuit board structure is shown. Figure 1 Compared with the diagram in Figure 2 The number of circuit boards shown in the figure is reduced and is shown in a greatly simplified manner. The specific number of such circuit boards 15 depends on the specific design of the electric motor 10, in particular the number of conductor bars 12. Each circuit board 15 includes a plurality of semiconductor switches 422. These semiconductor switches 422 together form the power part of the inverter, which provides the conductor bars 12 with an AC voltage.

[0048] In addition, part of the circuit board 15 or the entire circuit board 15 may include a drive circuit and other electronic components not shown in the drawings, such as a condenser. The semiconductor switch 422 is a power semiconductor, such as an IGBT, a MOSFET or a JFET, and may additionally include a diode not shown, depending on the wiring. The semiconductor switch 422 is connected to form a half bridge, for example. The condenser not shown may be, for example, an intermediate circuit condenser of a half bridge. Here, the semiconductor switch 422 of a circuit board 15 may be assigned to a single phase. In the case where the motor 10 has a large number of field conductors 12 and a corresponding number of phases, it is advantageous that a circuit board 15 carries a power section for multiple phases.

[0049] Furthermore, the printed circuit board 15 comprises contact points 421 which are connected to the conductor bars 12. The printed circuit board 15 is supported by a disk-shaped cooling plate 16, wherein the cooling plate 16 can be covered on both sides with the printed circuit board 15 for better utilization of space.

[0050] Since relatively large currents are required in the conductor bars of the electric motor 10, it is preferred that a plurality of power sections are connected in parallel for energization. This can be achieved, for example, by Figure 1 All six circuit board structures on three cooling plates 16 shown in FIG. 1 are connected to the conductor bars 12 in the same manner, thereby realizing a parallel electrical connection. Here, the following situation is utilized, that is, the conductor bars 12 or the connecting elements 18 to the conductor bars 12 penetrate the cooling plates 16 at the contact points in the same manner, thereby also penetrating the circuit boards 15, or in the case of the outermost cooling plates 16, at least contact the cooling plates 16, thereby also contacting the circuit boards 15.

[0051] Figure 3 The cross-section of the electric motor 10 is shown in an oblique view. It can be seen here that the connecting element 18 mechanically supports and penetrates three cooling plates 16. The connecting element 18 is connected to the conductor bar 12 via a ferrule 17. The output stages are connected in parallel and jointly supply the conductor bar 12 with current, which are located on the printed circuit board 15 in the areas in which one of the connecting elements 18 penetrates the cooling plate 16. Figure 3 As can be seen in the configuration shown in FIG, two of the connecting elements 18 pass through one circuit board 15, respectively. Therefore, each circuit board carries the output stages of two phases of the motor 10. In other variants of the motor 10, a single circuit board 15 can also carry only one phase or three or more phases, wherein the same number of connecting elements 18 pass through the circuit board 15.

[0052] The stator / rotor block 8 of the electric motor 10 and the electronics on the printed circuit board 15 generate heat. In addition to being electrical conductors, the conductor bars 12 and the connecting elements 18 are also a thermal bridge between these two components. However, it is important, especially with regard to the electronics, that no excessive additional heat input is generated, since the temperature of the electronic components cannot exceed approximately 80° C. for a long period of time. However, the complexity of increasing cooling in the area of ​​the printed circuit board is high.

[0053] Figure 4 A sectional view of a section of an electric motor 10 is shown. The sectional view shows two circuit boards 15 arranged on both sides of a cooling plate 16 . Figure 4 The arrangement in corresponds to Figures 1 to 3 Therefore, Figure 4The sectional view in FIG. 1 shows only two of the circuit boards 15 of the ring structure formed by the circuit boards 15. The cooling plate 16 is pushed onto the conductor bar 12 and is carried by the conductor bar 12. In order to be pushed onto the conductor bar 12, the conductor bar 12 tapers toward the end. The metal sleeve 25 creates an increased conductor cross section in the tapered region between the circuit board 15, i.e., the front and back sides of the cooling plate 16. The cooling plate and the circuit board 15 can be fixed, for example, by means of a nut 26. For this purpose, it is expedient for the conductor bar 12 to have an external thread in the end region.

[0054] The conductor bar 12 accordingly comprises a fluid channel 20, for example, as a hole. The fluid channel 20 is continuous and ends at the outer end of the conductor bar 12. A hose connection 23 can be arranged there, which is connected to a hose 24. The hose 24 and the fluid channel 20 allow a cooling fluid (for example, air or water) to flow through the conductor bar 12, thereby dissipating heat. Here, the fluid channel 20 can be led out of the conductor bar 12 at another point to realize a second connection, i.e., an outflow opening.

[0055] Can be Figure 4 The configuration shown in FIG. 1 is extended to connect more than one cooling plate 16. Figure 5 . In this embodiment, the end of the conductor bar 12 has a groove 26 towards the end, which in this example has an enlarged diameter compared to the fluid channel 20. The groove 26 is provided with an internal thread. A threaded rod 27 is screwed into the groove 26. The threaded rod 27 itself has a fluid channel 20, which in the screwed-in state continues the fluid channel 20 of the conductor bar 12.

[0056] Then, in Figure 5 In the example of FIG. 1 , a series of three cooling plates 16 each with a circuit board 15 are pushed onto a threaded rod 27. In order to ensure that current is conducted between the circuit boards 15 at the correct spacing under the contact pressure required for making contact and also to ensure electrical conduction, sleeves 25, 28 are inserted. Figure 4 In the embodiment of FIG. 1 , a hose connector 23 is arranged at the end of the threaded rod 27 , and the hose connector 23 connects the fluid channel 20 and the hose 24 .

[0057] exist Figure 6 An advantageous embodiment of a return flow channel for realizing a flow of a cooling fluid is shown in FIG. Figure 6The electric motor 10 is shown in a greatly simplified manner with the cooling plate 16 and the printed circuit board 15 omitted, and has a stator / rotor block 8 through which the conductor bars 12 of the stator 11 pass. The conductor bars 12 lead to a short-circuit ring 38 at one end, which connects the conductor bars 12. Here, the short-circuit ring 38 is designed so that the short-circuit ring 38 itself has a fluid channel 20, which is designed so that each of the fluid channels 20 connects two (in the simplest case, adjacent) conductor bars 12 to each other. In this way, a flow is achieved in which the first conductor bar 12 is an inlet, that is, the cooling fluid enters the inlet at the back 14 of the electric motor 10, and the conductor bar 12 adjacent thereto is an outlet, at which the cooling fluid also leaves at the back of the electric motor 10. The hoses 23 at the inlet and outlet can be connected at other locations to realize a cooling circuit. In this case, the heat can be dissipated to the environment via a heat exchanger or a radiator. The mentioned elements can be implemented as part of the electric motor 10. Alternatively, the cooling circuit may also already be present at the installation location of the electric motor 10 independently of the electric motor 10 , and the electric motor 10 may be connected to the cooling circuit together with other devices.

[0058] Since all conductor bars 12 are likewise heated by the side of the stator / rotor block 8 and are likewise connected to the circuit board 15, it is expedient to provide a fluid channel 20 for each conductor bar 12. However, in certain embodiments of the electric motor 10, the number of conductor bars 12 is larger, for example 48, 72 or even 120. In the latter case, there are therefore 60 outflows and 60 inflows, which must be connected or brought together at other locations and which must be made available for the water flow, for example by means of a pump system. Therefore, it is advantageous for certain embodiments of the electric motor 10, such as Figure 6 As shown, the fluid channels are also partially connected to each other on the back side 14. For this purpose, the connected hose 24 is led directly to another conductor bar 12 and connected there as well. It is suitable here that the conductor bars of other pairs are connected as in the case of the short-circuit ring 18 to achieve a meandering guidance of the cooling fluid. Therefore, the cooling fluid can be guided through 4, 6, 8 or more of the conductor bars 12 using a single inlet and a single outlet, thereby simplifying the construction. Therefore, according to the cooling needs, all the conductor bars can also be connected to form a cooling fluid path, but it is also possible to connect half, one third or any other fractional divisions to form a cooling fluid path.

[0059] It is particularly advantageous that the cooling fluid path formed by a plurality of fluid channels connected in series comprises the fluid channels of the following conductor bars, which are separated in azimuth order by one, two or more conductor bars located therebetween. If the conductor bars are numbered consecutively in azimuth, for example, the first cooling fluid path may comprise the fluid channels of conductor bars 1, 5, 9, 13, 17, ..., while the second cooling fluid path comprises the fluid channels of conductor bars 2, 6, 10, 14, 18, ..., the third cooling fluid path comprises the fluid channels of conductor bars 3, 7, 11, 15, 19, ..., and the fourth cooling fluid path comprises the fluid channels of conductor bars 4, 8, 12, 16, 20, .... With these four cooling fluid paths, all fluid channels are part of the cooling fluid path. In other words, the cooling fluid paths are intertwined. If such a cooling fluid path fails due to a technical defect, this will not affect the continuous block of conductor bars, but the lack of cooling will be advantageously evenly distributed on the conductor bars. The symmetry of the cooling is thus maintained.

[0060] In the examples described so far, the fluid channel is always designed as a hole or cavity in the corresponding element. Alternatively, the fluid channel can also be formed as an independent component and, for example, introduced into the conductor bar. Such a fluid channel is therefore an independent component. The fluid channel can be ceramic, for example, so that electrical insulation from the conductor bar 12 can be achieved. In an alternative design, the fluid channel can also be made of other materials, for example, it can also be made of a metallic material. In this case, an electrical line from the conductor bar 12 to other elements must be prevented, for example by using a plastic hose to guide water.

[0061] As an alternative to an open fluid channel 20 through which the cooling fluid flows in one direction, the fluid channel 20 in the conductor bar 12 can also be closed and designed as a heat pipe 30. Figure 7 Such a design is shown in FIG. Figure 7 The side view shows an electric motor 10 with a stator / rotor block 8 and a conductor bar 12. Furthermore, two cooling plates 16 are arranged on the rear side 14 of the electric motor on the conductor bars 12, on both sides of which printed circuit boards are mounted.

[0062] The heat pipes 30, 31 pass through substantially the entire length of the conductor bar. Here, the heat pipes 30, 31 are arranged so that their evaporator-side ends 31 are located in the region between the stator / rotor block 8 and one or more cooling plates 16. As a result, heat is mainly dissipated from this region, i.e., the waste heat of the output stage of the inverter is dissipated, and the waste heat from the stator / rotor block 8 is prevented from acting on the circuit board 15 and heating the output stage. The heat pipe 30 can be, for example, a copper water heat pipe.

[0063] On the one hand, the condenser-side end 32 of the heat pipe 30 can be located at the end of the conductor bar 12 remote from the stator / rotor block 8 on the back side 14 of the electric motor 10. On the other hand, the condenser-side end of the heat pipe 30 can also be located in the area of ​​the short-circuit ring 38. In both cases, the condenser-side end of the heat pipe 30 is assisted by cooling fins, for example, as an air heat exchanger or other type of heat exchanger. Figure 8 The corresponding design scheme is shown in FIG.

[0064] Figure 8 A section of the end face 13 of the electric motor 10 is shown. Here, the stator / rotor block 8 and the conductor bars 12 protruding from the stator / rotor block 8 are partially shown, and the conductor bars 12 end in the short-circuit ring 38. The conductor bars 12 contain the heat pipes 30, whose condenser-side ends are located in the region of the short-circuit ring 38. In the embodiment of FIG. 9 , the short-circuit ring 38 itself is formed by spaced-apart individual laminations 39.

[0065] In an alternative design not shown in Fig. 9, the short-circuit ring 38 can also be formed by axially combined individual laminations, or simply a solid ring. The short-circuit ring 38 is preferably contacted with the conductor bar by the following high-voltage process, using which the hollow conductor is also fixed in the stator lamination stack.

[0066] In such Figure 8 In the illustrated design with spaced-apart individual laminations 39, the short-circuit ring 38 has a significantly larger surface than a solid short-circuit ring. This surface serves as a heat sink for the heat pipe 30 in the conductor bar 12. In addition, this design can also be advantageous for avoiding eddy currents. A radial cooling air flow is generated by a fan 41 arranged radially on the motor shaft 7 within this short-circuit ring 38 of the stator 11. This air flow passes through the gaps between the individual laminations 39 and ensures improved heat dissipation of the short-circuit ring 38.

[0067] The cooling of the short-circuit rings 38 can be open (heat exchange with the ambient air, for example via air ducts in the stator) or can be a closed cooling circuit with secondary cooling. For this purpose, for example, air-to-air cooling via tube coolers or plate coolers or air-to-liquid cooling via shell coolers or top coolers can be used.

[0068] Reference numerals list

[0069] 7 Motor shaft

[0070] 8 Stator / rotor blocks

[0071] 9 Motor axis

[0072] 10. Electric Motor

[0073] 11. Stator

[0074] 12 Conductor rod

[0075] 13 End face

[0076] 14 Back

[0077] 15 Circuit Board

[0078] 16 Cooling Plate

[0079] 17 Baotou

[0080] 18 Connecting elements

[0081] 20 Fluid Channels

[0082] 23 Hose connector

[0083] 24 Hose

[0084] 25, 28 casing

[0085] 26 grooves

[0086] 27 Threaded rod

[0087] 38 short circuit ring

[0088] 30 Heat pipes

[0089] 31 End of evaporator side

[0090] 32 End of condenser side

[0091] 39 stacking

[0092] 41 Fan

[0093] 421 Contact Position

[0094] 422 Semiconductor switch

Claims

1. An electric motor (10), comprising: a stator (11) having a plurality of field conductors (12) designed as rods, - an inverter having one or more parallel-connected power sections for each of the field conductors (12) for controlling the field conductors, wherein The inverter comprises a controller for generating a control signal for the power section, in, - the output stage of the inverter is arranged on a plurality of circuit boards (15), - the circuit board (15) is arranged on at least one cooling plate (16), the cooling plate (16) is arranged such that the field conductor (12) or a current conductor (18) arranged on the field conductor (12) and extending the field conductor in the axial direction is mechanically effectively connected to the cooling plate, At least one cooling device is present, which comprises a fluid line (20) which is guided at least in sections within one of the field conductor (12) and / or the current conductor (18).

2. The electric motor (10) according to claim 1, wherein: A fluid line (20) is present for each of the field conductors (12) and / or the current conductors (18) and is guided at least in sections within the field conductors (12) and / or the current conductors (18).

3. An electric motor (10) according to any one of the preceding claims, wherein: The region (19) in which the fluid line (20) is guided in the field conductor (12) and / or the current conductor (18) is located axially between a cooling plate (16) and an axial start of the stator / rotor block (8).

4. The electric motor (10) according to claim 1, comprising a short-circuit ring (38) for the electrical connection of the field conductor (12) on a side of the electric motor (10) remote from the cooling plate (16), and wherein: Fluid lines (20) for at least two of the field conductors (12) are connected to one another in the short-circuit ring.

5. The electric motor (10) according to claim 4, wherein: The fluid lines (20) for at least two of the field conductors (12) are connected to one another on a side of the electric motor facing away from the short-circuit ring (38).

6. An electric motor (10) according to any one of the preceding claims, wherein: The fluid line (20) is partially formed by a threaded rod (27) which is screwed into one end of the field conductor (12), wherein the fluid line (20) continues in the field conductor (12).

7. The electric motor (10) according to claim 6, wherein: One or more cooling plates (16) and elements for axial positioning, in particular spacer sleeves (25, 28), are pushed alternately onto the threaded rod (27).

8. An electric motor (10) according to any one of the preceding claims, wherein: The fluid line (20) comprises a metallic material, in particular is made of a metallic material.

9. An electric motor (10) according to any one of the preceding claims, wherein: The fluid conduit (20) is formed by a cavity or a hole in the field conductor (12) and / or the current conductor (18).

10. The electric motor (10) according to any one of the preceding claims, wherein: The fluid line (20) is a heat pipe (30) and is arranged completely within one of the field conductors (12) and / or the current conductors (18) and / or a short-circuit ring (38) connected to the field conductor (12).

11. The electric motor (10) according to claim 10, wherein: The condenser-side end of the heat pipe (30) is arranged in the short-circuit ring (38), and the short-circuit ring (38) is formed by spaced-apart laminations.

12. An electric motor (10) according to any one of the preceding claims, wherein: The circuit board (15) is designed to be in the shape of a circular sector or an annular sector.

13. An electric motor (10) according to any one of the preceding claims, wherein: The cooling plate (16) is arranged perpendicular to the axis (9) of the electric motor (10).

14. An electric motor (10) according to any one of the preceding claims, designed for controlling each field conductor (12) with an individual phase.

15. The electric motor (10) according to any one of the preceding claims, wherein The inverter is designed to generate an AC voltage having an amplitude of 200 V or less, in particular 150 V or less, in particular 50 V or less.

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