Patent Application
20250167654
The invention relates to an electric motor, which can be designed in particular as an electric permanent-magnet synchronous machine (PMSM).
This type of electric motor has a stator that forms a number PZS of magnetic poles of PZS=2pS, with pS the number of pole pairs of the stator that are formed when a corresponding current is applied. The stator has a number NN of slots for electromagnetically generating the pole pairs. An (electrically energizable) stator winding is inserted into the slots to generate a rotating magnetic field, i.e., the stator winding is set up accordingly to generate the rotating magnetic field. To generate the desired magnetic rotating field, it is sufficient to energize the stator winding with a suitable alternating electric current, while electrical switching operations, such as those used in stepper motors, are not necessary. The electric motor can thus generate a continuous torque in normal operation, i.e., with appropriate continuous current supply with alternating current, so that the electric motor is particularly suitable as a drive motor for an elevator. The magnetic flux generated by energizing the stator winding can be at least partially guided by (in particular tooth-shaped) magnetic flux conductors of the stator.
The electric motor also has a rotor mounted movably about a rotation axis, wherein the rotor, or more precisely a rotor body of the rotor, carries permanent magnets. This rotor can be designed as an internal rotor (e.g., if the electric motor is to be used as a drive for an elevator) or as an external rotor (e.g., if the electric motor is to be used in a fan), depending on the desired application of the electric motor. In both cases, however, it can be characteristic that the permanent magnets are preferably arranged on a (inner or outer) circumference of the rotor/a rotor body of the rotor, i.e., on the circumferential side, so that the rotor carries the permanent magnets on the circumferential side. This can ensure that there is a (particularly very small) air gap between the rotor and stator, between the permanent magnets of the rotor and the stator (and not, for example, between a rotor body and the stator, wherein the rotor body carries the permanent magnets). This naturally has a considerable effect on the generated magnetic field distribution and can distinguish the electric motor, for example, from other electric motors in which permanent magnets are not arranged on the circumferential side but, for example, inside a rotor body of the rotor or axially offset with respect to the rotor body and/or axially offset inwards with respect to an outer circumference of the rotor body, wherein in these designs said air gap typically exists between the rotor body and the stator.
Due to legal requirements, the use of motors with higher efficiencies has become increasingly important in recent years. Corresponding normative agreements define energy-saving classes that have been included in the technical data by the manufacturers.
In order to reduce the significant machine-dependent losses, the current prior art relies on the increased use of copper in the motor winding, better sheet metal material, optimized fan geometry or an energetically optimized bearing. Especially for slow-running motors (e.g., at approximately 300 rpm), either permanent magnet motors with high-pole stator windings (more than 10 magnetic poles in the stator) have often been used, or low-pole (e.g. 2-, 4- or 6-pole) stator windings have been used as 2-hole windings in combination with high-pole rotors (e.g., with a rotor pole count of PZR>40).
As explained above, the number of pole pairs p is the number of pairs of magnetic poles within rotating electrical machines. An electric motor with three winding strands, each forming two poles, therefore has a pole pair number of pS=1 (there are 2 poles per phase). However, if there are a total of six winding strands in the stator, the electric motor can already have a number of pole pairs of pS=2.
In motors operated directly on the mains, the mains frequency and the number of pole pairs determine the rotating field speed of a rotating field machine. Synchronous machines rotate at exactly the rotating field speed, whereas asynchronous machines rotate at a slightly different speed (depending on the load). The rotating field speed ns can be determined as follows: ns=f/ps, where ps is the number of pole pairs and f is the mains frequency.
The mechanical power delivered by the electric motor is then the product of the torque delivered and the speed. For mains-powered motors with the same specified rated power, the rated torque is therefore typically proportional to the number of pole pairs. Motors with the same power but a larger number of pole pairs are therefore generally larger than motors with the same power but a smaller number of pole pairs. However, when comparing motors with the same basic principle and the same size, the achievable nominal torque is not always proportional to the number of pole pairs. Depending on the technology, the torque can increase more or less strongly (but always disproportionately) with an increasing number of pole pairs and can even decrease again when a higher number of pole pairs is exceeded. Accordingly, the number of pole pairs varies considerably in prior-art motors.
In the prior art, windings are inserted into the slots of the stator to form the poles in the stator. The number of pole pairs then results from the winding pattern of the stator windings. A characteristic measure for the winding structure is the number of holes q, which indicates how many slots are available per string m and pole of the stator (given by the pole count PZS=2pS). The required total number of slots NN in the stator is then calculated as: NN=(PZS m)/q.
For distributed windings, q≥1. If q is an integer, it is a so-called “whole-hole winding”. On the other hand, reference is made to a fractional hole winding if q is a fractionally rational number. For single-tooth windings, q<1 and is therefore always a fractionally rational number.
Against this background, the invention addresses the problem of improving the efficiency of an electric motor as described at the outset. In particular, a high electrical efficiency and a high power factor cos φ is to be achieved (cos φ is also referred to as the active power factor and indicates the ratio of the amount of active power P and apparent power S).
In particular, the invention addresses the specific problem of providing an electric motor which can generate a high torque at speeds of approximately 300 rpm and thereby combines a high electrical efficiency with a preferably high power factor cos φ. The invention thus pursues in particular the aim of providing a high-efficiency motor. A further boundary condition for the invention is the desire to enable such an electric motor to operate as vibration-free as possible, particularly in the speed range of approximately 300 rpm.
To solve this problem, one or more of the features disclosed herein are provided for an electric motor according to the invention. In particular, it is thus proposed according to the invention for solving the problem in an electric motor of the type mentioned at the outset that the stator winding is designed and can be energized in such a way that the following applies to the stator for the ratio of the number NN of its slots and the number NU of the primary areas formed by the stator: (NN/NU)<6.
This necessarily gives: NN<(6 NU) or NU>(NN/6). In other words, according to the invention, it can thus be provided that the winding of the coils of the stator is arranged and can be energized in such a way that, in particular in the case of a typical three-phase energization, a sequence of NU similar magnetic primary areas is produced or formed along the circumference of the stator, wherein a maximum of five slots (i.e., less than six slots) should form a respective primary area of the stator. It is particularly preferable here if a maximum of four grooves or even a maximum of only three grooves are used to form a respective primary area (then the following applies: (NN/NU)<5 or even (NN/NU)<4).
The number of primary areas NU can, for example, be calculated for the respective electric motor as the greatest common divisor (ggT) from the pole count of the rotor PZR and the number of slots of the stator NN, so that the following applies: NU=ggT(PZR, NN). Alternatively, the following can also apply: NU=ggT(PZS, NN) with PZS the number of magnetic poles that the stator can form (when the stator winding is energized).
A primary area in the sense of the invention can be understood here in particular as a (circular) segment of the stator, which is repeated periodically along the circumference of the stator, specifically in relation to the formation of the magnetic field distribution that results when the stator is energized. The primary areas can thus form a similar symmetry of magnetic poles (in each case in relation to a radial direction) or can form only one respective pole of the stator. Each of said segments can thus show a similar arrangement of the stator winding in order to define a sequence and radial orientation of magnetic poles (or of a magnetic pole) which is repeated in each of the primary areas. Thus, the number PZS of magnetic poles of the stator can deviate from the number NU of primary areas of the stator, i.e., in particular PZS>NU. Depending on the design of the stator winding, however, the following can also apply: PZS=NU.
Preferably, in an electric motor according to the invention, at least seven primary areas can be formed or designed along the circumference of the stator (with corresponding current flowing through the stator winding). In the case of larger motors (for example with an internal stator diameter of more than 200 mm), it can be advantageous to form at least 8 or even at least 10 primary areas along the circumference of the stator (by correspondingly designing the stator winding). Such a high number of primary areas (which, however, also depends on the size of the electric motor and may be correspondingly smaller for smaller diameters of the stator) is favorable in order to achieve a lower amplitude of the mechanical vibrations that occur in the stator, more precisely in the stator yoke (in the case of an internal rotor motor), when the electromagnetically generated poles of the stator interact with those of the rotor (during operation of the motor). This favors low-vibration operation of the electric motor.
A particularly preferred range of values for the design of an electric motor according to the invention can be as follows: Number of poles of the stator PZS>8, number of slots of the stator NN<50 and number of poles of the rotor PZR>50.
By designing the electric motor according to the invention, vibration excitation during operation of the motor can be greatly reduced compared to conventional electric motors. As a result, the vibration behavior of the motor (in the sense of reduced excitation of mechanical vibrations) and its environment can be improved, because only very low vibrations emanate from the electric motor during operation and thus low-noise operation of the motor is possible, which is of great advantage especially when used in elevators. The reason for this is the fact that, due to the high number of poles of the stator that is now possible, only very low mechanical vibration excitation occurs when the stator is mechanically loaded in the radial direction by interaction with the permanent magnets of the rotor when energized.
The improvement in vibration damping or reduction in vibration excitation also has the positive side effect that the metal plates typically used for the stator no longer need to be connected with an anchor bolt, as is the case with many previously known motors. As a result, a round cross-sectional shape of the stator laminations can be selected. This offers the advantage that an internally round housing can also be used to enclose an electric motor according to the invention. The connection between the motor and the housing can thus be achieved very easily without screws by means of shrinking, which offers further advantages. Thus, a further problem solved by the invention can be considered that of how the use of previous round motor housings can be maintained without disadvantages in terms of undesirable vibrations and despite an increase in the power factor of the electric motor.
As a result, both a high electrical efficiency and a high power factor can be achieved by the design according to the invention (cf. Table 1). This has advantages for the use of the motor in an electric drive system (for example in fans or elevators), since the frequency converter that may be required to operate the motor (depending on the specific design) can be comparatively small/compact and thus inexpensive, and a high electrical efficiency is also achieved.
An electric motor designed according to the invention can be used particularly advantageously as a slow-running motor with high torque at speeds of approximately 300 rpm, in particular as a so-called torque motor for industrial applications, or for example as a gearless elevator motor in elevators. Use in energy-efficient wheel hub motors or fans is also conceivable and advantageous.
As already mentioned, an electric motor according to the invention can preferably be designed as a permanent-magnet synchronous motor (PMSM), i.e. as an electric permanent-magnet synchronous machine (sometimes also referred to as a “permanently excited synchronous machine”). In particular, the rotor can therefore carry PZR permanent magnets that form a number PZR of magnetic poles.
Alternatively or additionally to the features discussed so far, the electric motor described at the outset can also be designed as follows to solve the problem: It can thus be provided, that among other features disclosed herein, the rotor of the electric motor forms a number PZR of magnetic poles (with the aid of said permanent magnets, i.e., the number PZR of magnetic poles can in particular correspond to the number of permanent magnets that the rotor carries) and that the following applies for the ratio of the pole count of the rotor PZR and the pole count PZS of the stator: PZR/PZS≥3. Preferred values are PZR/PZS≥5. At the same time, however, it can be advantageous to require at the same time: PZR/PZS≤10, i.e. a particularly favorable range of values for the above ratio is: 3≥PZR/PZS≤10; preferred values are: 4≥PZR/PZS≤8.
The invention has recognized that such a large ratio between PZR and PZS is particularly favorable in order to achieve a high electrical efficiency of the electric motor.
In such embodiments, the pole count/number of poles PZR of the rotor can be formed in particular according to the following law of formation: PZR=2 NN+/−PZS. In such a case, the following can therefore apply for the necessary number NN of slots of the stator: NN=(PZR−/+PZS)/2. Furthermore, according to the invention, in such embodiments the number of slots NN of the stator may preferably be as follows: NN<60 (maximum number of slots of the stator), and preferably additionally: NN≥6 (minimum number of slots of the stator). A particularly preferred value range for the number NN of stator slots is: 50≥NN≥12.
Alternatively or in addition to the features discussed so far, the electric motor described at the outset can also be designed as follows to solve the problem: It can thus be provided, that among other features disclosed herein, the rotor of the electric motor has a maximum outer diameter DRa and forms a number PZR of magnetic poles, wherein a permanent magnet is arranged in each case within a pole width BPR of the rotor of BPR=2πDRa/PZR. This pole width can therefore be understood as a circumferential portion along the outer circumference 2πDRa of the rotor, within which one permanent magnet on average is arranged.
Furthermore, magnetic flux conductors of the stator, which delimit the slots, can be designed in the form of teeth. The teeth can form a tooth width BZ at their base, which defines a respective slot width BN of the slots for holding the stator winding. Furthermore, it may be provided that a slot is formed between adjacent teeth of the stator with a slot width BS and that the following applies to the ratio of tooth width BZ to pole width BPR (24): BZ/BPR>0.4 or BZ>(0.4 BPR). In this case, it is particularly advantageous if the following also applies for the ratio of slot width BS and tooth width BZ: BS/BZ>1.0, i.e., BS>BZ. The invention has recognized that such dimensioning of the stator offers considerable advantages in order to improve the product of efficiency and power factor cos φ of the electric motor.
This approach can be described qualitatively in such a way that the width of the teeth BZ should be selected as a function of the pole width BPR of the rotor, but so wide that only slightly more than two tooth widths already make up one pole width. It is particularly preferable if the following applies: BZ>(0.5 BPR). In this case, a maximum of two tooth widths add up to a given pole width of the rotor. The teeth should therefore be comparatively wide compared to previously known electric motors. On the other hand, the tooth width should not be excessive. Therefore, in embodiments according to the invention, it can also be provided that the following additionally applies for the ratio of the tooth width BZ of the teeth of the stator and the pole width BPR of the rotor (cf. the above definition): BZ/BPR<0.7.
In addition, the slots, or more precisely the slot width BS, between the teeth of the stator, can also be designed to be comparatively wide, i.e., open. However, there are also limits to this opening, meaning that the ratio of slot width BS and tooth width BS can also be used: BS/BZ>1.2, i.e., the slot width BS can preferably be 20% greater than the width of the respective tooth at its base.
In further possible embodiments of the invention, the following may also apply: BS/BZ>1.3; preferably BS/BZ>1.4; particularly preferably BS/BZ>1.5.
Possible embodiments of the invention can provide, for example: BS>5 mm, preferably: BS>10 mm, particularly preferably: BS>11 mm. For a given inner diameter of the stator of DSI, it is therefore advantageous if the ratio of slot width and DSI (i.e., BS/DSI) is at least 3.0%, preferably at least 3.5%. For larger motors with inner diameters of more than 350 mm, however, this ratio can also fall to values of less than 2.5%.
It can also be provided that the following applies for the ratio of the useful slot width BS and the outer diameter of the stator DSa:BS/DSa>2%, preferably BS/DSa>2.5%. At the same time, however, it is advantageous if values of BS/DSa=0.34 are not exceeded. Thus, there is a preferred value range for the useful slot width BS of: 2%<BS/DSa<3.4% as a function of the outer diameter of the stator. This applies to both external rotor and internal rotor motors.
The value ranges described above with reference to the design of the slots and teeth of the stator make it possible to form a high number of magnetic poles of the stator PZS even in a confined installation space. For example, the following can apply to a motor according to the invention: PZS≥12, in particular with an internal stator diameter of less than 250 mm.
The aforementioned tooth-shaped magnetic flux conductors of the stator can preferably be designed in one piece with a stator yoke of the stator and/or can be made of a ferromagnetic material. These are also crucial in the formation of the magnetic primary area.
According to the invention, the problem can also be solved by further advantageous embodiments according to the description and claims that follow.
The concepts of the invention presented so far for dimensioning electric motors can be applied both to motors in which the magnetic flux runs in a radial direction and thus perpendicular to a rotation axis of the motor, or in an axial direction along the rotation axis. In other words, an electric motor according to the invention can thus be designed as an axial flux motor, in particular in the form of a disk rotor motor, or as a radial flux motor or even as a combination of an axial flux motor and a radial flux motor.
Furthermore, the rotor of the electric motor can be designed as an internal rotor or as an external rotor. If the rotor is designed as an internal rotor, the rotor preferably carries the permanent magnets on the outer circumference; if the rotor is designed as an external rotor, on the other hand, it carries them on the inner circumference. In both cases, an (especially very small) air gap can be formed between the respective permanent magnet and the stator.
As already mentioned, it can be advantageous, particularly for low-vibration operation of the electric motor, if at least seven, preferably at least ten, primary areas can be formed or are formed along the circumference of the stator. In the case of very small motors, however, a number of two primary areas may also be sufficient. The decisive factor is primarily the ratio of the number NN of slots in the stator and the number NU of primary areas.
According to a further advantageous embodiment, the ratio of the number of poles of the rotor PZR and the number of poles of the stator PZS can apply: PZR/PZS≤10 (then the following applies: PZR≤10 PZS), in particular PZR/PZS≤8 or even PZR/PZS≤5. The invention thus proposes limiting the number of poles/permanent magnets of the rotor to at most a factor of ten, or even a factor of eight or even a factor of five (as in the examples according to Table 2), depending on the number of poles of the stator PZS. If the number NU of primary areas of the stator should also be NU≥7 and the stator winding is designed so that only one magnetic pole is formed per primary area (so that PZS=NU≥7), this can, for example, lead to values of electric motors according to the invention as shown in Table 2.
In electric motor embodiments according to the invention, however, a certain minimum number of poles of the rotor should still be maintained in order to ensure good synchronization of the electric motor. For this reason, the following can preferably also be provided for the electric motor: PZR/PZS≥4, and particularly preferably PZR/PZS≥5.
In further possible embodiments of the invention, the following may also apply: PZR/PZS≤8, preferably PZR/PZS≤6, particularly preferably PZR/PZS≤5, for example as in the above examples of Table 2.
In other words, the stator pole count PZS=2pS can be selected to be comparatively high compared to previously known motors, for example with PZS≥8, preferably PZS≥10, particularly preferably PZS≥12, in particular PZS≥16. A particularly preferred range of values for the stator pole count PZS is: 12≥PZS≥20.
However, as already explained, the pole count PZR=2pR of the rotor can also be selected to be (comparatively) high, for example with PZR≥40, preferably PZR≥50 or even PZR≥60 (cf., for example, the examples in Table 2). In individual cases, the rotor pole count can therefore be 60, 80 or even 100 (cf. Table 2), depending on the size of the motor, wherein the number of poles will naturally tend to increase as the size of the motor increases. As there is typically only a very small air gap between the rotor (designed either as an external or internal rotor) and the stator, an advantageous dimensioning for an internal rotor, for example, can be that a permanent magnet of the rotor is arranged at least every 5 mm along the inner circumference of the stator, so that the following applies: DSi/PZR≤5.0 mm; preferably: DSi/PZR≤4.5 mm.
The teeth of the stator can preferably be T-shaped, in particular in such a way that the tooth width BZ is smaller than a respective tooth tip width BZK of the respective tooth. It is also helpful if the teeth are oriented strictly radially to the rotation axis.
Said teeth of the stator can thus form a tooth tip width BZK on their radial inner side. The ratio of slot width BS and tooth tip width BZK can then preferably be as follows: BS/BZK>0.45. In this case, the respective slot width therefore occupies a circumferential length that corresponds to more than 45% of the tooth tip width (which can also be measured along the circumference). In further possible embodiments of the invention, the following can also apply: BS/BZK>1.05; preferably BS/BZK>1.10; particularly preferably BS/BZK>1.20. In other words, the slot width can be much greater than is usual with conventional electric motors.
The technical effect achieved by such open slots is that a high power factor cos φ and simultaneously low electrical losses can be achieved for an electric motor with a stator pole count PZS and rotor pole count PZR that are not equal (as proposed here in particular). For motors with the same stator and rotor count (PZS=PZR), however, the use of such open slots is rather disadvantageous, especially for the power factor cos φ. Closed slots should therefore be used for such motors wherever possible.
The stator of an electric motor according to the invention can have fewer than two teeth per pole of the rotor. This means that the following can apply to the number ZZs of teeth on the stator: ZZs<2 PZR. In particular, the following can also apply: NN<2 PZR.
For the ratio of a minimum inner diameter DSi of the stator and a maximum outer diameter DSa of the stator, the invention proposes a dimensioning that complies with the following specification: DSi/DSa≥0.80. For an internal rotor, this means that in this case the rotor has an installation space available that is approximately 80% of the outer diameter of the stator (at least if the minimum necessary air gap between the rotating rotor and stator is ignored). This provides a large cross-sectional area (for a given maximum size of the electric motor) (this increases quadratically with the radius) through which the magnetic flux can be conducted, allowing larger torques to be generated.
The stator winding of the electric motor can be designed in different ways. For the number of holes q of the electric motor, defined as q=NN/(2pS m) with NN the number of slots of the stator, 2pS=PZS the number of magnetic poles of the stator and m the number of phases or strands of the stator winding, it is preferable if: q<1.5; preferably q=1, because then a comparatively short winding head length can be achieved, which offers advantages in terms of simple production of the electric motor. In other words, the concept according to the invention can be realized particularly well with a single-hole winding. In other words, the number of holes q can preferably be an integer.
The number of slots NN of the stator can preferably be an integer multiple of the number of pole pairs pS of the stator. This is because in this case a fractional-hole winding, which is expensive to manufacture, can be avoided and the stator winding can instead be realized as a whole-hole winding. For the same reason, it is advantageous if the number NN of slots does not exceed a value of 60, preferably 50.
A magnet width BM of a respective one of the permanent magnets of the rotor can be defined, for example, as a circular arc BM=Q2πDRa/NM, which is occupied by one of the permanent magnets, with DRa the maximum outer diameter of the rotor, Q the circumferential portion occupied by the respective permanent magnet and NM the number of permanent magnets of the rotor (3), wherein typically NM=PZR. Based on this definition, embodiments according to the invention are preferred for which the following applies: BM<20 mm, preferably: BM<15 mm. Furthermore, it may additionally be provided that the following applies: BM≥10 mm, particularly preferably: BM≥11 mm. These value ranges make it possible to form a sufficient number of rotor poles and at the same time comply with the limitations with regard to the number of stator poles required.
As already mentioned, the rotor of the electric motor can form a number PZR of magnetic poles with the aid of its permanent magnets. If the stator has an outer circumference of US=2πDSa, preferred embodiments of electric motors according to the invention are as follows: 25 mm<US/PZR<75 mm, particularly preferably: 28 mm<US/PZR<50 mm; these values thus indicate the respective circumferential length on the outer circumference of the stator, within which a magnet of the rotor is to be arranged in each case.
As has already been mentioned several times, the stator winding can have a plurality, in particular a number m, of strands or phases, or m different electrical phases can be formed with the m strands when the strands are energized accordingly. The electric motor can therefore preferably have a frequency converter with which the stator winding can be supplied with electrical voltage. In particular, the stator can have a three-phase/three-strand stator winding (m=3). In this case, the number of stator pole pairs pS can be a multiple of three; however, other configurations are also possible.
The permanent magnets of the rotor can preferably be electrically insulated from a rotor body of the rotor.
Furthermore, a respective flux direction of the permanent magnets of the rotor can also be oriented radially in relation to the rotation axis of the rotor.
A relative angular position of the magnetic poles of the rotor can have an angular offset in the circumferential direction within a first axial segment of the rotor (in comparison) to a relative angular position of magnetic poles within a second axial segment of the rotor.
Alternatively or additionally, a relative angular position of the magnetic poles of the stator in the circumferential direction within a first axial segment of the stator (in comparison) to a relative angular position of magnetic poles within a second axial segment of the stator may also have an angular offset.
In particular, such angular offsets can be designed in such a way that the poles of the rotor/stator are formed in a continuous slope along the rotation axis. Alternatively, such a configuration of an electric motor according to the invention can also provide for the poles of the rotor to be arranged in a stepped incline, similar to steps, along the rotation axis. The rotor can also be continuously inclined. Alternatively or additionally, such a stepped or continuous inclination of the poles can also be provided on the stator.
In particular, the invention proposes that an electric motor according to the invention is dimensioned and supplied with an electrical operating voltage in such a way that during operation in a speed range of approximately 300 rpm a maximum stator frequency of fS,max=200 Hz, preferably of fS,max=150 Hz is not exceeded. The stator frequency indicates the frequency at which the laminations forming the stator are remagnetized during motor operation, while the speed of the motor indicates the frequency at which the rotor rotates. It is particularly preferable if the electric motor is used in such a way that the stator frequency does not fall below a minimum of fS,min=20 Hz, preferably fS,min=15 Hz, during operation.
Such targeted use of an electric motor according to the invention makes it possible to operate the electric motor optimally in a speed range of approximately 300 rpm, i.e. with high efficiency and with acceptable heat generation due to the low-frequency remagnetization. This is of interest for numerous applications, in particular for driving elevators, where this speed range must be provided frequently and repeatedly by the electric motor. In a configuration as described above, electric motors according to the invention can therefore be used particularly effectively and efficiently in the speed range of approximately 300 rpm.
The invention will now be described in more detail with reference to exemplary embodiments, but is not limited to these exemplary embodiments. Further embodiments of the invention can be obtained from the following description of a preferred exemplary embodiment in conjunction with the general description, the claims and the drawings.
The following description of examples serves only to explain design variables, in particular the primary areas of the stator, which can be designed in accordance with the invention; possible design variables by which a motor in accordance with the invention can be characterized are shown in the following list. The electric motors shown in the figures thus do not yet show a design according to the invention; however, electric motor designs according to the invention are easily accessible to a person skilled in the art with the aid of the figures by applying the rules described above and in the claims for numerous design variables of the stator and/or the rotor. In the drawings, elements which correspond in their function are also given corresponding reference numerals even if their design or shaping differs.
In the drawings:
It can be seen in all figures that the permanent magnets 5 are arranged on the circumferential side, namely on the outer circumference of the respective internal rotor 3. Accordingly, the minimum air gap 23 (see
The stator 2 has a total of NN=24 grooves 14. The grooves 14 are formed by the spaces that exist between the magnetic flux conductors 8 of the stator 2, which are designed as teeth 10. A stator winding 4 (not illustrated), which has three strands (m=3), is inserted into the total of twenty-four slots 14.
When the stator winding 4 is energized accordingly, the stator 2 of
In the example shown in
Further design variables relevant to the invention are shown in
Based on these illustrations, embodiments of electric motors according to the invention, as previously described and in particular described in the claims, can now be reproduced comparatively easily. For example, an electric motor 1 according to the invention can be designed as shown in Table 1, for example with a rotor 3 that has a pole count of PZR=60, a stator 2 that forms a total of PZS=12 poles and an equal number NU of twelve primary areas 13 (so that a primary area 13 then defines only a single magnetic pole in each case and the following applies: NU=12), resulting in a ratio of PZR/PZS=5. For this purpose, NN=36 slots 14 can be provided on the stator 2.
Maintaining this principle, the pole count 3 of the rotor can then be increased to PZR=80 for larger sizes, for example. In this case, while retaining PZR/PZS=5, the pole count of the stator 2 can be PZS=16, wherein in this case sixteen primary areas 13 and NN=48 slots are provided on stator 2.
For an even larger design of an electric motor 1 according to the invention, the following can apply, for example: PZR=100; PZR/PZS=5; PZS=20=NU; NN=60.
Further possible embodiments of electric motors 1 according to the invention are described in the claims, wherein the respective design parameters can be understood with reference to
To summarize, for an electric motor 1 which has a stator 2 which is set up to generate a rotating magnetic rotating field, and which also has a rotor 3 which is mounted rotatably about a rotation axis 6 and which carries a number of permanent magnets 5, it is proposed, in order to increase the electrical efficiency but also to reduce mechanical vibrations during operation, that a stator winding 4 is inserted into slots 14 of the stator 2 and is energized with a multiphase current in such a way that the stator 2 forms a magnetic field which is characterized by a number NU of primary areas 13 and that at most five of the slots 14 of the stator 2 are used per primary area 13. Here, preferably at least seven, particularly preferably at least eight or even at least ten primary areas 13 can be formable or formed along the circumference of the stator 2 when the stator winding 4 is energized accordingly.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2022 104 731.8 | Feb 2022 | DE | national |
This application is a 371 National Phase of PCT/EP2023/055009, filed Feb. 28, 2023, which claims priority from German Patent Application No. 10 2022 104 731.8, filed Feb. 28, 2022, both of which are incorporated herein by reference as if fully set forth.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2023/055009 | 2/28/2023 | WO |
