An electrical machine and a method for operating an electrical machine are provided.
Typically, electrical machines comprise a stator and a rotor which is movable relative to the stator. Electrical machines may operate as a motor or as a generator, converting electrical energy into kinetic energy or vice versa. In operation, a magnetic field of the rotor interacts with a magnetic field of the stator. The stator typically has a stator winding and an iron core. For example, the stator winding may be formed by distributed overlapping windings or by tooth-concentrated windings. In both cases, higher harmonic components of the magnetomotive force may impair the operation of the electrical machine.
One problem to be solved is to provide an electrical machine that can be operated efficiently. Another problem to be solved is to provide a method for efficiently operating an electrical machine.
The problems are solved by the subject-matter of the independent claims. Advantageous embodiments and further developments are specified in the subclaims.
According to at least one embodiment of the electrical machine, the electrical machine includes a stator and a rotor which is movable relative to the stator. The rotor may be an internal rotor or an external rotor. If the rotor is an internal rotor, an outer side of the rotor faces the stator. The rotor can be arranged on a shaft. If the rotor is an external rotor, an inner side of the rotor faces the stator. In addition, the rotor has an axis of rotation. The stator may have the shape of a hollow cylinder. An air gap is arranged between the stator and the rotor. The air gap may extend between the stator and the rotor in a direction which is parallel to the axis of rotation of the rotor.
According to at least one embodiment of the electrical machine, the stator includes a stator core in which at least six slots are arranged. The stator core may comprise iron. The slots may each extend through the stator core. The slots may extend through the stator along the axis of rotation of the rotor. The slots may extend from a first side of the stator to a second side of the stator. Thus, the slots may extend completely through the stator core. The slots may also extend completely through the stator. The slots may each be open toward the air gap. The slots may be recesses in the stator core.
According to at least one embodiment of the electrical machine, the stator includes a distributed electrical winding which is at least partially arranged in the slots. The electrical winding may be a single-layer winding. The electrical winding may comprise at least three coils. Conductors from different coils can overlap in places on the first side. Thus, the electrical winding is not a tooth-concentrated or concentrated winding. Instead, each coil of the electrical winding may extend in at least two slots in places. The electrical winding may comprise an electrically conductive material. The electrical winding may be connected to power electronics and designed to generate a rotating field.
According to at least one embodiment of the electrical machine, the stator comprises at least six teeth. The stator core may comprise the teeth. The teeth may thus be formed from the stator core. The teeth may each extend through the stator along the axis of rotation of the rotor. The teeth may extend completely through the stator. The teeth may extend from the first side of the stator to the second side of the stator. The teeth may comprise the same material as the stator core. The stator may have at least ten teeth or at least fourteen teeth.
According to at least one embodiment of the electrical machine, one tooth of the stator is formed between two neighboring slots in each case. Each tooth may be formed by the region of the stator core between two slots each. The teeth can be uniformly distributed along the circumference of the stator. The slots can be uniformly distributed along the circumference of the stator. The stator can have as many teeth as slots.
According to at least one embodiment of the electrical machine, at least three of the teeth comprise a recess which extends at least partially through the respective tooth. The recesses may each be devoid of the material of the stator core. The recesses can thus be devoid of any material carrying a magnetic flux. This inhibits the magnetic flux in the area of the recesses. The recesses may each be arranged between two slots each. The recesses may each be designed as an additional slot in the stator. At least one tooth of the stator is devoid of the recesses. This can mean that no recess is arranged in at least one tooth of the stator. It is further possible that half of the teeth of the stator is devoid of the recesses.
According to at least one embodiment of the electrical machine, in operation of the electrical machine a working wave of the magnetomotive force differs from a fundamental wave of the magnetic flux. The working wave is the harmonic component of the magnetomotive force which is mainly used for torque generation. The harmonic components of the magnetomotive force are obtained, for example, if the magnetomotive force is split into its harmonic components, e.g., by means of a Fourier decomposition. In so doing, the fundamental wave is the harmonic component of order 1. Thus, in the operation of the electrical machine, a harmonic component of the magnetomotive force with an order different from 1 is used for torque generation. The order of the harmonic component, which is used as working wave, can be larger than 1.
According to at least one embodiment of the electrical machine, the electrical machine comprises a stator, and a rotor which is movable relative to the stator, wherein the stator includes a stator core in which at least six slots are arranged, the stator includes a distributed electrical winding arranged at least partially in the slots, the stator includes at least six teeth, one tooth of the stator is formed between two neighboring slots in each case, at least three of the teeth have a recess extending at least partially through the respective tooth, and in operation of the electrical machine a working wave of the magnetomotive force differs from a fundamental wave of the magnetic flux.
A non-magnetic material can be arranged in the recesses in the stator. For example, air is arranged in the recesses. Thus, the recesses act as flux barriers in the stator. This can mean that the recesses each form a mechanical barrier to reduce the fundamental wave of the magnetic flux. Depending on the design of the electrical machine, the fundamental wave can be weakened by over 90% by using recesses in the stator. At the same time, the working wave can be boosted. This can mean that the fundamental wave of the magnetomotive force for a stator with flux barriers is reduced compared to the fundamental wave of the magnetomotive force for a stator without flux barriers. Furthermore, for at least one harmonic component of the magnetomotive force with an order greater than 1 for a stator with flux barriers, the amplitude may be increased compared to the harmonic component of the magnetomotive force with the same order for a stator without flux barriers.
The harmonic component with the largest amplitude can be used as the working wave. Thus, compared to a stator without any recesses, the amplitude of at least some of the harmonic components of the magnetomotive force, which are not used as working wave, is reduced in the stator having recesses compared to a stator without any recesses. Therefore, less losses occur in operation of the electrical machine. This means that the electrical machine can be operated efficiently.
How much the amplitude of the fundamental wave is reduced and how much the amplitude of harmonic components with an order greater than 1 are increased depends on the design of the stator.
It is further possible for the electrical machine to have a winding factor greater than 1 for a harmonic component of the magnetomotive force with an order greater than 1. The winding factor may be given by the product of the zoning factor and the pitch factor. In electrical machines without recesses or flux barriers, the winding factor is at most 1. If the recesses in the stator are also included in the calculation of the winding factor, the electrical machine described here will have a winding factor of greater than 1 for some harmonic components of the magnetomotive force with an order greater than 1. With a winding factor of greater than 1, a greater torque can be generated in sum with the same supply current. This means that the electrical machine can be operated efficiently.
The formation of the recesses in the stator does not require any significant additional effort in production, since the laminated sheets of the stator are usually stamped parts anyway and the recesses can be punched out in the same work step.
According to at least one embodiment of the electrical machine, the electrical winding comprises coils which are each wound around at least two of the teeth. This may mean that each coil of the electrical winding is wound around at least two of the teeth. Thus, the electrical winding is a distributed winding. The electrical winding may have at least three coils. On the first side and/or on the second side of the stator, individual conductor portions of the coils may overlap one another. By machining the recesses into the stator, the flux density of harmonic components of the magnetomotive force with an order greater than 1 can be amplified for the distributed electrical winding.
According to at least one embodiment of the electrical machine, the recesses are devoid of the electrical winding. This may mean that the electrical winding is not arranged in the recesses. The recesses may be devoid of electrically conductive material. The fact that the recesses are devoid of the electrical winding allows the recesses to act as flow barriers.
According to at least one embodiment of the electrical machine, the recesses each extend in a radial direction, the radial directions each extending parallel to a radius in a cross-section through the stator and the radius extends through the respective tooth. The recesses may each have an elongated extension along a radial direction. Each recess may extend along a different radial direction than the other recesses. The recesses may each extend completely through the stator in one of the radial directions. It is also possible that at least one connecting piece is arranged in each recess, so that the recesses have at least one interruption along the respective radial directions. By having the recesses extend along the radial directions, the recesses can separate two slots from each other in each case. This may mean that the recesses each extend between two slots. This allows the recesses to act as flow barriers.
According to at least one embodiment of the electrical machine, the recesses extend further along the respective radial direction than the neighboring slots. This may mean that each recess extends along the radial direction along which it extends further than the two slots directly neighboring the respective recess. Thus, in a cross-section through the stator, the recesses may each have a longer extension than the slots. The recesses may extend from an outer side of the stator towards an inner side of the stator. Here, the recesses can each extend along a radial direction in one of the teeth to a region of the respective tooth that is neighboring the rotor. By extending further than the neighboring slots, the recesses separate two slots from each other in each case. Thus, the recesses can act as flow barriers.
According to at least one embodiment of the electrical machine, the recesses are formed such that a harmonic component of the magnetomotive force, which is used as a working wave, has a larger amplitude than a harmonic component of the magnetomotive force of the same order of an electrical machine without recesses. This may mean that the recesses cause the amplitude of a harmonic component of the magnetomotive force used as a working wave to be increased compared to the case where the electrical machine has no recesses. Thus, the electrical machine can be operated more efficiently.
According to at least one embodiment of the electrical machine, the electrical machine is not a stepper motor.
According to at least one embodiment of the electrical machine, each of the recesses forms a mechanical barrier in order to reduce the fundamental wave of the magnetic flux and increase the working wave of the magnetomotive force. The electrical machine can thus be operated more efficiently.
According to at least one embodiment of the electrical machine, the recesses extend along a direction that is perpendicular to a cross-section through the stator. This may mean that the recesses extend along a direction that is parallel to the axis of rotation of the rotor. Thus, the recesses may extend from the first side of the stator to the second side of the stator. The recesses may extend from the first side completely to the second side of the stator. It is also possible that at least one connecting web is arranged in each of the recesses along the distance from the first side to the second side. This can increase the mechanical stability of the stator. By extending in a direction perpendicular to the cross-section through the stator, the recesses can act as flow barriers.
According to at least one embodiment of the electrical machine, a non-magnetic material is arranged in each of the recesses. The non-magnetic material can completely fill the recesses in each case. For example, air is arranged in the recesses. Due to the fact that a non-magnetic material is arranged in the recesses, the recesses can act as flow barriers.
According to at least one embodiment of the electrical machine, the recesses are uniformly distributed along the circumference of the stator. This may mean that any two directly neighboring recesses are equally spaced along the circumference of the stator. Thus, the recesses can act as flux barriers in the same way for different poles of the stator.
According to at least one embodiment of the electrical machine, the recesses are each adjacent to at least an outer side of the stator. It is possible that the recesses are adjacent to an outer side of the stator arranged at the outer circumference of the stator. The recesses may be open towards the outer side of the stator. It is also possible that the recesses are adjacent to an inner side of the stator. The recesses can be open toward the inner side of the stator. Thus, the recesses can act as flow barriers.
According to at least one embodiment of the electrical machine, every other tooth along the circumference of the stator comprises one of the recesses. This may mean that every other tooth along the circumference of the stator has exactly one of the recesses. This design of the stator may result in the flux density of the fundamental wave being substantially reduced and the flux density of at least one harmonic component having an order greater than 1 being substantially increased.
According to at least one embodiment of the electrical machine, each tooth has one of the recesses. This may mean that exactly one of the recesses is arranged in each tooth. This design can lead to a higher reduction of the flux density of the fundamental wave than in the case that only every other tooth has one of the recesses. Furthermore, an increase of the flux density of at least one harmonic component with the order greater than 1 is possible.
According to at least one embodiment of the electrical machine, the stator has at most as many recesses as slots. Thus, one recess can be arranged between each two slots. This design of the stator may have the effect that the flux density of the fundamental wave is substantially reduced and the flux density of at least one harmonic component with an order of greater than 1 is substantially increased.
According to at least one embodiment of the electrical machine, the stator has more than six teeth. For example, the stator has at least ten teeth or at least 14 teeth. With a larger number of teeth, the stator may have a larger number of magnetic poles.
According to at least one embodiment of the electrical machine, at least two components of the electrical winding are arranged in each slot, which are designed to be supplied with different phase currents. For example, conductor portions of two different coils of the electrical winding may be arranged in a slot. Thus, at least two conductor portions of different coils of the electrical winding may be arranged in each slot. Within each slot, the conductor portions of the different coils may be electrically isolated from one another. Thus, the slots may have a two-layer or multilayer design.
A method for operating an electrical machine is also provided. The electrical machine may be operated by the method. All features of the described electrical machine are also disclosed for the method for operating an electrical machine and vice versa.
According to at least one embodiment of the method for operating an electrical machine, the method comprises operating the electrical machine with a working wave of the magnetomotive force, the working wave differing from a fundamental wave of the magnetic flux. The fact that the electrical machine is operated may mean that a torque is generated with the electrical machine. Thus, the electrical machine is operated in such a way that a working wave is used for torque generation, which differs from a fundamental wave of the magnetic flux.
According to at least one embodiment of the method, the electrical machine comprises a stator comprising a stator core in which at least six slots are arranged, a distributed electrical winding which is at least partially arranged in the slots, and at least six teeth, the electrical machine comprising a rotor which is movable relative to the stator, one tooth of the stator being formed between two adjacent slots in each case, and at least three of the teeth comprising a recess which extends at least partially through the respective tooth.
The method has the same advantages as the electrical machine. Thus, the method allows the electrical machine to be operated efficiently.
According to at least one embodiment of the method, a harmonic of the magnetomotive force is used as a working wave, the harmonic comprising an order equal to the number of slots plus 1 or the number of slots minus 1. This can mean that the number of slots of the stator added with 1 results in the order of the harmonic component of the magnetomotive force, which is used as working wave. It is also possible that the number of slots of the stator minus 1 is equal to the order of the harmonic component of the magnetomotive force, which is used as the working wave. Thus, in both cases, the working wave that is used is a harmonic component of the magnetomotive force that has an order greater than 1. With these two possibilities of the order of the harmonic component, which is used as working wave, the increase of the flux density and of the winding factor is highest due to the fact that the recesses are arranged in the stator. Thus, the harmonic components with these two order numbers are suitable for efficient torque generation.
It is also possible that the design of the electrical winding is repeated n times along the circumference of the stator, where n is a natural number. In this case, a harmonic of the magnetomotive force having an order of the number of slots plus n or the number of slots minus n is used as the working wave.
A further electrical machine is provided. Each electrical machine described here solves the problem to be solved. All the same features or identically designated features of the electrical machines described herein are in each case also disclosed for the other electrical machines, and vice versa.
According to at least one embodiment of the electrical machine, the electrical machine includes a stator, and a rotor which is movable relative to the stator.
According to at least one embodiment of the electrical machine, the stator includes a stator core in which at least three slots are arranged.
According to at least one embodiment of the electrical machine, the stator includes at least three teeth and at least three rod-shaped electrical conductors. The electrical conductors may each have the shape of a rod. The electrical conductors may comprise an electrically conductive material, for example copper or aluminum. The electrical conductors may each extend through the stator parallel to the axis of rotation of the rotor. The electrical conductors may be dimensionally stable, which may mean that they are not bendable. The electrical conductors may be designed to be supplied with a separate electrical phase in each case. For this purpose, each electrical conductor may be separately connected to power electronics.
According to at least one embodiment of the electrical machine, at least one of the conductors is arranged in each of the slots. One of the conductors may be arranged in each slot.
According to at least one embodiment of the electrical machine, one tooth of the stator is formed between two neighboring slots in each case.
According to at least one embodiment of the electrical machine, at least three of the teeth comprise a recess which extends at least partially through the respective tooth.
According to at least one embodiment of the electrical machine, in operation of the electrical machine a working wave of the magnetomotive force differs from a fundamental wave of the magnetic flux.
According to at least one embodiment of the electrical machine, the electrical machine includes a stator, and a rotor which is movable relative to the stator, the stator comprising a stator core in which at least three slots are arranged, the stator comprising at least three teeth and at least three rod-shaped electrical conductors, at least one of the conductors being arranged in each of the slots, one tooth of the stator being formed between two neighboring slots in each case, at least three of the teeth having a recess which extends at least partially through the respective tooth, in operation of the electrical machine a working wave of the magnetomotive force differing from a fundamental wave of the magnetic flux.
The electrical machine has the advantages described above. Instead of a distributed electrical winding, the electrically conductive rods are used here. Also in this design, the arrangement of recesses in the stator results in the flux density of the fundamental wave being reduced compared to the situation where no recesses are arranged in the stator. In addition, the flux density for at least one harmonic component of the magnetomotive force with an order greater than 1 may be increased in the case where the stator has recesses compared to the case where the stator has no recesses.
According to at least one embodiment of the electrical machine, the three conductors are electrically short-circuited on one side of the stator. The three conductors can be electrically short-circuited on the first side of the stator. For this purpose, a short-circuit ring can be arranged on the first side of the stator. The short-circuit ring may comprise an electrically conductive material. The conductors can be electrically conductively connected to the short-circuit ring. On the second side of the stator, the conductors can be connected to power electronics. Thus, the conductors may each be supplied with a separate electrical phase.
A further method for operating an electrical machine is also provided. The further electrical machine can be operated with the further method. All of the same features or identically designated features of the electrical machines and methods described herein are respectively also disclosed for the further electrical machines and methods, and vice versa.
According to at least one embodiment of the method for operating an electrical machine, the method includes operating the electrical machine with a working wave of the magnetomotive force, the working wave differing from a fundamental wave of the magnetic flux.
According to at least one embodiment of the method for operating an electrical machine, the electrical machine comprises a stator comprising a stator core in which at least three slots are arranged, at least three teeth, and at least three rod-shaped electrical conductors, the electrical machine comprises a rotor which is movable relative to the stator, at least one of the conductors is arranged in the slots in each case, one tooth of the stator is formed between two adjacent slots in each case, and at least three of the teeth comprise a recess which extends at least partially through the respective tooth.
The method has the same advantages as the electrical machine. Thus, the method allows the electrical machine to be operated efficiently.
In the following, the electrical machine and the method for operating an electrical machine are explained in more detail in connection with exemplary embodiments and the associated Figures.
Figures LA, 1B, 1C, 1D and 1E illustrate an exemplary embodiment of the electrical machine. In addition, an exemplary embodiment of the method for operating an electrical machine is described.
With
The stator 21 has a stator core 23 in which six slots 24 are arranged. An air gap 34 is arranged between the stator 21 and the rotor 22. The slots 24 are each open toward the air gap 34. The stator 21 further comprises a distributed winding which is at least partially arranged in the slots 24. The distributed winding 25 may comprise at least three coils 28. Further, the stator 21 has six teeth 26, with one tooth 26 formed between two neighboring slots 24 in each case. The distributed winding 25 is distinguished in that the coils 28 of the winding 25 are not each wound around only one tooth 26. In the exemplary embodiment in
The teeth 26 each have a recess 27 extending through the respective tooth 26. The recesses 27 are devoid of the electrical winding 25. It is also possible that at least one connecting piece is arranged in each recess 27. Such connecting pieces are not shown in the Figures.
The recesses 27 each extend in a radial direction r, the radial directions r each being parallel to a radius in cross-section through the stator 21 and the radius extending through the respective tooth 26. Along the respective radial direction r, the recesses 27 extend further than the neighboring slots 24. A non-magnetic material 29, for example air, is arranged in each of the recesses 27. The recesses 27 each adjoin an outer side 30 and an inner side 33 of the stator 21. However, it is also possible that the recesses 27 extend less far along the radial directions r than shown in
In operation of the electrical machine 20, a working wave of the magnetomotive force differs from a fundamental wave of the magnetic flux. Thus, according to one exemplary embodiment of the method for operating an electrical machine 20, the electrical machine 20 is operated with a working wave of the magnetomotive force that differs from a fundamental wave of the magnetic flux.
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The exemplary embodiment of Figure LA thus allows to use as working wave a harmonic component of the magnetomotive force the order of which differs from 1. In this case it is suitable to use as working wave a harmonic of the magnetomotive force, which has an order of 5 or 7. This means that as working wave a harmonic of the magnetomotive force is used, which has an order equal to the number of slots 24 plus 1 or the number of slots 24 minus 1.
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Here and in the following exemplary embodiments, the electrical machine 20 may have a rotor 22 with permanent magnets and a number of pole pairs, the number of pole pairs corresponding to the order of the harmonic component used as the working wave.
The recesses 27 are each arranged in the teeth 26, which are located between two slots 24, in which conductor portions 35 of two coils 28 of different phases are arranged. The teeth 26, which are located between two slots 24, in which conductor portions 35 of the same phase are arranged, are devoid of recesses 27.
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On the first side 36 of the stator 21, the conductors 31 are electrically short-circuited. For this purpose, the conductors 31 are electrically connected to a short-circuit ring 32, which is arranged on the first side 36 of the stator 21. On the second side 37, the conductors 31 are connected to power electronics so that each conductor 31 can be supplied with its own phase. Thus, the electrical machine 20 has seven phases.
According to one embodiment of the method for operating an electrical machine 20, the electrical machine 20 of
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Number | Date | Country | Kind |
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102022113435.0 | May 2022 | DE | national |