Dual three-phase linear synchronous motor for super high-speed maglev device and super high-speed maglev transportation

Abstract

This invention discloses a dual three-phase linear synchronous motor for ultra-high-speed maglev equipment and ultra-high-speed maglev transportation. The invention provides a dual three-phase linear synchronous motor for ultra-high-speed maglev equipment. The linear synchronous motor includes multiple unit motors, each unit motor comprising: a stator and a mover with excitation elements; the stator includes: a stator core and two sets of three-phase windings disposed on the stator core, the two sets of symmetrical three-phase windings constituting a dual three-phase stator winding; the phase shift angle of the two sets of three-phase windings is 60°; the pole slot configuration of the unit motor is n slots and m poles, where n / (3×m)=1, and m is not less than 2; the stator windings adopt a double-layer short-pitch structure with a span of 2 slots, enabling high-speed maglev transportation to operate smoothly at ultra-high speeds (600km / h+).

Description

Technical Field

[0001] This invention relates to the field of motors, and in particular to a dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment and ultra-high-speed magnetic levitation transportation. Background Technology

[0002] The development of 600 km / h conventional maglev equipment (such as maglev trains) has been remarkable in recent years, with long-stator linear motors being a key component supporting the operation of ultra-high-speed maglev transportation. The stator core of the linear motor in ultra-high-speed maglev transportation is installed below the track, employing a three-phase wave winding configuration. The traction converter is excited by a three-phase current to generate a traveling wave magnetic field, which interacts with the excitation magnetic field generated by the levitation electromagnets on the maglev train, forming the levitation force and traction force required for train operation. However, as train speeds increase, the back electromotive force amplitude of each phase winding of the three-phase linear motor increases, limiting the traction force output performance of the linear motor under constant voltage. Furthermore, the fault-tolerant operation capability under high-speed traction motor and converter failures is insufficient, severely restricting the safe and stable operation of ultra-high-speed maglev transportation. Summary of the Invention

[0003] The purpose of this invention is to provide a dual three-phase linear synchronous motor for ultra-high-speed maglev equipment and ultra-high-speed maglev transportation, so that ultra-high-speed maglev transportation can operate smoothly under existing high speed conditions.

[0004] To solve the above-mentioned technical problems, the embodiments of the present invention provide a dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment. The linear synchronous motor includes multiple unit motors, each unit motor including: a stator and a mover with excitation elements; the stator includes: a stator core and two sets of three-phase windings disposed on the stator core, the two sets of symmetrical three-phase windings constituting a dual three-phase stator winding; the phase shift angle of the two sets of three-phase windings is 60°; the pole slot configuration of the unit motor is n slots m poles, where n / (3×m)=1, and m is not less than 2; the stator winding adopts a double-layer short-pitch structure with a span of 2 slots.

[0005] In one embodiment, the first set of three-phase windings includes three phases A, B, and C, and the second set of three-phase windings includes three phases D, E, and F. Based on the upper coil edge of the stator slot of the unit motor, the first and seventh slots are assigned to the A-phase winding, the third and ninth slots are assigned to the B-phase winding, the fifth and eleventh slots are assigned to the C-phase winding, the second and eighth slots are assigned to the D-phase winding, the fourth and tenth slots are assigned to the E-phase winding, and the sixth and twelfth slots are assigned to the F-phase winding.

[0006] In one embodiment, the unit motor has a twelve-slot, four-pole configuration.

[0007] In one embodiment, the specific coil connection path of the first set of three-phase windings within a unit motor is as follows: Phase A winding includes two first coils A connected in series, one first coil A is formed by the upper coil side of the first slot and the lower coil side of the third slot, and the other first coil A is formed by the upper coil side of the seventh slot and the lower coil side of the ninth slot; Phase B winding includes two first coils B connected in series, one first coil B is formed by the upper coil side of the third slot and the lower coil side of the fifth slot, and the other first coil B is formed by the upper coil side of the ninth slot and the lower coil side of the eleventh slot; Phase C winding includes two first coils C connected in series, one first coil C is formed by the upper coil side of the fifth slot and the lower coil side of the seventh slot, and the other first coil C is formed by the upper coil side of the eleventh slot and the lower coil side of the first slot of the adjacent unit motor.

[0008] In one embodiment, the specific coil connection path of the second set of three-phase windings within a unit motor is as follows: the D-phase winding includes two second coils D, one second coil D is formed by the upper coil side of the second slot and the lower coil side of the fourth slot, and the other second coil D is formed by the upper coil side of the eighth slot and the lower coil side of the tenth slot, and the two second coils D are connected in series; the E-phase winding includes two second coils E, one second coil E is formed by the upper coil side of the fourth slot and the lower coil side of the sixth slot, and the other second coil E is formed by the upper coil side of the tenth slot and the lower coil side of the twelfth slot, and the two second coils E are connected in series; the F-phase winding includes two second coils F, one second coil F is formed by the upper coil side of the sixth slot and the lower coil side of the eighth slot, and the other second coil F is formed by the upper coil side of the twelfth slot and the lower coil side of the second slot of the adjacent unit motor, and the two second coils F are connected in series.

[0009] In one embodiment, the long stator of the linear synchronous motor is formed by connecting multiple unit motors longitudinally end to end; at any junction of the Nth unit motor and the N+1th unit motor, the tail end of the second coil in the Nth unit motor of each phase winding A, B, C, D, E, and F is connected in series with the head end of the first coil of the corresponding phase in the N+1th unit motor.

[0010] In one embodiment, the tail ends of the first set of three-phase windings are connected to form a first independent neutral point, and the tail ends of the second set of three-phase windings are connected to form a second independent neutral point. The first independent neutral point and the second independent neutral point are electrically isolated from each other and are not connected together.

[0011] In one embodiment, the stator core has two layers of coils stacked along the depth of the slot, and the inner wall of the slot is adapted to the shape of the two layers of coils stacked therein.

[0012] In one embodiment, there is a gap between the coil located in the slot of the stator core and the slot opening.

[0013] The present invention provides a high-speed magnetic levitation transportation system, comprising: a high-speed magnetic levitation device, and a dual three-phase linear synchronous motor as described in any of the above embodiments; the linear synchronous motor comprises a plurality of unit motors, each unit motor comprising: a stator and a mover, the mover being mounted on the high-speed magnetic levitation device.

[0014] Compared to existing technologies, the embodiments of this invention, particularly the novel 60-degree phase-shift dual three-phase short-pitch electrically excited linear synchronous motor for high-speed maglev, reduce the amplitude of the no-load back electromotive force, improve the fluctuation of cogging traction force, and reduce the current amplitude per phase required for the same traction force output, thus providing fault-tolerant operation capability for high-speed maglev traction systems. Simultaneously, it maintains thrust and levitation performance and efficiency levels comparable to benchmark solutions, without requiring modifications to the existing mover structure. This provides a traction motor solution for high-speed maglev transportation that combines high performance, high reliability, and high engineering feasibility. Attached Figure Description

[0015] One or more embodiments are illustrated by way of example with reference numerals in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0016] Figure 1 This is a schematic diagram of the lower stator winding configuration of a unit motor of a dual three-phase linear synchronous motor according to an embodiment of the present invention; Figure 2 This is a phasor diagram of the lower stator winding of a unit motor of a dual three-phase linear synchronous motor according to an embodiment of the present invention; Figure 3 This is a comparison diagram of the cogging thrust waveforms of a dual three-phase linear synchronous motor and a conventional three-phase electrically excited linear synchronous motor according to an embodiment of the present invention, wherein... Figure 3 (a) is the cogging thrust waveform of the motor proposed in this invention. Figure 3 (b) is the cogging thrust waveform of a traditional three-phase electrically excited linear synchronous motor; Figure 4 This is a comparison diagram of the no-load back electromotive force waveforms of a dual three-phase linear synchronous motor and a conventional three-phase electrically excited linear synchronous motor according to an embodiment of the present invention, wherein... Figure 4 (a) is the no-load back electromotive force waveform of the motor proposed in this invention. Figure 4 (b) is the no-load back electromotive force waveform of a traditional three-phase electrically excited linear synchronous motor; Figure 5 This is a comparison diagram of the stator current waveforms of a dual three-phase linear synchronous motor and a conventional three-phase electrically excited linear synchronous motor according to an embodiment of the present invention, wherein... Figure 5 (a) is the stator current waveform of the motor proposed in this invention. Figure 5 (b) is the stator current waveform of a traditional three-phase electrically excited linear synchronous motor; Figure 6 This is a comparison diagram of the electromagnetic thrust waveforms of a dual three-phase linear synchronous motor and a conventional three-phase electrically excited linear synchronous motor according to an embodiment of the present invention. Figure 6 (a) is the electromagnetic thrust waveform of the motor proposed in this invention. Figure 6 (b) is the electromagnetic thrust waveform of a traditional three-phase electrically excited linear synchronous motor; Figure 7 This is a comparison diagram of the load-bearing back electromotive force waveforms of a dual three-phase linear synchronous motor and a conventional three-phase electrically excited linear synchronous motor according to an embodiment of the present invention. Figure 7 (a) is the waveform of the back electromotive force of the motor under load proposed in this invention. Figure 7 (b) is the load-bearing back electromotive force waveform of a traditional three-phase electrically excited linear synchronous motor; Figure 8 This is a comparison chart of the load-bearing back electromotive force (THD) analysis of a dual three-phase linear synchronous motor and a conventional three-phase electrically excited linear synchronous motor according to an embodiment of the present invention. Figure 8 (a) is the load-bearing back electromotive force (THD) analysis of the motor proposed in this invention. Figure 8 (b) is the load-bearing back electromotive force (THD) analysis of a traditional three-phase electrically excited linear synchronous motor; Figure 9 This is a comparison diagram of the no-load back EMF fundamental wave amplitude of five types of linear synchronous motors according to an embodiment of the present invention; Figure 10 This is a comparison diagram of the thrust of five types of linear synchronous motors according to an embodiment of the present invention; Figure 11 This is a comparison diagram of the levitation forces of five types of linear synchronous motors according to an embodiment of the present invention; Figure 12 This is a partial structural schematic diagram of the stator core of a unit motor of a dual three-phase linear synchronous motor according to an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been presented in the various embodiments of the present invention to enable the reader to better understand this application. However, the technical solutions claimed in this application can be implemented even without these technical details and various changes and modifications based on the following embodiments.

[0018] In the following description, certain specific details are set forth for the purpose of illustrating various disclosed embodiments in order to provide a thorough understanding of the various disclosed embodiments. However, those skilled in the art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known apparatuses, structures, and techniques associated with this application may not have been shown or described in detail to avoid unnecessarily obscuring the description of the embodiments.

[0019] Unless the context requires otherwise, throughout the specification and claims, the word “comprising” and its variations, such as “including” and “having”, shall be understood to have an open, inclusive meaning, that is, to be interpreted as “including, but not limited to”.

[0020] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings to provide a clearer understanding of the purpose, features, and advantages of the present invention. It should be understood that the embodiments shown in the drawings are not intended to limit the scope of the present invention, but are merely illustrative of the essential spirit of the technical solution of the present invention.

[0021] Throughout this specification, references to "an embodiment" or "an embodiment" indicate that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Therefore, the appearance of "in an embodiment" or "an embodiment" in various places throughout the specification does not necessarily refer to the same embodiment. Furthermore, a particular feature, structure, or characteristic may be combined in any manner in one or more embodiments.

[0022] The singular forms “a” and “the” used in this specification and the appended claims include plural references unless otherwise expressly stated herein. It should be noted that the term “or” is generally used to mean “and / or” unless otherwise expressly stated herein.

[0023] In the following description, in order to clearly demonstrate the structure and working method of the present invention, a number of directional terms will be used. However, terms such as "front", "back", "left", "right", "outside", "inside", "outward", "inward", "up", and "down" should be understood as convenient terms and not as limiting terms.

[0024] Embodiments of the present invention are described below with reference to the accompanying drawings.

[0025] The first embodiment of the present invention relates to a dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment. The dual three-phase linear synchronous motor comprises multiple unit motors, each unit motor including a stator and a mover with excitation elements. The stator includes a stator core and two sets of three-phase windings disposed on the stator core, the two sets of symmetrical three-phase windings constituting a dual three-phase stator winding. Each unit motor includes a stator and a mover, at least one of which is a magnet; generally, electromagnets are used in high-speed magnetic levitation vehicles, but permanent magnets can also be used in practice. The phase shift angle between the two sets of windings of the unit motor is 60°. The pole slot configuration of the unit motor is n slots and m poles, where n / (3×m)=1, and m is not less than 2. The stator winding adopts a double-layer short-pitch structure with a span of 2 slots. In this embodiment, a twelve-slot, four-pole configuration with a span of 2 slots is used as an example, and the speed is increased from 430 km / h to 600 km / h. In other embodiments, the speed is not limited to 600 km / h and may be other speeds. This embodiment is only intended to demonstrate that the speed-up maglev transportation can achieve stable movement with minimal engineering improvements and reduce costs.

[0026] Maglev trains consist of a moving train connected to a stator on the track. The moving train propels the train along the stator. Current development trends necessitate increasing the operating speed from 430 km / h to 600 km / h. However, existing three-phase linear motor traction systems suffer from high back electromotive force amplitudes in each phase winding, limiting the traction output performance of the linear motor at high speeds. Furthermore, the fault-tolerant operation capability under traction motor and converter failures is insufficient, severely hindering the safe and stable operation of high-speed maglev transportation. In contrast, dual three-phase motors, due to their low torque ripple, dispersed power per phase, and high fault redundancy, are widely used in high-power transportation applications such as electric vehicles, ships, and electric multi-electric aircraft. Compared to three-phase motors, dual three-phase motors have two sets of three-phase windings, resulting in lower stator power requirements per phase, higher transformer safety, superior traction output performance at high speeds, higher control redundancy in the traction system, and fault-tolerant operation under fault conditions, leading to higher reliability. This invention addresses this by setting two sets of three-phase windings with a 60° spatial phase shift, creating electrically independent power channels between the two sets. When one set of three-phase windings or its corresponding converter fails, another healthy set of three-phase windings can operate independently, continuing to provide derating but continuously usable traction to the train. This fault tolerance capability is particularly critical for high-speed maglev transportation systems operating at 600 km / h—at high speeds, a complete loss of traction power would have serious consequences, while the fault-tolerant design of this invention allows the train to continue operating to a safe stopping point or maintenance depot even when a single winding fails, significantly improving the safety and reliability of the system.

[0027] By employing a double-layer short-pitch structure with a two-slot span, the electrical angle between the two effective sides of each phase winding coil is shortened from the full-pitch 180° to 120°. According to motor design theory, the short-pitch factor is sin(2 / 3×90°)=0.866, meaning the fundamental flux linkage through the coil is reduced by approximately 13.4%. Combined with the double three-phase windings, the back EMF amplitude of each three-phase winding decreases under no-load conditions at 600km / h. This reduction in back EMF directly alleviates the withstand voltage requirements of the traction converter, reduces the selection difficulty of power switching devices (such as IGBTs), and lowers system insulation costs, which has significant engineering value for high-speed maglev transportation systems operating at 600km / h. Through the synergistic effect of the 60-degree phase-shifted double three-phase windings and the two-slot short-pitch structure, effective suppression of major spatial harmonics is achieved. A 60-degree phase shift causes the 5th harmonic (phase difference 5 × 60° = 300°, equivalent to -60°) and 7th harmonic (phase difference 7 × 60° = 420°, equivalent to 60°) generated by the two windings to cancel each other out during synthesis. Simultaneously, the short-pitch structure with a span of 2 slots weakens tooth harmonics (such as the 11th and 13th harmonics). These two harmonic suppression methods cover harmonic components in different frequency bands, forming a complementary and synergistic effect. The improvement in back EMF waveform quality brings the following beneficial effects: reduced thrust pulsation, improved train running stability; reduced additional losses, decreased motor temperature rise; reduced electromagnetic noise, improved ride comfort. By setting the pole slot configuration of the unit motor to n slots and m poles (where n / (3...)...) m) = 1, and m is not less than 2), so that the pole slots of the motor meet the integer slot condition q = 1, and the slot pitch angle is always 60° electrical angle. This configuration enables the present invention to achieve dual three-phase upgrade by changing the winding connection method without changing the existing high-speed magnetic levitation long stator core structure parameters.

[0028] High-speed maglev trains operate at extremely high speeds of 600 km / h. The higher the speed, the greater the amplitude of the back electromotive force (EMF) generated by the stator windings cutting the excitation magnetic field. This back EMF increases linearly with speed, and excessively high back EMF restricts the DC bus voltage level of the traction converter. The conventional approach to this problem in existing technologies is "high speed, high voltage; to reduce speed, improve hardware," i.e., using power devices with higher voltage ratings and improving insulation levels to "passively adapt" to the rising back EMF. This design approach ignores the possibility of "actively reducing back EMF through electromagnetic design." Compared to existing technologies where those skilled in the art are constrained by conventional thinking and have long focused on how to withstand back EMF through hardware upgrades rather than considering how to actively reduce back EMF by addressing the motor's winding structure, generally believing that modifications to the stator core and levitation electromagnets are necessary, this invention avoids the enormous engineering cost of remanufacturing the entire stator core, significantly reducing manufacturing costs and construction time, and possessing outstanding engineering practicality and economic efficiency.

[0029] Specifically, each stator core segment is considered a unit motor, with each segment measuring 1032mm in length. The slot pitch of the linear synchronous motor stator core is 86mm, and the pole pitch of the mover levitation electromagnet is 266.5mm, thus determining the stator pole pitch to be 258mm. The unit motor has a twelve-slot, four-pole configuration. From a theoretical perspective, the matching relationship between the stator pole pitch of 258mm and the mover pole pitch of 266.5mm is based on the following considerations: During the operation of the maglev train, the stator armature magnetic field and the mover excitation magnetic field need to remain synchronized, and the matching of the stator and mover pole pitch directly determines the smoothness of the traction output. The twelve-slot, four-pole configuration results in q=1 slot per pole per phase, with a slot pitch angle of 60 electrical degrees, providing a structural foundation for the subsequent implementation of a 60-degree phase-shifted double three-phase winding. Based on existing high-speed maglev scenarios, the stator core and excitation components do not require major engineering modifications; only the coil winding needs to be changed, reducing the difficulty of the manufacturing process. It should be noted that in other alternative embodiments, the pole and slot configuration of the unit motor can also be other configurations that satisfy n slots and m poles, where n / (3×m)=1 and m is not less than 2, such as a 24-slot, 8-pole configuration. When using a 24-slot, 8-pole configuration, each unit motor contains 24 slots and 8 poles, also satisfying the integer slot condition q=1, and the slot pitch angle is also 60 electrical degrees, thus enabling the same 60-degree phase shift double three-phase short-pitch winding. That is, when the transport capacity needs to be increased, the transport capacity mover length and stator length can be doubled, making it applicable to new transportation lines. The winding connection method of this alternative scheme follows the same phase band allocation rule as the 12-slot, 4-pole configuration. Other pole and slot combinations will not be specifically described here.

[0030] Furthermore, the first set of three-phase windings includes phases A, B, and C, and the second set of three-phase windings includes phases D, E, and F. The two sets of three-phase stator windings have a 60-degree electrical phase shift in space. For example... Figure 2 As shown, Figure 2 The stator winding phasor diagram for a single-unit motor is shown below. The phase shift angle of the two symmetrical three-phase windings is 60 degrees. In principle, the 60-degree electrical angle phase shift design is based on harmonic cancellation theory: the 5th and 7th spatial harmonics in a dual three-phase motor are the main factors causing thrust pulsation. When the two windings are 60 electrical degrees out of phase, the phase of the 5th harmonic in the second winding changes by 5 × 60° = 300° (equivalent to -60°) relative to the first winding, and the phase of the 7th harmonic changes by 7 × 60° = 420° (equivalent to 60°). Both are in opposite or nearly opposite phase to their corresponding harmonics in the first winding, thus achieving mutual cancellation. This principle is consistent with... Figure 2 The phasor diagram shown corresponds to the geometric relationship of the two sets of windings spatially misaligned by 60 degrees. For example... Figure 1 As shown, each slot has a corresponding serial number from 1 to 12. The first slot corresponds to serial number 1, the second slot to serial number 2, and so on up to the twelfth slot, which corresponds to serial number 12. Taking the upper coil edge of the stator slot of the unit motor as a reference, the first and seventh slots are assigned to the A-phase winding, the third and ninth slots to the B-phase winding, the fifth and eleventh slots to the C-phase winding, the second and eighth slots to the D-phase winding, the fourth and tenth slots to the E-phase winding, and the sixth and twelfth slots to the F-phase winding. That is, slot vector 1 / 7 is assigned to the A-phase winding, slot vector 3 / 9 to the B-phase winding, slot vector 5 / 11 to the C-phase winding, slot vector 2 / 8 to the D-phase winding, slot vector 4 / 10 to the E-phase winding, and slot vector 6 / 12 to the F-phase winding. Compared to a full-span (3-slot) design, a 2-slot span results in a fundamental short-pitch coefficient of sin(2 / 3 × 90°) = 0.866, meaning the fundamental flux linkage is reduced by approximately 13.4%, effectively lowering the back electromotive force amplitude. This principle is applied in… Figure 4The no-load back EMF comparison verified that the no-load back EMF amplitude of the motor of this invention is 179.2V, which is 11.6% lower than the 202.7V of the traditional three-phase motor. Meanwhile, the attenuation coefficient of the short-pitch factor for the 5th harmonic is sin(5×60°)=sin300°=-0.866, and the attenuation coefficient for the 7th harmonic is sin(7×60°)=sin420°=0.866. Although the short pitch itself has limited attenuation of the 5th and 7th harmonics, it forms a synergistic effect with the harmonic cancellation effect of the 60-degree phase shift of the dual three-phase motor, resulting in a significant reduction in the total harmonic distortion rate. From a technical implementation perspective, the double-layer short-pitch structure allows each stator slot to accommodate the upper and lower layers of coils from different phase windings, achieving the physical arrangement of two sets of three-phase windings within the limited space of 12 slots, avoiding the need to increase the number of slots. From the perspective of its effects, the short-pitch structure configuration directly leads to a decrease in the amplitude of the back electromotive force, while weakening higher harmonics and improving the waveform quality of the back electromotive force.

[0031] In one embodiment, the stator core slot has two layers of coils stacked along the slot depth direction, and the inner wall surface 101 of the slot is adapted to the shape of the two layers of coils stacked therein, such as the inner wall surface 101 of the slot being gourd-shaped as shown in the figure. Figure 12 As shown, the slot opening is large enough to accommodate the coil insertion, and the inner wall surface 101 is arc-shaped, but the curvature of the arc surface can be set according to actual conditions. This slot design improves the utilization rate of the slot surface, is beneficial for coil fixation and heat dissipation, and can improve the operational reliability of the motor. Understandably, in other embodiments, the slot opening may be provided with a connector that can be movably connected to the stator core, and the coil is held in the slot by the connector.

[0032] In another embodiment, the coil located in the slot of the stator core has a gap between it and the slot opening, that is, the coil is buried in the slot and the slot opening is not exposed, thereby reducing AC loss.

[0033] Furthermore, such as Figure 1As shown, each slot has a corresponding serial number from 1 to 12. The first slot corresponds to serial number 1, the second slot to serial number 2, and so on up to the twelfth slot, which corresponds to serial number 12. The specific coil connection path of the first set of three-phase windings in a unit motor is as follows: Phase A winding includes two first coils A connected in series. One first coil A is formed by the upper coil side of the first slot and the lower coil side of the third slot, and the other first coil A is formed by the upper coil side of the seventh slot and the lower coil side of the ninth slot; Phase B winding includes two first coils B connected in series. One first coil B is formed by the upper coil side of the third slot and the lower coil side of the fifth slot, and the other first coil B is formed by the upper coil side of the ninth slot and the lower coil side of the eleventh slot; Phase C winding includes two first coils C connected in series. One first coil C is formed by the upper coil side of the fifth slot and the lower coil side of the seventh slot, and the other first coil C is formed by the upper coil side of the eleventh slot and the lower coil side of the first slot of the adjacent unit motor.

[0034] In addition, the specific coil connection path of the second set of three-phase windings in a unit motor is as follows: the D-phase winding contains two second coils D, one second coil D is formed by the upper coil side of the second slot and the lower coil side of the fourth slot, and the other second coil D is formed by the upper coil side of the eighth slot and the lower coil side of the tenth slot. The two second coils D are connected in series. The E-phase winding contains two second coils E, one second coil E is formed by the upper coil side of the fourth slot and the lower coil side of the sixth slot, and the other second coil E is formed by the upper coil side of the tenth slot and the lower coil side of the twelfth slot. The two second coils E are connected in series. The F-phase winding contains two second coils F, one second coil F is formed by the upper coil side of the sixth slot and the lower coil side of the eighth slot, and the other second coil F is formed by the upper coil side of the twelfth slot and the lower coil side of the second slot of the adjacent unit motor. The two second coils F are connected in series.

[0035] The core of the above coil connection path lies in the fact that each phase winding contains two coils, which are spatially separated by six slots. Since the slot pitch angle is 60 electrical degrees, and six slots correspond to 360 electrical degrees, the electromotive forces (EMFs) of the two coils are completely phased, achieving arithmetic superposition of EMFs after being connected in series. Taking phase A as an example... Figure 1As shown, the first coil A consists of the upper layer of slot 1 (first slot) and the lower layer of slot 3 (third slot), while the second coil A consists of the upper layer of slot 7 (seventh slot) and the lower layer of slot 9 (ninth slot). Slots 1 (first slot) and 7 (seventh slot) are separated by 6 slot positions, or 360 electrical degrees, ensuring that the electromotive forces (EMFs) of the two coils are in phase. Simultaneously, the span of each coil is 2 slots (e.g., from the upper layer of slot 1 to the lower layer of slot 3), achieving a short-pitch structure. In principle, this series connection method, where "coils in phase differ by one pole pitch," ensures that the EMFs within each phase winding are superimposed rather than canceled. The short-pitch structure with a 2-slot span results in a distance of 2 slot positions (120 electrical degrees) between the two effective sides of each coil, instead of the full-pitch 3 slot positions (180 electrical degrees), thus reducing the magnetic flux through the coils. From an effectiveness perspective, this coil connection path results in the total number of turns in each phase winding being the sum of the turns of the two coils. This achieves a short-pitch effect while maintaining a suitable number of turns, providing a structural basis for reducing the back electromotive force amplitude. It should be noted that in the above embodiment of the coil connection path, the number of turns of the first coil A and the second coil A can be the same or different; those skilled in the art can adjust this according to actual electromagnetic performance requirements.

[0036] The long stator of the linear synchronous motor is formed by mechanically splicing multiple unit motors longitudinally end-to-end. At any junction between the Nth and N+1th unit motors, the tail end of the second coil in the Nth unit motor of each phase winding (A, B, C, D, E, F) is connected in series with the head end of the first coil of the corresponding phase in the N+1th unit motor. This cross-unit connection method ensures the continuity and synchronization of the armature magnetic field along the entire long stator, preventing phase jumps or amplitude abrupt changes in the armature magnetic field when the maglev train passes through the unit motor junctions, thus guaranteeing continuous traction output. The winding ends of each unit motor are prefabricated in the factory, requiring only the connection of the corresponding phase leads during on-site splicing, making construction convenient and quick. This splicing method allows the length of the long stator to be flexibly extended according to actual line requirements, without being limited by the length of a single core section, providing high engineering flexibility.

[0037] Furthermore, the tail ends of the first set of three-phase windings are connected to form a first independent neutral point, and the tail ends of the second set of three-phase windings are connected to form a second independent neutral point. The first and second independent neutral points are electrically isolated from each other and not connected together. This neutral point isolation ensures that the two sets of three-phase windings are completely electrically independent. When one set of windings or its corresponding converter fails, the other set of windings can operate independently, providing derating thrust output to the train. The isolated neutral point prevents zero-sequence current from forming a circulating current path between the two sets of windings, reducing additional losses. Simultaneously, the two sets of windings can be powered by two independent converters respectively, or by a multi-bridge converter sharing a DC bus. This design provides fault-tolerant operation capability for the high-speed maglev traction system. When one set of three-phase windings or its converter fails, the other set of three-phase windings can continue to operate, maintaining the train's basic traction output and preventing the train from completely losing power.

[0038] Using a three-phase electrically excited linear synchronous motor as a comparison, the electromagnetic performance of the two motors was compared and verified using AnsysMaxwell 2D finite element simulation at a speed of 600 km / h. Figure 3 (a) is the cogging thrust waveform of the motor proposed in this invention. Figure 3 Figure (b) shows the cogging thrust waveform of a traditional three-phase linear synchronous motor. As can be seen from the figure, the cogging torque RMS of the proposed high-speed maglev dual-three-phase linear synchronous motor with a 60-degree phase shift is 11.06 N, while the cogging torque RMS of the three-phase linear synchronous motor is 11.53 N. The proposed motor has a smaller cogging torque. The reduction in cogging torque stems from the cancellation effect of the dual-three-phase 60-degree phase shift structure on cogging harmonics; the cogging torque components of the two windings partially cancel each other out during synthesis. A smaller cogging torque means less thrust fluctuation during low-speed operation, which is beneficial for the smooth start-stop and precise position control of the maglev train.

[0039] like Figure 4 (a) is the no-load back electromotive force waveform of the motor proposed in this invention. Figure 4 (b) shows the no-load back EMF waveform of a traditional three-phase electrically excited linear synchronous motor. The proposed motor has a no-load back EMF amplitude of 179.2V, which is 11.6% lower than the 202.7V amplitude of the three-phase motor. The reduction in no-load back EMF is due to the short-pitch structure reducing the flux linkage through the coil, with the fundamental flux linkage reduced by approximately 13.4% (short-pitch factor 0.866). From an effectiveness perspective, a lower no-load back EMF means that, under the same DC bus voltage, the motor can achieve a higher operating speed, or the converter's withstand voltage rating can be reduced, thereby lowering system costs and insulation requirements.

[0040] At a speed of 600 km / h, the operating condition is set to output the average electromagnetic thrust. The stator current waveform comparison diagram is shown below. Figure 5As shown, Figure 5 (a) is the stator current waveform of the motor proposed in this invention. Figure 5 (b) shows the stator current waveform of a traditional three-phase electrically excited linear synchronous motor. A comparison of electromagnetic thrust waveforms is shown below. Figure 6 As shown, Figure 6 (a) is the electromagnetic thrust waveform of the motor proposed in this invention. Figure 6 (b) shows the electromagnetic thrust waveform of a traditional three-phase electrically excited linear synchronous motor. A comparison of the back electromotive force waveform under load is shown below. Figure 7 As shown, Figure 7 (a) is the waveform of the back electromotive force of the motor under load proposed in this invention. Figure 7 (b) shows the back EMF waveform of a traditional three-phase electrically excited linear synchronous motor under load. Under stator current excitation, the stator current amplitude per phase of the proposed motor is 980A, a 42.3% decrease compared to the 1698A stator current amplitude per phase of the three-phase motor. The reduction in current amplitude stems from the reduction in back EMF and the current shunting effect of the two windings: under the same thrust output demand, a lower back EMF per phase means a smaller required current amplitude; simultaneously, the two windings share the output power, reducing the current burden on each winding. A lower current amplitude means reduced current stress on the converter power devices, reduced system losses, and improved efficiency. The back EMF amplitude under load is 191V, a 12.0% decrease compared to the 217V back EMF amplitude of the three-phase motor. The total harmonic distortion (THD) analysis of the back EMF under load is as follows: Figure 8 As shown, Figure 8 (a) is the load-bearing back electromotive force (THD) analysis of the motor proposed in this invention. Figure 8 (b) shows the total harmonic distortion (THD) of the load-bearing back electromotive force (EMF) of a traditional three-phase electrically excited linear synchronous motor. The proposed motor has a load-bearing back EMF THD of 4.34%, while the THD of the three-phase motor is 6.77%, indicating a significant optimization in both the back EMF amplitude and harmonic content. The reduction in THD stems from the synergistic effect of the 60-degree phase shift in the dual three-phase system canceling out the 5th and 7th harmonics and the weakening of higher-order tooth harmonics by the short-pitch windings. A lower THD means that the back EMF waveform is closer to a sine wave, which is beneficial for improving the motor's operational stability and reducing electromagnetic noise and additional losses.

[0041] The following is a systematic horizontal comparison of the key electromagnetic performance indicators of five motors (M1 to M5) under a uniform speed of 600 km / h, including no-load back EMF, thrust characteristics, levitation force characteristics, losses, and efficiency. Figures 9-11M1 is a single-phase three-phase single-layer twelve-slot four-pole linear synchronous motor (Shanghai line reference scheme), M2 is a double-phase three-phase single-layer twenty-four-slot four-pole linear synchronous motor, M3 is a double-phase three-phase double-layer twelve-slot four-pole linear synchronous motor (span 1), M4 is the double-phase three-phase double-layer twelve-slot four-pole linear synchronous motor of the present invention (span 2), and M5 is a double-phase three-phase double-layer twelve-slot four-pole linear synchronous motor (span 3).

[0042] From the perspective of no-load back EMF, such as Figure 9 As shown, the smaller the no-load back EMF of the motor, the lower the voltage withstand requirement of the converter. M2 has the largest no-load back EMF because M2, after being optimized to achieve the same stator magnetic flux density as M1, has lower leakage flux and a larger main magnetic flux, but this results in the converter needing to withstand a higher voltage. M5, due to only changing the winding configuration and using a full-pitch coil, does not have a reduced no-load back EMF compared to M1, indicating that the full-pitch scheme is not advantageous in this regard. Short-pitch schemes reduce the magnetic flux through the coil by decreasing the armature winding coil pitch, thereby reducing the no-load back EMF, so M3 and M4 are better in this respect. However, M3 uses an ultra-short-pitch structure with a 1-slot pitch, resulting in an excessively low fundamental short-pitch coefficient, which leads to a significant decrease in thrust output capability. Therefore, M4 (2-slot pitch) is the optimal short-pitch scheme. In principle, the short-pitch factor of the 2-slot span is 0.866, and the fundamental wave loss is about 13.4%; the short-pitch factor of the 1-slot span is sin(1 / 3×90°)=0.5, and the fundamental wave loss is as high as 50%. Therefore, the 2-slot span achieves the best balance between reducing back EMF and maintaining thrust output.

[0043] From the perspective of thrust and levitation force, if only the motor itself is considered, the larger the average value of thrust and levitation force and the smaller the fluctuation, the better the motor performance. For example... Figure 10 , Figure 11 As shown, M2 has the highest average thrust and levitation force with the smallest fluctuations. This is because the structure of the M2 motor differs from the other four motors. M2 and M1 maintain the same stator magnetic flux density, resulting in a larger main magnetic flux, a larger air gap magnetic flux density, and thus greater thrust and levitation force. However, M2, due to its two sets of three-phase windings with a 30° phase shift angle, has lower 5th and 7th harmonic content in the air gap magnetic flux density. Furthermore, its narrower stator slots result in smaller magnetic flux density variations, leading to smaller fluctuations in thrust and levitation force. The other four motors have the same stator and drive structure, resulting in similar thrust and levitation force performance.

[0044] From the perspective of losses and efficiency, referring to Table 1 below, which compares the losses and efficiencies of the five types of motors, the lower the losses, the less heat the motor generates, the easier the heat dissipation, and the higher the efficiency. Due to the increased number of conductors in the slots, the cross-sectional area of ​​the armature winding conductors in motors M2 through M5 can only be reduced, resulting in larger DC copper losses than M1. Considering the skin effect, the copper losses of the five motors will increase to varying degrees, but the order of magnitude remains unchanged: from largest to smallest, M3, M2, M4, M5, and M1. Specifically, M2's increase is due to its smaller armature winding conductor cross-sectional area, while M3's is due to the larger armature winding current required to maintain thrust performance. Finally, except for M3, whose efficiency is significantly reduced, the other two-phase three-phase topologies are similar to M1. In summary, the M4, a twelve-slot four-pole double-layer winding dual three-phase linear synchronous motor with an armature winding span of two stator slots, has the best overall performance: the decrease in back EMF reduces the pressure on the converter caused by speed increase, and while maintaining the same thrust and levitation performance, it keeps losses and efficiency at a level similar to that of the M1.

[0045] Table 1. Back EMF, Losses, and Efficiency of 5 Types of Motors:

[0046] The working process of the high-speed maglev 60-degree phase-shift dual three-phase short-pitch electrically excited linear synchronous motor in this embodiment is as follows: When the maglev train starts, the traction converter supplies two sets of three-phase currents with a phase difference of 60 electrical degrees to the stator windings. The first set of three-phase windings (phases A, B, and C) and the second set of three-phase windings (phases D, E, and F) are powered by two independent three-phase converters, and the output voltage phases of the two converters are also 60 electrical degrees apart, matching the spatial phase shift angle of the two windings. After the current is supplied, each set of three-phase windings generates a traveling wave magnetic field. Since the spatial phase shift angle of the two windings is 60 electrical degrees, and the phase difference of the supplied current is also 60 electrical degrees, the two traveling wave magnetic fields are superimposed in the same direction in space, forming a traveling wave magnetic field that moves longitudinally along the long stator. This traveling wave magnetic field interacts with the excitation magnetic field generated by the levitation electromagnet on the mover, generating the traction force and levitation force required for train operation. The mechanism by which the traveling wave magnetic field generates traction on the mover is as follows: the traveling wave magnetic field moves longitudinally along the long stator at synchronous speed, and the excitation magnetic field of the mover is dragged accordingly. The magnetic pull between the two forms the traction force. Because the spatial phase shift and current phase shift of the two windings are matched, the amplitude of the synthesized traveling wave magnetic field is the superposition of the individual effects of the two windings, while the harmonic components are weakened by the cancellation effect of the 60-degree phase shift. When the train runs at a high speed of 600 km / h, the mover cuts the stator windings, generating a back electromotive force (EMF). Due to the short-pitch (2-slot span) structure of each phase winding, the magnetic flux through the coil is reduced by approximately 13.4%, and the back EMF amplitude is reduced by approximately 11.6% to 12.0% compared to a traditional three-phase motor. The reduced back EMF allows the motor to achieve higher operating speeds under the same DC bus voltage, or allows for lower DC bus voltages at the same speed. When a three-phase winding or its corresponding converter fails, because the neutral points of the two three-phase windings are isolated, the short-circuit current of the faulty winding will not affect the other winding through the neutral point. The control system can disconnect the faulty winding and continue to supply power only from another set of healthy three-phase windings, generating derated but continuously usable traction, enabling the train to continue running to the next safe stopping point or maintenance depot.

[0047] In summary, this working process achieves the following beneficial effects: First, during normal operation, the two windings work together, reducing the current per phase by approximately 42.3%, thus reducing the current stress on the converter; Second, during high-speed operation, the back EMF amplitude is reduced by approximately 12.0%, lowering the requirements on the converter's DC bus voltage; Third, the back EMF harmonic THD is reduced from 6.77% to 4.34%, improving the current waveform quality and reducing additional losses and electromagnetic noise; Fourth, during fault operation, one winding can still operate independently, providing fault-tolerant operation capability.

[0048] The second embodiment of the present invention relates to an ultra-high-speed magnetic levitation transportation system, comprising: a high-speed magnetic levitation device, and a dual three-phase linear synchronous motor as described in the above embodiment; the linear synchronous motor comprises multiple unit motors, each unit motor comprising: a stator and a mover, the mover being mounted on the high-speed magnetic levitation device.

[0049] The preferred embodiments of the present invention have been described in detail above, but it should be understood that, if necessary, aspects of the embodiments can be modified to utilize aspects, features, and concepts from various patents, applications, and publications to provide other embodiments.

[0050] In light of the detailed description above, these and other changes can be made to the embodiments. Generally, the terminology used in the claims should not be considered limited to the specific embodiments disclosed in the specification and claims, but should be understood to include all possible embodiments together with the full scope of equivalents enjoyed by these claims.

[0051] It is not difficult to see that this embodiment is a system implementation corresponding to the first embodiment, and this embodiment can be implemented in conjunction with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment, and will not be repeated here to reduce repetition. Accordingly, the relevant technical details mentioned in this embodiment can also be applied to the first embodiment.

[0052] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of the present invention.

Claims

1. A dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment, characterized in that, The linear synchronous motor includes multiple unit motors, each unit motor including: a stator and a mover with excitation elements; the stator includes: a stator core and two sets of three-phase windings disposed on the stator core, the two sets of symmetrical three-phase windings forming a double three-phase stator winding; the phase shift angle of the two sets of three-phase windings is 60°; the pole slot configuration of the unit motor is n slots m poles, where n / (3×m)=1, and m is not less than 2; the stator winding adopts a double-layer short-pitch structure with a span of 2 slots.

2. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 1, characterized in that, The first set of three-phase windings includes phases A, B, and C, and the second set of three-phase windings includes phases D, E, and F. Based on the upper coil edge of the stator slot of the unit motor, the first and seventh slots are assigned to the A-phase winding, the third and ninth slots to the B-phase winding, the fifth and eleventh slots to the C-phase winding, the second and eighth slots to the D-phase winding, the fourth and tenth slots to the E-phase winding, and the sixth and twelfth slots to the F-phase winding.

3. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 2, characterized in that, The unit motor has a twelve-slot, four-pole configuration.

4. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 3, characterized in that, The specific coil connection path of the first set of three-phase windings in a unit motor is as follows: Phase A winding includes two first coils A connected in series. One first coil A is formed by the upper coil side of the first slot and the lower coil side of the third slot, and the other first coil A is formed by the upper coil side of the seventh slot and the lower coil side of the ninth slot; Phase B winding includes two first coils B connected in series. One first coil B is formed by the upper coil side of the third slot and the lower coil side of the fifth slot, and the other first coil B is formed by the upper coil side of the ninth slot and the lower coil side of the eleventh slot; Phase C winding includes two first coils C connected in series. One first coil C is formed by the upper coil side of the fifth slot and the lower coil side of the seventh slot, and the other first coil C is formed by the upper coil side of the eleventh slot and the lower coil side of the first slot of the adjacent unit motor.

5. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 4, characterized in that, The specific coil connection path of the second set of three-phase windings in a unit motor is as follows: The D-phase winding contains two second coils D. One second coil D is formed by the upper coil side of the second slot and the lower coil side of the fourth slot, and the other second coil D is formed by the upper coil side of the eighth slot and the lower coil side of the tenth slot. The two second coils D are connected in series. The E-phase winding contains two second coils E. One second coil E is formed by the upper coil side of the fourth slot and the lower coil side of the sixth slot, and the other second coil E is formed by the upper coil side of the tenth slot and the lower coil side of the twelfth slot. The two second coils E are connected in series. The F-phase winding contains two second coils F. One second coil F is formed by the upper coil side of the sixth slot and the lower coil side of the eighth slot, and the other second coil F is formed by the upper coil side of the twelfth slot and the lower coil side of the second slot of the adjacent unit motor. The two second coils F are connected in series.

6. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 1, characterized in that, The long stator of the linear synchronous motor is formed by connecting multiple unit motors longitudinally end to end. At any junction of the Nth unit motor and the (N+1)th unit motor, the tail end of the second coil of each phase winding A, B, C, D, E, and F in the Nth unit motor is connected in series with the head end of the first coil of the corresponding phase in the (N+1)th unit motor.

7. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 1, characterized in that, The tail ends of the first set of three-phase windings are connected to form the first independent neutral point, and the tail ends of the second set of three-phase windings are connected to form the second independent neutral point. The first independent neutral point and the second independent neutral point are electrically isolated from each other and are not connected together.

8. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 1, characterized in that, The stator core has two layers of coils stacked along the depth of the slot, and the inner wall of the slot is adapted to the shape of the two layers of coils stacked therein.

9. The dual three-phase linear synchronous motor for ultra-high-speed magnetic levitation equipment according to claim 1, characterized in that, There is a gap between the coil located in the slot of the stator core and the slot opening.

10. A high-speed maglev transportation system, characterized in that, include: High-speed magnetic levitation equipment, and a dual three-phase linear synchronous motor as described in any one of claims 1-9; Each unit motor includes a stator and a mover, with the mover mounted on the high-speed magnetic levitation equipment.

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