RU2739939C1 - Hybrid electromagnet for maglev system - Google Patents

Abstract

FIELD: transportation.

SUBSTANCE: invention relates to device for magnetic suspension of levitation vehicles. Hybrid electromagnet includes permanent magnets, electromagnetic coil and magnetic conductor consisting of three poles. Permanent magnets are installed opposite on both sides from magnetic conductor central pole, besides, electromagnetic coil covers magnetic conductor center pole and at least partially permanent magnets and is located between extreme poles. Magnetic conductor pole length is larger than that of permanent magnets and electromagnetic coil. Permanent magnets are located at the base of the magnetic conductor poles, and ends of the magnetic conductors protrude above the permanent magnets and the electromagnetic coil in one direction.

EFFECT: efficient powerful hybrid electromagnet.

9 cl, 1 dwg

Description

The technical field to which the invention relates

The invention relates to a magnetic suspension device for levitation vehicles, in particular, to hybrid electromagnets for a maglev system.

State of the art

For transportation of people or goods using magnetic levitation, several types of suspensions have been proposed, in which the vehicle is held without mechanical contact with the overpass (track structure) by ponderomotive forces ("magnetic cushion") generated by electromagnets or permanent magnets. A traction linear motor can accelerate a vehicle on a magnetic suspension to speeds significantly higher than the speed of conventional vehicles.

A type of magnetic suspension for a maglev vehicle (TC), classified as an electromagnetic suspension (EMF), is considered. The principle of operation of EMF is based on the attraction of an electromagnet (EM) or permanent magnet (PM) to ferromagnets. In the EMF of the vehicle, EM and PM are attracted to a ferromagnetic guide located on the track structure. In this case, a levitation gap is maintained between the ferromagnetic guide and the EMF magnets. During levitation, the weight of the vehicle is balanced by the magnetic force of the EMF. Such an equilibrium is fundamentally unstable and its maintenance requires constant active control over the value of the levitation (air) gap, the stabilization of which is provided by controlling the magnitude of the EM current using a special algorithm.

The flow of the operating current through the conductor of the electromagnet is accompanied by the release of heat, i.e. requires energy and cooling. These costs increase with increasing current, i.e. with an increase in the lifting force of the EMF. To reduce energy consumption (increase energy efficiency) of a conventional EMF (only EM without PM), a combined electromagnetic suspension (KEMP) is used, in which a PM is installed in addition to the EM. While maintaining the vehicle weight at the initial level, the force of attraction of the PM to the ferromagnetic guide of the overpass makes it possible to reduce the force generated by the EM (i.e., to reduce the EM current) by an appropriate amount, thereby reducing the EM energy consumption. In the case of maintaining the force of attraction of the EM (keeping the same current in the EM), the use of the PM allows increasing the weight of the vehicle without additional energy consumption. The change in the vehicle weight while maintaining the value of the levitation gap can be compensated for by changing the magnitude of the force of attraction of the PM to the ferromagnetic guide, as, for example, in the combined EMF patent RU2611858. To stabilize the levitation gap, the patent RU2611858 uses a pair of EMs located below and above the ferromagnetic guide.

EMF in conventional (only EM) and combined (EM and PM) design provides two functions: (1) actual suspension, i.e. the creation of a magnetic force of attraction to the ferromagnetic guide, which balances the vehicle weight at a given air gap (by setting a certain value of the operating current in the EM), and (2) active stabilization of the gap size. Both functions are performed by controlling the magnitude of the current in the EM according to a special algorithm. The control is carried out in such a way that the average value of the control current at the selected working gap provides the value of the suspension force of the EMF equal to the weight of the vehicle, and the corresponding small additive variations in the control current (relative to the average value) ensure the stability of the gap.

The value of the average current in a conventional EMF is much greater (by 1-2 orders of magnitude) than the average amplitude of the current variation. It is the magnitude of the average current that determines the high power consumption of a conventional EMF. In a combined EMF (for example, in RU2611858), levitation can be carried out with an average current value comparable in magnitude to the average amplitude of the current variation, i.e. with significantly less power consumption.

More than 20 years ago, circuits of electromagnets were proposed, into the magnetic circuit of which PMs were inserted in different ways. Such magnets are called hybrid electromagnets (HEM), and the corresponding suspensions are called hybrid EMF (HEMF). In the application of EMF for vehicles, one can expect a number of significant consumer advantages over KEMP, such as compactness (better weight and size characteristics), lower power consumption, etc. In addition, in comparison with traditional electromagnetic suspensions, hybrid electromagnetic suspensions turned out to be smaller and lighter.

The design of a hybrid electromagnet with an arrangement of a magnetic circuit, EM and PM, described in the publication Safaei, Suratgar, Afshar, and Mirsalim, 2015. F. Safaei, A.A. Suratgar, A. Afshar, and M. Mirsalim. Characteristics Optimization of the Maglev Train Hybrid Suspension System Using Genetic Algorithm. Energy Conversion, IEEE Transactions on, PP (99), 1_8, 2015, and is a bipolar HEV.

The authors of this design proposed a physically based solution to the configuration of EM and PM, built into a common magnetic circuit to obtain maximum force with minimum consumption of magnetic material and with the ability to effectively control the magnitude of the force. Based on the results of our optimization of such a design, a typical configuration with a PM was obtained, the thickness of which is comparable to the size of the air gap, and the surface area significantly exceeds the area of the pole.

The disadvantages of the configuration described in this article include:

- A significant level of magnetic induction outside its working surface (the surface of the ferromagnetic poles of the HEV facing towards the ferromagnetic guide between which there is an air gap). This poses a serious threat in terms of the possibility of adhesion of foreign magnetic objects and complicates maintenance;

- Large stray fields in the surrounding space in the absence of a ferromagnetic guide, which puts forward special requirements for their storage;

- Low efficiency of using the material of permanent magnets to generate the force of attraction to the ferromagnetic guide (low specific characteristics, such as, for example, the ratio of the force of attraction to the weight of the PM or the entire HEV).

Disclosure of invention

The problem to be achieved by the proposed device is to eliminate the above-mentioned disadvantages.

The problem of the invention is solved by means of a hybrid electromagnet, which includes permanent magnets, an electromagnetic coil and a magnetic circuit having three poles. Two permanent magnets are installed on either side of the middle pole. Their magnetization vectors are oriented oppositely. The electromagnetic coil covers the middle pole of the magnetic circuit and permanent magnets. It is located between the extreme poles.

The length of the poles of the magnetic circuit is greater than the height of the permanent magnets and the electromagnetic coil. Permanent magnets (and preferably an electromagnetic coil) are located at the base of the poles of the magnetic circuit, and the ends of the poles of the magnetic circuit protrude above the permanent magnets and the electromagnetic coil in one direction.

In one embodiment of the hybrid electromagnet, at least one pole of the magnetic circuit may contain an additional permanent magnet, the direction of which is coordinated with the direction of the permanent magnets near the middle pole of the magnetic circuit (taking into account the geometry of the magnetic circuit that changes the direction of the magnetic field). In addition, the hybrid electromagnet can contain additional electromagnetic coils, covering the extreme poles of the magnetic circuit. The magnetic circuit is preferably symmetrical about the middle pole, and the poles of the magnetic circuit are preferably parallel to one another. In addition, the poles of the magnetic circuit mainly lie in the same plane. The hybrid electromagnet may contain yokes connecting the outermost poles with permanent magnets adjacent to the middle pole or additional yokes connected to it.

The object of the invention is also solved by means of a vehicle designed to move along an overpass with a ferromagnetic rail, having a magnetic suspension using a hybrid electromagnet according to any of the above options.

The technical result of the present invention is to create an effective hybrid electromagnet for EMF, providing levitation with "zero power consumption", which, in comparison with a conventional EM, is more compact and light (i.e., with smaller dimensions / weight) while providing the same magnetic field ( force) in the levitation gap, or it can create a magnetic field of greater magnitude while maintaining the same dimensions / weight, which is another variant of the manifestation of the same technical result. Defining the specified technical result in other words, we can say that it consists in increasing the specific force of the electromagnet, i.e. the ratio of the lift force to the weight of the electromagnet at a fixed clearance.

Achievement of the technical result is due to more efficient use in the levitation gap of the magnetic flux generated by the PM in the HEV with this (W-shaped) configuration. This significantly reduces the level of stray fields and halves the number and weight of electromagnetic coils.

Due to the increased efficiency of the hybrid electromagnet in accordance with the present invention, it is possible to reduce its size compared to the hybrid electromagnets of the prior art, including prototypes. That is, the hybrid electromagnet according to the present invention becomes compact due to its efficiency. Compactness is to be understood as the reduction in size of the hybrid device over the prior art due to the increased efficiency, whereby the hybrid electromagnet of the present invention provides the same or greater magnetic field values in a smaller size than prior art devices.

Brief Description of Drawings

The figure shows a cross-sectional view of a compact hybrid electromagnet in accordance with the present invention.

Implementation of the invention

The invention will now be described with reference to the accompanying figure, which depicts a preferred embodiment of the invention. The following description and drawing are not intended to limit the scope of protection, which is defined by the claims, but are given in order to simplify the understanding of the essence of the invention and possible variants of its implementation, which are not exhausted by those presented in the figure and in the description. The invention is further described in relation to, but is not limited to, a compact hybrid electromagnet for a maglev system, that is, for a vehicle designed to travel on an overpass with ferromagnetic guides and having a magnetic suspension using a hybrid electromagnet, but is not limited to this purpose and can be used in relation to any application magnetic devices.

The description of the invention is given for a hybrid electromagnet in the orientation shown in the figure, in accordance with which the bases of the poles of the magnetic circuit (adjacent in the figure to the yokes) are located at the bottom, and the ends of the poles are at the top. However, this arrangement does not limit the scope of protection of the invention and is given only for the purpose of simplifying the explanation. In the general case, defined by the claims, the orientation of the compact electromagnet is not uniquely specified and may vary. In accordance with the change in the orientation of the electromagnet, the arrangement of its parts in space also changes.

Pole bases can be called pole ends, which are located at the base of the magnetic circuit. The difference between them and the other ends of the poles used to create a magnetic field in the gap with the ferro-rail is that the upper ends of the poles are open, free and the magnetic field from them is directed upward towards the ferro-rail, and the lower ends of the poles (that is, their bases) are interconnected by means of permanent magnets and yokes, if any, which direct the magnetic field from the base (lower end) of one pole to the base of the other pole, thereby forming, together with permanent magnets and yokes (or without the latter), the base of the magnetic circuit.

The figure shows a cross-sectional view of a hybrid electromagnet containing a collecting magnetic circuit. The magnetic circuit contains the following elements: the middle pole 1, the yoke 2 and two extreme poles 3. In addition to the magnetic circuit, the hybrid electromagnet contains permanent magnets 4 and 5 and an electromagnetic coil 6. The shown hybrid electromagnet is mainly oriented for use in the MAGLEV transport system, for which it is located under a ferromagnetic guide (rail) 10 with an equilibrium gap, which ensures the balancing of the weight of the vehicle by the ponderomotive forces of the PM and electromagnets. The ends of the poles (upper, free) are facing the rail, their bases (that is, the lower ends) are connected to the yoke.

This circuit can be represented as a combination of two two-pole HEVs into a three-pole circuit with the same clearance as in the prototype. Let us note two new positive properties manifested in such a three-pole HEV: (1) an increase in the average magnetic flux density in the gap of the middle pole of the new HEV in comparison with the two original HEV, leading to an increase in the force of attraction to the guide by more than 2 times, given that the mass a three-pole HEV is less than the mass of two two-pole HEV (the number of coils does not double when two two-pole HEV are combined into a three-pole circuit, since there is still one coil, but located not vertically, but horizontally, and in addition, the mass of the magnetic circuit is slightly less due to more optimal location of the poles); (2) the opposite inclusion of the magnetization vectors of two PMs in the GEM leads to a faster decay of the stray fields with distance from the GEM, thereby significantly improving the electromagnetic compatibility.

The magnitude of the magnetic moment of permanent magnets (the product of the specific magnetization by the volume of the magnet) determines the force generated by the hybrid magnet at the desired air gap.

The assembled magnetic circuit of the present hybrid electromagnet can also be called an W-shaped (or E-shaped) magnetic circuit containing poles 1 and 3, connected by yokes 2, and in the yokes 2 are permanent magnets 4 and 5. Since permanent magnets 4 and 5 "replace" part yoke 2, then they can be considered as elements of the W-shaped magnetic circuit, if such an extension of the definition of the magnetic circuit is used. Thus, the yokes 2 connect the extreme poles 3 with the permanent magnets 4 and 5 adjacent to the middle pole 1 (directly or through additional yokes - in the latter version, the permanent magnets can be considered connected to the middle pole using additional yokes).

In some embodiments, the prefabricated ("W-shaped") magnetic circuit may not contain yokes, which are completely replaced by permanent magnets directly connecting the respective ends of the extreme poles to the end of the middle pole. In addition, the magnetic circuit may contain additional yokes connecting the permanent magnets to the middle pole. The magnetic circuit is preferably symmetrical about the middle pole, and the poles of the magnetic circuit are preferably parallel to each other. In addition, the poles of the magnetic circuit mainly lie in the same plane. Such an arrangement of magnetic circuits in one plane can be described as being in the same plane of their ends, that is, finding in the same plane of points located at the ends of the poles, for example, on their faces, corners or planes (mainly points that are equally located at the ends of the poles).

The magnetic circuit in the considered configuration combines the magnetic fluxes of permanent magnets and an electromagnetic coil and concentrates it in the gap between the poles 1, 3 of the magnetic circuit of the hybrid electromagnet and the ferromagnetic guide 10. In this case, the combination of magnetic fluxes has a vector character - the fluxes can both be added and subtracted depending on the sign of the current in the coil.

The configuration of a hybrid magnet, consisting of yokes 2, poles 1, 3, permanent magnets 4, 5 and an electromagnetic coil 6, provides a more efficient direction of the magnetic flux in the gap, and, as a consequence, an increase in the force of attraction with an overall reduction in weight compared to prototypes.

Due to the better flux linkage of the middle pole, the lifting force, with the same volume of permanent magnets and the same total area of the poles, will be higher than in the prototype. Therefore, as well as due to the more compact arrangement of the coil, the width of the ferromagnetic guide grows more slowly than the thickness of the overpass decreases, which leads to a reduction in the cost of the overpass.

The permanent magnets 4 and 5 are preferably of the same dimensions and generate substantially the same magnetic fields. However, the magnetization vectors of these magnets are oppositely oriented, which is reflected in the fact that the permanent magnets in the figure have different reference numbers 4 and 5.

The length of the poles of the magnetic circuit, that is, the dimensions along the poles between their bases and ends (or, in other words, between the ends of each pole), must be greater than the height of the permanent magnets and the electromagnetic coil, that is, the size of the permanent magnets and the electromagnetic coil in the same direction passing along poles (in the figure - from bottom to top). This ratio of the sizes of the poles, magnets and the coil is necessary for the full concentration of the magnetic field in the poles of the magnetic circuit before it is directed into the gap with the ferro-rail and, accordingly, to increase the efficiency of the hybrid electromagnet. With such dimensions, the ends of the poles of the magnetic circuit will protrude above the permanent magnets and the electromagnetic coil, and the permanent magnets and the electromagnetic coil will be separated from the ferro-rail by a gap greater than the gap between the ferro-rail and the pole ends, as a result of which the magnetic field from the permanent magnets and the electromagnetic coil will be concentrated at the poles, and not create parasitic pickups or reduce the total magnetic field, as is the case when the permanent magnets and the electromagnetic coil are located too close to the ferro rail.

The permanent magnets and the electromagnetic coil, as shown in the figure, are located at the base of the poles of the magnetic circuit, and the free ends of the poles of the magnetic circuit (i.e. the ends of the poles opposite to those involved in the formation of the base of the magnetic circuit) protrude above the permanent magnets and the electromagnetic coil in one direction ... This arrangement of the permanent magnets (and preferably the electromagnetic coil) at the base, as well as the orientation of the free ends of the poles to one side, provides the greatest concentration of the magnetic field in the ferro rail and, therefore, maximizes the efficiency of the hybrid electromagnet.

The vehicle, in the suspensions of which hybrid electromagnets are installed, is held above the track structure with an equilibrium gap only by permanent magnets, which ensure levitation without energy consumption.

Permanent magnets 4 and 5 are installed on both sides of the middle pole 1 of the magnetic circuit in such a way that their magnetization vectors are directed oppositely. The figure shows that magnets 4 and 5 are turned towards each other by the north poles N. The magnetic fluxes from both magnets are combined in the middle pole 1. In the ferromagnetic guide 10 of the track structure, the combined magnetic flux is divided into two, each of which is then closed through the south poles S corresponding permanent magnets.

Due to the counter-installation of permanent magnets, a decrease in stray fields is ensured. Thanks to the more efficient use of solenoid coils, the weight of the hybrid electromagnet is reduced.

Hybrid electromagnetic gimbals allow in stationary conditions to levitate with virtually no energy consumption, which is called zero-power control.

The air gap, in which the force of attraction created by the permanent magnets of the hybrid magnet included in the vehicle suspension is equal to the vehicle weight is defined as the equilibrium clearance, and the corresponding suspension position is defined as the equilibrium position.

The value of the control current in the EMF during levitation of the vehicle is usually near zero with a small amplitude of variations determined by the degree of deviation from the equilibrium position. Significantly different from zero current pulses, in accordance with the control algorithm, will be briefly supplied to the coil only in cases of either a sharp change in the vehicle weight (loading or unloading), or the appearance of a significant change (jump) in the gap size (for example, at the joints of the guides, when "Takeoff" and "landing"), as a result of which the size of the gap will begin to change and take on a new stationary (equilibrium) value.

Strong Rare Earth Permanent Magnets (NdFeB) are used to provide levitation, and electromagnets are used to stabilize the levitation gap. The force generated by the PM balances the vehicle's weight at a certain equilibrium value of the air gap, which ensures vehicle levitation with minimal power consumption. When the vehicle weight changes, due to loading or unloading, the air gap between the poles of the hybrid magnet and the ferromagnetic guide ("rail") will change towards its equality with the equilibrium gap at the moment. The actively controlled EV maintains and stabilizes the equilibrium air gap, while the balance of the weight is still provided by the force generated by the PM.

The magnetic flux, which is created by the permanent magnets of the proposed hybrid magnet in the air gap between the poles of the magnetic circuit and the ferromagnetic guide, determines the force with which it is attracted to the ferromagnetic guide. The force of attraction in this case depends on the size of the air gap.

The electromagnetic coil is necessary to stabilize the equilibrium levitation gap between the poles of the hybrid electromagnet and the ferromagnetic guide when parked and in all modes of vehicle movement, including possible external short-term effects on the car itself (for example, guide irregularities, gusts of wind, movement of cargo or passengers).

The stabilization of the equilibrium gap is ensured by changing the control current in the electromagnetic coil according to a special algorithm that changes the magnitude and direction of the current. Since the system is in an unstable equilibrium position, the control current in the solenoid coil constantly fluctuates around zero values, which ensures the minimum power consumption (levitation with the so-called "zero power consumption").

The electromagnetic coil 6 is located between the extreme poles 3 of the magnetic circuit, covering the middle pole 1 of the magnetic circuit and the permanent magnets 4 and 5. The coil 6 can cover the permanent magnets completely, as shown in the figure (that is, when the permanent magnets are inside the smallest contour of the turns of the coil), or partially when part of the permanent magnets is inside the smallest contour of the coil turns, and part of the permanent magnets goes beyond the contour of the turns - for example, if the yoke 2 is made in the form of permanent magnets connected to permanent magnets 4 and 5, respectively (taking into account the alignment of the magnetization directions), or if the permanent magnets have a shape that includes the yokes 2 passing from the bottom of the coil.

In the figure, the electromagnetic coil 6 is shown in two sections, in which the current flows in opposite directions. The figure, for example, shows that in the left section the current flows from the observer, and in the right - towards the observer. The directions of the currents can also be reversed. Depending on the direction of the current in the coil, the magnetic flux generated by it is either added to the magnetic flux of permanent magnets, or subtracted. Accordingly, the magnitude of the ponderomotive force, which attracts the poles of the hybrid magnet to the ferromagnetic guide, increases or decreases. The magnitude and direction of the current in the coil depends on the current conditions and is determined by the control algorithm.

The use of powerful high-coercive permanent magnets, which create a strong permanent magnetic field, makes it possible to provide an increased load-carrying capacity of a levitating vehicle with such hybrid electromagnets with minimal energy consumption.

Due to the arrangement of the electromagnetic coil in accordance with the invention shown in the figure, only one coil is required to provide “zero power consumption” levitation, which reduces the weight of the hybrid electromagnet compared to alternatives with a different number of electromagnetic coils.

In some embodiments, additional permanent magnets can be installed in one or more poles and / or in the yoke of the W-shaped magnetic circuit, the orientation (direction) of which is coordinated with the orientation (direction) of the permanent magnets near the middle pole of the magnetic circuit (taking into account the geometry of the magnetic circuit changing the direction magnetic field). The orientation (i.e., the direction of magnetization) of the additional magnets is determined with respect to the direction of the magnetic field (i.e., the direction of magnetization) created by the permanent magnets 4 and 5 at the middle pole 1 of the magnetic circuit. The use of additional permanent magnets makes it possible to further increase the specific force of the hybrid electromagnet, since when replacing a part of the magnetic circuit with permanent magnets, the mass will not change, and the force of the magnetic field formed in the gap between the magnetic circuit and the overpass increases. The permanent magnets are preferably mounted symmetrically with respect to the middle pole to maximize the increase in the useful (i.e., directed into the gap) magnetic field.Additional permanent magnets can be installed both asymmetrically or have different magnetization values for long-term compensation of the tilt (roll) of the hybrid electromagnet relative to the ferromagnetic guide.

In addition, in some embodiments, the hybrid electromagnet may contain additional electromagnetic coils, covering the extreme poles of the magnetic circuit. This further increases the variable component of the magnetic field without increasing the height of the hybrid electromagnet. The additional coils can be supplied with different currents to create angular momentum in order to compensate for the tilt (roll) of the hybrid electromagnet relative to the ferromagnetic guide.

A hybrid electromagnet can also be called a compact hybrid electromagnet, a hybrid magnet or a compact hybrid magnet, a magnetic device, or a compact magnetic device. Each of these names can be supplemented with the characteristic "universal" or indicating a specific purpose. Generally, the hybrid electromagnet of the present invention is intended for use in a maglev system, that is, in a vehicle such as a train traveling along a ferromagnetic rail overpass using magnetic levitation provided by the hybrid electromagnet. At the same time, the hybrid electromagnet of the present invention can be used in other systems, devices and products, including those with other purposes.

All technical results indicated in the description, including additional ones, are achieved with the help of a hybrid electromagnet in accordance with the present invention simultaneously and inseparably from each other. The embodiment shown in the accompanying figure, as well as further detailed embodiments, are intended to facilitate an understanding of the invention and should not be construed as limiting the scope of protection of the invention as defined by the following claims. The described options can be combined and combined in any combination that ensures the implementation of the principle of operation and the achievement of the stated technical results. As a result of the combination of individual options, additional technical results can be achieved.

Claims (9)

1. Hybrid electromagnet, which includes permanent magnets, an electromagnetic coil and a magnetic circuit consisting of three poles, and the permanent magnets are installed oppositely on both sides of the middle pole of the magnetic circuit, and the electromagnetic coil covers the middle pole of the magnetic circuit and at least partially permanent magnets and is located between the extreme poles, and the length of the poles of the magnetic circuit is greater than the height of the permanent magnets and the electromagnetic coil, and the permanent magnets are located at the base of the poles of the magnetic circuit, and the ends of the poles of the magnetic circuit protrude above the permanent magnets and the electromagnetic coil in one direction. 2. A hybrid electromagnet according to claim 1, characterized in that at least one pole of the magnetic circuit contains an additional permanent magnet, the direction of which is coordinated with the direction of the permanent magnets near the middle pole of the magnetic circuit. 3. Hybrid electromagnet according to claim 1, characterized in that it contains additional electromagnetic coils at the extreme poles and covering them. 4. A hybrid electromagnet according to claim 1, characterized in that the magnetic circuit is symmetrical about the middle pole. 5. Hybrid electromagnet according to claim. 1, characterized in that the poles of the magnetic circuit are parallel to each other. 6. A hybrid electromagnet according to claim 1, characterized in that the poles of the magnetic circuit lie in the same plane. 7. The hybrid electromagnet of claim. 1, characterized in that it contains yokes connecting the extreme poles with permanent magnets adjacent to the middle pole. 8. Hybrid electromagnet according to claim 1, characterized in that it contains yokes connecting the extreme poles with permanent magnets connected to the middle pole by additional yokes. 9. A vehicle designed to move along an overpass with ferromagnetic guides, having a magnetic suspension using hybrid electromagnets according to any one of paragraphs. 1-8.

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