Distributed winding natural electromagnetic magnetic suspension energy storage flywheel motor

Abstract

The application relates to a distributed winding natural electromagnetic magnetic suspension energy storage flywheel motor, belonging to the technical field of motors. The application is aimed at solving the problems of large volume of the magnetic suspension bearing of the existing flywheel motor and difficulty in control. The distributed winding natural electromagnetic magnetic suspension energy storage flywheel motor comprises a rotor iron core and a rotor permanent magnet, a stator iron core is divided into n sections along the axial direction, the ratio of the slot number Z of the stator iron core to the phase number m of the stator winding is an even number, each-phase stator winding comprises Zm branches, the Zm branches are averagely divided into two groups, and the branches in the two groups one-to-one correspond to each other and jointly form Z2m pairs of windings, and the two groups of branches are symmetrically arranged with the center of the stator iron core as the symmetric center.

Description

Technical Field

[0001] This invention belongs to the field of motor technology. Background Technology

[0002] Flywheel energy storage stores energy through a high-speed rotating flywheel, achieving a cyclical conversion between electrical and kinetic energy. It is a purely physical energy storage method.

[0003] The latest technological development direction for flywheel energy storage is the use of magnetic levitation technology. This allows the flywheel rotor to rotate in a fully magnetically levitated state in a vacuum environment, minimizing frictional losses, increasing energy storage density and energy conversion efficiency, and extending its service life. Compared with other energy storage technologies, magnetic levitation flywheel energy storage technology offers advantages such as high safety and reliability, long service life, high energy density, fast discharge response, high energy conversion efficiency, short construction period, no location restrictions, low operation and maintenance costs, and a green and pollution-free lifecycle. It has wide applications and huge market potential, making it an important technological development direction in the energy storage field.

[0004] Flywheel energy storage systems have high energy density and power density, low environmental requirements, and are modular. Their charging and discharging times can reach the minute level, and the depth of discharge is easy to detect. They can be applied in a wide range of situations. At the same time, flywheel energy storage has a long service life and is easy to maintain, which greatly reduces the cost of energy storage.

[0005] With the continuous development of power electronics technology, magnetic levitation technology, and new material development and research, flywheel energy storage technology has become increasingly sophisticated, and its applications have spread to transportation, distributed energy systems, power supply, military industry, aerospace, medical care, and even agriculture, making it one of the most promising energy storage technologies at present.

[0006] In flywheel energy storage systems, the shaft system is an important device for power transmission and also the main part of flywheel energy loss, affecting the stability, efficiency and lifespan of the flywheel system.

[0007] Flywheel bearing systems can be categorized into several types: mechanical bearings, contact magnetic lifting mechanical bearings, and non-contact magnetic levitation bearings. Traditional mechanical bearings experience significant frictional losses during operation, resulting in substantial energy loss during charging and discharging in flywheel energy storage systems, leading to relatively low speeds. Contact magnetic lifting mechanical bearings primarily utilize magnetic levitation technology to elevate the flywheel body, reducing the load on the mechanical bearing and thus increasing flywheel speed and extending bearing life. While contact magnetic lifting mechanical bearings employ magnetic levitation technology, they do not achieve true non-contact magnetic levitation; they are essentially still mechanical bearings, bearing weight during operation. Therefore, flywheel products using contact magnetic lifting mechanical bearings typically have lower speeds, usually less than 8000 RPM, classifying them as "low-speed" flywheels. More importantly, these bearings typically require replacement every 3-4 years, along with regular lubrication changes. This not only increases equipment replacement and labor costs but also presents challenges for on-site bearing replacement, such as space constraints, impact on surrounding equipment, and the need for extensive auxiliary equipment for disassembly, installation, and testing. In addition, the flywheel must be completely stationary before bearing replacement can be performed. Stopping, starting, and vacuuming the flywheel system can take several hours, and these extra downtime hours can cause significant losses for users.

[0008] To meet the requirements of high capacity, high power, and long operating time in flywheel systems, advanced flywheel systems must use magnetic levitation bearings to effectively eliminate mechanical friction, reduce noise, and minimize losses. However, levitizing the motor rotor is very costly; typically, the magnetic levitation bearing accounts for 60% of the volume in a magnetic levitation motor, and its controller is both expensive and complex. Magnetic levitation motors are a prohibitively expensive luxury, remaining largely unattainable. Summary of the Invention

[0009] The present invention aims to solve the problems of large volume and difficulty in control of magnetic levitation bearings in existing flywheel motors, and provides a distributed winding natural electromagnetic magnetic levitation energy storage flywheel motor.

[0010] A distributed winding natural electromagnetic levitation energy storage flywheel motor includes a coaxially nested shaft, stator, and rotor. The stator includes a stator core and stator windings, and the rotor includes a rotor core and rotor permanent magnets. The stator core is divided axially into... part, The number of slots in the stator core is a positive integer greater than or equal to 3. Number of phases of stator windings The ratio is even, and each phase stator winding includes A side road, The branch roads are divided into two groups, and the branch roads in the two groups correspond one-to-one to form a total of For the windings, the two sets of branches are arranged in a centrally symmetrical manner with the center of the stator core as the center of symmetry.

[0011] Furthermore, the aforementioned distributed winding natural electromagnetic levitation energy storage flywheel motor also includes a housing, with the shaft, stator, and rotor all located inside the housing. Each end of the shaft is connected to the housing via a bearing.

[0012] Furthermore, an elastic washer is provided between the bearing and the housing.

[0013] Furthermore, a magnet sleeve is coaxially fitted onto the outside of the rotor.

[0014] Furthermore, the material of the aforementioned magnetic sleeve is a non-magnetic metal.

[0015] Furthermore, the stator is coaxially nested outside the rotor, and the space between the stator and the outer casing is a vacuum cavity.

[0016] Furthermore, the aforementioned rotor permanent magnet is a surface-mounted permanent magnet.

[0017] Furthermore, the aforementioned rotor permanent magnet is an embedded permanent magnet.

[0018] This invention discloses a distributed winding natural electromagnetic levitation energy storage flywheel motor, which integrates radial active natural magnetic levitation technology and axial passive magnetic levitation technology to completely levitate the flywheel naturally, while also possessing excellent synchronous drive functionality. Simultaneously, the vacuum chamber is located around the outer stator of the flywheel motor, and the vacuum chamber is thick and strong. Due to natural magnetic levitation, as long as the motor rotates, the motor flywheel rotor is naturally in a levitation state, requiring no additional sensors or controllers. The natural magnetic levitation high-speed flywheel motor can achieve speeds exceeding 20,000 revolutions per minute, exhibiting natural, high reliability, and simplicity. Attached Figure Description

[0019] Figure 1 This is a diagram showing the stator winding connection structure of a distributed winding natural electromagnetic levitation energy storage flywheel motor.

[0020] Figure 2 A schematic diagram of the radial cross-section of a surface-mount magnet flywheel motor;

[0021] Figure 3 A schematic diagram of the axial cross-section of an embedded magnet flywheel motor;

[0022] Figure 4 This is a schematic diagram of the radial cross-section of an embedded magnet flywheel motor. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0024] Specific implementation method one: Refer to Figure 1 and Figure 2 This embodiment describes a distributed winding natural electromagnetic levitation energy storage flywheel motor, comprising a shaft, rotor, stator, and housing 7 coaxially nested from the inside out. The shaft, stator, and rotor are all located inside the housing 7, with a vacuum cavity between the stator and the housing. Each end of the shaft is connected to the housing via a bearing 6, and an elastic washer 8 is provided between the bearing 6 and the housing. The stator includes a stator core 1 and stator windings 2. The rotor includes a rotor core 3 and rotor permanent magnets 4.

[0025] The stator core 1 is divided into 9 segments along the axial direction to achieve greater passive magnetic levitation capability. The gaps between each segment are... , This refers to the electromagnetic air gap of the motor. When When the axial length of each segment is less than 4 to 5 times the axial length of the segment, the axial magnetic levitation stiffness is related to the number of segments. Proportional. The maximum stiffness of the axial passive magnetic levitation after segmentation is approximately: ,in This refers to the stiffness of a single-segment axial passive magnetic levitation. However, the effective axial working range of the magnetic levitation is reduced, approximately 0.95. .

[0026] The stator core 1 has 24 axial stator slots on its inner circumference. Each stator slot contains two stator poles, with each pole located in one of two adjacent slots. The stator winding 2 is three-phase. Each phase has a U, V, W three-phase winding port at its beginning and a U, V, W three-phase winding midpoint O at its end. This forms the U, V, W three-phase winding ports and the midpoint of the three-phase winding. Each phase stator winding 2 includes eight branches, which are divided into two groups. The branches in each group correspond one-to-one, forming four pairs of windings. The beginning and end points of the four pairs of windings are connected in parallel. The two groups of branches are arranged symmetrically about the center of the stator core 1.

[0027] Specifically, there is an attractive force between the stator core 1 and the rotor permanent magnet 4. Under the action of the bearing 6, the air gap between the stator and rotor remains equal, and the attractive force is equal everywhere along the circumference. The bearing 6 makes the radial attractive force in the motor air gap equal everywhere and cancels each other out. However, if the motor rotates and the bearing 6 fails, then there will inevitably be a deviation in the air gap on the same diameter on both sides of the shaft. At this time, the rotor permanent magnet 4 will be attracted to the side with the smaller air gap, and the back electromotive force of the parallel branch on the side with the smaller air gap will inevitably increase, and the current will decrease. Conversely, the back electromotive force of the parallel branch on the side with the larger air gap will decrease, and the current will increase. Thus, the radial tension on the side with the larger air gap increases, and the radial tension on the side with the smaller air gap decreases, which will inevitably cause the air gap to change in the direction of decreasing deviation and stabilize the air gap deviation. In this embodiment, the two sets of branches in each phase winding are centrally symmetrically arranged and can generate a centrally symmetrical torque couple. Therefore, after the motor rotates, it has the ability to radially and naturally magnetically levitate and restore alignment. Because this embodiment has 12 pairs of centrally symmetrical parallel branches in its three-phase windings, it can actively restore the motor rotor alignment from 24 directions. In the initial state when the motor is not running and not rotating, the back electromotive force is zero, and there is no radial natural magnetic levitation restoring force. The permanent magnet rotor will be randomly attracted to the side with the smaller air gap. Therefore, when the motor is not running and rotating, the permanent magnet rotor is radially unstable. In this case, bearing 6 needs to be activated. This embodiment possesses dynamic radial natural electromagnetic levitation and passive axial magnetic levitation functions using a conventional motor drive method without adding any sensors or controllers. As a permanent magnet motor, the motor of this invention naturally also has excellent four-quadrant motor control functions.

[0028] In summary, although the motor rotor in this embodiment does not have static radial electromagnetic levitation capability when it is not rotating, it only has axial passive magnetic levitation capability. At this time, the bearing 6 can be used for radial support. Since the motor speed is zero, the bearing 6 experiences very little force. Once started, the motor's radial electromagnetic levitation immediately takes effect, giving the motor of this embodiment both dynamic radial natural electromagnetic levitation and passive axial magnetic levitation functions.

[0029] Furthermore, in this embodiment, the rotor permanent magnet 4 is a surface-mounted permanent magnet. A conductive layer and a magnetic sleeve 5 are fitted around the outer circumference of the 4-pole permanent magnet. The material of the magnetic sleeve 5 can be non-magnetic metals such as aluminum, copper, or stainless steel. This embodiment is a synchronous motor capable of induction asynchronous start, automatically entering synchronous motor operation after reaching near synchronous speed, and becoming a truly electric motor with both static and dynamic natural electromagnetic levitation.

[0030] In this embodiment, a bearing 6 is used to improve the load variation on the output shaft. The size of the bearing 6 can be smaller than that of a conventional bearing to reduce bearing friction. An elastic washer 8 is fitted around the outer circumference of the bearing 6 to provide mechanical cushioning and reduce motor vibration and noise. The bearing clearance of the bearing 6 is increased from a negative clearance to 0.1~1mm. Under the action of the restoring force of natural electromagnetic levitation, the axis of the motor output shaft remains stable. At this time, even with the bearing 6, natural electromagnetic levitation can still allow the motor rotor to rotate with minimal energy loss, resulting in minimal vibration and noise.

[0031] Specific Implementation Method Two: Refer to Figure 1 , 3 Section 4 details this embodiment, which describes a distributed winding natural electromagnetic levitation energy storage flywheel motor. It includes a shaft, rotor, stator, and housing 7, coaxially nested from the inside out. The shaft, stator, and rotor are all located inside the housing 7. Each end of the shaft is connected to the housing via a bearing 6, and an elastic washer 8 is provided between the bearing 6 and the housing. The stator includes a stator core 1 and stator windings 2. The rotor includes a rotor core 3 and rotor permanent magnets 4.

[0032] The stator core 1 is divided into 9 segments along the axial direction to achieve greater passive magnetic levitation capability. The gaps between each segment are... , This refers to the electromagnetic air gap of the motor. When When the axial length of each segment is less than 4 to 5 times the axial length of the segment, the axial magnetic levitation stiffness is related to the number of segments. Proportional. The maximum stiffness of the axial passive magnetic levitation after segmentation is approximately: ,in This refers to the stiffness of a single-segment axial passive magnetic levitation. However, the effective axial working range of the magnetic levitation is reduced, approximately 0.95. .

[0033] The stator core 1 has 24 axial stator slots on its inner circumference. Each stator slot contains two stator poles, with each pole located in one of two adjacent slots. The stator winding 2 is three-phase. Each phase has a U, V, W three-phase winding port at its beginning and a U, V, W three-phase winding midpoint O at its end. This forms the U, V, W three-phase winding ports and the midpoint of the three-phase winding. Each phase stator winding 2 includes eight branches, which are divided into two groups. The branches in each group correspond one-to-one, forming four pairs of windings. The beginning and end points of the four pairs of windings are connected in parallel. The two groups of branches are arranged symmetrically about the center of the stator core 1.

[0034] Specifically, there is an attractive force between the stator core 1 and the rotor permanent magnet 4. Under the action of the bearing 6, the air gap between the stator and rotor remains equal, and the attractive force is equal everywhere along the circumference. The bearing 6 makes the radial attractive force in the motor air gap equal everywhere and cancels each other out. However, if the motor rotates and the bearing 6 fails, then there will inevitably be a deviation in the air gap on the same diameter on both sides of the shaft. At this time, the rotor permanent magnet 4 will be attracted to the side with the smaller air gap, and the back electromotive force of the parallel branch on the side with the smaller air gap will inevitably increase, and the current will decrease. Conversely, the back electromotive force of the parallel branch on the side with the larger air gap will decrease, and the current will increase. Thus, the radial tension on the side with the larger air gap increases, and the radial tension on the side with the smaller air gap decreases, which will inevitably cause the air gap to change in the direction of decreasing deviation and stabilize the air gap deviation. In this embodiment, the two sets of branches in each phase winding are centrally symmetrically arranged and can generate a centrally symmetrical torque couple. Therefore, after the motor rotates, it has the ability to radially and naturally magnetically levitate and restore alignment. Because this embodiment has 12 pairs of centrally symmetrical parallel branches in its three-phase windings, it can actively restore the motor rotor alignment from 24 directions. In the initial state when the motor is not running and not rotating, the back electromotive force is zero, and there is no radial natural magnetic levitation restoring force. The permanent magnet rotor will be randomly attracted to the side with the smaller air gap. Therefore, when the motor is not running and rotating, the permanent magnet rotor is radially unstable. In this case, bearing 6 needs to be activated. This embodiment possesses dynamic radial natural electromagnetic levitation and passive axial magnetic levitation functions using a conventional motor drive method without adding any sensors or controllers. As a permanent magnet motor, the motor of this invention naturally also has excellent four-quadrant motor control functions.

[0035] In summary, although the motor rotor in this embodiment does not have static radial electromagnetic levitation capability when it is not rotating, it only has axial passive magnetic levitation capability. At this time, the bearing 6 can be used for radial support. Since the motor speed is zero, the bearing 6 experiences very little force. Once started, the motor's radial electromagnetic levitation immediately takes effect, giving the motor of this embodiment both dynamic radial natural electromagnetic levitation and passive axial magnetic levitation functions.

[0036] Furthermore, in this embodiment, the rotor permanent magnet 4 is an embedded 4-pole permanent magnet. Sixteen squirrel-cage bars are evenly distributed on the outer circumference of the rotor, and a squirrel-cage end ring is present at the axial end of the rotor, making it a motor with induction starting capability. This allows this embodiment to function as a synchronous motor with induction asynchronous starting, capable of asynchronously starting and reaching near synchronous speed before automatically entering synchronous motor operation, and thus becoming a motor with both static and dynamic natural electromagnetic levitation.

[0037] In this embodiment, a bearing 6 is used to improve the load variation on the output shaft. The size of the bearing 6 can be smaller than that of a conventional bearing to reduce bearing friction. An elastic washer 8 is fitted around the outer circumference of the bearing 6 to provide mechanical cushioning and reduce motor vibration and noise. The bearing clearance of the bearing 6 is increased from a negative clearance to 0.1~1mm. Under the action of the restoring force of natural electromagnetic levitation, the axis of the motor output shaft remains stable. At this time, even with the bearing 6, natural electromagnetic levitation can still allow the motor rotor to rotate with minimal energy loss, resulting in minimal vibration and noise.

[0038] This invention employs radial natural electromagnetic levitation technology, axial passive magnetic levitation, and bearings, completely eliminating volume, losses, and costs. All currents in the motor windings of this invention work together to naturally levitate the motor rotor, thus providing a large natural electromagnetic levitation force. This invention provides a flywheel motor levited within a vacuum chamber, with excellent four-quadrant motor control, and the natural magnetic levitation high-speed flywheel motor can achieve speeds exceeding 20,000 revolutions per minute. The vacuum chamber of this invention is located outside the outer stator of the flywheel motor, and has a large thickness and high strength. Due to natural magnetic levitation, no additional sensors or controllers are required; as long as the motor rotates, the motor flywheel rotor is naturally levited, exhibiting natural, high reliability, and simplicity. The vacuum chamber of this invention only has three motor wires inside and outside, making the interface very simple and reliable.

[0039] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A distributed winding natural electromagnetic magnetic suspension energy storage flywheel motor, comprising coaxially nested rotating shaft, stator and rotor, the stator comprising stator core (1) and stator winding (2), the rotor comprising rotor core (3) and rotor permanent magnet (4), characterized in that The stator core (1) is divided along the axial direction into part, The interval between each segment is a positive integer greater than or equal to 3. , The electromagnetic air gap of the motor, the number of slots of the stator core (1) The number of phases of the stator winding (2) The ratio is even, and each phase stator winding (2) includes A side road, The branch roads are divided into two groups, and the branch roads in the two groups correspond one-to-one to form a total of For the winding, the two sets of branches are set in a centrally symmetrical manner with the center of the stator core (1) as the center of symmetry, which can generate a centrally symmetrical torque couple. After the motor starts to rotate, it has the ability to restore centering in a radial natural magnetic levitation manner. Further comprising a shell (7), the rotating shaft, stator and rotor are located inside the shell (7), both ends of the rotating shaft are connected with the shell through a bearing (6); The stator is coaxially nested outside the rotor, and a vacuum cavity is formed between the outside of the stator and the shell (7).

2. A distributed winding natural electromagnetic maglev energy storage flywheel motor according to claim 1, characterized in that, An elastic washer (8) is arranged between the bearing (6) and the shell.

3. A distributed winding natural electromagnetic maglev energy storage flywheel motor according to claim 1 or 2, characterized in that, A magnetic steel sleeve (5) is coaxially sleeved outside the rotor.

4. A distributed winding natural electromagnetic maglev energy storage flywheel motor according to claim 3, characterized in that, The material of the magnetic steel sleeve (5) is non-magnetic metal.

5. A distributed winding natural electromagnetic maglev energy storage flywheel motor according to claim 1, characterized in that, The rotor permanent magnet (4) is a surface-mounted permanent magnet.

6. A distributed winding natural electromagnetic maglev energy storage flywheel motor according to claim 1, characterized in that, The rotor permanent magnet (4) is an embedded permanent magnet.

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