Linear motor gravity energy storage device

Abstract

The invention provides a linear motor gravity energy storage device. A lifting objective table is arranged in a vertical shaft frame, a stator is arranged on the inner side of the vertical shaft frame, a stator winding is arranged in the stator, a rotor is arranged on the objective table, and the rotor is composed of a rotor iron yoke and a permanent magnet array. A linear motor is formed between the rotor and the stator, and the objective table is driven to ascend through the linear motor during energy storage; and the energy is released, so that the objective table falls to drive the linear motor to generate power. According to the linear motor gravity energy storage device, on one hand, the dynamic permanent magnet type rotor structure form is adopted, the permanent magnet consumption can be reduced, and the permanent magnet installation cost is reduced; on the other hand, the armature winding is arranged on the stator, the problem that a power supply cable moves along with the rotor in a traditional gravity energy storage device is avoided, and the overall reliability is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of energy storage equipment, and in particular relates to a linear motor gravity energy storage device. Background Art

[0002] In mechanical energy storage, solid gravity energy storage is a new large-scale energy storage technology with great potential. Compared with other large-scale energy storage technologies, it has advantages in terms of high efficiency, longevity, flexibility and economy. At present, solid gravity energy storage can be mainly divided into two categories: slope type and vertical type. Vertical solid gravity energy storage has low dependence on the environment and terrain, and is convenient for large-scale equipment. Most existing vertical solid gravity energy storage devices use a rotating motor to connect the traction system and connect the weights through ropes. The two sides of the weights are fixed by sliding tracks, and energy storage and power generation are achieved by lifting and releasing the weights.

[0003] Yan Wenju and others from China University of Mining and Technology (Yan Wenju, Wang Yang, Sun Xinzhu, et al., Research Progress and Key Technologies of Abandoned Mine Gravity Energy Storage System Based on Linear Motors [J]. Energy Storage Science and Technology: 1-15) proposed that the use of linear motors to replace traditional winches can improve the energy conversion efficiency of solid gravity energy storage, extend service life, reduce the cost of the entire life cycle, and improve the dynamic response speed, which can further realize the coordinated operation of large-scale gravity energy storage. However, the existing linear motor gravity energy storage device based on the moving coil type has a large amount of permanent magnets and high installation costs because the shaft depth can reach hundreds to thousands of meters. On the other hand, the power supply cable must follow the mover to move up and down at a great depth. The related protection mechanism is complex and prone to fatigue damage, and the reliability is insufficient, making it difficult for this technology to be substantially popularized and applied. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a linear motor gravity energy storage device to solve the reliability problem of power supply cables.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A linear motor gravity energy storage device, comprising:

[0007] A loading platform is connected in a liftable manner in the shaft frame;

[0008] The stator is fixed on the inner side of the shaft frame and has a stator winding arranged therein;

[0009] A mover is arranged on the stage and is composed of a mover iron yoke and a permanent magnet array;

[0010] A linear motor is formed between the mover and the stator, wherein the linear motor drives the loading platform to rise when energy is stored; and when energy is released, the loading platform falls to drive the linear motor to generate electricity.

[0011] Furthermore, the linear motor is a three-sided linear motor.

[0012] Furthermore, the stator includes three columns of stator units, which are respectively fixed on three side walls of the shaft frame; each column of stator units has multiple stator modules arranged in the vertical direction, the stator module is composed of m symmetrical stator windings and stator cores, and each stator module is respectively connected to a motor driver.

[0013] Furthermore, m≥3.

[0014] Furthermore, the mover includes three mover units, which are respectively paired with the three columns of stator units; the mover unit includes a mover iron yoke and a permanent magnet array, wherein the mover iron yoke is fixed on the side wall of the stage, and the permanent magnet array is arranged on the outside of the mover iron yoke along the vertical direction.

[0015] Furthermore, the motor driver is a linear motor four-quadrant driver, and the motor drivers are connected in a common bus manner.

[0016] Furthermore, the loading platform is connected to the shaft frame via linear bearings, wherein linear bearing rollers are provided at the four corners of the loading platform, and a linear bearing track is provided on the inner side of the shaft frame.

[0017] Furthermore, a loading track is provided on the loading platform; and a displacement sensor is provided in the shaft frame to monitor the position of the mover.

[0018] Furthermore, during operation, a plurality of stator modules adjacent to the mover unit are enabled in each stator unit.

[0019] Furthermore, the mover unit and the stator module are equal in length;

[0020] When running in the energy storage state, the stator modules at the lower edge of the active unit and two positions above drive the stage to move upward;

[0021] When running in the energy release state, the stator modules at the upper edge of the active unit and the two lower positions are moved downward by the gravitational potential energy, driving the linear motor to generate electricity.

[0022] The beneficial effects of the present invention are:

[0023] (1) The present invention provides a linear motor gravity energy storage device, which, on the one hand, adopts a dynamic permanent magnet mover structure. By arranging permanent magnets on the mover, the amount of permanent magnets can be saved and the permanent magnet installation cost can be reduced. On the other hand, a stator winding is arranged on the stator, that is, by arranging the armature winding on the stator, the problem of the power supply cable moving with the mover in the traditional gravity energy storage device is avoided, thereby improving the overall reliability.

[0024] (2) The present invention adopts a three-sided linear motor, which can fully utilize the shaft space and improve the power density and energy density in a limited space.

[0025] (3) In the present invention, each side stator unit is composed of multiple stator modules arranged and spliced ​​vertically, which can realize modular design and processing, reduce design and manufacturing costs, and facilitate installation; each stator module is independently connected to a four-quadrant driver, and each stator module is individually controlled by the motor driver. According to the position information of the mover obtained by the displacement sensor, only a few stator modules around the mover unit are set in working state during the energy storage and release process. At the same time, the smooth unit switching algorithm of the relevant motor is cooperated to realize smooth control of the motor power input and output, which can improve the power factor, reduce the volume, and improve the energy conversion efficiency of the linear motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a structural diagram of the linear motor gravity energy storage device of the present invention;

[0027] Figure 2 It is the structural diagram of the moving parts in the present invention;

[0028] Figure 3 This is a structural diagram of the stator assembly in the present invention;

[0029] Figure 4 This is a schematic diagram of the common bus connection of the segmented linear motor four-quadrant driver in the present invention;

[0030] Figure 5 It is a schematic diagram of the magnetization direction of the permanent magnet in the present invention;

[0031] Figure 6 It is a control logic flow chart of the segmented linear motor four-quadrant driver in the present invention;

[0032] Figure 7 This is a schematic diagram of the stator module enabled state in an embodiment of the present application.

[0033] Reference numerals:

[0034] 1-carrying platform; 2-carrying track; 3-linear bearing roller; 4-motor iron yoke;

[0035] 5-permanent magnet array; 6-stator core; 7-stator winding; 8-motor driver;

[0036] 9-displacement sensor; 10-linear bearing track; 11-moving unit; 12-stator module;

[0037] 13-DC bus. DETAILED DESCRIPTION

[0038] Embodiments of the present invention are described in detail below, examples of the illustrated embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0039] 1. Structure

[0040] like Figure 1 The linear motor energy storage device shown includes a shaft frame with a square cross section. A loading platform 1 is arranged in the shaft frame, and the loading platform 1 can be raised and lowered along the shaft. A linear motor is arranged between the shaft frame and the loading platform 1, which is used to store energy and generate electricity (release energy) under the lifting action of the loading platform 1. The stator of the linear motor is arranged on the shaft frame, and the mover is arranged on the loading platform 1.

[0041] In this embodiment, a three-sided linear motor is specifically used, that is, three sets of corresponding mover units 11 and stator units are provided. Figure 1 and Figure 3 As shown, three columns of stator units are arranged in the shaft frame, and the three columns of stator units are respectively fixed on the three side walls in the shaft frame. Each column of stator units is arranged with n (n≥1) stator modules 12 in the vertical direction; the stator module 12 is composed of m-phase (m≥3) symmetrical stator windings 7 and stator cores 6, wherein the stator winding 7 can be wound in a distributed manner or in a centralized manner, and the conductor can be wound by multiple strands of conductors or made by laser welding of flat wire windings, and the multi-phase windings can be connected in a star shape or a polygonal shape; each stator module 12 is respectively connected to a motor driver 8, and the motor driver 8 is specifically a four-quadrant linear motor driver, which is used to realize the charging and discharging power control of the linear motor, and the motor drivers 8 are connected in a common busbar manner ( Figure 4 shown).

[0042] Reference Figure 1 and Figure 2 As shown, a mover unit 11 is provided on each of the three sides of the stage 1, respectively facing the three rows of stator units. The mover unit 11 includes a mover iron yoke 4 and a permanent magnet array 5, wherein the mover iron yoke 4 is fixed on the side wall of the stage 1, and the mover iron yoke 4 is made of stacked silicon steel sheets or processed from soft magnetic composite materials, and the permanent magnet array 5 is arranged on the outside of the mover iron yoke 4 along the vertical direction, wherein the permanent magnets can be magnetized in the opposite magnetization directions of two adjacent magnetization directions along the air gap direction ( Figure 5 (a) in the figure), or magnetized by the Halbach method ( Figure 5 In this embodiment, the length of the mover unit 11 (the dimension along the moving direction of the mover) is equal to that of a single mover module 12.

[0043] like Figure 1 and Figure 2 As shown, the stage 1 is connected to the shaft frame through linear bearings, wherein linear bearing rollers 3 are provided at the four corners of the stage 1, and linear bearing tracks 10 are provided at corresponding positions on the inner side of the shaft frame. A displacement sensor 9 is provided in the shaft frame to monitor the position of the stage 1 (i.e., the position of the mover); specifically, a laser ranging sensor can be used, and of course other forms of position or displacement sensors can also be used, as long as the function of monitoring the position of the mover is satisfied. In order to facilitate the loading of heavy objects, a loading track 2 is provided on the surface of the stage 1.

[0044] 2. Control

[0045] Reference Figure 6 and Figure 7 As shown, when the linear motor energy storage device is working, only a number of stator modules 12 adjacent to the mover unit 11 are set in the stator unit on each side and are in working state, and corresponding vector control is performed to ensure stable operation of the energy storage device and reduce unnecessary energy consumption.

[0046] The setting subunit is provided with the first to nth stator modules 12 from bottom to top;

[0047] 1) When the linear motor energy storage device operates in the energy storage state: taking the lower edge of the mover unit 11 as a judgment reference, when the lower edge of the mover unit 11 is within the range of the kth stator module 12, the kth, k+1th, and k+2th stator modules 12 are enabled, and the remaining stator modules 12 are turned off; in each of the above-mentioned enabled stator modules 12, the m-phase symmetrical stator winding 7 is passed through an m-phase sinusoidal synchronous current adapted to the moving speed of the mover, thereby generating an electromagnetic force between the stator and the mover, driving the mover and the loading platform 1 on which it is located to move upward, and converting the electrical energy into the gravitational potential energy of the heavy object;

[0048] 2) When the linear motor energy storage device operates in the energy release state: taking the upper edge of the mover unit 11 as the judgment reference, when the upper edge of the mover unit 11 is within the range of the kth stator module 12, the kth, k-1, and k-2 stator modules 12 are enabled. At this time, the stage 1 drives the mover to fall by gravity, so that the stator winding 7 in the corresponding stator module 12 cuts the magnetic flux lines generated by the permanent magnet array 5, generates an induced electromotive force, and finally converts it into electrical energy through the motor driver 8 to feed back to the power grid.

[0049] The motor driver 8 adopts a current-speed-power three-loop control method, in which the inner loop is a current loop, which is used to control the current of the linear motor's direct and quadrature axes to drive the motor to move; the middle loop is a speed loop, which controls the linear motor's movement speed; the outer loop is a power loop, which realizes the power flow of the gravity energy storage device by setting the positive and negative reference power. Between two adjacent motor drivers 8 in the vertical direction, a related smoothing unit switching algorithm is used to realize the smooth input and output of electric power.

[0050] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0051] The present invention is not limited to the above-mentioned embodiments. Any obvious improvement, substitution or deformation that can be made by those skilled in the art without departing from the essential content of the present invention belongs to the protection scope of the present invention.

Claims

1. A linear motor gravity energy storage device, characterized in that: include: A loading platform (1) is connected to the shaft frame in a liftable manner; A stator, fixed to the inner side of the shaft frame, in which a stator winding (7) is arranged; A mover is arranged on the object carrier (1) and is composed of a mover iron yoke (4) and a permanent magnet array (5); A linear motor is formed between the mover and the stator, wherein when energy is stored, the linear motor drives the loading platform (1) to rise; when energy is released, the loading platform (1) falls, driving the linear motor to generate electricity.

2. The linear motor gravity energy storage device according to claim 1, characterized in that: The linear motor is a three-sided linear motor.

3. The linear motor gravity energy storage device according to claim 2, characterized in that: The stator comprises three rows of stator units, which are respectively fixed on three side walls of the shaft frame; each row of stator units has a plurality of stator modules (12) arranged in a vertical direction, the stator module (12) is composed of m-phase symmetrical stator windings (7) and stator cores (6), and each stator module (12) is respectively connected to a motor driver (8).

4. The linear motor gravity energy storage device according to claim 3, characterized in that: m≥3。 5. The linear motor gravity energy storage device according to claim 3, characterized in that: The mover comprises three mover units (11), which are respectively matched with the three rows of stator units; the mover unit (11) comprises a mover iron yoke (4) and a permanent magnet array (5), wherein the mover iron yoke (4) is fixed on the side wall of the stage (1), and the permanent magnet array (5) is arranged on the outside of the mover iron yoke (4) in a vertical direction.

6. The linear motor gravity energy storage device according to claim 3, characterized in that: The motor driver (8) is a linear motor four-quadrant driver, and the motor drivers (8) are connected in a common bus manner.

7. The linear motor gravity energy storage device according to claim 1, characterized in that: The object carrier (1) is connected to the shaft frame via linear bearings, wherein linear bearing rollers (3) are provided at the four corners of the object carrier (1), and a linear bearing track (10) is provided on the inner side of the shaft frame.

8. The linear motor gravity energy storage device according to claim 1, characterized in that: The loading platform (1) is provided with a loading track (2); a displacement sensor (9) is provided in the shaft frame for monitoring the position of the mover.

9. The linear motor gravity energy storage device according to claim 5, characterized in that: During operation, a plurality of stator modules (12) adjacent to the mover unit (11) are enabled in each stator unit.

10. The linear motor gravity energy storage device according to claim 9, characterized in that: The mover unit (11) and the stator module (12) are of equal length; When operating in the energy storage state, the stator module (12) at the position where the lower edge of the active subunit (11) is located and at two positions above drives the loading platform (1) to move upward; When operating in the energy release state, the stator module (12) at the upper edge of the active element unit (11) and two positions below it, and the loading platform (1) move downward according to the gravitational potential energy, driving the linear motor to generate electricity.

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