Method for eliminating longitudinal edge effect of direct-current traction system

Abstract

The invention discloses a method for eliminating the longitudinal edge effect of a direct current traction system, which is suitable for eliminating the longitudinal edge effect of the direct current traction system in rail transit, the longitudinal edge effect comprises a first type of longitudinal edge effect, and the first type of longitudinal edge effect is the formation of longitudinal pulsating flux density; the elimination method comprises the step of increasing the magnetic conductance equivalent spacing of the direct-current traction system so as to reduce the longitudinal pulsating flux density. The traction efficiency is improved by eliminating the longitudinal edge effect of the direct-current traction system in the rail transit.

Description

Technical Field

[0001] The present application relates to the field of rail transit technology, and in particular to a method for eliminating longitudinal edge effects of a DC traction system. Background Art

[0002] In recent years, the agglomeration effect of metropolitan areas has become increasingly obvious. In order to alleviate the problem of urban traffic congestion, urban rail transit has developed rapidly. Rail transit is the main mode of transportation and has gradually become the first choice for the general public. However, rail transit is a double-edged sword. While it brings convenience to people, it also has more or less safety hazards. Therefore, the requirements for the operation system and vehicles are getting higher and higher to ensure the safe and reliable operation of vehicles. The train traction system in rail transit is a key system to ensure the reliable and safe operation of trains. The operating status and service life of the vehicle traction equipment system play a decisive role. The entire traction system needs to be regularly inspected and maintained to avoid accidents caused by failures.

[0003] The linear induction motor (LIM) traction system is a new type of transportation mode with wheel-rail support and guidance, non-adhesion direct drive, and is widely used in low-speed magnetic levitation trains, urban subways and light rails. Compared with rotary motor traction locomotives, it has the advantages of low overall system energy consumption, low cost, strong climbing ability, small turning radius, low vibration and noise, safety and comfort, and low maintenance. It is particularly suitable for transportation in densely populated large cities. The linear asynchronous motor is an asynchronous motor that converts electrical energy into mechanical energy for linear motion. It can be regarded as a motor evolved from a rotary motor. Therefore, the main advantage of the linear motor is that it directly generates linear motion without the need for an intermediate conversion device. Based on this characteristic, the linear asynchronous motor has a large starting thrust, can achieve a wide range of acceleration and deceleration, the components are not affected by centrifugal force, and the linear speed is not limited.

[0004] However, in the actual use of the linear induction motor (LIM) traction system, due to the longitudinal magnetic circuit being broken and the large gap between the primary and secondary, the magnetic field and eddy current distribution generated by the relative motion between the primary and secondary are distorted. This distortion is called the dynamic longitudinal edge effect of the motor. Due to the generation of the dynamic longitudinal edge effect, the driving thrust is reduced and the loss is increased, especially for high-speed and low-slip motors. The longitudinal edge effect deteriorates the working performance of the motor and must be carefully considered when designing the motor.

[0005] Therefore, this field is in urgent need of a new solution to solve the above technical problems. Summary of the invention

[0006] The purpose of the present application is to provide a method for eliminating the longitudinal edge effect of a DC traction system, thereby improving the traction efficiency by eliminating the longitudinal edge effect of a DC traction system in rail transit.

[0007] To this end, an embodiment of the present application provides a method for eliminating the longitudinal edge effect of a DC traction system, which is applicable to eliminating the longitudinal edge effect of a DC traction system in rail transit, wherein the longitudinal edge effect includes a first type of longitudinal edge effect, wherein the first type of longitudinal edge effect is the formation of longitudinal pulsating magnetic flux density;

[0008] The elimination method comprises:

[0009] The permeance equivalent spacing of the DC traction system is increased to reduce the longitudinal pulsating magnetic flux density.

[0010] In a possible implementation, the expression of the magnetic permeance equivalent spacing is:

[0011]

[0012] Among them, d is the equivalent spacing of magnetic permeance, δe is the electromagnetic air gap, Kδ1, Kδ2, Kδ3 are correction coefficients for correcting the DC traction system, P is the number of magnetic poles, and r / lδ is the winding ratio of the DC traction system.

[0013] In a possible implementation, Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and Kδ1 is the equivalent electromagnetic air gap density of the DC motor, expressed as:

[0014]

[0015] Wherein, t is the primary tooth pitch of the DC traction system, and h1 is the slot width of the DC traction system;

[0016] The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsation flux density includes: reducing the primary tooth pitch t of the DC traction system and reducing the slot width h1 to increase the permeance equivalent spacing of the DC traction system.

[0017] In a possible implementation, Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and Kδ2 is the intensity of the fixed slot current of the stator of the DC traction system, expressed as:

[0018]

[0019] Wherein, D is the gap distance between the fixed slot and the stator;

[0020] The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsation flux density includes: increasing the gap distance D between the fixed slot and the stator of the DC traction system to increase the permeance equivalent spacing of the DC traction system.

[0021] In a possible implementation, the value range of D is 2.3 mm to 2.5 mm.

[0022] In a possible implementation, Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and Kδ3 is an influencing parameter of the DC traction system, expressed as follows:

[0023]

[0024] Wherein, l1 is the transverse lamination thickness of the DC traction system;

[0025] The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsating magnetic flux density includes: reducing the transverse lamination thickness l1 to increase the permeance equivalent spacing of the DC traction system.

[0026] In a possible implementation, the method further includes:

[0027] The permeance equivalent spacing of the DC traction system is increased to reduce the longitudinal pulsating magnetic flux density.

[0028] In a possible implementation, the longitudinal edge effect includes a second type of longitudinal edge effect, and the second type of longitudinal edge effect is an increase in complex electromagnetic power;

[0029] The elimination method comprises:

[0030] The air gap spacing is reduced to reduce the complex electromagnetic power.

[0031] In a possible implementation, the expression of the complex electromagnetic power is:

[0032]

[0033] Among them, m1 is the complex amplitude of magnetic flux density, I1 is the induced eddy current, Zeo is the air gap spacing, Da is the inductive impedance, and Dj is the longitudinal edge coefficient caused by the induced current.

[0034] In a possible implementation, the elimination method further includes:

[0035] The inductive impedance Da and the longitudinal edge coefficient Dj caused by the induced current are reduced to reduce the complex electromagnetic power.

[0036] In an embodiment of the present application, a method for eliminating the longitudinal edge effect of a DC traction system is proposed. The core of this method is to completely eliminate the longitudinal edge effect in the DC traction system. Specifically, through a series of technical means, the two key factors of longitudinal pulsation magnetic flux density and complex electromagnetic power are effectively eliminated. By eliminating these factors, this method can effectively solve the problems of the first type of longitudinal edge effect and the second type of longitudinal edge effect in the DC traction system. In this way, the traction efficiency of the DC traction system is significantly improved when it is used as a traction tool in the field of rail transit. This improvement is not only reflected in the enhancement of traction force, but also in the improvement of energy utilization efficiency and the enhancement of system stability, thereby providing strong technical support for the efficient operation of the rail transit system. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In addition, in the drawings, the same components are marked with the same reference numerals, and the drawings are not drawn according to the actual scale.

[0038] Figure 1 The process of the method for eliminating the longitudinal edge effect of the DC traction system provided by the embodiment of the present application is shown as follows Figure 1 ;

[0039] Figure 2 The process of the method for eliminating the longitudinal edge effect of the DC traction system provided by the embodiment of the present application is shown as follows Figure 2 . DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0041] The linear asynchronous motor has a large starting thrust and can achieve a wide range of acceleration and deceleration. The components are not affected by centrifugal force and the linear speed is not limited.

[0042] However, in practical applications, the linear induction motor (LIM) traction system faces some challenges. Due to the interruption of the longitudinal magnetic circuit and the large gap between the primary and secondary, the magnetic field and eddy current distribution will be distorted when the primary and secondary move relative to each other. This distortion is called the dynamic longitudinal edge effect of the motor. The existence of the dynamic longitudinal edge effect will lead to a decrease in driving thrust and an increase in loss, especially in high-speed and low-slip motors. This effect is more significant. The longitudinal edge effect will deteriorate the working performance of the motor. Therefore, this factor must be carefully considered when designing the motor to ensure that the motor can operate efficiently and stably.

[0043] The main purpose of this application is to solve at least one of the above technical problems, so a method for eliminating the longitudinal edge effect of a DC traction system is proposed. Through this method, the longitudinal edge effect generated by the DC traction system in rail transit can be effectively eliminated, thereby significantly improving the efficiency of the traction system.

[0044] Specifically, the method uses a series of technical means and measures to eliminate the longitudinal edge effect that may occur during the operation of the DC traction system. The longitudinal edge effect refers to the phenomenon of uneven traction force in the DC traction system due to factors such as uneven current distribution. This phenomenon not only affects the running stability of the train, but also reduces traction efficiency and increases energy consumption.

[0045] The method of this application can effectively eliminate the longitudinal edge effect in the DC traction system, thereby improving traction efficiency, reducing energy consumption, and ensuring the stable operation of the rail transit system. The application of this innovative technology can not only improve the overall performance of rail transit, but also provide passengers with a more comfortable and safe travel experience.

[0046] In an embodiment of the present application, an effective method is proposed to eliminate the longitudinal edge effect occurring in a DC traction system. This method is particularly suitable for the field of rail transit, in which DC traction systems often encounter the problem of longitudinal edge effects. The longitudinal edge effect is mainly divided into two types, of which the first type of longitudinal edge effect is mainly caused by the interruption of the magnetic circuit of the linear motor. Specifically, this effect includes the uneven distribution of the air gap magnetic flux along the longitudinal axis and the weakening of the end magnetic flux due to the existence of the semi-used slots of the linear motor and the magnetic shunts at the ends and back of the core. In addition, this effect will also cause the formation of longitudinal pulsating magnetic flux, which in turn leads to the weakening of the longitudinal traveling wave field. Therefore, the first type of longitudinal edge effect mainly refers to the formation of longitudinal pulsating magnetic flux and the related problems it brings.

[0047] Please refer to Figure 1 and Figure 2The elimination method proposed in this application based on the first type of longitudinal edge effect includes:

[0048] S100: increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsating magnetic flux density.

[0049] In order to reduce the longitudinal pulsation flux density in the DC traction system, it can be achieved by increasing the equivalent spacing of the magnetic permeance. Specifically, by adjusting and optimizing the equivalent spacing of the magnetic permeance in the system, the intensity of the longitudinal pulsation flux density can be effectively reduced. This adjustment can be achieved by changing the design of the magnetic circuit, increasing the thickness of the magnetic material, or changing the arrangement of the magnetic material. In this way, the flux density fluctuation in the DC traction system can be significantly reduced, thereby improving the stability and reliability of the system.

[0050] It should be noted that DC asynchronous motors are divided into even-numbered motors and odd-numbered motors, and the mathematical expression of the air gap flux density is as follows:

[0051] DC asynchronous motors can be divided into two types according to their internal structure and working principle: even-numbered motors and odd-numbered motors. These two types of motors have their own characteristics in design and application, but their basic working principle is to use DC power to drive the motor.

[0052] An even-numbered motor means that the armature winding inside the motor is composed of an even number of magnetic poles. During the operation of this motor, the current is evenly distributed between the magnetic poles, making the motor torque more stable, and the vibration and noise relatively small. Even-numbered motors are usually suitable for application scenarios that require high stability and low noise, such as precision instruments and medical devices.

[0053] An odd-numbered motor means that the armature winding inside it is composed of an odd number of magnetic poles. Due to the presence of an odd number of magnetic poles, this type of motor will produce a special rotation effect during operation, which makes its torque fluctuate greatly, but also has a higher starting torque. Odd-numbered motors are usually suitable for application scenarios that require a larger starting torque, such as lifting machinery and large industrial equipment.

[0054] In general, these two classifications of DC asynchronous motors can select the appropriate motor type according to specific application requirements and working environment to achieve the best operating effect.

[0055]

[0056] Where Bδ1 is the traveling wave magnetic flux density amplitude, Bc1 and Bc2 are the pulsating magnetic field magnetic flux density amplitudes, and the mathematical expression is as follows:

[0057]

[0058] d is the equivalent distance of the magnetic permeance corresponding to the shunt flux. Only by increasing the equivalent distance d of the magnetic permeance can the longitudinal pulsation magnetic flux of the DC motor be reduced. The longitudinal pulsation magnetic flux is the main factor of the DC motor loss and affects the overall performance of the DC motor. δe is the electromagnetic air gap. The electromagnetic air gap is located between the primary and secondary windings of the DC traction system (the embodiment of the present application is a linear asynchronous motor) and is the main place for energy conversion. The common linear asynchronous motor air gap height is about 10 mm, which is usually a fixed parameter. δe ensures that there is no contact between the primary and secondary windings. Kδ1, Kδ2, and Kδ3 are correction coefficients set in the one-dimensional model to correct the uneven magnetic flux in the tooth slot, normal, and lateral directions, respectively.

[0059] Increasing the permeance equivalent distance d can reduce the longitudinal pulsation flux density of the DC motor, reduce losses and improve performance. The electromagnetic air gap δe is the key to energy conversion in the DC traction system and is usually fixed at around 10mm to avoid winding contact. Kδ1, Kδ2, and Kδ3 are coefficients for correcting the flux density inhomogeneity in the one-dimensional model.

[0060] In an additional example, the elimination method further includes adjusting the size of the electromagnetic air gap δe to further reduce the longitudinal pulsation flux density. By optimizing the size of the electromagnetic air gap δe, the distribution of the magnetic flux can be effectively controlled, thereby reducing the non-uniformity of the flux density and improving the operating efficiency of the motor.

[0061] In addition, the elimination method may also include using specific materials to construct the housing of the DC traction system to enhance its magnetic permeability. Selecting materials with high magnetic permeability can reduce magnetic resistance, thereby reducing energy loss on the magnetic flux path and further improving the performance of the motor.

[0062] In a possible implementation, the expression of the magnetic permeance equivalent spacing is:

[0063]

[0064] Among them, d is the permeance equivalent spacing, δe is the electromagnetic air gap, Kδ1, Kδ2, Kδ3 are correction coefficients for correcting the DC traction system, P is the number of pole pairs, and r / lδ is the winding ratio of the DC traction system. When analyzing the DC traction system in detail, first, d represents the permeance equivalent spacing, which refers to the equivalent distance that the magnetic lines of force pass through in the magnetic circuit. This parameter is of great significance for calculating magnetic flux and magnetic resistance. Secondly, δe represents the electromagnetic air gap, that is, the air gap between the rotor and the stator in the motor or generator. The size of this air gap directly affects the flux density and efficiency of the system.

[0065] In order to more accurately correct the relevant parameters of the DC traction system, three correction coefficients are introduced: Kδ1, Kδ2 and Kδ3. These coefficients take into account the impact of different factors on system performance, such as temperature changes, material properties, and manufacturing tolerances. Through these correction coefficients, we can more accurately calculate the actual performance of the system and optimize the design and operating parameters.

[0066] In addition, P stands for the number of pole pairs, which is an important parameter that describes the number of magnetic poles in a motor or generator. The number of pole pairs determines the number of pole pairs of the motor, which in turn affects its speed and torque characteristics. In motor design, the proper selection of the number of pole pairs is crucial to meet specific application requirements.

[0067] Finally, r / lδ represents the winding ratio of the DC traction system, which refers to the ratio of resistance to inductance in the motor winding. This ratio has a significant impact on the motor's starting performance, operating efficiency, and temperature rise. By adjusting the winding ratio, the dynamic and static performance of the motor can be optimized to better adapt to different working conditions.

[0068] In summary, through in-depth understanding and precise calculation of these key parameters, the embodiments of the present application can fully grasp the electromagnetic characteristics of the DC traction system, thereby achieving more efficient and reliable motor design and operation.

[0069] In an optional example, Kδ1, Kδ2, Kδ3 are correction coefficients of the DC traction system, Kδ1 is the equivalent electromagnetic air gap density of the DC motor, and the expression is:

[0070]

[0071] Wherein, t is the primary tooth pitch of the DC traction system, and h1 is the slot width of the DC traction system;

[0072] S100: The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsating magnetic flux density includes: S101: reducing the primary tooth pitch t of the DC traction system, and reducing the slot width h1, to increase the permeance equivalent spacing of the DC traction system. In order to reduce the longitudinal pulsating magnetic flux density of the DC traction system, measures need to be taken to increase the permeance equivalent spacing of the DC traction system. Specifically, reducing the primary tooth pitch t of the DC traction system and simultaneously reducing the slot width h1 can effectively increase the permeance equivalent spacing of the DC traction system. Such adjustments help reduce the fluctuation of magnetic flux density, thereby improving the stability and efficiency of the system.

[0073] In an optional example, the Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and the Kδ2 is the intensity of the fixed slot current of the stator of the DC traction system, expressed as:

[0074]

[0075] Wherein, D is the gap distance between the fixed slot and the stator;

[0076] S100: Increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsating magnetic flux density includes: S102: increasing the gap distance D between the fixed slot and the stator of the DC traction system to increase the permeance equivalent spacing of the DC traction system.

[0077] In order to reduce the longitudinal pulsating flux density, it is necessary to increase the permeance equivalent spacing of the DC traction system. Specifically, by increasing the gap distance D between the fixed slot and the stator in the DC traction system, the permeance equivalent spacing can be effectively increased, thereby achieving the purpose of reducing the longitudinal pulsating flux density.

[0078] In a possible implementation, the value range of D is 2.3 mm to 2.5 mm. Specifically, the value of D can be 2.3 mm, 2.4 mm, or 2.5 mm. Such a setting ensures that the value of D is within this range, thereby meeting specific technical requirements or design standards. In this way, the dimensional accuracy and performance of the relevant parts or equipment can be ensured to achieve the expected effect.

[0079] In a possible implementation, Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and Kδ3 is an influencing parameter of the DC traction system, expressed as follows:

[0080]

[0081] Wherein, l1 is the transverse lamination thickness of the DC traction system;

[0082] S100: Increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsating magnetic flux density includes: S103: reducing the transverse lamination thickness l1 to increase the permeance equivalent spacing of the DC traction system.

[0083] In order to increase the permeance equivalent spacing of the DC traction system and thereby reduce the longitudinal pulsation flux density, the specific implementation method includes: in step S103, by reducing the thickness l1 of the transverse laminations, the permeance equivalent spacing of the DC traction system is further increased. Such adjustment helps to optimize the magnetic performance of the system, reduce the loss caused by flux density pulsation, and thus improve the operating efficiency and stability of the entire system.

[0084] In a possible implementation, the elimination method provided in the embodiment of the present application further includes:

[0085] S200: Increasing the equivalent spacing of the magnetic permeance of the DC traction system to reduce the longitudinal pulsating magnetic flux density.

[0086] It should be noted that, from the expression of the equivalent distance d of the magnetic permeance, it can be seen that the method to eliminate the first type of longitudinal edge effect is to increase the number of poles P. In the present invention, the number of poles of the electrode is set to P less than 14. The number of poles is also the key to eliminating the first type of longitudinal edge effect. In addition, the present invention regards the longitudinal continuous arrangement of the motor as an infinite extension of the magnetic circuit. This method is used to eliminate the phenomenon of end weakening, thereby overcoming a type of longitudinal edge effect.

[0087] In one possible implementation, the longitudinal edge effect includes a second type of longitudinal edge effect, and the second type of longitudinal edge effect is an increase in complex electromagnetic power. Specifically, this second type of longitudinal edge effect refers to the increase in complex electromagnetic power under specific conditions. The increase in complex electromagnetic power can be understood as the accumulation and enhancement of electromagnetic energy in the electromagnetic field due to the influence of certain specific factors. This phenomenon may occur in the process of electromagnetic wave propagation, especially in certain specific media or structures, such as in waveguides, resonant cavities or other systems with specific geometric shapes and material properties. By precisely controlling and utilizing this second type of longitudinal edge effect, higher energy transmission efficiency and better performance can be achieved in electromagnetic devices and systems.

[0088] Based on the above content, the elimination method provided in the embodiment of the present application includes:

[0089] S300: reducing the air gap distance to reduce the complex electromagnetic power.

[0090] By reducing the air gap spacing, the complex electromagnetic power can be effectively reduced. Specifically, the reduction in the air gap spacing will lead to a reduction in the magnetic resistance in the magnetic circuit, making it easier for the magnetic flux to pass through, thereby reducing the loss of electromagnetic power. This adjustment can significantly improve the efficiency of the electromagnetic system, making the device more energy-efficient and efficient during operation.

[0091] In a possible implementation, the expression of the complex electromagnetic power is:

[0092]

[0093] Among them, m1 is the complex amplitude of magnetic flux density, I1 is the induced eddy current, Zeo is the air gap spacing, Da is the inductive impedance, and Dj is the longitudinal edge coefficient caused by the induced current.

[0094] In the electromagnetic induction system, m1 represents the complex amplitude of the magnetic flux density, which is a complex parameter that describes the change of the magnetic field. I1 represents the induced eddy current, which is the current generated in the conductor due to the change of the magnetic field. Zeo refers to the air gap spacing, that is, the thickness of the air or other non-magnetic medium in the magnetic circuit, which has an important influence on the magnetic resistance of the system. Da represents the inductive impedance, which is the impedance effect generated by the induced current in the circuit. Dj represents the longitudinal edge coefficient caused by the induced current, which is a parameter that describes the uneven distribution of the magnetic field generated by the induced current at the edge of the conductor.

[0095] In an optional example, the elimination method further includes:

[0096] S400: reducing the inductive impedance Da and the longitudinal edge coefficient Dj caused by the inductive current to reduce the complex electromagnetic power.

[0097] The system takes a series of measures to reduce the inductive impedance Da and the longitudinal edge coefficient Dj generated by the induced current, thereby effectively reducing the value of the complex electromagnetic power. Specifically, the inductive impedance is reduced by optimizing the design and adjusting the relevant parameters. Inductive impedance is one of the important factors affecting the performance of the electromagnetic system. By reducing the inductive impedance, the overall performance of the system can be significantly improved. In addition, the embodiment of the present application can also reduce the longitudinal edge coefficient Dj caused by the induced current. The longitudinal edge coefficient is a parameter that describes the distribution of the induced current at the edge of the conductor. Reducing this coefficient helps to reduce energy loss and improve the efficiency of the system. By comprehensively considering the optimization of the inductive impedance and the longitudinal edge coefficient, the method provided in the embodiment of the present application successfully reduces the complex electromagnetic power, thereby improving the stability and reliability of the system.

[0098] In an embodiment of the present application, a method for eliminating the longitudinal edge effect of a DC traction system is proposed. The core of this method is to completely eliminate the longitudinal edge effect in the DC traction system. Specifically, by eliminating the longitudinal pulsating magnetic flux density and complex electromagnetic power, the two types of longitudinal edge effects that affect the DC traction system are effectively eliminated. These two types of longitudinal edge effects are respectively referred to as the first type of longitudinal edge effect and the second type of longitudinal edge effect. Through this method, the traction efficiency of the DC traction system when used as a traction tool in the field of rail transit can be significantly improved. This improvement is not only reflected in the enhancement of traction force, but also in the improvement of energy utilization efficiency and the protection of track and vehicle structures, thereby providing strong technical support for the stable operation and long-term maintenance of the rail transit system.

[0099] It should be noted that the phrases "one embodiment", "an embodiment", "an exemplary embodiment", "some embodiments", etc. mentioned in the specification indicate that the described embodiments may include certain features, structures or characteristics, but not every embodiment may include the certain features, structures or characteristics. In addition, such phrases do not necessarily refer to the same embodiment. In addition, when describing certain features, structures or characteristics in conjunction with an embodiment, it is within the knowledge of those skilled in the art to implement such features, structures or characteristics in conjunction with other embodiments, whether explicitly or not explicitly described.

[0100] It should be easily understood that “on,” “above,” and “over” in the present disclosure should be interpreted in the broadest manner, so that “on” not only means “directly on something,” but also includes the meaning of “on something” with intervening features or layers therebetween, and “above” or “over” not only includes the meaning of “above” or “over,” but also may include the meaning of “above” or “over something” with no intervening features or layers therebetween (i.e., directly on something).

[0101] In addition, spatially relative terms, such as "below," "below," "beneath," "above," "above," etc., may be used herein for ease of description to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation shown in the figures. The device may have other orientations (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0102] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for eliminating the longitudinal edge effect of a DC traction system, which is suitable for eliminating the longitudinal edge effect of a DC traction system in rail transportation, and is characterized in that: The longitudinal edge effect includes a first type of longitudinal edge effect, wherein the first type of longitudinal edge effect is the formation of longitudinal pulsating magnetic flux density; The elimination method comprises: The permeance equivalent spacing of the DC traction system is increased to reduce the longitudinal pulsating magnetic flux density.

2. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 1, characterized in that: The expression of the magnetic permeance equivalent spacing is: Among them, d is the equivalent spacing of magnetic permeance, δe is the electromagnetic air gap, Kδ1, Kδ2, Kδ3 are correction coefficients of the DC traction system, P is the number of magnetic poles, and r / lδ is the winding ratio of the DC traction system.

3. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 2, characterized in that: The Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and the Kδ1 is the equivalent electromagnetic air gap density of the DC motor, expressed as: Wherein, t is the primary tooth pitch of the DC traction system, and h1 is the slot width of the DC traction system; The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsation flux density includes: reducing the primary tooth pitch t of the DC traction system and reducing the slot width h1 to increase the permeance equivalent spacing of the DC traction system.

4. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 2, characterized in that: The Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and the Kδ2 is the intensity of the fixed slot current of the stator of the DC traction system, and the expression is: Wherein, D is the gap distance between the fixed slot and the stator; The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsation flux density includes: increasing the gap distance D between the fixed slot and the stator of the DC traction system to increase the permeance equivalent spacing of the DC traction system.

5. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 4, characterized in that: The value range of D is 2.3 mm to 2.5 mm.

6. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 2, characterized in that: The Kδ1, Kδ2, and Kδ3 are correction coefficients of the DC traction system, and the Kδ3 is an influencing parameter of the DC traction system, and the expression is: Wherein, l1 is the transverse lamination thickness of the DC traction system; The method of increasing the permeance equivalent spacing of the DC traction system to reduce the longitudinal pulsating magnetic flux density includes: reducing the transverse lamination thickness l1 to increase the permeance equivalent spacing of the DC traction system.

7. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 2, characterized in that: Also includes: The permeance equivalent spacing of the DC traction system is increased to reduce the longitudinal pulsating magnetic flux density.

8. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 1, characterized in that: The longitudinal edge effect includes a second type of longitudinal edge effect, wherein the second type of longitudinal edge effect is an increase in complex electromagnetic power; The elimination method comprises: The air gap spacing is reduced to reduce the complex electromagnetic power.

9. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 8, characterized in that: The expression of the complex electromagnetic power is: Among them, m1 is the complex amplitude of magnetic flux density, I1 is the induced eddy current, Zeo is the air gap spacing, Da is the inductive impedance, and Dj is the longitudinal edge coefficient caused by the induced current.

10. The method for eliminating the longitudinal edge effect of a DC traction system according to claim 9, characterized in that: The elimination method also includes: The inductive impedance Da and the longitudinal edge coefficient Dj caused by the induced current are reduced to reduce the complex electromagnetic power.

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