Electrical machine

Abstract

The invention relates to an electrical machine comprising a stator, a rotor (5), at least one motor winding (6) and a magnetohydrodynamic temperature-control arrangement (10) that is integrated in the stator and / or the rotor (5) and comprises a closed channel system, which has at least one channel (14A) for guiding an electrically and thermally conductive medium (16) and is thermally coupled to the stator and / or the rotor (5), and at least one magnetohydrodynamic pump module (12) that comprises an electrode device (18) and is designed to channel an electric current (IP) through the medium (16) at a channel section (14.1) using the electrode device (18) and, utilizing a magnetic field (B) generated in the electrical machine, to generate a Lorentz force (FL) that accelerates the medium (16) in the channel section (14.1) in targeted fashion, and a resulting pressure build-up brings about a desired volume flow of the medium (16) through the at least one channel (14A), wherein the at least one magnetohydrodynamic pump module (12) is designed and positioned such that the electrode device (18) channels the electric current (IP) through the medium (16) perpendicularly to the profile of field lines of the magnetic field (B) and perpendicularly to the channel section (14.1), and the channel section (14.1) is oriented perpendicularly to the profile of the magnetic field (B).

Description

[0001] Description

[0002] title

[0003] Electric machine

[0004] The invention relates to an electrical machine with a stator, a rotor, at least one motor winding and at least one temperature control arrangement.

[0005] Magnetohydrodynamics (MHD) is a branch of physics. It describes the behavior of electrically conductive fluids penetrated by magnetic and electric fields. Magnetohydrodynamics in the narrower sense deals with liquids, especially plasmas, which are described as fluids within the framework of MHD. Typical areas of application of magnetohydrodynamics are flow control and flow measurement in metallurgy and semiconductor single crystal growth. In metallurgy, for example, magnetic fields can be used to influence the flow of liquid metals such as steel or aluminum. In their application, a distinction must be made between static and time-dependent magnetic fields. Static, i.e. time-independent, magnetic fields lead to a dampening of turbulence and are therefore used, for example, in the form of magnetic brakes in the continuous casting of steel.Time-dependent magnetic fields are used, for example, for electromagnetic support during the casting of aluminum.

[0006] Disclosure of the invention

[0007] The electric machine with the features of independent patent claim 1 has the advantage that at least one magnetohydrodynamic temperature control arrangement enables scalable temperature control (cooling or heating) of components of a stator and / or a rotor of the electric machine. For example, heat generated in the stator and / or rotor of the electric machine can be absorbed, dissipated, and distributed directly at the point of origin. This prevents thermal "hotspots." Alternatively, specific areas of the electric machine can be heated as needed.

[0008] Embodiments of the present invention provide an electric machine having a stator, a rotor, at least one motor winding and at least one magnetohydrodynamic tempering arrangement integrated into the stator and / or the rotor.The at least one magnetohydrodynamic temperature control arrangement comprises at least one closed channel system, which has at least one channel for conducting an electrically and thermally conductive medium and is thermally coupled to the stator and / or the rotor, and at least one magnetohydrodynamic pump module, which comprises an electrode device and is designed to conduct an electrical current through the electrically and thermally conductive medium via the electrode device at at least one channel section and to generate a Lorentz force by utilizing a magnetic field generated in the stator and / or rotor, which specifically accelerates the electrically and thermally conductive medium in the at least one channel section and a resulting pressure build-up brings about a desired volume flow of the electrically and thermally conductive medium through the at least one channel of the closed channel system.In this case, the at least one magnetohydrodynamic pump module is designed and positioned such that the electrode device conducts the electric current perpendicular to the course of field lines of the magnetic field and perpendicular to the at least one channel section through the electrically and thermally conductive medium and the at least one channel section is aligned perpendicular to the course of the field lines of the magnetic field.

[0009] Depending on the structural conditions, at least one channel of the closed channel system can have a cross-section in the range of 1 mm 2 up to 100mm 2Of course, larger or smaller cross-sections are also possible. Such a variable design option allows the at least one channel to be routed as close as possible to temperature-sensitive components while maintaining a small distance. In order to achieve a planar effect, the at least one channel can, for example, be shaped in a meandering shape and / or have a parallel channel structure. The at least one magnetohydrodynamic pump module can be positioned anywhere in the electrical machine, as long as the conditions regarding the direction of current flow or the direction of the electric field, the direction of the field lines of the magnetic field and the orientation of the at least one channel section can be met.

[0010] Through embodiments of the at least one magnetohydrodynamic temperature control arrangement, heat can be transported through the electrically and thermally conductive medium in the closed channel system in the electric machine, for example, not only in the stator and / or rotor, but also, through thermal coupling with at least one cooling channel, through a coolant guided in the at least one cooling channel. This allows unwanted heat to be easily dissipated from the electric machine. Furthermore, embodiments of the magnetohydrodynamic temperature control arrangement enable significantly more powerful and efficient electric machines compared to the prior art, for example through individual and / or dynamic and / or continuous and / or targeted and / or uniform cooling of individual components of the electric machine to be cooled.If necessary, individual and / or dynamic and / or continuous and / or targeted and / or uniform heating of components of the electric machine is also possible. Furthermore, the absence of mechanically moving parts results in low mechanical wear and low noise levels for the at least one magnetohydrodynamic pump module.

[0011] Embodiments of the electrical machine can, for example, be operated as a generator or as a motor. For example, the electrical machine can be designed as a synchronous machine, an asynchronous machine, or a permanently excited synchronous machine in which permanent magnets are arranged on the rotor. The internal magnetic field of the electrical machine is used in the at least one pump module to generate the Lorentz force in the electrically and thermally conductive medium. The electrical current for generating the Lorentz force in the electrically and thermally conductive medium can, for example, be taken from the power branch of the electrical machine or can be fed to the at least one pump module by an additional introduction, for example via induction or a wiper, from an external power source or from an internal energy source, such as a battery in the rotor.

[0012] An electrically and thermally conductive medium is understood below to mean a medium with an electrical conductivity greater than 1 S / m (Siemens per meter). Preferably, the electrically and thermally conductive medium has a significantly higher electrical conductivity (100 to 1000 S / m). The electrically and thermally conductive medium can, for example, be an electrically and thermally conductive liquid, an electrically and thermally conductive gas, an ionic liquid, at least one electrolyte, at least one plasma, at least one liquid metal, such as gallium, lithium, sodium, or mercury, and / or at least one liquid metal alloy, such as a sodium-potassium alloy. In addition, the electrically and thermally conductive medium can also be a fluid with electrically conductive particles, such as graphite flakes, copper granules, etc.Preferably, a non-toxic liquid metal alloy of gallium, indium, and tin can be used as an electrically and thermally conductive medium. This is liquid at atmospheric pressure at temperatures as low as -20°C and can be easily heated from a lower temperature to a temperature of -20°C or higher. However, the examples of electrically and thermally conductive media described here are not exhaustive.

[0013] The measures and further developments listed in the dependent claims make advantageous improvements to the electrical machine specified in independent patent claim 1 possible.

[0014] It is particularly advantageous that the electrode device can comprise two electrodes. In this case, a first electrode of the electrode device can introduce the electrical current at a predetermined current density into the electrically and thermally conductive medium at the at least one channel section, and a second electrode of the electrode device can discharge the electrical current from the electrically and thermally conductive medium at the at least one channel section. The electrical current for the at least one magnetohydrodynamic pump module can be discharged from at least one power branch of at least one motor winding of the electrical machine to the electrode device of the at least one magnetohydrodynamic pump module or can be conducted to the electrode device of the at least one magnetohydrodynamic pump module via an additional discharge device.

[0015] In a further advantageous embodiment of the electric machine, the at least one magnetohydrodynamic pump module can be electrically connected in parallel or in series with the at least one motor winding. This enables particularly simple transmission of the electrical current for the at least one magnetohydrodynamic pump module. Alternatively, the at least one magnetohydrodynamic pump module can tap a voltage at the at least one motor winding. The electrical current for the at least one magnetohydrodynamic pump module is then derived from the tapped voltage.

[0016] In a further advantageous embodiment of the electrical machine, the at least one channel of the closed channel system can be thermally coupled to at least one heat source in at least one section and thermally coupled to at least one heat sink in at least one other section. The volume flow of the electrically and thermally conductive medium in the closed channel system can absorb heat generated at the at least one heat source through convective heat transfer from the at least one heat source and transfer it to the at least one heat sink, thereby cooling the heat source. Since the at least one channel can be routed to any desired location, appropriate temperature control can be achieved at any desired location on the electrical machine.

[0017] In a further advantageous embodiment of the electric machine, the at least one section of the at least one channel thermally coupled to the heat source can be magnetically shielded. This advantageously prevents existing magnetic fields from adversely affecting the volume flow of the electrically and thermally conductive medium.

[0018] In a further advantageous embodiment of the electric machine, the at least one heat source can be, for example, a permanent magnet of the rotor, at whose corners facing the stator heat can be generated during operation. The rotor can be effectively cooled by at least one magnetohydrodynamic temperature control arrangement integrated into the rotor. Furthermore, hot spots at the corners of the permanent magnets of the rotor of a permanent-magnet synchronous machine facing the stator can be effectively avoided.

[0019] In a further advantageous embodiment of the electric machine, the heat sink can be a cooling channel through which a coolant can be conducted. The cooling channel can be integrated, for example, into a rotor shaft.

[0020] In a further advantageous embodiment of the electric machine, the closed channel system can have at least two channels connected in parallel for fluid flow and / or at least two channels connected in series for fluid flow. This means that the closed channel system can comprise several channels connected in parallel for fluid flow, several channels connected in series for fluid flow, or a combination of several channels connected in parallel for fluid flow and several channels connected in series for fluid flow. For example, the at least one magnetohydrodynamic pump module can be arranged on a channel section that is fluidically connected at both ends to several channels connected in parallel for fluid flow. As a result, one magnetohydrodynamic pump module can accelerate the electrically and thermally conductive medium for several channels connected in parallel for fluid flow.

[0021] In a further advantageous embodiment of the electric machine, at least two magnetohydrodynamic pump modules can be arranged fluidically in parallel on the at least two channels connected fluidically in parallel and / or fluidically in series on the at least two channels connected fluidically in series. This means that a magnetohydrodynamic pump module can be arranged on each of several channels connected fluidically in parallel or channels connected fluidically in series. For example, a first magnetohydrodynamic pump module can be arranged on a first channel and a second magnetohydrodynamic pump module can be arranged on a second channel, which is connected fluidically in parallel to the first channel. As a result, the two magnetohydrodynamic pump modules each accelerate the electrically and thermally conductive medium in "their" channel.Alternatively, for example, a first magnetohydrodynamic pump module can be arranged on a channel section which is fluidically connected at one end to a plurality of fluidically parallel channels, and a second magnetohydrodynamic pump module can be arranged on a channel section which is fluidically connected at one end to the plurality of fluidically parallel channels. As a result, the two magnetohydrodynamic pump modules connected in series can jointly accelerate the electrically and thermally conductive medium for a plurality of fluidically parallel channels. Furthermore, at least two magnetohydrodynamic pump modules can be arranged fluidically in series one behind the other on a common channel of the channel system and jointly accelerate the electrically and thermally conductive medium in the common channel.In addition, the use of multiple magnetohydrodynamic pump modules allows for a smaller design of the individual magnetohydrodynamic pump modules. This compact design of the individual magnetohydrodynamic pump modules and the use of multiple magnetohydrodynamic pump modules allow for flexible and more efficient use of the available installation space than with a single large magnetohydrodynamic pump module.

[0022] In a further advantageous embodiment of the electrical machine, the at least two magnetohydrodynamic pump modules can be connected electrically in parallel or electrically in series. By connecting several pump modules in series, the required electrical current can be significantly reduced compared to just one pump module at the same voltage, corresponding to the number of pump modules connected electrically in series. Compared to known systems with just one pump module, connecting at least two pump modules in series also reduces the electrical losses in the electrically and thermally conductive medium and in an electrical supply line of the magnetohydrodynamic pump module, which also increases efficiency. In addition, depending on the structure of an associated closed channel system, corresponding channels of the channel system or areas of the electrical machine can also be individually temperature-controlled as required, which ensures uniform cooling orHeating and a uniform temperature distribution can be achieved on the stator and / or rotor of the electric machine. This results in fewer mechanical stresses and heat flows. Since the individual pump modules can be designed very small, any channel structure can be individually controlled with regard to the temperature in at least one channel using associated pump modules, so that corresponding sections of the stator and / or rotor can be optimally tempered. This can significantly improve the service life of the electric machine.

[0023] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. In the drawings, like reference numerals designate components or elements that perform the same or similar functions.

[0024] Short description of the drawings

[0025] Fig. 1 shows a schematic sectional view of an embodiment of an electrical machine according to the invention.

[0026] Fig. 2 shows a schematic electrical equivalent circuit diagram of a first embodiment of a rotor for the electrical machine according to the invention from Fig. 1.

[0027] Fig. 3 shows a schematic electrical equivalent circuit diagram of a second embodiment of a rotor for the electrical machine according to the invention from Fig. 1 .

[0028] Fig. 4 shows a schematic electrical equivalent circuit diagram of a third exemplary embodiment of a rotor for the electrical machine according to the invention from Fig. 1. Fig. 5 shows a schematic electrical equivalent circuit diagram of a fourth exemplary embodiment of a rotor for the electrical machine according to the invention from Fig. 1.

[0029] Fig. 6 shows a schematic sectional view of a section of an embodiment of a rotor for an electrical machine according to the invention designed as a permanent magnet synchronous machine.

[0030] Embodiments of the invention

[0031] As can be seen from Figs. 1 to 6, the illustrated embodiment of an electric machine 1 according to the invention comprises a stator 3, a rotor 5, at least one motor winding 6, and at least one magnetohydrodynamic temperature control arrangement 10, which is integrated into the stator 3 and / or the rotor 5. The at least one magnetohydrodynamic temperature control arrangement 10 comprises at least one closed channel system 14, which has at least one channel 14A for conducting an electrically and thermally conductive medium 16 and is thermally coupled to the stator 3 and / or the rotor 5, and at least one magnetohydrodynamic pump module 12, which comprises an electrode device 18 and is designed to supply an electrical current IP to at least one channel section 14 via the electrode device 18.1 through the electrically and thermally conductive medium 16 and, by utilizing a magnetic field B generated in the stator 3 and / or rotor 5, to generate a Lorentz force FL which specifically accelerates the electrically and thermally conductive medium 16 in the at least one channel section 14.1 and a resulting pressure build-up brings about a desired volume flow of the electrically and thermally conductive medium 16 through the at least one channel 14A of the closed channel system 14. In this case, the at least one magnetohydrodynamic pump module 12 is designed and positioned such that the electrode device 18 conducts the electrical current IP perpendicular to the course of field lines of the magnetic field B and perpendicular to the at least one channel section 14.1 through the electrically and thermally conductive medium 16 and the at least one channel section 14.1 is aligned perpendicular to the course of the field lines of the magnetic field B. As can be seen from Fig.1, in the illustrated embodiment of the electric machine 1, several magnetohydrodynamic tempering arrangements 10 are integrated into the rotor 5 of the electric machine 1, two of which are visible.

[0032] Here, the closed channel system 14 of the temperature control arrangements 10 can have at least two channels 14A connected in fluid parallel and / or at least two channels 14A connected in fluid series. For example, the closed channel system 14 can comprise only channels 14A connected in fluid parallel or only channels 14A connected in fluid series. Alternatively, the closed channel system can comprise a combination of channels 14A connected in fluid parallel and channels 14A connected in fluid series.

[0033] As can be further seen from Fig. 2 to 5, the electrode device 18 of the at least one magnetohydrodynamic pump module 12 comprises two electrodes 18A, 18B. A first electrode 18A of the electrode device 18 introduces the electrical current IP at a predetermined current density at the at least one channel section 14.1 into the electrically and thermally conductive medium 16, and a second electrode 18B of the electrode device 18 discharges the electrical current IP at the at least one channel section 14.1 from the electrically and thermally conductive medium 16.

[0034] As can be further seen from Fig. 2 to 5, the electric current IP for the at least one magnetohydrodynamic pump module 12 in the illustrated embodiments of the rotor 5 can be derived from at least one power branch of at least one motor winding 6 of the electric machine 1, here of the rotor 5, to the electrode device 18 of the at least one magnetohydrodynamic pump module 12.

[0035] In alternative embodiments of the electric machine 1 not shown, the electric current IP for the at least one magnetohydrodynamic pump module 12 can be conducted to the electrode device 18 of the at least one magnetohydrodynamic pump module 12 by an additional introduction device.

[0036] As can be further seen from Fig. 2, the illustrated magnetohydrodynamic temperature control arrangement 10A in the illustrated first embodiment of the rotor 5A comprises a magnetohydrodynamic pump module 12, which is electrically connected in parallel with the at least one motor winding 6. This means that the current in the power branch is divided into the electrical current IP for the magnetohydrodynamic pump module 12 and the electrical current IM for the at least one motor winding 6.

[0037] As can be further seen from Fig. 3, the illustrated magnetohydrodynamic temperature control arrangement 10B in the illustrated second embodiment of the rotor 5B comprises a magnetohydrodynamic pump module 12, which is electrically connected in series with the at least one motor winding 6. This means that the current in the power branch is equal to the electrical current IP for the magnetohydrodynamic pump module 12 and equal to the electrical current IM for the at least one motor winding 6.

[0038] As can also be seen from Fig. 4, the illustrated magnetohydrodynamic temperature control arrangement 10C in the illustrated third embodiment of the rotor 5C comprises a magnetohydrodynamic pump module 12, which taps a voltage from the at least one motor winding 6. As a result, the magnetohydrodynamic pump module 12 is electrically connected in parallel to an upper winding section 6.1 of the at least one motor winding 6, and the electrical parallel circuit consisting of the magnetohydrodynamic pump module 12 and the upper winding section 6.1 of the at least one motor winding 6 are electrically connected in series to a lower winding section 6.2 of the at least one motor winding 6. This means that the current in the power branch in the electrical parallel circuit consisting of the magnetohydrodynamic pump module 12 and the upper winding section 6.1 of the at least one motor winding 6 into the electrical current IP for the magnetohydrodynamic pump module 12 and the electrical current IM for the at least one motor winding 6. After the electrical parallel connection of the magnetohydrodynamic pump module 12 and the upper winding section 6.1 of the at least one motor winding 6, the total current from the electrical current IP for the magnetohydrodynamic pump module 12 and the current IM for the at least one motor winding 6 flows through the lower winding section 6.2 of the at least one motor winding 6.

[0039] As can further be seen from Fig. 5, the illustrated magnetohydrodynamic temperature control arrangement 10D in the illustrated fourth embodiment of the rotor 5D comprises two magnetohydrodynamic pump modules 12A, 12B, which are fluidically arranged one behind the other in series on a common channel 14A of the closed channel system 14 and jointly accelerate the electrically and thermally conductive medium 16 in the common channel 14A. The two magnetohydrodynamic pump modules 12A, 12B and the at least one motor winding 6 are electrically connected in series. This means that the current in the power branch is equal to the electrical current IP for the first magnetohydrodynamic pump module 12A and equal to the electrical current IP for the second magnetohydrodynamic pump module 12B and equal to the electrical current IM for the at least one motor winding 6.

[0040] In an alternative embodiment not shown, the two magnetohydrodynamic pump modules 12A, 12B are electrically connected in parallel. Furthermore, several magnetohydrodynamic pump modules 12A, 12B can also be arranged fluidically in series one behind the other on several fluidically parallel channels 14A of the closed channel system 14 and jointly accelerate the electrically and thermally conductive medium 16 in the common channel 14A.

[0041] As can further be seen from Fig. 1, the at least one channel 14A of the closed channel system 14 of the two magnetohydrodynamic temperature control arrangements 10 shown is each thermally coupled in at least one section to at least one heat source (not shown in detail). In at least one other section, the at least one channel 14A of the two magnetohydrodynamic temperature control arrangements 10A shown is thermally coupled to a heat sink designed as an axial cooling channel 7, through which a coolant 9 can be conducted. A channel 14A, lower in the illustration, of the magnetohydrodynamic temperature control arrangement 10, upper in the illustration, is thermally coupled to the cooling channel 7 over its entire length shown. In addition, a channel 14A, upper in the illustration, of the magnetohydrodynamic temperature control arrangement 10, lower in the illustration, is thermally coupled to the cooling channel 7 over its entire length shown.As a result, the volume flow of the electrically and thermally conductive medium 16 in the closed channel systems 14 of the two magnetohydrodynamic temperature control arrangements 10 shown absorbs heat generated at the at least one heat source (not shown in detail) through convective heat transfer from the at least one heat source and transfers it to the coolant 9 guided in the cooling channel 7. Since the at least one channel 14 can be routed to any desired location, corresponding temperature control can be achieved at any desired location on the electrical machine 1. Preferably, the at least one section of the at least one channel 14 that is thermally coupled to the heat source is magnetically shielded.

[0042] As can be further seen from Fig. 6, the heat sources in the illustrated embodiment of the rotor 5E, which is used in an electric machine 1 designed as a permanent-magnet synchronous machine, are permanent magnets 5.1, at whose corners facing the stator 3 heat can be generated during operation. As can be further seen from Fig. 6, the channels 14A of the at least one magnetohydrodynamic temperature control arrangement integrated into the rotor 5E are arranged at the corner regions of the permanent magnets 5.1, so that the heat generated during operation can be effectively dissipated. This effectively prevents hot spots at the corners of the permanent magnets 5.1 of the rotor 5E facing the stator 3.

Claims

Claims 1. An electrical machine (1) comprising a stator (3), a rotor (5), at least one motor winding (6), and at least one magnetohydrodynamic temperature control arrangement (10) which is integrated into the stator (3) and / or the rotor (5), wherein the at least one magnetohydrodynamic temperature control arrangement (10) comprises at least one closed channel system (14) which has at least one channel (14A) for guiding an electrically and thermally conductive medium (16) and is thermally coupled to the stator (3) and / or the rotor (5), and at least one magnetohydrodynamic pump module (12) which comprises an electrode device (18) and is designed to supply an electrical current (IP) to at least one channel section (14) via the electrode device (18).1) through the electrically and thermally conductive medium (16) and, by utilizing a magnetic field (B) generated in the stator (3) and / or rotor (5), to generate a Lorentz force (FL) which specifically accelerates the electrically and thermally conductive medium (16) in the at least one channel section (14.1), and a resulting pressure build-up brings about a desired volume flow of the electrically and thermally conductive medium (16) through the at least one channel (14A) of the closed channel system (14), wherein the at least one magnetohydrodynamic pump module (12) is designed and positioned such that the electrode device (18) conducts the electrical current (IP) perpendicular to the course of field lines of the magnetic field (B) and perpendicular to the at least one channel section (14.1) through the electrically and thermally conductive medium (16), and the at least one channel section (14.1) is oriented perpendicular to the course of the field lines of the magnetic field (B).

2. Electrical machine (1) according to claim 1, characterized in that the electrode device (18) comprises two electrodes (18A, 18B), wherein a first electrode (18A) of the electrode device (18) introduces electrical current (IP) with a predetermined current density at the at least one channel section (14.1) into the electrically and thermally conductive medium (16) and a second electrode (18B) of the electrode device (18) discharges the electrical current (IP) at the at least one channel section (14.1) from the electrically and thermally conductive medium (16).

3. Electrical machine (1) according to claim 1 or 2, characterized in that the electrical current (IP) for the at least one magnetohydrodynamic pump module (12) can be derived from at least one power branch of at least one motor winding (6) of the electrical machine (1) to the electrode device (18) of the at least one magnetohydrodynamic pump module (12) or can be conducted to the electrode device (18) of the at least one magnetohydrodynamic pump module (12) by an additional introduction device.

4. Electrical machine (1) according to claim 3, characterized in that the at least one magnetohydrodynamic pump module (12) is electrically connected in parallel or electrically in series to the at least one motor winding (6).

5. Electrical machine (1) according to claim 3 or 4, characterized in that the at least one magnetohydrodynamic pump module (12) taps a voltage at the at least one motor winding (6).

6. Electrical machine (1) according to one of claims 1 to 5, characterized in that the at least one channel (14A) of the closed channel system (14) is thermally coupled to at least one heat source in at least one section and is thermally coupled to at least one heat sink in at least one other section.

7. Electrical machine (1) according to claim 6, characterized in that the volume flow of the electrically and thermally conductive medium (16) in the closed channel system (14) transfers heat which is which is created by at least one heat source, absorbs heat from the at least one heat source by convective heat transfer and transfers it to the at least one heat sink and causes cooling of the heat source.

8. Electrical machine (1) according to claim 6 or 7, characterized in that the at least one section of the at least one channel (14A) thermally coupled to the heat source is magnetically shielded.

9. Electrical machine (1) according to one of claims 6 to 8, characterized in that the at least one heat source is a permanent magnet (5.1) of the rotor (5), at whose corners facing the stator (3) heat is generated.

10. Electrical machine (1) according to one of claims 6 to 9, characterized in that the heat sink is a cooling channel (7) through which a coolant (9) can be conducted.

11. Electrical machine (1) according to one of claims 1 to 10, characterized in that the closed channel system (14) has at least two fluidically parallel connected channels (14A) and / or at least two fluidically series connected channels (14A).

12. Electrical machine (1) according to claim 11, characterized in that at least two magnetohydrodynamic pump modules (12) are arranged fluidically in parallel on the at least two fluidically parallel connected channels (14A) and / or fluidically in series on the at least two fluidically series connected channels (14A).

13. Electrical machine (1) according to one of claims 1 to 12, characterized in that at least two magnetohydrodynamic pump modules (12) are arranged fluidically in series one behind the other on a common channel (14A) of the channel system (14) and the electrically and thermally conductive medium (16) accelerate together in the common channel (14A).

14. Electrical machine (1) according to claim 12 or 13, characterized in that the at least two magnetohydrodynamic Pump modules (12) are electrically connected in parallel or electrically in series.

Images