CA2731616A1 - Permanent magnet synchronous machine - Google Patents
Permanent magnet synchronous machine Download PDFInfo
- Publication number
- CA2731616A1 CA2731616A1 CA2731616A CA2731616A CA2731616A1 CA 2731616 A1 CA2731616 A1 CA 2731616A1 CA 2731616 A CA2731616 A CA 2731616A CA 2731616 A CA2731616 A CA 2731616A CA 2731616 A1 CA2731616 A1 CA 2731616A1
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- Canada
- Prior art keywords
- permanent magnet
- rotor
- synchronous machine
- permanent
- magnetic pole
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K21/00—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets
- H02K21/12—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets
- H02K21/14—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures
- H02K21/16—Synchronous motors having permanent magnets; Synchronous generators having permanent magnets with stationary armatures and rotating magnets with magnets rotating within the armatures having annular armature cores with salient poles
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
- H02K1/2706—Inner rotors
- H02K1/272—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis
- H02K1/274—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets
- H02K1/2753—Inner rotors the magnetisation axis of the magnets being perpendicular to the rotor axis the rotor consisting of two or more circumferentially positioned magnets the rotor consisting of magnets or groups of magnets arranged with alternating polarity
- H02K1/278—Surface mounted magnets; Inset magnets
- H02K1/2781—Magnets shaped to vary the mechanical air gap between the magnets and the stator
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/27—Rotor cores with permanent magnets
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Permanent Field Magnets Of Synchronous Machinery (AREA)
- Permanent Magnet Type Synchronous Machine (AREA)
Abstract
At a permanent magnet synchronous machine that includes a stator with a plurality of electromagnetic poles and a rotor (10) with several permanent magnetic poles (12), according to the invention at least one of the permanent magnetic poles (12) of the rotor (10) is formed from separate permanent magnet segments (14) which in the course of their production have been provided with a particularly high field strength and which are arranged side by side at the at least one permanent magnetic pole (12) in the peripheral direction in such a manner that in the event of rotation of the rotor (10) a sinusoidal excitation arises in the electromagnetic poles of the stator.
Description
Description Permanent magnet synchronous machine Background of the invention The invention relates to a permanent magnet synchronous machine or permanently excited synchronous machine that includes a stator with a plurality of electromagnetic poles and a rotor with several permanent magnetic poles. In particular, the invention relates to a synchronous generator of a wind power plant and to the use of a synchronous generator in a wind power plant.
Synchronous machines are electromechanical transducers which are operated with current as an electric motor or which generate current as a generator.
There are three-phase or single-phase synchronous machines, which each exhibit at least one stator winding (mostly on the outside) in which a magnetic rotating field is generated and/or in which an electrical voltage is induced.
The rotor (mostly on the inside) bears permanent magnet magnets for the purpose of field generation. Synchronous machines of such a type are permanent magnet rotating-field machines in which the rotational speed is equal to the alternating voltage frequency divided by the number of pole pairs of the rotor. The rotational speed of the rotor is accordingly equal to the rotational speed of the electromagnetic rotating field. The rotor rotates synchronously with the rotating field. In order to be able to operate a synchronous machine at various rotational speeds, a frequency converter and/or an inverter is required.
The active power of synchronous machines of such a type is established by the rotor displacement angle that results by way of torsion angle between the rotor of the loaded synchronous machine and the rotor of the unloaded synchronous machine.
At the present time, generic synchronous machines are employed, above all, as alternating current (a. c.) generators and three-phase generators in power stations. But synchronous generators of a different type are also employed, for example, in motor vehicles as alternators. Hitherto in this connection, at the rotor for the purpose of field generation use has been made of permanent-magnets (self-excitation) as permanent excited magnets for generators having low power (watt and kilowatt range), whereas at the rotor of generators of high power (megawatt range) use has been made of electromagnets (external excitation).
Wind power plants are often equipped with asynchronous machines in a four-pole configuration. These machines have high rotational speeds. For the purpose of adapting the rotational speed, a transmission is therefore required between the rotor-blade axle and the generator, by virtue of which the structure is susceptible to wear of the transmission and of the bearings. Gearless, slowly rotating generators, on the other hand, require a higher number of poles and hence a larger diameter as well as higher weight. In particular, however, weight is an important design factor in wind power plants.
Underlying object The object underlying the invention is to create a permanent magnet synchronous machine that with comparatively low production costs is able to provide a high power, works reliably in operation, and at the same time has a high efficiency.
Solution according to the invention In accordance with the invention this object is achieved with a permanent magnet synchronous machine according to Claim 1. Advantageous further developments of the invention are described in the dependent claims.
In the permanent magnet synchronous machine according to the invention there are provided a stator with a plurality of electromagnetic poles and a rotor with several permanent magnetic poles. Furthermore, at least one of the permanent magnetic poles of the rotor is formed from separate permanent magnet segments which in the course of their production have been provided with a particularly high field strength and which are arranged side by side on the at least one permanent magnetic pole in the peripheral direction in such a manner that in the event of rotation of the rotor a sinusoidal excitation arises in the electromagnetic poles of the stator.
With the solution according to the invention, a synchronous machine is created that is easy to produce and that has a high power with, at the same time, low eddy-current losses and a high efficiency. This has a positive effect not only on the costs of production and on the total energy balance of the synchronous machine according to the invention but also on downstream working processes, such as the converting of the generated a.c. voltage. Accordingly, in combination with the synchronous machine according to the invention in particular an inverter situated downstream has to have only a comparatively small reserve power.
The flux densities of the permanent magnets according to the invention preferably amount to between 0.9 tesla and 1.7 tesla, preferably between 1.1 tesla and 1.5 tesla, most preferably 1.3 tesla. The maximal magnetic field strengths amount to 2000 kA/m to 2700 kA/m, preferably to 2200 kA/m to 2500 kA/m, most preferably 2350 kA/m. The permanent magnets are advantageously produced from neodymium-iron-boron (Nd-Fe-B).
Synchronous machines are electromechanical transducers which are operated with current as an electric motor or which generate current as a generator.
There are three-phase or single-phase synchronous machines, which each exhibit at least one stator winding (mostly on the outside) in which a magnetic rotating field is generated and/or in which an electrical voltage is induced.
The rotor (mostly on the inside) bears permanent magnet magnets for the purpose of field generation. Synchronous machines of such a type are permanent magnet rotating-field machines in which the rotational speed is equal to the alternating voltage frequency divided by the number of pole pairs of the rotor. The rotational speed of the rotor is accordingly equal to the rotational speed of the electromagnetic rotating field. The rotor rotates synchronously with the rotating field. In order to be able to operate a synchronous machine at various rotational speeds, a frequency converter and/or an inverter is required.
The active power of synchronous machines of such a type is established by the rotor displacement angle that results by way of torsion angle between the rotor of the loaded synchronous machine and the rotor of the unloaded synchronous machine.
At the present time, generic synchronous machines are employed, above all, as alternating current (a. c.) generators and three-phase generators in power stations. But synchronous generators of a different type are also employed, for example, in motor vehicles as alternators. Hitherto in this connection, at the rotor for the purpose of field generation use has been made of permanent-magnets (self-excitation) as permanent excited magnets for generators having low power (watt and kilowatt range), whereas at the rotor of generators of high power (megawatt range) use has been made of electromagnets (external excitation).
Wind power plants are often equipped with asynchronous machines in a four-pole configuration. These machines have high rotational speeds. For the purpose of adapting the rotational speed, a transmission is therefore required between the rotor-blade axle and the generator, by virtue of which the structure is susceptible to wear of the transmission and of the bearings. Gearless, slowly rotating generators, on the other hand, require a higher number of poles and hence a larger diameter as well as higher weight. In particular, however, weight is an important design factor in wind power plants.
Underlying object The object underlying the invention is to create a permanent magnet synchronous machine that with comparatively low production costs is able to provide a high power, works reliably in operation, and at the same time has a high efficiency.
Solution according to the invention In accordance with the invention this object is achieved with a permanent magnet synchronous machine according to Claim 1. Advantageous further developments of the invention are described in the dependent claims.
In the permanent magnet synchronous machine according to the invention there are provided a stator with a plurality of electromagnetic poles and a rotor with several permanent magnetic poles. Furthermore, at least one of the permanent magnetic poles of the rotor is formed from separate permanent magnet segments which in the course of their production have been provided with a particularly high field strength and which are arranged side by side on the at least one permanent magnetic pole in the peripheral direction in such a manner that in the event of rotation of the rotor a sinusoidal excitation arises in the electromagnetic poles of the stator.
With the solution according to the invention, a synchronous machine is created that is easy to produce and that has a high power with, at the same time, low eddy-current losses and a high efficiency. This has a positive effect not only on the costs of production and on the total energy balance of the synchronous machine according to the invention but also on downstream working processes, such as the converting of the generated a.c. voltage. Accordingly, in combination with the synchronous machine according to the invention in particular an inverter situated downstream has to have only a comparatively small reserve power.
The flux densities of the permanent magnets according to the invention preferably amount to between 0.9 tesla and 1.7 tesla, preferably between 1.1 tesla and 1.5 tesla, most preferably 1.3 tesla. The maximal magnetic field strengths amount to 2000 kA/m to 2700 kA/m, preferably to 2200 kA/m to 2500 kA/m, most preferably 2350 kA/m. The permanent magnets are advantageously produced from neodymium-iron-boron (Nd-Fe-B).
The solution according to the invention further utilises the finding that a permanent magnet excitation permits a structural design that, in comparison with an electrical excitation, is smaller by about 30 %, lighter and hence also more cost-effective, having a particularly favourable effect in wind power plants with regard to the aforementioned weight aspects.
Advantageous further developments of the invention In a first advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments, arranged side by side, of the at least one permanent magnetic pole are configured with varying size for generating the sinusoidal excitation. The varying size of the permanent magnet segments makes it possible, with one and the same magnetisation process, to make magnets available having varying field strength which are subsequently arranged on the rotor in such a way that a (where appropriate, stepped) curve for the field strength arises, which in the event of rotation of the rotor results in a sinusoidal excitation in the electromagnetic poles of the stator.
The permanent magnet segments configured in such a manner are particularly preferably configured in plate-like manner and have, in particular, varying heights. Since they have the basic shape of a simple rectangular solid, such permanent magnet segments can be produced with particularly little manufacturing effort.
The stepwise arrangement of the permanent magnet segments is preferably effected along a sine curve which constitutes the base curve for the cross-sectional shape of the permanent magnet segments arranged side by side. On this base curve at the individual step a temporal averaging is carried out. In this connection the average is taken of how high the permanent magnet segment has to be designed to be in order that in cross-section as a rectangular surface it covers the surface area of the surface interval of the sine curve.
Advantageous further developments of the invention In a first advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments, arranged side by side, of the at least one permanent magnetic pole are configured with varying size for generating the sinusoidal excitation. The varying size of the permanent magnet segments makes it possible, with one and the same magnetisation process, to make magnets available having varying field strength which are subsequently arranged on the rotor in such a way that a (where appropriate, stepped) curve for the field strength arises, which in the event of rotation of the rotor results in a sinusoidal excitation in the electromagnetic poles of the stator.
The permanent magnet segments configured in such a manner are particularly preferably configured in plate-like manner and have, in particular, varying heights. Since they have the basic shape of a simple rectangular solid, such permanent magnet segments can be produced with particularly little manufacturing effort.
The stepwise arrangement of the permanent magnet segments is preferably effected along a sine curve which constitutes the base curve for the cross-sectional shape of the permanent magnet segments arranged side by side. On this base curve at the individual step a temporal averaging is carried out. In this connection the average is taken of how high the permanent magnet segment has to be designed to be in order that in cross-section as a rectangular surface it covers the surface area of the surface interval of the sine curve.
In a second advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments, arranged side by side, of the at least one permanent magnetic pole are configured with an outer contour that is sinusoidal in cross-section for generating the sinusoidal excitation. By way of outer contour here, that part of the contour of the cross-section is designated which is directed radially outwards. Permanent magnet segments arranged side by side that have been configured in such a manner result, with justifiable manufacturing effort for the overall magnetic pole, in a sectionalised magnetic-pole shape that induces a particularly accurately sinusoidal voltage.
In particularly advantageous manner the entire permanent magnetic pole is configured externally to be sinusoidal in its contour. This sine shape can be configured cost-effectively by means of the arrangement in rows, according to the invention, of particularly strongly magnetised permanent magnet segments produced as individual structural elements. At the same time, permanent magnetic poles of such a type result in a particularly strong and, at the same time, particularly accurately sinusoidal excitation. This excitation is, at the same time, made available with particularly small eddy-current losses.
In a third advantageous further development of the permanent magnet synchronous machine according to the invention the at least one permanent magnetic pole is configured with four to six individual permanent magnet segments. In principle, it is the case that the higher the number of permanent magnet segments per permanent magnetic pole, the better can the sine shape be simulated in the case of a stepped arrangement of permanent magnet segments.
In order to configure an efficiently operating permanent magnetic pole with comparatively little manufacturing effort, in accordance with the invention it has been ascertained that said permanent magnetic pole should exhibit four to six individual permanent magnet segments.
In a fourth advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole on the periphery of the rotor cover only a region of between 70 % and 95 % of the peripheral distance resulting by virtue of the pole pitch for this permanent magnetic pole. With a permanent magnetic pole of such a type, within the individual pole pitch a remaining free or residual region arises which offers free space as a transition region between the permanent magnetic poles. The transition region may serve as tolerance compensation between the arrangements of the permanent magnet segments on the individual permanent magnetic poles. As a result, the manufacturing effort for the positionally accurate placing of the permanent magnet segments arranged individually side by side in accordance with the invention is reduced overall. Furthermore, this residual region also offers space for further elements such as, for example, screws or clips which may serve for stationary attachment of the permanent magnet segments. This type of arrangement results furthermore in a good distribution of heat in the stator of the synchronous machine according to the invention.
In a fifth advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole are attached in stationary manner on a mounting plate which in turn is connected to the rotor in stationary manner. A mounting plate of such a type enables a precise manufacture of the individual permanent magnetic poles as separate assemblies. These assemblies can be produced independently of a residual manufacture in a prefabrication and can as such be subjected to quality control.
In a sixth advantageous further development of the permanent magnet synchronous machine according to the invention the mounting plate adhered to the rotor. The adhesion bonding of such a type is a particularly simple and cost-effective type of assembly which, at the same time, is reliable in terms of processing.
By way of screws, use is preferably made of those consisting of non-magnetic material, in particular of aluminium. Material of such a type excludes any influence on the excitation at the stator.
In a seventh advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole are covered externally and/or radially on the outside. The covering of such a type offers not only protection against corrosion but, at the same time, also protection against chipping of material of the permanent magnet segments.
The covering is advantageously formed from a non-magnetic material, in particular from plastic. Such material likewise has no influence on the excitation at the stator and is, at the same time, inexpensive. The covering is preferably screwed together with the aforementioned mounting plate. In this way a particularly simple, cost-effective and, at the same time, positionally accurate assembly both of the mounting plate (and hence of the permanent magnet segments) and of the cover can be achieved.
In an eighth advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole are adhered or attached with adhesive onto the rotor, in particular to the mounting plate. By means of adhesive bonding, in the course of this manufacturing step of the attachment of the permanent magnet segments to the rotor all the prerequisites for a durably stationary and positionally accurate positioning are obtained.
In particularly advantageous manner the entire permanent magnetic pole is configured externally to be sinusoidal in its contour. This sine shape can be configured cost-effectively by means of the arrangement in rows, according to the invention, of particularly strongly magnetised permanent magnet segments produced as individual structural elements. At the same time, permanent magnetic poles of such a type result in a particularly strong and, at the same time, particularly accurately sinusoidal excitation. This excitation is, at the same time, made available with particularly small eddy-current losses.
In a third advantageous further development of the permanent magnet synchronous machine according to the invention the at least one permanent magnetic pole is configured with four to six individual permanent magnet segments. In principle, it is the case that the higher the number of permanent magnet segments per permanent magnetic pole, the better can the sine shape be simulated in the case of a stepped arrangement of permanent magnet segments.
In order to configure an efficiently operating permanent magnetic pole with comparatively little manufacturing effort, in accordance with the invention it has been ascertained that said permanent magnetic pole should exhibit four to six individual permanent magnet segments.
In a fourth advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole on the periphery of the rotor cover only a region of between 70 % and 95 % of the peripheral distance resulting by virtue of the pole pitch for this permanent magnetic pole. With a permanent magnetic pole of such a type, within the individual pole pitch a remaining free or residual region arises which offers free space as a transition region between the permanent magnetic poles. The transition region may serve as tolerance compensation between the arrangements of the permanent magnet segments on the individual permanent magnetic poles. As a result, the manufacturing effort for the positionally accurate placing of the permanent magnet segments arranged individually side by side in accordance with the invention is reduced overall. Furthermore, this residual region also offers space for further elements such as, for example, screws or clips which may serve for stationary attachment of the permanent magnet segments. This type of arrangement results furthermore in a good distribution of heat in the stator of the synchronous machine according to the invention.
In a fifth advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole are attached in stationary manner on a mounting plate which in turn is connected to the rotor in stationary manner. A mounting plate of such a type enables a precise manufacture of the individual permanent magnetic poles as separate assemblies. These assemblies can be produced independently of a residual manufacture in a prefabrication and can as such be subjected to quality control.
In a sixth advantageous further development of the permanent magnet synchronous machine according to the invention the mounting plate adhered to the rotor. The adhesion bonding of such a type is a particularly simple and cost-effective type of assembly which, at the same time, is reliable in terms of processing.
By way of screws, use is preferably made of those consisting of non-magnetic material, in particular of aluminium. Material of such a type excludes any influence on the excitation at the stator.
In a seventh advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole are covered externally and/or radially on the outside. The covering of such a type offers not only protection against corrosion but, at the same time, also protection against chipping of material of the permanent magnet segments.
The covering is advantageously formed from a non-magnetic material, in particular from plastic. Such material likewise has no influence on the excitation at the stator and is, at the same time, inexpensive. The covering is preferably screwed together with the aforementioned mounting plate. In this way a particularly simple, cost-effective and, at the same time, positionally accurate assembly both of the mounting plate (and hence of the permanent magnet segments) and of the cover can be achieved.
In an eighth advantageous further development of the permanent magnet synchronous machine according to the invention the permanent magnet segments of the at least one permanent magnetic pole are adhered or attached with adhesive onto the rotor, in particular to the mounting plate. By means of adhesive bonding, in the course of this manufacturing step of the attachment of the permanent magnet segments to the rotor all the prerequisites for a durably stationary and positionally accurate positioning are obtained.
For the purpose of adhesive bonding both of the mounting plate and of the permanent magnet segments, use is preferably made of a two-component adhesive, which guarantees particularly high holding forces.
In a ninth advantageous further development of the permanent magnet synchronous machine according to the invention so many electromagnetic poles and/or so many permanent magnetic poles are formed on the periphery of stator and rotor that they have no common divisor. With a configuration of such a type, particularly small arresting moments can be achieved.
Advantageously 39 electromagnetic poles with, in each case, 6 winding circuits and also 4 permanent magnetic poles are provided. These result in a ratio of 234 to 24, in the case of which the aforementioned small cogging torques and particularly low noise emissions arise. Furthermore, the voltage drops less during loading, and the synchronous machine according to the invention has a particularly good power factor within the entire operating range.
Brief description of the drawings In the following an exemplary embodiment of the solution according to the invention will be elucidated in more detail on the basis of the accompanying schematic drawings. Shown are:
Fig. 1 a partial cross-section of a permanent magnetic pole on the rotor of a first exemplary embodiment of a permanent magnet synchronous machine according to the invention, Fig. 2 a first graphic illustration for elucidating the gradation of permanent magnet segments on the permanent magnetic pole according to Fig. 1, Fig. 3 a second graphic illustration for elucidating the gradation of permanent magnet segments on the permanent magnetic pole according to Fig. 1 and Fig. 4 a partial cross-section of a permanent magnetic pole on the rotor of a second exemplary embodiment of a permanent magnet synchronous machine according to the invention.
Detailed description of the exemplary embodiment In Fig. 1 a rotor 10 of a permanent magnet synchronous machine not illustrated any further is represented in partional manner. The rotor 10 here is surrounded on the outside by a stator of the synchronous machine.
On the rotor 10 several permanent magnetic poles 12 are formed, two of which can be seen in Fig. 1. In each instance oppositely oriented magnetic north and south poles are situated side by side.
The permanent magnetic poles 12 are each assembled from several permanent magnet segments 14 which in the course of their production have been individually provided with a field strength of 2350 kA/m and have subsequently been arranged side by side in such a manner that they jointly form a permanent magnetic pole 12, which in the event of rotation of the rotor 10 results in a sinusoidal excitation in electromagnetic poles of the stator. The voltage U;
induced thereby in associated stator windings is calculated with the rotational speed n, the constant k and the magnetic flux F by means of the formula U;=k*F*n.
In order to obtain the aforementioned sinusoidal excitation, the permanent magnet segments 14 arranged side by side are designed to be stepped in such a manner that they jointly form a magnetic pole which has a sinusoidal form overall. Accordingly, the permanent magnet segments 14, considered together, are configured to be sinusoidal. With a view to limiting the manufacturing effort, in the present case the individual permanent magnetic pole 12 is configured with six permanent magnet segments 14. According to Fig. 2 these six permanent magnet segments 14 result at the stator in a voltage with three stepped values U1, U2 and U3 over the time t. Furthermore, the voltage has a total period T
which is characterised by the traversing of the two voltage half-oscillations.
The period length of the individual partial voltages per permanent magnet segment 14 within the two voltage half-oscillations amounts to T/14. The number 14 results as the sum of two times six permanent magnet segments and two zero values of the voltage. The zero values of the voltage arise by virtue of the fact that the permanent magnet segments 14 each cover only about 86 % of the peripheral distance resulting by virtue of the pole pitch for the individual permanent magnetic poles 12. The remaining 14 % form two residual regions which serve as tolerance compensation between adjacent permanent magnetic poles 12 and, as will be elucidated below, for fastening the permanent magnet segments 14 to the rotor 10. The pole pitch results computationally from the diameter of the rotor 10 and from the number of pole pairs.
The size or the height of the individual, plate-shaped permanent magnet segments 14 according to Fig. 1 is ascertained by a temporal averaging in respect of the sinusoidal progression of the voltage being striven for. This averaging is illustrated in Fig. 3 for an individual permanent magnet segment 14.
In this connection the function u(t) of the induced voltage is simulated with a rectangular pulse of pulse duration t = t2 - t1. For the mean value Um of the voltage it follows that the rectangular area resulting from the mean value Um and the pulse duration t is equal to the integral area below the function u(t) within this pulse duration t. In order that the mean value is illustrated correctly, the shaded areas in Fig. 3 have to be equally large.
In a ninth advantageous further development of the permanent magnet synchronous machine according to the invention so many electromagnetic poles and/or so many permanent magnetic poles are formed on the periphery of stator and rotor that they have no common divisor. With a configuration of such a type, particularly small arresting moments can be achieved.
Advantageously 39 electromagnetic poles with, in each case, 6 winding circuits and also 4 permanent magnetic poles are provided. These result in a ratio of 234 to 24, in the case of which the aforementioned small cogging torques and particularly low noise emissions arise. Furthermore, the voltage drops less during loading, and the synchronous machine according to the invention has a particularly good power factor within the entire operating range.
Brief description of the drawings In the following an exemplary embodiment of the solution according to the invention will be elucidated in more detail on the basis of the accompanying schematic drawings. Shown are:
Fig. 1 a partial cross-section of a permanent magnetic pole on the rotor of a first exemplary embodiment of a permanent magnet synchronous machine according to the invention, Fig. 2 a first graphic illustration for elucidating the gradation of permanent magnet segments on the permanent magnetic pole according to Fig. 1, Fig. 3 a second graphic illustration for elucidating the gradation of permanent magnet segments on the permanent magnetic pole according to Fig. 1 and Fig. 4 a partial cross-section of a permanent magnetic pole on the rotor of a second exemplary embodiment of a permanent magnet synchronous machine according to the invention.
Detailed description of the exemplary embodiment In Fig. 1 a rotor 10 of a permanent magnet synchronous machine not illustrated any further is represented in partional manner. The rotor 10 here is surrounded on the outside by a stator of the synchronous machine.
On the rotor 10 several permanent magnetic poles 12 are formed, two of which can be seen in Fig. 1. In each instance oppositely oriented magnetic north and south poles are situated side by side.
The permanent magnetic poles 12 are each assembled from several permanent magnet segments 14 which in the course of their production have been individually provided with a field strength of 2350 kA/m and have subsequently been arranged side by side in such a manner that they jointly form a permanent magnetic pole 12, which in the event of rotation of the rotor 10 results in a sinusoidal excitation in electromagnetic poles of the stator. The voltage U;
induced thereby in associated stator windings is calculated with the rotational speed n, the constant k and the magnetic flux F by means of the formula U;=k*F*n.
In order to obtain the aforementioned sinusoidal excitation, the permanent magnet segments 14 arranged side by side are designed to be stepped in such a manner that they jointly form a magnetic pole which has a sinusoidal form overall. Accordingly, the permanent magnet segments 14, considered together, are configured to be sinusoidal. With a view to limiting the manufacturing effort, in the present case the individual permanent magnetic pole 12 is configured with six permanent magnet segments 14. According to Fig. 2 these six permanent magnet segments 14 result at the stator in a voltage with three stepped values U1, U2 and U3 over the time t. Furthermore, the voltage has a total period T
which is characterised by the traversing of the two voltage half-oscillations.
The period length of the individual partial voltages per permanent magnet segment 14 within the two voltage half-oscillations amounts to T/14. The number 14 results as the sum of two times six permanent magnet segments and two zero values of the voltage. The zero values of the voltage arise by virtue of the fact that the permanent magnet segments 14 each cover only about 86 % of the peripheral distance resulting by virtue of the pole pitch for the individual permanent magnetic poles 12. The remaining 14 % form two residual regions which serve as tolerance compensation between adjacent permanent magnetic poles 12 and, as will be elucidated below, for fastening the permanent magnet segments 14 to the rotor 10. The pole pitch results computationally from the diameter of the rotor 10 and from the number of pole pairs.
The size or the height of the individual, plate-shaped permanent magnet segments 14 according to Fig. 1 is ascertained by a temporal averaging in respect of the sinusoidal progression of the voltage being striven for. This averaging is illustrated in Fig. 3 for an individual permanent magnet segment 14.
In this connection the function u(t) of the induced voltage is simulated with a rectangular pulse of pulse duration t = t2 - t1. For the mean value Um of the voltage it follows that the rectangular area resulting from the mean value Um and the pulse duration t is equal to the integral area below the function u(t) within this pulse duration t. In order that the mean value is illustrated correctly, the shaded areas in Fig. 3 have to be equally large.
The aforementioned averaging takes place in respect of each permanent magnet segment 14. The temporal juxtaposition of the mean values Um leads approximately to the desired sinusoidal expression of voltage.
In Fig. 4 an exemplary embodiment is represented of permanent magnet segments 14 which, with a view to refinement of the desired sinusoidal excitation, have been configured with an outer contour that is sinusoidal in cross-section.
In both exemplary embodiments (Fig. 1 and Fig. 4) the permanent magnet segments 14 are attached to the rotor 10 in special manner so as to be stationary. To this end, flattened portions 18 are formed on a shaft 16 pertaining to the rotor 10, distributed over the periphery of the shaft in the ratio of the pole pitch. The permanent magnet segments 14 have been adhered side by side onto an associated mounting plate 20 in the desired shape arrangement. The mounting plate 20 has, in turn, been attached to an associated flattened portion 18 in stationary manner by means of a layer 22 of adhesive consisting of two-component adhesive.
Over the permanent magnet segments 14 attached so as to be stationary in such a manner a covering 24 made of plastic has been placed at each individual permanent magnetic pole 12, said covering being fastened to the aforementioned free regions by means of aluminium screws 26.
In conclusion let it be noted that all the features that are mentioned in the application documents, and in particular in the dependent claims, are also to be afforded protection in their own right, individually or in arbitrary combination, despite the formal subordinating reference to one or more particular claims that has been specified.
In Fig. 4 an exemplary embodiment is represented of permanent magnet segments 14 which, with a view to refinement of the desired sinusoidal excitation, have been configured with an outer contour that is sinusoidal in cross-section.
In both exemplary embodiments (Fig. 1 and Fig. 4) the permanent magnet segments 14 are attached to the rotor 10 in special manner so as to be stationary. To this end, flattened portions 18 are formed on a shaft 16 pertaining to the rotor 10, distributed over the periphery of the shaft in the ratio of the pole pitch. The permanent magnet segments 14 have been adhered side by side onto an associated mounting plate 20 in the desired shape arrangement. The mounting plate 20 has, in turn, been attached to an associated flattened portion 18 in stationary manner by means of a layer 22 of adhesive consisting of two-component adhesive.
Over the permanent magnet segments 14 attached so as to be stationary in such a manner a covering 24 made of plastic has been placed at each individual permanent magnetic pole 12, said covering being fastened to the aforementioned free regions by means of aluminium screws 26.
In conclusion let it be noted that all the features that are mentioned in the application documents, and in particular in the dependent claims, are also to be afforded protection in their own right, individually or in arbitrary combination, despite the formal subordinating reference to one or more particular claims that has been specified.
List of Reference Symbols rotor 5 12 permanent magnetic pole 14 permanent magnet segment 16 shaft 18 flattened portion mounting plate 10 22 layer of adhesive 24 covering 26 screw
Claims (10)
1. Permanent magnet synchronous machine that comprises a stator with a plurality of electromagnetic poles and a rotor (10) with several permanent magnetic poles (12), characterised in that at least one of the permanent magnetic poles (12) of the rotor (10) is formed from separate permanent magnet segments (14) which in the course of their production have been provided with a particularly high field strength and which are arranged side by side at the at least one permanent magnetic pole (12) in the peripheral direction in such a manner that in the event of rotation of the rotor (10) a sinusoidal excitation arises in the electromagnetic poles of the stator.
2. Permanent magnet synchronous machine according to Claim 1, characterised in that the permanent magnet segments (14) arranged side by side of the at least one permanent magnetic pole (12) are configured with varying size for generating the sinusoidal excitation.
3. Permanent magnet synchronous machine according to Claim 1 or 2, characterised in that the permanent magnet segments (14) arranged side by side of the at least one permanent magnetic pole (12) are configured with an outer contour that is sinusoidal in cross-section for generating the sinusoidal excitation.
4. Permanent magnet synchronous machine according to one of Claims 1 to 3, characterised in that the at least one permanent magnetic pole (12) is configured with four to six individual permanent magnet segments (14).
5. Permanent magnet synchronous machine according to Claim 1 or 2, characterised in that the permanent magnet segments (14) of the at least one permanent magnetic pole (12) on the periphery of the rotor (10) cover only a region of between 70 % and 95 % of the peripheral distance resulting by virtue of the pole pitch for this permanent magnetic pole (12).
6. Permanent magnet synchronous machine according to one of Claims 1 to 5, characterised in that the permanent magnet segments (14) of the at least one permanent magnetic pole (12) are attached in stationary manner on a mounting plate (20) which in turn is connected to the rotor (10) in stationary manner.
7. Permanent magnet synchronous machine according to Claim 6, characterised in that the mounting plate (20) is adhered to the rotor (10).
8. Permanent magnet synchronous machine according to one of Claims 1 to 7, characterised in that the permanent magnet segments (14) of the at least one permanent magnetic pole (12) are covered externally.
9. Permanent magnet synchronous machine according to one of Claims 1 to 8, characterised in that the permanent magnet segments (14) of the at least one the permanent magnetic pole (12) are adhered onto the rotor (10), in particular to the mounting plate (20), with adhesive.
10. Permanent magnet synchronous machine according to one of Claims 1 to 9, characterised in that just so many electromagnetic poles and/or so many permanent magnetic poles (12) are formed on the periphery of stator and rotor (10) that they have no common divisor.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/EP2008/005993 WO2010009742A1 (en) | 2008-07-22 | 2008-07-22 | Permanently excited synchronous machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2731616A1 true CA2731616A1 (en) | 2010-01-28 |
Family
ID=40800463
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2731616A Abandoned CA2731616A1 (en) | 2008-07-22 | 2008-07-22 | Permanent magnet synchronous machine |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP2301140B1 (en) |
| JP (1) | JP2011528890A (en) |
| KR (1) | KR101493795B1 (en) |
| CN (1) | CN102204070B (en) |
| CA (1) | CA2731616A1 (en) |
| DK (1) | DK2301140T3 (en) |
| WO (1) | WO2010009742A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120025654A1 (en) * | 2010-02-02 | 2012-02-02 | Siemens Aktiengesellschaft | Rotor of a permanent magnet synchronous machine |
| EP2763284A3 (en) * | 2013-01-31 | 2016-10-12 | Gamesa Innovation & Technology, S.L. | Construction arrangement of a permanent magnet rotor for a generator |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2378634A1 (en) * | 2010-04-13 | 2011-10-19 | Siemens Aktiengesellschaft | Electrical machine and permanent-magnet |
| EP2378633A1 (en) * | 2010-04-13 | 2011-10-19 | Siemens Aktiengesellschaft | Electrical machine and permanent-magnet |
| DE102010041593A1 (en) * | 2010-09-29 | 2012-03-29 | Siemens Aktiengesellschaft | Cover for protecting permanent magnets of pole of rotor utilized as e.g. outer rotor in wind force generator of gearless wind turbine, has central cover region arranged between two side walls |
| EP2479872B1 (en) * | 2011-01-25 | 2017-08-30 | Siemens Aktiengesellschaft | Permanently excited synchronous machine with a rotor |
| US8633627B2 (en) * | 2011-08-30 | 2014-01-21 | General Electric Company | Electric machine |
| TWI481158B (en) * | 2011-12-02 | 2015-04-11 | Ind Tech Res Inst | Multi-layer micro-structure magnet |
| CA2822158A1 (en) * | 2012-08-17 | 2014-02-17 | Envision Energy (Denmark) Aps | Electrical machine with magnetic flux intensifier |
| CN102904359B (en) * | 2012-11-16 | 2015-09-09 | 无锡先锋电机有限公司 | A kind ofly be applicable to magneto that entirety magnetizes and preparation method thereof |
| US9520752B1 (en) * | 2015-09-30 | 2016-12-13 | Faraday & Future Inc. | Interior permanent magnet machine for automotive electric vehicles |
| CN106972652B (en) * | 2017-05-05 | 2020-04-03 | 芜湖市海联机械设备有限公司 | Permanent magnet |
| JP2019030063A (en) * | 2017-07-26 | 2019-02-21 | Tdk株式会社 | Magnet structure and motor |
| CN112531938B (en) * | 2020-11-26 | 2022-04-15 | 珠海格力电器股份有限公司 | Rotor core, rotor, motor, compressor and air conditioner |
| CN113726114B (en) * | 2021-08-05 | 2022-12-20 | 包头长安永磁电机有限公司 | Double-stator permanent magnet synchronous motor for underwater vehicle |
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| JPS6158457A (en) * | 1984-08-29 | 1986-03-25 | Fanuc Ltd | Permanent magnet field synchronous motor |
| DE3730615A1 (en) | 1987-09-11 | 1989-03-30 | Marinescu Marlene | ELECTRICAL MACHINE WITH PERMANENT MAGNETIC EXCITATION |
| FR2742936B1 (en) * | 1995-12-22 | 1998-02-13 | Leroy Somer Moteurs | SYNCHRONOUS ELECTRIC MACHINE WITH PERMANENT MAGNETS SUITABLE FOR OPERATING AT CONSTANT POWER ON A WIDE RANGE OF SPEED |
| CN2317573Y (en) * | 1997-07-15 | 1999-05-05 | 管郡枢 | permanent magnet synchronous generator |
| JP4397466B2 (en) * | 1999-07-06 | 2010-01-13 | 東芝三菱電機産業システム株式会社 | Permanent magnet rotating electric machine |
| JP2005080340A (en) * | 2003-08-28 | 2005-03-24 | Kokusan Denki Co Ltd | Magneto rotor for rotary electric machine |
| JP4739726B2 (en) * | 2004-10-28 | 2011-08-03 | 日本電産テクノモータホールディングス株式会社 | Three-phase brushless DC motor for electric tools |
| EP1750350A2 (en) * | 2005-08-04 | 2007-02-07 | LG Electronics Inc. | Motor with single bent permanent magnet and its method of manufacture |
| US20070138891A1 (en) | 2005-12-19 | 2007-06-21 | Emerson Electric Co. | Magnet retention and positioning sleeve for surface mounted rotor assemblies |
| JP2008067561A (en) * | 2006-09-11 | 2008-03-21 | Yaskawa Electric Corp | Permanent-magnet electromotor |
| DE102006048966A1 (en) * | 2006-10-17 | 2008-04-30 | Siemens Ag | Magnet module for a permanent magnet excited electric machine |
-
2008
- 2008-07-22 CA CA2731616A patent/CA2731616A1/en not_active Abandoned
- 2008-07-22 JP JP2011519042A patent/JP2011528890A/en active Pending
- 2008-07-22 CN CN2008801309212A patent/CN102204070B/en active Active
- 2008-07-22 EP EP08801493.1A patent/EP2301140B1/en not_active Not-in-force
- 2008-07-22 KR KR1020117004099A patent/KR101493795B1/en active IP Right Grant
- 2008-07-22 DK DK08801493.1T patent/DK2301140T3/en active
- 2008-07-22 WO PCT/EP2008/005993 patent/WO2010009742A1/en active Application Filing
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20120025654A1 (en) * | 2010-02-02 | 2012-02-02 | Siemens Aktiengesellschaft | Rotor of a permanent magnet synchronous machine |
| EP2763284A3 (en) * | 2013-01-31 | 2016-10-12 | Gamesa Innovation & Technology, S.L. | Construction arrangement of a permanent magnet rotor for a generator |
Also Published As
| Publication number | Publication date |
|---|---|
| KR101493795B1 (en) | 2015-02-16 |
| WO2010009742A1 (en) | 2010-01-28 |
| CN102204070B (en) | 2013-09-18 |
| KR20110134371A (en) | 2011-12-14 |
| EP2301140A1 (en) | 2011-03-30 |
| DK2301140T3 (en) | 2019-01-07 |
| EP2301140B1 (en) | 2018-09-05 |
| JP2011528890A (en) | 2011-11-24 |
| CN102204070A (en) | 2011-09-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20140722 |