Electric motor and corresponding application

Abstract

The invention relates to an electric motor 1 that has a stator 2, which is designed to produce a rotating magnetic field, and a rotor 3, which is rotatably mounted about a rotation axis 6 and which has a number of permanent magnets 5. The aim of the invention is to increase the electric efficiency but also reduce vibrations during operation. This is achieved in that a stator winding 4 is inserted into grooves 14 of the stator 2 and is energized using a multiphase current, the stator 2 forms a magnetic field which is characterized by a number NU of base areas 13, and maximally five of the grooves 14 of the stator 2 are used per base area 13. In the process, preferably at least seven, more preferably at least eight or even at least ten base areas 13 are formed or can be formed along the circumference of the stator 2 in a corresponding energizing process of the stator winding 4 (fig. 1).

Description

[0001] Electric motor and associated use The invention relates to an electric motor, which can be designed in particular as an electric permanent magnet synchronous machine (PMSM). This electric motor has a stator which has a number of PZ S at magnetic poles of PZ S = 2p S trained, with p S the number of pole pairs of the stator that are formed when the current is applied. For the electromagnetic generation of the pole pairs, the stator has a number N Non slots. Here, an (electrically energizable) stator winding is inserted into the slots to generate a rotating magnetic field, i.e. the stator winding is accordingly configured to generate the rotating magnetic field. To generate the desired rotating magnetic field, it is sufficient to energize the stator winding with a suitable alternating electrical current, while electrical switching operations, as used in stepper motors, are not necessary. The electric motor can thus generate a continuous torque during normal operation, i.e. with appropriate continuous energization 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 guided at least partially through (in particular tooth-shaped) magnetic flux conductors of the stator.The electric motor further comprises a rotor mounted for movement about an axis of rotation, 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 an (inner or outer) circumference of the rotor / a rotor body of the rotor, i.e., on the circumference, so that the rotor carries the permanent magnets on its circumference. 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, where the rotor body carries the permanent magnets).This naturally has a significant impact on the generated magnetic field distribution and can, for example, distinguish the electric motor from other electric motors in which permanent magnets are not arranged circumferentially, but rather, for example, inside a rotor body of the rotor, or axially offset from the rotor body, and / or axially offset inward relative to an outer circumference of the rotor body. In these designs, the aforementioned air gap typically exists between the rotor body and the stator. Due to legal requirements, increased attention has been paid in recent years to the use of motors with higher efficiency levels. Corresponding normative agreements define energy-saving classes, which manufacturers have incorporated into their technical specifications.To reduce the significant machine-related losses, the state of the art has so far relied on increased use of copper in the motor winding, better sheet metal material, optimized fan geometry, or energy-optimized bearings. Especially for slow-running motors (e.g., at approximately 300 rpm), permanent magnet motors with high-pole stator windings (more than 10 magnetic poles in the stator) have often been used, or there have also been low-pole (e.g., 2-, 4-, or 6-pole) stator windings as 2-hole windings in combination with high-pole rotors (e.g., with a rotor pole count of PZ). R > 40). As explained, the number of pole pairs p is the number of pairs of magnetic poles within rotating electrical machines. An electric motor with three winding phases, each forming two poles, thus has a pole pair number of p according to a common definition. S= 1 (there are 2 poles per phase). However, if there are a total of six winding phases in the stator, the electric motor can already have a pole pair number of p S = 2. In motors operated directly from 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, while asynchronous machines (load-dependent) rotate at a slightly different speed. The rotating field speed n s can be determined as follows: n s = f / p s , with p sthe number of pole pairs and f the mains frequency. The mechanical power delivered by the electric motor is then the product of the supplied torque and the speed. For mains-operated motors with the same specified rated power, the rated torque is therefore typically proportional to the number of pole pairs. Motors of the same power but with a larger number of pole pairs are therefore generally larger than motors of the same power but with a smaller number of pole pairs. When comparing motors with the same basic principle and the same size, the achievable rated torque is not fundamentally proportional to the number of pole pairs. Depending on the technology, the torque can increase more or less (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 state-of-the-art motors.To form the poles in the stator, the current technique involves inserting windings into the stator slots. The number of pole pairs is then determined from the winding pattern of the stator windings. A characteristic measure of the winding structure is the number of holes q, which indicates how many slots per phase m and pole of the stator (given by the number of poles PZ). S = 2p S ) are available. The required total number of slots N N in the stator is then: N N = (PZ Sm) / q. With distributed windings, q ≥ 1. If q is an integer, it is a so-called “whole winding”. On the other hand, a fractional hole winding is referred to when q is a fractional rational number. With single-tooth windings, q < 1 and is therefore always a fractional rational number. Against this background, the object of the invention is to improve the efficiency of an electric motor as described above. In particular, a high electrical efficiency and a high power factor cos φ are to be achieved (cos φ is also referred to as the active power factor and indicates the ratio of the active power P to the apparent power S). The invention is based in particular on the specific object of providing an electric motor which can generate high torque at speeds of approximately 300 rpm and combines high electrical efficiency with the highest possible power factor cos φ.The invention therefore pursues the particular objective of providing a high-efficiency motor. A further boundary condition for the invention is the desire to enable the most vibration-free operation of such an electric motor, particularly in the speed range of approximately 300 rpm. To achieve this object, the features of claim 3 are provided according to the invention for an electric motor. In particular, to achieve the object in an electric motor of the type mentioned at the outset, the invention proposes that the stator winding be designed and energizable in such a way that for the stator, the ratio of the number N. N its grooves and number N U of the primary areas formed by the stator: (N N / N U ) < 6. It necessarily follows that: N N < (6 N U ) or N U > (N N / 6). In other words, according to the invention, it can be provided that the winding of the coils of the stator is laid and energized in such a way that, in particular with a typical three-phase current supply, a sequence of N U similar magnetic primary regions along the circumference of the stator, whereby a maximum of five slots (i.e., less than six slots) should form a respective primary region of the stator. It is particularly preferred if a maximum of four slots or even only a maximum of three slots are used to form a respective primary region (then the following applies: (N N / N U ) < 5 or even (N N / N U ) < 4). The number of original areas N U can be calculated, for example, for the respective electric motor as the greatest common divisor (GCD) of the number of poles of the rotor P ZR and the number of slots of the stator N N , so that: N U = gcd(PZR ,N N ). Alternatively, the following may also apply: N U = gcd(P ZS ,N N ) with P ZS the number of magnetic poles that the stator can form (when energized to the stator winding). A primary region in the sense of the invention can be understood here in particular as a (circular) segment of the stator that repeats periodically along the circumference of the stator, specifically with regard to the formation of the magnetic field distribution that results when energized to the stator. The primary regions can thus form a similar symmetry of magnetic poles (each with respect to a radial direction) or can also form only one respective pole of the stator. Each of said segments can thus exhibit a similar arrangement of the stator winding in order to define a sequence and radial orientation of magnetic poles (or of one magnetic pole) that repeats in each of the primary regions. Thus, the number PZS on magnetic poles of the stator of the number N U at the original areas of the stator, so in particular P ZS > N U . Depending on the design of the stator winding, the following may also apply: P ZS = N U. In an electric motor according to the invention, at least seven primary regions can preferably be formed or can be formed along the circumference of the stator (with appropriate current supply to the stator winding). In larger motors (for example with an inner stator diameter of more than 200 mm), it can be advantageous to form at least 8 or even at least 10 primary regions along the circumference of the stator (by appropriately designing the stator winding). Such a high number of primary regions (which, however, also depends on the size of the electric motor and can be correspondingly smaller for smaller stator diameters) is advantageous in order to achieve a lower amplitude of the mechanical vibrations that arise in the stator, more precisely in the stator yoke (in an internal rotor motor), when the electromagnetically generated poles of the stator interact with those of the rotor (during operation of the motor).This promotes low-vibration operation of the electric motor. A particularly preferred value range for the design of an electric motor according to the invention can be as follows: Number of stator poles PZ. S > 8, number of stator slots N N < 50 and number of poles of the rotor PZ R> 50. The inventive design of the electric motor makes it possible to significantly reduce vibration excitation during operation of the motor compared to conventional electric motors. This can improve the vibration behavior of the motor (in the sense of reduced excitation of mechanical vibrations) and its surroundings because only very low vibrations emanate from the electric motor during operation, thus enabling quiet motor operation, which is particularly advantageous when used in elevators. The reason for this is the fact that, due to the high number of poles now possible in the stator, only very low mechanical vibration excitation occurs when the stator is mechanically loaded in the radial direction due to interaction with the permanent magnets of the rotor when energized. The improvement in vibration damping orReducing vibration excitation also has the positive side effect that the metal sheets typically used for the stator no longer need to be connected with an anchor screw, as is the case with many previously known motors. This allows a round cross-sectional shape for the stator sheets to be selected. This offers the advantage that a housing that is round on the inside can also be used to house an electric motor according to the invention. The connection between motor and housing can thus be achieved very easily and without screws by means of shrinkage, which offers further advantages. Thus, a further object achieved by the invention can be seen in how the use of previous round motor housings can be retained without disadvantages with regard to unwanted vibrations and despite an increase in the power factor of the electric motor.As a result, the design according to the invention enables both high electrical efficiency and a high power factor to be achieved (see Table 1). This has advantages for the use of the motor in an electrical drive system (for example, in fans or elevators), since the frequency converter required to operate the motor (depending on the specific design) can be made comparatively small / compact and thus inexpensive, and 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"). Thus, the rotor can, in particular, be P. ZR Permanent magnets carrying a number of P ZR magnetic poles. Alternatively or in addition to the features discussed so far, the electric motor described at the outset can also be designed as follows to achieve the object: Thus, in addition or as an alternative to the features of claim 3, it can be provided that the rotor of the electric motor has a number of PZ R of magnetic poles (with the help of the said permanent magnets, ie the number P ZR of magnetic poles can in particular correspond to the number of permanent magnets that the rotor carries) and that for the ratio of the number of poles of the rotor PZR and number of poles P ZS of the stator: P ZR / P ZS ≥ 3. Preference is given to values ​​of P ZR / P ZS ≥ 5. At the same time, it can be advantageous to also demand: P ZR / P ZS ≤ 10, ie a particularly favorable range of values ​​for the above ratio is: 3 ≥ P ZR / P ZS 10; preferred is: 4 ≥ P ZR / P ZS ≤ 8. The invention has recognized that such a large ratio between P ZR and P ZS is particularly advantageous in order to achieve a high electrical efficiency of the electric motor. In such designs, the number of poles / number of poles P ZR of the rotor in particular according to the following formation law: P ZR = 2 N N + / - P ZS. In such a case, the necessary number N N on the stator slots: N N = (P ZR - / + P ZS) / 2. Furthermore, according to the invention, in such embodiments, the number of grooves N N of the stator are preferred: N N < 60 (maximum number of stator slots), and preferably additionally: N N ≥ 6 (minimum number of stator slots). A particularly preferred range for the number N N on slots of the stator is: 50 ≥ N N ≥ 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 achieve the object: Thus, in addition or as an alternative to the features of claim 1 and / or to those of claim 3, it can be provided that the rotor of the electric motor has a maximum outer diameter D Ra and a number of PZ R at magnetic poles, whereby within a pole width B PR of the rotor of B PR = 2 π D Ra / PZ REach permanent magnet is arranged in a pole width of 2πD. Ra of the rotor, within which a permanent magnet is arranged on average. Furthermore, magnetic flux conductors of the stator, which delimit the slots, can be designed in the form of teeth. The teeth can have a tooth width B at their base. Z which have a respective groove width B N of the slots for receiving the stator winding. Furthermore, it can be provided that a slot is formed between adjacent teeth of the stator, each slot having a slot width B S and that for the ratio of tooth width B Z to pole width B PR (24) applies: B Z / B PR > 0.4 or B Z > (0.4 B PR ). In this case, it is particularly advantageous if the ratio of slot width B S and tooth width B Zapplies: B S / B Z > 1.0, i.e. B S > B Z . The invention has recognized that such a dimensioning of the stator offers considerable advantages in improving the product of efficiency and power factor cos φ of the electric motor. This approach can be described qualitatively as follows: the teeth in their width B Z depending on the pole width B PR of the rotor, but so wide that only slightly more than two tooth widths already constitute a pole width. It is particularly preferred if the following applies: B Z ≥ (0.5 B PR). In this case, a maximum of two tooth widths add up to a given pole width of the rotor. The teeth should therefore be designed to 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 ratio of tooth width B Z the teeth of the stator and pole width B PR of the rotor (see the definition above) additionally applies: B Z / B PR < 0.7. In addition, the slots, more precisely the slot width B S, between the teeth of the stator should also be designed to be comparatively wide, i.e. open. However, there are limits to this opening, so the ratio of slot width B S and tooth width B S can apply: B S / B Z > 1.2. That is, the slot width B Scan preferably be 20% larger than the width of the respective tooth at its base. In further possible embodiments of the invention, the following may also apply: B S / B Z > 1.3; preferably B S / B Z > 1.4; particularly preferred B S / B Z > 1.5. Possible embodiments of the invention may, for example, provide: B S > 5 mm, preferred: B S > 10 mm, particularly preferred: B S > 11 mm. For a given stator inner diameter of D SI It is therefore advantageous if the ratio of slot width and D SI (as if S / D SI ) is at least 3.0%, preferably at least 3.5%. However, for larger engines with inner diameters of more than 350 mm, this ratio can also be reduced to values ​​of less than 2.5%. It can also be provided that the ratio of the effective slot width B S and outer diameter of the stator D Sa applies: Bs / D Sa > 2%, preferably B s / D Sa > 2.5%. At the same time, however, it is advantageous if values ​​of B s / D Sa = 0.34 must not be exceeded. This provides a preferred range of values ​​for the effective slot width B S of: 2% < B s / D Sa < 3.4% as a function of the stator's outer diameter. This applies to both external rotor and internal rotor motors. The value ranges described above with regard to the design of the stator's slots and teeth allow for a high number of magnetic poles of the stator P even in a confined space. ZS For example, in an engine according to the invention, the following applies: P ZS≥ 12, in particular with a stator inner diameter of less than 250 mm. The said tooth-shaped magnetic flux conductors of the stator can preferably be designed as one piece with a stator yoke of the stator and / or from a ferromagnetic material. These also play a crucial role in the formation of the magnetic primary region. According to the invention, the object can also be achieved by further advantageous embodiments according to the subclaims. 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 the radial direction and thus perpendicular to a rotational axis of the motor, or in the axial direction along the rotational 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 disc 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 permanent magnets are preferably located on the outer circumference; if the rotor is designed as an external rotor, however, they are located on the inner circumference. In both cases, an air gap (in particular a very small one) can be formed between the respective permanent magnet and the stator. As already mentioned, it can be advantageous, especially for low-vibration operation of the electric motor, if at least seven, preferably at least ten, primary regions can be formed or are formed along the circumference of the stator.For very small engines, however, even two primary ranges may be sufficient. The decisive factor is primarily the ratio of the number to N. N on slots of the stator and number N U According to a further advantageous embodiment, the ratio of the number of poles of the rotor PZ R and number of poles of the stator PZ S apply: PZ R / PZ S ≤ 10 (then the following applies: PZ R ≤ 10 PZ S ), especially PZ R / PZ S ≤ 8 or even PZ R / PZ S ≤ 5. The invention therefore proposes to limit the number of poles / permanent magnets of the rotor to a maximum of 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 PZ S . Target for the number N U at the stator's primary areas, N U≥ 7 and the stator winding is designed in such a way that only one magnetic pole is formed per primary area (so that PZ S = N U ≥ 7), this can lead, for example, to values ​​of electric motors according to the invention as shown in Table 2. Tab. 2 – Design parameters of three electric motors according to the invention of different sizes However, in the inventive designs of electric motors, a certain minimum number of rotor poles should still be maintained to ensure good synchronization of the electric motor. Therefore, it can preferably also be provided for the electric motor that: PZ R / PZ S ≥ 4, particularly preferred may be: PZ R / PZ S ≥ 5. In further possible embodiments of the invention, the following may also apply: PZ R / PZ S ≤ 8, preferably PZ R / PZ S ≤ 6, particularly preferred PZ R / PZ S≤ 5, as in the examples above in Table 2. In other words, the number of poles PZ S = 2p S The stator should be chosen to have a relatively high number of poles compared to previously known motors, for example with PZ S ≥ 8, preferably PZ S ≥ 10, particularly preferably PZ S ≥ 12, especially PZ S ≥ 16. A particularly preferred range of values ​​for the number of poles of the stator P ZS is: 12 ≥ P ZS ≥ 20. As already explained, the number of poles PZ R = 2p R of the rotor (comparatively) high-pole, for example with PZ R ≥ 40, preferably PZ R ≥ 50 or even PZ R≥ 60 (see, for example, the examples in Table 2). In individual cases, the number of poles of the rotor can thus be 60, 80, or even 100 (see Table 2), depending on the size of the motor, although the number of poles will naturally tend to increase with increasing motor size. Since typically only a very small air gap remains between the rotor (either designed as an external or internal rotor) and the stator, an advantageous dimensioning for an internal rotor, for example, can be to arrange a permanent magnet of the rotor at least every 5 mm along the inner circumference of the stator, so that: D Si / P ZR ≤ 5.0 mm; preferred is: D Si / P ZR ≤ 4.5 mm The teeth of the stator can preferably be T-shaped, in particular such that the tooth width B z smaller than a respective tooth tip width B ZKof the respective tooth. Furthermore, it is helpful if the teeth are oriented strictly radially to the axis of rotation. The teeth of the stator can thus have a tooth tip width B on their radial inner side. ZK For the ratio of slot width B S and tooth tip width B ZK can then be preferred: B S / B ZK > 0.45. In this case, the respective slot width occupies a circumferential length corresponding 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 may also apply: B S / B ZK > 1.05; preferably B S / B ZK > 1.10; particularly preferred B S / B ZK> 1.20. This means that the slot width can be made much larger than is usual for conventional electric motors. The technical effect achieved by such open slots is that in an electric motor with a stator pole number PZ S and number of rotor poles PZ R which are unequal (as proposed here in particular), a high power factor cos φ and at the same time low electrical losses can be achieved. For motors with the same number of stator and rotor poles (PZ S = PZ R ), the use of such open slots is rather disadvantageous, especially for the power factor cos φ. Therefore, closed slots should be used in such motors if possible. The stator of an electric motor according to the invention can have fewer than two teeth per pole of the rotor. This allows for the number ZZ s on teeth on the stator apply: ZZ s < 2 PZ R. This also applies in particular: N N < 2 PZ R . For the ratio of a minimum inner diameter D Si of the stator and a maximum outer diameter D Sa of the stator, the invention proposes a dimensioning that complies with the following specification: D Si / D Sa≥ 0.80. For an internal rotor, this means that the rotor has a space available that is approximately 80% of the stator's outer diameter (at least if the minimum required air gap between the rotating rotor and stator is neglected). 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 for the generation of greater torque. 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 = N N / (2p S m) with N N the number of slots of the stator, 2p S = PZ Sthe number of magnetic poles of the stator and m the number of phases or strands of the stator winding, it is preferred if q < 1.5; preferably q = 1, because then a comparatively short winding head length can be achieved, which offers advantages with regard to simple production of the electric motor. This means that the inventive concept can be implemented particularly well with a single-hole winding. In other words, the number of holes q can preferably be an integer. The number of slots N N of the stator can preferably be an integer multiple of the number of pole pairs p S of the stator. In this case, a fractional-hole winding, which is complex to manufacture, can be avoided and the stator winding can instead be realized as a full-hole winding. For the same reason, it is advantageous if the number N N of the grooves does not exceed a value of 60, preferably 50. A magnet width B Mof each of the permanent magnets of the rotor can be defined, for example, as a circular arc B M = Q 2 π D Ra / N M , which is occupied by one of the permanent magnets, with D Ra the maximum outer diameter of the rotor, Q the circumferential portion occupied by the respective permanent magnet and N M the number of permanent magnets of the rotor (3), where typically N M = P ZR . Based on this definition, embodiments according to the invention are preferred for which the following applies: B M < 20 mm, preferred: B M < 15 mm. Furthermore, it may be additionally provided that: B M ≥ 10 mm, particularly preferred: B M≥ 11 mm. These value ranges allow for a sufficient number of rotor poles while simultaneously complying with the limitations regarding the required number of stator poles. As already mentioned, the rotor of the electric motor, with the help of its permanent magnets, can form a number of PZ R at magnetic poles. If the stator has an outer circumference of U S = 2 π D Sa preferred embodiments of electric motors according to the invention provide: 25 mm < U S / PZ R < 75 mm, particularly preferred is: 28 mm < U S / PZ R< 50 mm; These values ​​thus indicate the respective circumferential length on the outer circumference of the stator, within which a rotor magnet is to be arranged. As already mentioned several times, the stator winding can have several, in particular a number m, strands or phases, or with the m strands, m different electrical phases can be formed with appropriate current supply to the strands. The electric motor can therefore preferably have a frequency converter with which the stator winding can be supplied with electrical voltage. The stator can in particular have a three-phase / three-strand stator winding (m = 3). In this case, the number of stator pole pairs p Sa 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 be aligned radially with respect to the axis of rotation 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 can also have an angular offset 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.Such angular offsets can in particular be designed such that the poles of the rotor / stator are formed in a continuous inclination along the axis of rotation. Such a design of an electric motor according to the invention can alternatively also provide that the poles of the rotor are arranged in a stepped inclination, similar to steps, along the axis of rotation. The rotor can furthermore also be continuously inclined. Alternatively or additionally, such a stepped or continuous inclination of the poles can also be provided on the stator. The invention proposes in particular that an electric motor according to the invention is dimensioned and supplied with an electrical operating voltage such that when operated in a speed range of approximately 300 rpm, a maximum stator frequency of f. S,max = 200 Hz, preferred by f S,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 motor speed indicates the frequency at which the rotor rotates. It is particularly preferred if the electric motor is used in such a way that a minimum stator frequency of f S,min = 20 Hz, preferably from f S,min= 15 Hz, is not undercut. 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 development due to the low-frequency magnetization reversal. This is of interest for numerous applications, in particular for driving elevators, where precisely this speed range must be provided frequently and repeatedly by the electric motor. With a design 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 using exemplary embodiments, but is not limited to these exemplary embodiments.Further developments of the invention can be derived from the following description of a preferred embodiment in conjunction with the general description, the claims and the drawings. The following description of examples serves merely to explain design parameters, in particular of basic areas of the stator, which can be designed according to the invention; possible design parameters by which a motor according to the invention can be characterized are listed in the following. The electric motors shown in the figures therefore do not yet demonstrate an embodiment according to the invention; however, embodiments of electric motors according to the invention are easily accessible to the person skilled in the art with the aid of the figures by applying the rules described above and in the claims for numerous design parameters of the stator and / or the rotor.In the drawings, elements that have the same function are given the same reference numerals, even if they have a different design or shape. It shows: Fig. 1 a highly simplified schematic cross-section through a conventional electric motor, Fig. 2 a further view similar to that in Figure 1 of another electric motor, Fig. 3 a further view similar to that in Figure 1 of another electric motor, Fig. 4 a detailed view of the electric motor from Figure 3, with only one quadrant being shown. Figure 1 shows a highly simplified schematic cross-section through an electric motor 1, as is previously known in the art. The electric motor 1 has a stator 2 and a rotor 3 designed as an internal rotor and carrying a total of twenty permanent magnets 5, the rotor 3 being mounted for rotation about the shown axis of rotation 6. In other words, the rotor 3 thus has a number of magnetic poles P. ZR= 20, which corresponds to the number of its permanent magnets 5 (where each of the permanent magnets 5 forms a north / south pole pair). It can be seen in all figures that the permanent magnets 5 are arranged circumferentially, namely on the outer circumference of the respective inner rotor rotor 3. Accordingly, the minimum air gap 23 (see Fig. 1), through which the magnetic flux must pass, is formed between the respective permanent magnet 5 and the respective tooth 10 of the stator 2. If the inventive concept is transferred to an external rotor motor, this would also apply, except that the permanent magnets 5 would then be placed on the inner circumference of the external rotor rotor (located on the outside with respect to the stator), so that the permanent magnets 5 would again be aligned with the stator teeth 10. The stator 2 has a total number of N N= 24 slots 14. The slots 14 are formed by the spaces between the magnetic flux conductors 8 of the stator 2, which are designed as teeth 10. A stator winding 4 (not illustrated) is inserted into the total of twenty-four slots 14, which has three strands (m = 3). With appropriate current supply to the stator winding 4, the stator 2 of Figure 1 can generate a rotating magnetic field, wherein the stator 2 has a number of PZ S at magnetic poles and where: PZ S = 2p S with p Sthe number of pole pairs of the stator 2. When the stator winding is energized with alternating electrical current, the rotor 3 can be set in rotation without any electrical switching operations, because the stator winding 4 then generates a rotating magnetic field, which pulls the rotor 3 along. This allows a continuous torque to be generated with the electric motor 1 during normal operation. In the example shown in Figure 1, the stator 2 forms two pole pairs per phase and thus a total of four poles per phase, so that the number of poles is: PZ S= 12, since m = 3 strands are used in the stator winding 4. This means that two slots 14 of the total of twenty-four slots form a magnetic pole of the stator 2. This results in a sequence of a total of four primary regions 13, each showing a similar sequence of three poles of the stator 2 (one pole per strand and primary region 13). Each of the four primary regions 13 is formed by a total of six slots 14 (5 full slots plus two half slots each on the left and right edge of the primary region 13), which thus occupy the circular segment of the stator 2 illustrated in Figure 1. The said sequence of three magnetic poles is repeated periodically along the circumference of the stator 2 in each of the four primary regions 13, with each of the four primary regions 13 showing not only the same number of poles (namely three), but also a similar symmetry of the magnetic field distribution with respect to the radial axis R.This means that, for example, it is sufficient to simulate the field distribution in one of the primary regions 13 in order to be able to calculate the entire field distribution generated by the stator 2. Figures 2 and 3 show further examples of previously known electric motors 1, wherein the respective stator 2 can form four primary regions 13 (Figure 2) or eight primary regions 13 (Figure 3) with appropriate current supply to the stator winding 4. In the case of Figure 3, four teeth 10 with the four associated slots 14, or the stator winding 4 inserted therein (with appropriate current supply), form a primary region 13. Figure 4 shows a detailed view of a quadrant of the electric motor 1 illustrated in Figure 3. It can be seen that the permanent magnets 5 of the rotor 3 are arranged, as usual, evenly along the outer circumference of the rotor 3, which is designed as an internal rotor.Each permanent magnet 5, which has a magnet width 21 (measured as the length of a circular arc on the surface of the rotor body), occupies a pole width 12 of B. PR = 2 π D Ra / PZ R with D Ra the outer diameter 20 of the rotor 3 (see Fig. 1) and PZ R the number of magnetic poles of the rotor 3. Each of the permanent magnets 5 forms a pole of the rotor 3, so that the number of poles PZ R of the rotor 3 is equal to the number of permanent magnets 5 of the rotor 3 (in the case of Figure 3, PZ R = 8). Further design dimensions relevant to the invention are shown in Figures 1 and 2, namely the outer diameter 19 of the stator 2 D Sa , the inner diameter 18 of the stator 2 D Si , the air gap 23 between stator 2 and rotor 3, the outer diameter 20 of the rotor 3 D Ra , the slot width 15 B S , the groove width B N 22, the tooth tip width 16 B ZK, and the tooth width B Z 17 of the T-shaped teeth 10. As indicated by the dashed and dotted circles in Figure 1, these values ​​can be measured along circumferential lines. The tooth width B Z 17 can, for example, be located at the base of the respective tooth 10, for example at the point of the largest groove width 22 B N a groove 14. Based on these illustrations, it is now relatively easy to understand inventive embodiments of electric motors, as described above and in particular in the claims. For example, an inventive electric motor 1 can be designed as indicated in Table 1, for example, with a rotor 3 having a pole number of P ZR = 60, a stator 2, which has a total of P ZS = 12 poles and an equal number N Uof twelve primary areas 13 (so that each primary area 13 defines only one magnetic pole and the following applies: N U = 12), resulting in a ratio of P ZR / P ZS = 5. For this purpose, N N = 36 slots 14 are provided on the stator 2. While maintaining this principle, for larger sizes, for example, the number of poles of the rotor 3 can be increased to P ZR = 80. In this case, while maintaining P ZR / P ZS = 5 the number of poles of the stator 2 P ZS = 16, where in this case sixteen original areas 13 and N N = 48 slots are provided on the stator 2. For an even larger design of an electric motor 1 according to the invention, for example, the following can apply: P ZR = 100; P ZR / P ZS = 5; P ZS = 20 = N U ; N N= 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 from Figures 1 to 4 (which serve only for illustration purposes). By adhering to the dimensioning of the stator 2 and the design of the rotating magnetic field generated by the stator 2 proposed by the invention, both low-vibration and simultaneously highly efficient operation of the electric motor 1 can be ensured. The approaches presented here for designing a high-efficiency electric motor 1 can be applied to motors with both internal rotor and external rotor rotors 3. For this purpose, only the stated design parameters must be observed.In summary, for an electric motor 1 having a stator 2 which is designed to generate a rotating magnetic field, and a rotor 3 which is mounted rotatably about an axis of rotation 6 and which carries a number of permanent magnets 5, it is proposed 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 supplied with a multi-phase current such that the stator 2 forms a magnetic field which is defined by a number N. U at primary regions 13 and that a maximum of five of the slots 14 of the stator 2 are used per primary region 13. Preferably, at least seven, particularly preferably at least eight, or even at least ten primary regions 13 can be formed or can be formed along the circumference of the stator 2 with appropriate current supply to the stator winding 4.

[0002] List of reference symbols 1 Electric motor 2 Stator 3 Rotor 4 Stator winding 5 Permanent magnet (of 3) 6 Rotation axis 7 Stator yoke 8 Magnetic flux conductor (of 2) 9 Magnetic flux conductor (of 3) 10 Tooth (of 2) 11 Slot (between 8 / 10) 12 Pole width (e.g. outer circumference of 3, within which a permanent magnet is arranged) 13 Ur area 14 Slot (of 2) 15 Slot slot width B S (Width of 11) 16 (stator) tooth tip width B ZK (Width of 10 at the head end (radially inside)) 17 (stator) tooth width B Z (Width of 10, outside the head area at the base) 18 Stator inner diameter (inner diameter of 2) 19 Stator outer diameter (outer diameter of 2) 20 Rotor outer diameter (outer diameter of 3) 21 Magnet width (circular arc length of 5) 22 Slot width B N (Width of 14) 23 Air gap (between 2 and 3) Used design parameters PZ S = 2p S = Number of magnetic poles of the stator p S = Number of pole pairs of the stator PZR = number of poles of the rotor p R = Number of pole pairs of the rotor N N = Number of slots of the stator N U = Number of primary areas of the stator B PR = 2 π D Ra / PZ R = Pole width of the rotor D Ra = Outer diameter of the rotor B N = Slot width of the stator slots B Z = Tooth width B S = Slot width B ZK = Tooth tip width ZZ s = Number of teeth of the stator D Si = inner diameter of the stator D Sa = outer diameter of the stator q = N N / (2p S m) = Number of holes m = Number of used (current) phases or strands of the stator winding B M = Q 2 π D Ra / N M = Magnet width of each of the permanent magnets of the rotor Q = the circumferential portion occupied by the permanent magnets (in %) N M = Number of permanent magnets of the rotor U S = 2 π D Sa = Outer circumference of the stator

Claims

Claims 1. Electric motor (1), preferably configured as an electric permanent magnet synchronous machine (PMSM), with - a stator (2) comprising a number of PZ S at magnetic poles of PZ S = 2p S trains, with p S the number of pole pairs of the stator (2), - where the stator (2) has a number N N having slots (14) in which a stator winding (4) is arranged, which is configured to generate a rotating magnetic field, and - a rotor (3) movably mounted about a rotating axis (6), which carries permanent magnets (5) on its circumferential side, characterized in that - the rotor (3) has a number of PZ R forms at magnetic poles corresponding to the number of its permanent magnets (5), and - that for the ratio of the number of poles of the rotor PZ R and pole number PZ S The stator is subject to: PZ R / PZ S ≥ 3.

2. Electric motor (1) according to claim 1, wherein furthermore: PZ R / PZ S≤ 10.

3. Electric motor (1) according to the preamble of claim 1 or according to claim 1 or according to claim 2, characterized in that the stator winding (4) is designed and energizable such that for the stator (2) for the ratio of number N N its grooves (14) and number N U at the original areas (13) the following applies: N N / N U < 6.

4. Electric motor (1) according to the preamble of claim 1 or according to one of claims 1 to 3, characterized in that the rotor (3) has a maximum outer diameter (19) D Ra features and a number of PZ R forms at magnetic poles, - that within a pole width (24) B PR of the rotor (3) of B PR = 2πD Ra / PZ R a permanent magnet (5) is arranged in each, - that magnetic flux conductors (8) of the stator (2) which delimit the slots (14) are formed in the form of teeth (10), wherein the teeth (10) have a tooth width B at their base Z(17) form a respective groove width B N (22) of the slots (14) for receiving the stator winding (4) is defined, - that a slot (11) is formed between adjacent teeth (10) with a slot width B S (15) - that for the ratio of tooth width B Z (17) to pole width B PR (24) applies: B Z > (0.4 B PR ) and - that for the ratio of slot width B S (15) and tooth width B Z (17) applies: B S > B Z5. Electric motor (1) according to any one of the preceding claims, wherein the electric motor (1) is configured as an axial flux motor, in particular in the form of a disc rotor motor, or as a radial flux motor, or as a combination of an axial flux motor and a radial flux motor, and / or wherein the rotor (3) is configured as an internal rotor and carries the permanent magnets (5) on its outer circumference, or as an external rotor and carries the permanent magnets (5) on its inner circumference.

6. Electric motor (1) according to claim 3, wherein at least seven, preferably at least ten, areas (13) along the circumference of the stator (2) trainable or are trained.

7. Electric motor (1) according to claim 1 or 2, - wherein additionally the following applies: PZ R / PZ S ≤ 10, - preferably where: PZ R / PZ S ≥ 4, - particularly preferred, where: PZ R / PZ S≥ 5.

8. Electric motor (1) according to one of the preceding claims, - wherein the number of poles PZ S = 2p S of the stator (2) is selected to be high-pole, with PZ S ≥ 8, preferably PZ S ≥ 10, especially preferred PZ S ≥ 12, especially PZ S ≥ 16.

9. Electric motor (1) according to one of the preceding claims, - wherein the number of poles PZ R = 2p R of the rotor (3) is selected to be high-pole, with PZ R ≥ 40, preferably PZ R ≥ 50.

10. Electric motor (1) according to claim 4, - wherein additionally: B Z / B PR < 0.7 - preferably, where: B S / B Z > 1,2.

11. Electric motor (1) according to claim 4 or 10, wherein the teeth (10) of the stator (2) are T-shaped, in particular such that the tooth width B z (17) smaller than a respective tooth head width B ZK(16) of the respective tooth (10) is omitted, and / or - are oriented radially to the axis of rotation (6).

12. Electric motor (1) according to one of claims 4, 10 or 11, - wherein the teeth (10) of the stator (2) have a tooth head width B on their radial inner side. ZK (16) form, and - wherein the ratio of slot width B S (15) and tooth head width B ZK (16) applies: B S / B ZK > 0.

45.

13. Electric motor (1) according to one of claims 4 or 10 to 12, wherein the stator (2) has fewer than two teeth (10) per pole of the rotor (3), such that for the number ZZ s On teeth (10) on the stator (2) the following applies: ZZ s < 2 PZ R 14. Electric motor (1) according to one of the preceding claims, - wherein for a ratio of a minimum inner diameter (18) D Si of the stator (2) and a maximum outer diameter (19) D Sa of the stator (2) holds: D Si / D Sa≥ 0.

8.

15. Electric motor (1) according to one of the preceding claims, - wherein a number of holes q of the electric motor (1) is defined as q = N N / (2p S m) with N N the number of slots of the stator (2), 2p S = PZ S the number of magnetic poles of the stator (2) and m the number of phases or strands of the stator winding (4), and - that the number of holes q is: q < 1.5; preferably q = 1.

16. Electric motor (1) according to one of the preceding claims, - wherein the number of slots N N an integer multiple of the number of pole pairs p S of the stator (2) is, preferably wherein: N N < 60, - in particular such that a full-hole winding is realized instead of a fractional-hole winding, - in particular wherein the number of holes q is an integer.

17. Electric motor (1) according to one of the preceding claims, - wherein a magnet width B M(21) of each of the permanent magnets (5) of the rotor (3) is defined as a circular arc B M = Q 2 π D Ra / N M , which is occupied by one of the permanent magnets (5), with - D Ra the maximum outer diameter (19) of the rotor (3), - Q the circumferential fraction occupied by the permanent magnets (5) and - N M the number of permanent magnets (5) of the rotor (3), and where: B M < 20 mm, preferably: B M < 15 mm.

18. Electric motor (1) according to one of the preceding claims, - wherein the rotor (3) has a number of PZ R at magnetic poles, - the stator (2) has an outer circumference of U S = 2πD Sa (19) exhibits and - where: 25 mm < U S / PZ R < 75 mm; - particularly preferred: 28 mm < U S / PZ R< 50 mm; 19. Electric motor (1) according to one of the preceding claims, - wherein the stator winding (4) has several, in particular a number m, strands or phases, - preferably the electric motor (1) has a frequency converter with which the stator winding (4) can be supplied with electrical voltage, and / or - wherein the stator (2) has a three-phase stator winding (4) (m = 3), in particular wherein the stator pole pair number p Sa multiple of three.

20. Electric motor (1) according to one of the preceding claims, - wherein the permanent magnets (5) of the rotor (3) are electrically insulated from a rotor body (6) of the rotor (3) and / or - wherein a respective flux direction of the permanent magnets (5) of the rotor (3) is oriented radially with respect to the axis of rotation (6) of the rotor.

21. Electric motor (1) according to one of the preceding claims, - wherein a relative angular position of the magnetic poles of the rotor (3) in the circumferential direction within a first axial segment of the rotor (3) has an angular offset to a relative angular position of magnetic poles within a second axial segment of the rotor (3), - in particular such that the poles of the rotor (3) are formed in a continuous skew along the axis of rotation (6).

22. Use of an electric motor (1) according to one of the preceding claims, characterized in that - the electric motor (1) is dimensioned and supplied with an electrical operating voltage such that a maximum stator frequency of f is achieved during operation. S,max = 200 Hz, preferably from f S,max = 150 Hz, is not exceeded, - particularly preferably wherein a minimum stator frequency of f is maintained during operation S,min = 20 Hz, preferably from f S,min = 15 Hz, which is not undercut.

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