CN114696565A - Linear motor and magnetic suspension traffic system - Google Patents
Linear motor and magnetic suspension traffic system Download PDFInfo
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- CN114696565A CN114696565A CN202011629176.5A CN202011629176A CN114696565A CN 114696565 A CN114696565 A CN 114696565A CN 202011629176 A CN202011629176 A CN 202011629176A CN 114696565 A CN114696565 A CN 114696565A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K41/00—Propulsion systems in which a rigid body is moved along a path due to dynamo-electric interaction between the body and a magnetic field travelling along the path
- H02K41/02—Linear motors; Sectional motors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K3/00—Details of windings
- H02K3/02—Windings characterised by the conductor material
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K3/00—Details of windings
- H02K3/04—Windings characterised by the conductor shape, form or construction, e.g. with bar conductors
- H02K3/28—Layout of windings or of connections between windings
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K55/00—Dynamo-electric machines having windings operating at cryogenic temperatures
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02N—ELECTRIC MACHINES NOT OTHERWISE PROVIDED FOR
- H02N15/00—Holding or levitation devices using magnetic attraction or repulsion, not otherwise provided for
Abstract
The linear motor comprises a rotor and a stator, wherein the rotor comprises a plurality of superconducting coils; the stator comprises a plurality of stator coil sets, and the stator coil sets are arranged in parallel with the superconducting coils; each stator coil set comprises a first stator coil group and a second stator coil group, the first stator coil group is positioned on one side, close to the superconducting coil, of the second stator coil group, the first stator coil group and the second stator coil group respectively comprise M stator coils, and the first stator coil group and the second stator coil group are arranged in a staggered mode so that a secondary harmonic generated by the first stator coil group and a secondary harmonic magnetic field generated by the second stator coil group can be offset; the linear motor can reduce electromagnetic vibration and eddy current loss caused by magnetic field harmonic waves generated by a stator to a rotor, and avoid quench of a superconducting coil; the reliability of the superconducting coil is improved.
Description
Technical Field
The invention relates to the technical field of magnetic suspension linear motors, in particular to a linear motor and a magnetic suspension traffic system.
Background
The superconducting linear motor composed of the hollow stator winding and the superconducting magnet has the advantages of high thrust, high thrust density, high efficiency and the like, and has very wide application prospects in the fields of aerospace electromagnetic emission, ultrahigh-speed rail transit and the like. However, when the superconducting linear motor works, a secondary harmonic magnetic field generated by a stator winding of the superconducting linear motor can generate great electromagnetic force vibration and eddy current loss on the superconducting magnet, and quench of the superconducting magnet caused by vibration friction and eddy current loss is easily caused, so that the system of the superconducting linear motor fails. Therefore, the reduction of the secondary harmonic magnetic field generated by the stator winding on the surface of the superconducting magnet is greatly helpful for reducing the vibration and the heating of the superconducting magnet and further improving the stability and the reliability of the superconducting magnet. In addition, because of the large single-phase power, the linear motor generally uses an open winding mode, i.e., each phase is independently supplied with power, to reduce the capacity of a single converter, but the power supply mode requires that the content of counter potential harmonic waves generated by each phase coil is reduced as much as possible, so as to improve the sine type of the supply current.
In the prior art, the total harmonic magnetic field is reduced by adopting a mode that adjacent two-phase coils are arranged in a front-back manner and are provided with overlapped concentrated winding stators. However, this arrangement is only suitable for the situation where the number of phases is a multiple of 3 and the number of phases is odd, and thus has a large limitation; in addition, the concentrated winding stator can not effectively reduce the harmonic magnetic field of all orders and the counter potential harmonic, because the secondary harmonic component is increased while the primary harmonic component is eliminated.
The other method is a distributed winding stator adopting a skewed slot arrangement, but in the method, two vertical edges of each winding need to span adjacent multiphase windings, so that the upper and lower ineffective edges of each winding are too long, and the problems of large material consumption and difficult arrangement are brought; in an actual arrangement scene, each phase coil and other phase coils are provided with overlapped multiphase windings, so that the overall thickness of the stator is increased, the space required by arrangement is increased, and huge space waste is formed.
Therefore, how to reduce the secondary harmonic magnetic field and the counter potential harmonic generated by the stator winding on the surface of the superconducting magnet still remains a technical problem to be solved at present.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present disclosure is to provide a linear motor, which reduces electromagnetic vibration and eddy current loss caused by magnetic field harmonics generated by a stator to a superconducting coil, and avoids quench of the superconducting coil; the reliability of the superconducting coil is improved.
In order to solve the technical problems, the specific technical scheme is as follows:
in one aspect, a linear motor is provided herein, which includes a mover and a stator, where the mover includes a plurality of superconducting coils, and the plurality of superconducting coils are uniformly arranged on a same plane at intervals;
the stator includes a plurality of sets of stator coils arranged in parallel with the superconducting coils;
each stator coil set comprises a first stator coil group and a second stator coil group, the first stator groups under different stator coil sets are positioned on the same plane, the second stator coil groups under different stator coil sets are positioned on the same plane, the first stator coil group is positioned on one side, close to the superconducting coil, of the second stator coil group, the first stator coil group and the second stator coil group respectively comprise M stator coils, and the first stator coil group and the second stator coil group are arranged in a staggered mode so that a secondary harmonic generated by the first stator coil group and a secondary harmonic magnetic field generated by the second stator coil group can be mutually offset.
Further, each of the stator coils is arranged in parallel with the superconducting coil, the arrangement order of the M-phase stator coils in the first stator coil group is the same as the arrangement order of the M-phase stator coils in the second stator coil group, and each of the stator coils in the first stator coil group and the stator coils having the same phase in the second stator coil group are arranged in a staggered manner so that counter electromotive harmonics generated by the stator coils in the first stator coil group and the counter electromotive harmonics generated by the stator coils in the second stator coil group cancel each other out.
Specifically, the stator coils in the first stator coil group and the stator coils in the second stator coil group having the same phase are connected in series.
Further, the number of turns of each phase of the stator coil in the first stator coil group is the same, the number of turns of each phase of the stator coil in the second stator coil group is the same, and the number of turns of the stator coil in the first stator coil group is smaller than that of the stator coil in the second stator coil group.
Further, the pitch of the stator coils of each phase in the first stator coil group is equal, the pitch of the stator coils of each phase in the second stator coil group is equal, and the pitch of the stator coils in the first stator coil group is larger than the pitch of the stator coils in the second stator coil group.
Specifically, the pole pitch of the superconducting coil is an integral multiple of the misalignment distance between two stator coils connected in series.
Specifically, the pole pitch of the superconducting coil is an integral multiple of the center distance of two adjacent stator coils in the first stator coil group, and the pole pitch of the superconducting coil is an integral multiple of the center distance of two adjacent stator coils in the second stator coil group.
Preferably, the outer diameters of the M-phase stator coils in the first stator coil group and the outer diameters of the M-phase stator coils in the second stator coil group are both equal, and the inner diameter of the M-phase stator coils in the first stator coil group is larger than the inner diameter of the M-phase stator coils in the second stator coil group.
Specifically, the motor further comprises a connecting terminal which is arranged on the side of the second stator coil group far away from the superconducting coil, wherein each of the M-phase stator coils in the first stator coil group comprises a first lead-in end and a first lead-out end, each of the M-phase stator coils in the second stator coil group comprises a second lead-in end and a second lead-out end, the first lead-out end of each stator coil in the first stator coil group is connected with the second lead-in end of the stator coil with the same phase in the second stator coil group, and the connecting terminal is connected with the first lead-in end and the second lead-out end.
On the other hand, the magnetic suspension transportation system comprises a train, a train track and the linear motor provided by the technical scheme, wherein the train track is used for the train to run, and the linear motor is used for realizing the acceleration and the guidance of the train;
the superconducting coil is arranged on the side surface of the train body; the stator is arranged on the train track
By adopting the technical scheme, the linear motor provided by the invention can reduce the magnetic field harmonic generated by the stator, reduce the electromagnetic vibration and eddy current loss caused by the magnetic field harmonic to the rotor, avoid the quench of the superconducting coil serving as the rotor, improve the reliability of the superconducting coil and ensure the working quality of the linear motor.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the embodiments or technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 shows a schematic structural view of a first embodiment of a linear electric machine as provided herein;
FIG. 2 illustrates a schematic structural view of a second embodiment of a linear electric machine as provided herein;
FIG. 3 is a simulation graph of harmonic magnetic field canceling performance as a function of misalignment distance between a first stator coil group and a second stator coil group;
fig. 4 is a simulation diagram of back emf harmonic cancellation performance as a function of misalignment distance between a stator coil in a first stator coil group and a stator coil in the same phase in a second stator coil group;
fig. 5 is a schematic diagram showing the arrangement and connection relationship of stator coils.
Description of the symbols of the drawings:
1. a superconducting coil;
2. a stator coil set;
3. a first stator coil group;
4. a second stator coil group;
5. a connection terminal;
51. a first lead-in end of the stator coil a 1;
52. a second outlet terminal of stator coil a 2;
53. a first lead-out terminal of stator coil b 1;
54. a second lead-out terminal of stator coil b 2;
6. an electrical cable.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments herein without making any creative effort, shall fall within the scope of protection.
It should be noted that the terms "first," "second," and the like in the description and claims herein and in the above-described drawings are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments herein described are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, apparatus, article, or device that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or device.
A linear motor is a transmission device that directly converts electric energy into mechanical energy for linear motion without any intermediate conversion mechanism. The linear motor has the advantages of high thrust, high thrust density, high efficiency and the like, so that the linear motor has very wide application prospects in the fields of aerospace electromagnetic emission, ultrahigh-speed rail transit and the like. The magnetic suspension train is a rail transportation tool which uses the electromagnetic force generated by a linear motor to draw the train to run and has no contact with the land. When the linear motor is applied to a magnetic suspension train, the active cells of the linear motor are required to be arranged on two sides of a train body, and the stators are required to be arranged on tracks on two sides of the train body.
When the superconducting magnet is used as the rotor, the secondary harmonic magnetic field generated by the stator coil can generate great electromagnetic force vibration and eddy current loss on the superconducting magnet, so that the superconducting magnet is quenched, and a superconducting linear motor system fails. In addition, the open-winding power supply mode used by the linear motor also needs to reduce the content of counter potential harmonic generated by each phase coil as much as possible so as to improve the sine type of the power supply current.
In the prior art, the total harmonic magnetic field is reduced by adopting a mode that adjacent two-phase coils are arranged in a front-back manner and are provided with overlapped concentrated winding stators. However, the arrangement mode is only suitable for the situation that the phase number is multiple of 3 and the phase number is odd so as to ensure that the inductance resistance characteristics of each phase of coil are consistent when the coils are continuously arranged, so that the arrangement mode has great limitation; in addition, by adopting the centralized winding stator, while the main harmonic component is eliminated, the secondary harmonic component is increased, and the effective reduction of the harmonic magnetic field of all orders and the counter potential harmonic cannot be realized. The other method is a distributed winding stator adopting a skewed slot arrangement, but in the method, two vertical edges of each winding need to span adjacent multiphase windings, so that the upper and lower ineffective edges of each winding are too long, and the problems of large material consumption and difficult arrangement are brought; in an actual arrangement scene, each phase coil is a multi-phase winding which is overlapped with other adjacent phase coils, so that the overall thickness of the stator is increased, the space required for arranging the stator is increased, and huge space waste is formed; the vertical edge inclined arrangement designed for eliminating counter potential harmonic waves can bring huge unidirectional suspension force to the rotor, and the stability of the rotor is influenced.
In order to solve the above problems, embodiments herein provide a linear motor that can eliminate the influence of a secondary harmonic generated by a stator coil on a superconducting magnet without increasing a secondary harmonic component, and can effectively reduce the space and economic cost required for stator layout. As shown in fig. 1, a linear motor provided in an embodiment of the present specification includes a mover and a stator;
the rotor comprises a plurality of superconducting coils 1, and the superconducting coils 1 are sequentially and uniformly arranged on the same plane at intervals along the advancing direction of the train;
the stator comprises a plurality of stator coil sets 2, the stator coil sets 2 are positioned on the same plane, and the plane of the stator coil set 2 is parallel to the plane of the superconducting coil 1;
each stator coil set includes a first stator coil group 3 and a second stator coil group 4, the first stator groups belonging to different stator coil sets are located on the same plane, the second stator coil groups belonging to different stator coil sets are located on the same plane, and the first stator coil group 3 is located on the side of the second stator coil group 4 close to the superconducting coil 1; that is, the first stator coil group 3 and the superconducting coil are arranged in parallel, and the second stator coil group 4 and the superconducting coil 1 are arranged in parallel;
the first stator coil group 3 and the second stator coil group 4 each include M-phase stator coils, and the first stator coil group 3 and the second stator coil group 4 are disposed at a position offset from each other so that a secondary harmonic magnetic field generated by the first stator coil group 3 and a secondary harmonic magnetic field generated by the second stator coil group 4 cancel each other.
In the embodiment of the present invention, the fact that the first stator coil group 3 and the second stator coil group 4 each include M phases of stator coils means that: the number of phases of the stator coils in the first stator coil group 3 and the number of phases of the stator coils in the second stator coil group 4 are equal to each other and are M phases, where M is an integer greater than 3.
The stator coil generates fundamental waves for the traction train to advance, and simultaneously generates magnetic field harmonics of various orders (of the magnetic field harmonics of multiple orders, one order accounts for the main component of the total harmonic magnetic field, and the magnetic field harmonics of other orders account for the minor component of the total harmonic magnetic field). For the first stator coil group 3 relatively close to the superconducting coil 1, it generates magnetic field harmonics of various orders; the second stator coil group 4, which is relatively far from the superconducting magnet 1, generates magnetic field harmonics of various orders. According to the superconducting magnet, the first stator coil group 3 and the second stator coil group 4 are relatively staggered by a certain distance, so that the magnetic field harmonic of the main component generated by the first stator coil group 3 is offset with the magnetic field harmonic of the main component generated by the second stator coil group 4, and the total magnetic field harmonic generated by the first stator coil group and the second stator coil group is reduced, and the influence of the total magnetic field harmonic on the superconducting magnet is reduced.
Because the order number of the harmonic magnetic field generated by the six-phase motor is less than that of the harmonic magnetic field generated by the three-phase motor (the six-phase motor can generate 5, 7, 11 and higher harmonics, wherein the 5 th harmonic magnetic field is the main component in the total harmonic magnetic field, and the three-phase motor can generate 2, 4, 5, 7 and higher harmonic magnetic fields, and the 2 nd harmonic magnetic field is the main component in the total harmonic magnetic field generated by the three-phase motor); with the increase of the number of phases of the six-phase motor, the amplitude of the harmonic magnetic field of the lowest order is reduced, namely the 5 th harmonic magnetic field generated by the six-phase motor is smaller than the 2 nd harmonic magnetic field generated by the three-phase motor; besides, in the embodiment of the present specification, in consideration of the cost problem of the coil arrangement of each phase as the number of phases increases, it is preferable that each of the first stator coil group 3 and the second stator coil group 4 is provided with six-phase stator coils, and the phases of the adjacent two-phase stator coils are different by 60 °. Of course, the number of phases of the stator coils in the first stator coil group 3 and the second stator coil group 4 may be adjusted according to actual use requirements, that is, M may take a value other than 6.
As shown in fig. 3, the graph is a simulation in which the harmonic magnetic field canceling effect varies with the shift distance between the first stator coil group and the second stator coil group, the abscissa axis of the graph is the ratio of the shift distance between the first stator coil group and the second stator coil group to the pole pitch of the superconducting coil, and the ordinate axis of the graph is the ratio of the total harmonic magnetic field generated by the stator coils to the fundamental magnetic field.
As can be seen from the figure, when the misalignment distance between the first stator coil group 3 and the second stator coil group 4 is one fifth of the pole pitch of the superconducting magnet, the ratio of the total 5 th harmonic magnetic field generated by the stator coils to the fundamental magnetic field is lower than 0.02, i.e. the 5 th harmonic magnetic field is greatly eliminated.
This is because, when the first stator coil group 3 and the second stator coil group 4 are each provided with six-phase stator coils, the periods of the fundamental wave magnetic field generated by the first stator coil group 3 and the fundamental wave magnetic field generated by the second stator coil group 4 are both 2 τ; the periods of the 5 th harmonic magnetic field generated by the first stator coil group and the 5 th harmonic magnetic field generated by the second stator coil group are both
When the dislocation distance between the first stator coil group 3 and the second stator coil group 4 is one fifth of the pole distance of the superconducting magnet, the phase of the 5 th harmonic generated by the first stator coil group 3 is different from that of the 5 th harmonic generated by the second stator coil group 4 in phase
And thus cancel each other out.
It should be noted that, in some intervals, the fundamental magnetic field generated by the second stator coil group 4 has a certain phase difference with the fundamental magnetic field generated by the first stator coil group 3, but generally the fundamental magnetic field generated by the first stator coil group is still added.
The harmonic content generated by the first stator coil group 3 and the harmonic content generated by the second stator coil group 4 are both constant, and the harmonic after the same-phase harmonics are staggered by a certain angle is the original phase harmonic (the period is constant), so that a new order harmonic magnetic field cannot be increased. After the stator coils are arranged in a staggered mode, the 7 th harmonic magnetic field generated by the second stator coil group 4 also has a cancellation effect on the 7 th harmonic magnetic field generated by the first stator coil group 3; therefore, the total harmonic magnetic field generated by the first stator coil group 3 and the second stator coil group 4 is reduced, and the interference and damage of the harmonic magnetic field generated by the stator to the superconducting coil are reduced.
In summary, in order to improve the effect of eliminating the 5 th harmonic magnetic field generated by the second stator coil group 4 from the 5 th harmonic magnetic field generated by the first stator coil group 3 and reduce the influence of the harmonic magnetic field generated by the stator coils on the superconducting magnet, the present application sets the offset distance between the first stator coil group 3 and the second stator coil group 4 to be one fifth of the pole pitch of the superconducting coil, that is, the pole pitch of the superconducting coil 1 is 5 times the offset distance between the first stator coil group and the second stator coil group, that is, the pole pitch is the same as the offset distance between the first stator coil group and the second stator coil group
D1 is the distance from the center of the first stator coil group 3 to the center of the second stator coil group 4 in the same stator coil set, that is, the course offset distance between the first stator coil group 3 and the second stator coil group 4;
d2 is the distance between the center positions of two adjacent superconducting coils 1, i.e. the pole pitch of the superconducting coils 1.
Further, in the present embodiment, as shown in fig. 2 and 5, each stator coil in the first stator coil group 3 and each stator coil in the second stator coil group 4 are arranged in parallel with the superconducting coil 1. And the arrangement order of the M-phase stator coils in the first stator coil group 3 is the same as the arrangement order of the M-phase stator coils in the second stator coil group 4.
Since M is preferably 6 in the examples of the present specification, the 6 phases are referred to as a phase, B phase, C phase, D phase, E phase and F phase, respectively. Hereinafter, for convenience of description, the six-phase stator coils in the first stator coil group 3 are sequentially denoted as a1, b1, c1, d1, e1, and f 1; accordingly, the six-phase stator coils in the second stator coil group 4 are sequentially denoted as a2, b2, c2, d2, e2, and f 2. That is, stator coil a1 has the same phase as stator coil a2, stator coil b1 has the same phase as stator coil b2, stator coil c1 has the same phase as stator coil c2, stator coil d1 has the same phase as stator coil d2, stator coil e1 has the same phase as stator coil e2, and stator coil f1 has the same phase as stator coil f 2.
In the embodiment of the present specification, each stator coil in the first stator coil group 3 and the stator coil having the same phase in the second stator coil group 4 are offset so that counter electromotive harmonics generated in the respective stator coils in the first stator coil group 3 and the counter electromotive harmonics generated in the respective stator coils in the second stator coil group 4 cancel each other out. That is, stator coil a1 is offset from stator coil a2, stator coil b1 is offset from stator coil b2, stator coil c1 is offset from stator coil c2, stator coil d1 is offset from stator coil d2, stator coil e1 is offset from stator coil e2, and stator coil f1 is offset from stator coil f 2.
In practical use, each phase of stator coil needs to be electrically connected, and each electrically connected stator coil generates counter potential harmonics, which causes the sine type of the supply current to be poor. In the embodiment described herein, counter electromotive harmonics generated in the stator coils in the same phase are cancelled out by offsetting the stator coils in the same phase from each other in the same electronic coil set, the first stator coil group 3, and the second stator coil group 4.
As shown in fig. 4, a simulation diagram of the counter-electromotive harmonic cancellation effect on the stator that varies with the misalignment distance between the stator coil in the first stator coil group 3 and the stator coil in the same phase in the second stator coil group 4 is shown, in which the abscissa axis represents the ratio of the misalignment distance to the pole pitch of the superconducting coil, and the ordinate axis represents the ratio of the total counter-electromotive harmonic generated by the stator coil to the fundamental magnetic field.
As can be seen from fig. 4, when the misalignment distance between the stator coils in the first stator coil group 3 and the stator coils in the second stator coil group 4 having the same phase is one fifth of the pole pitch of the superconducting magnet, the ratio of the total 5-th back-emf harmonic generated by the stator coils to the fundamental magnetic field is lower than 0.02, i.e., the stator-generated 5-th back-emf harmonic is greatly eliminated.
This is because each of the stator coils in the first stator coil group 3 generates a back electromotive force harmonic period
The counter-potential harmonics generated by each stator coil in the second stator coil group 4 also have a period of
Therefore, when the stator coils of the same phase are staggered by one fifth of the pole pitch of the superconducting coils, the waveform of the back emf harmonic generated by the stator coil of the first stator coil group 3 in each half period is exactly opposite to the waveform of the back emf harmonic generated by the stator coil of the same phase in the second stator coil group 4 in each half period, and the back emf harmonics generated by the stator coils of the same phase are mutually cancelled after the superposition.
Therefore, in the embodiment described herein, the first stator coil group 3 and the second stator coil group 4 are each provided with a six-phase stator coil, and it is preferable to set the offset distance between the stator coils of the same phases to be one fifth of the pole pitch of the superconducting coils, that is, to set the pole pitch of the superconducting coils
Where D3 is the distance by which the stator coil in the first stator coil group 3 is displaced from the stator coil in the same phase in the second stator coil group 4;
that is, stator coil a1 and stator coil a2 are offset from each other by one-fifth the superconducting coil pole pitch 1, stator coil b1 and stator coil b2 are offset from each other by one-fifth the superconducting coil pole pitch, and similarly, other stator coils of the same phase are offset from each other by one-fifth the superconducting coil pole pitch.
It can be seen that the first stator coil group 3 and the second stator coil group 4 are offset from each other by the same distance as the stator coils in the same phase, and it can also be understood that the first stator coil group 3 and the second stator coil group 4 belonging to the same electronic coil assembly 2 are offset from each other by the same pole pitch of the superconducting coil 1 by exactly one fifth of the pole pitch of the stator coils in the same phase.
Therefore, the linear motor provided by the embodiment of the present specification has the effect of reducing the magnetic field harmonics of each order generated by the stator coils and the back electromotive force harmonics of the stator coils after setting the offset distance between the stator coils of the same phase belonging to the same stator coil set 2 to be one fifth of the pole pitch of the superconducting coils.
Since the first stator coil group 3 is closer to the superconducting coil 1 than the second stator coil group 4, if the 5 th harmonic magnetic field generated by the first stator coil group 3 is the same as the 5 th harmonic magnetic field generated by the second stator coil group 4, the influence of the 5 th harmonic magnetic field generated by the first stator coil group on the superconducting coil 1 is larger than the influence of the 5 th harmonic magnetic field generated by the second stator coil group 4 on the superconducting coil 1; i.e. the 5 th harmonic magnetic field generated by the second stator coil set 4 will not be sufficient to completely cancel the 5 th harmonic magnetic field generated by the first stator coil set 3.
Similarly, since the first stator coil group 3 is closer to the superconducting coil 1 than the second stator coil group 4, if the back electromotive harmonics generated by each stator coil in the first stator coil group 3 are the same in magnitude as the back electromotive harmonics generated by each stator coil in the second stator coil group 4, the back electromotive harmonics generated by each stator coil in the second stator coil group 4 will not be enough to completely cancel the back electromotive harmonics generated by each stator coil in the first stator coil group 3.
Therefore, in the embodiment described herein, it is preferable that the number of turns of the 6-phase stator coil in the first stator coil group 3 is the same, the number of turns of the 6-phase stator coil in the second stator coil group is the same, and the number of turns of each stator coil in the first stator coil group 3 is smaller than the number of turns of each stator coil in the second stator coil group 4.
That is, in the present embodiment, the number of turns of each stator coil in the first stator coil group 3 close to the superconducting coil 1 may be made smaller than the number of turns of each stator coil in the second stator coil group 4 far from the superconducting coil, so that the secondary harmonic generated by the second stator coil group 4 is made slightly larger than the secondary harmonic generated by the first stator coil group 3, thereby improving the cancellation effect between the two on the superconducting coil 1 side.
It is also possible to provide the first stator coil group 3 with equal pitch of the stator coils of each phase, the second stator coil group 4 with equal pitch of the stator coils of each phase, and the first stator coil group 3 with a larger pitch of the stator coils than the second stator coil group 4. That is, the cancellation effect on the superconducting coil side can also be improved by increasing the pitch of the respective stator coils in the second stator coil group 4 so as to increase the total secondary magnetic field harmonics generated by the second stator coil group 4 and to increase the back electromotive force harmonics generated by the respective stator coils in the second stator coil group 4.
Of course, the number of turns of the coil and the coil pitch can also be considered to have the effect on the generated magnetic field harmonic and counter-potential harmonic, that is, the number of turns of each stator coil in the second stator coil group 4 can be increased, and simultaneously, the pitch of each stator coil in the second stator coil group 4 can be reduced.
In addition to this, it is also possible to increase the current flowing through each of the stator coils in the second stator coil group 4, increase the counter electromotive force harmonics generated by each of the stator coils in the second stator coil group 4, and increase the total secondary magnetic field harmonics generated by the second stator coil group 4.
In the present embodiment, the stator coils belonging to the same stator coil set 2 are connected in series with each other, that is, the stator coil a1 is connected in series with the stator coil a2, and the stator coil b1 is connected in series with the stator coil b 2.
The pole pitch of the superconducting coil 1 is integral multiple of the dislocation distance between two stator coils connected in series. Note that, as described above, the pole pitch of the superconducting coils is 5 times the misalignment distance between the stator coil in the first stator coil group 3 and the stator coil in the same phase in the second stator coil group. However, when the first stator coil group 3 and the second stator coil group 4 are provided with stator coils having other phases, the magnetic field harmonics generated by the first stator coil group 3 and the second stator coil group 4 may be other orders of magnetic field harmonics, for example, 8-order magnetic field harmonics, which are the main components. At this time, under the knowledge of the principle that the linear motor provided in the embodiment of the present specification eliminates the secondary magnetic field harmonic and reduces the counter potential harmonic, a distance that the first stator coil group 3 is staggered from the second stator coil group 4 may be set to be one eighth of a pole pitch of the superconducting coil, that is, the pole pitch of the superconducting coil is eight times of a staggered distance between the first stator coil group 3 and the second stator coil group 4; and misplacing the stator coils belonging to the same phase in the same stator coil set 2 by one eighth of the pole pitch of the superconducting coils.
In order to better realize the traction of the stator to the rotor, in the embodiment of the present specification, the pole pitch of the superconducting coil 1 is an integral multiple of the center distance between two adjacent stator coils in the same first stator coil group 3; the pole pitch of the superconducting coil 1 is integral multiple of the center distance of two adjacent stator coils in the same second stator coil group 4;
specifically, when the first stator coil group 3 is provided with six-phase stator coils, the pole pitch of the superconducting coil 1 is set to be 3 times the center distance of the adjacent two-phase stator coils, and when the second stator coil group 4 is provided with six-phase stator coils, the pole pitch of the superconducting coil 1 is set to be 3 times the center distance of the adjacent two-phase stator coils, that is, the second stator coil group 4 is provided with six-phase stator coils
Where D4 is the center distance between two adjacent stator coils belonging to the same first stator coil group 3 or the center distance between two adjacent stator coils belonging to the same second stator coil group 4.
Preferably, in the embodiment of the present specification, the outer diameter of each stator coil in the first stator coil group 3 is set to be equal to the outer diameter of each stator coil in the second stator coil group 4; the inner diameter of each stator coil in the first stator coil group 3 is set larger than the inner diameter of each stator coil in the second stator coil group 4. For example, as shown in fig. 5, the stator coil a1 is "thinner" than the stator coil a 2.
In this way, it is possible to realize that the pitch of each stator coil in the first stator coil group 3 is larger than the pitch of each stator coil in the second stator coil group 4; moreover, because the outline dimensions of the stator coils are the same, the space occupied by the first stator coil group 3 is approximately consistent with the space occupied by the second stator coil group 4, so that the stator coil set is more attractive in arrangement, and the arrangement space is saved; in addition, the universality of parts and components can be improved and the process preparation efficiency can be improved to a certain extent.
In the embodiment of the present specification, the present invention further includes a connection terminal 5 provided on a side of the second stator coil group 3 away from the superconducting coil 1, where each of the M-phase stator coils in the first stator coil group 3 includes a first lead-in terminal and a first lead-out terminal, each of the M-phase stator coils in the second stator coil group 4 includes a second lead-in terminal and a second lead-out terminal, the first lead-out terminal of each of the stator coils in the first stator coil group 3 is connected to the second lead-in terminal of the stator coil having the same phase in the second stator coil group 4, and the connection terminal is connected to the first lead-in terminal and the second lead-out terminal.
The connecting terminal is arranged on one side of the second stator coil group 3 far away from the superconducting coil 1, so that the influence of the superconducting coil 1 on the connecting terminal can be reduced, and the cable laying is facilitated to a certain extent.
As shown in the drawings, in the present embodiment, it is preferable that, in the same stator coil assembly 2, the first lead-in terminal 51 of the stator coil a1, the second lead-out terminal 52 of the stator coil a2, the first lead-out terminal 53 of the stator coil b1, and the second lead-out terminal 54 of the stator coil b2 are collectively arranged; arranging a first leading-in end of the stator coil c1, a second leading-out end of the stator coil c2, a first leading-out end of the stator coil d1 and a second leading-out end of the stator coil d2 in the same stator coil assembly 2 in a centralized manner; and collectively arranging a first lead-in terminal of the stator coil e1, a second lead-out terminal of the stator coil e2, a first lead-out terminal of the stator coil f1 and a second lead-out terminal of the stator coil f2 in the same stator coil group 2.
Each stator coil set 2 is respectively provided with three bundles of connecting terminals, and when different stator coil sets are connected, the three bundles of connecting terminals of two adjacent stator coil sets 2 are correspondingly connected only through the cables 6. Therefore, through the wiring manner, the linear motor provided by the embodiment of the specification can greatly reduce the requirement for the hole of the bearing beam for arranging the stator, and in addition, the flexible power supply cable can be led out from one side far away from the superconducting coil through the wiring connection manner, so that the electromagnetic vibration generated by the influence of the magnetic field of the superconducting coil on the cable can be reduced to the greatest extent, and the reliability of the connection and fixing position of the cable is improved.
In addition, in the embodiment of the present specification, when different stator coils are connected to a stator coil in the same phase, only cable connection is required, and the wire of each phase of stator coil does not need to span multiple adjacent phases until the wire is crossed to the next stator coil, which is beneficial to solving the problem of stator coil layout cost. In the embodiment of the specification, each stator coil set 2 only needs to be provided with the first stator coil group 3 and the second stator coil group 4, that is, only two layers of stator coils need to be provided, so that the overall thickness of the stator can be greatly reduced, and the space required by arranging the stator is greatly saved.
According to the linear motor, the stator coils in the first stator coil group and the second stator coil group are staggered by one fifth of the pole distance of the superconducting coils, so that five times of space harmonic magnetic fields generated at the superconducting coils when the stator coils are supplied with sinusoidal current are completely eliminated, seven times of space harmonic magnetic fields are partially eliminated, other extra harmonic components are not introduced, and vibration and heating of the superconducting coils can be greatly reduced;
moreover, the five counter potential harmonics in the counter potentials generated by the stator coils can be completely eliminated, the seven counter potential harmonics can be partially eliminated, other extra harmonic components are not introduced, the interference of the counter potential harmonics on the control of the converter can be greatly reduced, and the harmonic components of the propulsion current are reduced;
on the other hand, the embodiment of the present specification further provides a magnetic suspension transportation system, including a train, a train track and the linear motor provided by the above technical solution, where the train track is used for the train to run, and the linear motor is used for accelerating and guiding the train;
the superconducting coil 1 is arranged on the side surface of the train body; the stator is disposed on the train track.
The principles and embodiments of this document are explained herein using specific examples, which are presented only to aid in understanding the methods and their core concepts; meanwhile, for the general technical personnel in the field, according to the idea of this document, there may be changes in the concrete implementation and the application scope, in summary, this description should not be understood as the limitation of this document.
Claims (10)
1. A linear motor is characterized by comprising a rotor and a stator, wherein the rotor comprises a plurality of superconducting coils which are uniformly arranged on the same plane at intervals;
the stator includes a plurality of sets of stator coils arranged in parallel with the superconducting coils;
each stator coil set comprises a first stator coil group and a second stator coil group, the first stator groups under different stator coil sets are positioned on the same plane, the second stator coil groups under different stator coil sets are positioned on the same plane, the first stator coil group is positioned on one side, close to the superconducting coil, of the second stator coil group, the first stator coil group and the second stator coil group respectively comprise M stator coils, and the first stator coil group and the second stator coil group are arranged in a staggered mode so that a secondary harmonic generated by the first stator coil group and a secondary harmonic magnetic field generated by the second stator coil group can be mutually offset.
2. The linear motor according to claim 1, wherein the M-phase stator coils in the first stator coil group are arranged in the same order as the M-phase stator coils in the second stator coil group, and each stator coil in the first stator coil group and the stator coil having the same phase in the second stator coil group are offset so that counter potential harmonics generated from the respective stator coils in the first stator coil group and the second stator coil group cancel each other out.
3. A linear motor according to claim 2, wherein the stator coils in the first stator coil group and the stator coils in the second stator coil group having the same phase are connected in series.
4. A linear motor according to claim 3, wherein the number of turns of each phase stator coil in the first stator coil group is the same, the number of turns of each phase stator coil in the second stator coil group is the same, and the number of turns of the stator coil in the first stator coil group is smaller than the number of turns of the stator coil in the second stator coil group.
5. A linear motor according to claim 3, wherein the pitch of each phase stator coil in the first stator coil group is equal, the pitch of each phase stator coil in the second stator coil group is equal, and the pitch of the stator coil in the first stator coil group is larger than the pitch of the stator coil in the second stator coil group.
6. A linear motor according to any one of claims 4 or 5, wherein the pole pitch of the superconducting coils is an integral multiple of the misalignment distance between two stator coils connected in series.
7. A linear motor according to claim 2, wherein a pole pitch of the superconducting coil is an integral multiple of a center distance between two adjacent stator coils in the first stator coil group, and a pole pitch of the superconducting coil is an integral multiple of a center distance between two adjacent stator coils in the second stator coil group.
8. The linear motor according to claim 7, wherein the outer diameters of the M-phase stator coils in the first stator coil group and the outer diameters of the M-phase stator coils in the second stator coil group are both equal, and the inner diameter of the M-phase stator coils in the first stator coil group is larger than the inner diameter of the M-phase stator coils in the second stator coil group.
9. A linear motor according to claim 1, further comprising a connection terminal provided on a side of a second stator coil group remote from the superconducting coil, wherein each of the M-phase stator coils in the first stator coil group includes a first lead-in terminal and a first lead-out terminal, wherein each of the M-phase stator coils in the second stator coil group includes a second lead-in terminal and a second lead-out terminal, wherein the first lead-out terminal of each of the stator coils in the first stator coil group is connected to the second lead-in terminal of a stator coil of the same phase in the second stator coil group, and wherein the connection terminal is connected to the first lead-in terminal and the second lead-out terminal.
10. A magnetic levitation transportation system comprising a train, a train track for running the train, and a linear motor according to any one of claims 1 to 9 for accelerating and guiding the train;
the superconducting coil is arranged on the side surface of the train body; the stator is disposed on the train track.
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