Magnetic levitation reluctance coil gun, projectile magnetic levitation method and control system

Abstract

The application discloses a magnetic suspension magnetic resistance type coil gun, a magnetic suspension method of a projectile and a control system. The control system comprises a control circuit, a power circuit and a sensor. The control circuit controls the conduction of the coil through the power circuit based on the information collected by the sensor or the preconfigured conduction time, so that the total impulse of the centering force received by the projectile in a first area is greater than the total impulse of the side force received in a second area, and the total angular impulse of the stable torque received by the projectile in the first area is greater than the total angular impulse of the unstable torque received in the second area. The control system can be used in cooperation with other projectile launchers. The power circuit is connected to the last-stage coil. The application can suspend the projectile in the middle of the barrel, improves the shooting accuracy, reduces the requirements for the material strength and mechanical accuracy, and enables the projectile to maintain the stable posture for a period of time after being fired.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic launchers, and in particular to a method and control system for projectile magnetic levitation of a magnetoresistive coilgun, as well as a magnetically levitated magnetoresistive coilgun. Background Technology

[0002] An electromagnetic railgun is a device that uses an electromagnetic field to accelerate a projectile. It is divided into two categories: coilguns and railguns. Common coilguns include two types: induction coilguns (induction guns) and magnetoresistive coilguns (magnetoresistive guns).

[0003] For high-performance coilguns, the "radial motion" of the projectile is a topic worthy of in-depth study. Generally speaking, we want the projectile to float in the middle of the barrel, such as... Figure 1 As shown in (a), 1 represents the projectile, 5 represents the barrel wall, 6 represents the barrel axis, and 7 represents the projectile's path. The projectile is suspended in the middle of the barrel and can automatically return to the center even if it is disturbed by external forces. This requires some special operations; otherwise, the projectile will most likely stick to the barrel wall, such as... Figure 1 As shown in (b), the projectile, even if initially in the middle, will be pushed against the barrel wall by various minute disturbances. Even if it is disturbed again and detaches from the barrel wall, it will be pushed against the barrel wall again.

[0004] Induction guns, a type of coilgun, have seen some research on projectile magnetic levitation, for example...

[0005] In their paper "In-bore projectile dynamics in the linear induction launcher (LIL).1.Oscillations" (IEEE Transactions on Magnetics), Ki-Bong Kim, Zabar, Z, et al. described how the projectile in a linear induction launcher is subjected to centering (levitation) forces and propulsion forces. Due to their uneven distribution, these forces cause the projectile to rotate and translate along its axis.

[0006] Ki-Bong Kim et al., using induction guns as an example, summarized the relationship between the "accelerating force (repulsive force) and levitation force" between two ideal current loops and their relative positions in their paper "Restoring force between two noncoaxial circular coils" (IEEE Transactions on Magnetics):

[0007] The aforementioned literature indicates that for induction guns, when the distance between the center of the projectile and the center of the coil is close, the projectile can achieve magnetic levitation. However, when the distance between the projectile and the coil is greater, the electromagnetic force exerted on the projectile will cause it to come into contact with the gun barrel.

[0008] However, current research in magnetic reluctance guns mainly focuses on the "axial motion" characteristics of the projectile, such as its velocity and kinetic energy. There is little research on the "radial motion" characteristics of magnetic reluctance gun projectiles, such as whether the projectile rests against the barrel wall or floats in the middle of the barrel.

[0009] "Axial" and "radial" refer to cylindrical projectiles. For non-cylindrical projectiles, they refer to "the direction of the projectile's movement" and "the plane perpendicular to the direction of the projectile's movement."

[0010] Two typical examples of magnetic reluctance guns are as follows:

[0011] CN102278912A discloses a switched magnetoresistive multi-stage accelerating coil gun, and

[0012] CN114087919A discloses a modular multi-stage coilgun.

[0013] Documents CN102278912A and CN114087919A describe multi-stage magnetoresistive guns, and both are equipped with position sensors. For example, CN102278912A mentions "photoelectric switches", and CN114087919A mentions "a pair of coils wound in opposite directions". However, neither of them mentions projectile magnetic levitation or its implementation method.

[0014] Another common technical solution is the pure open-loop delay scheme. Unlike the two patent documents mentioned above, this scheme does not use sensors to detect the projectile's position during acceleration and deceleration; instead, a predetermined coil is activated at a predetermined time. This scheme keeps the projectile within the stable region of the magnetic field, ensuring that the relative position of the magnetic field and the projectile remains as expected even under random disturbances. This technical solution is well-known to those skilled in the art.

[0015] Furthermore, document CN104575194A discloses a method for establishing a magnetic levitation model based on an electromagnetic railgun. However, the "magnetic levitation" mentioned therein is actually "free fall motion," which is unrelated to the "magnetic levitation" described in this patent.

[0016] A small section of the book "Principles of Electromagnetic Guns" (Wang Ying and Xiao Feng, National Defense Industry Press, 1995) (Chapter 3 Coilguns, 3.1 Theoretical Basis of Coilguns, 3.1.2 A Brief Discussion on Magnetic Levitation, pp. 98-101) discusses the magnetic levitation of coilgun projectiles. However, the technical solution described involves adding an extra set of metal guide slats to the gun barrel. The projectile's motion generates eddy currents within these guide slats. These eddy currents interact with the projectile's current to generate levitation force. This requires additional facilities, increasing the cost and size of the electromagnetic gun and hindering portable design. Summary of the Invention

[0017] The purpose of this invention is to provide a method for magnetic levitation of projectiles in a reluctance electromagnetic railgun, in order to achieve magnetic levitation of projectiles without adding additional facilities, in order to address the problems mentioned above.

[0018] The technical solution adopted in this invention is as follows:

[0019] This invention provides a method for magnetic levitation of projectiles in a reluctance coilgun, the reluctance coilgun comprising at least one coil, the method comprising:

[0020] Control the current conduction time of the coil so that:

[0021] The total impulse of the centering force on the projectile in the first region is greater than the total impulse of the edge-moving force on it in the second region; and

[0022] The total angular impulse of the stabilizing moment experienced by the projectile in the first region is greater than the total angular impulse of the buckling moment experienced by the projectile in the second region.

[0023] The first region is located in a region where the magnitude of the electromagnetic force on the projectile is inversely correlated with the distance from the coil, and the second region is located in a region where the magnitude of the electromagnetic force on the projectile is positively correlated with the distance from the coil.

[0024] Furthermore, the first region is located in the region where the magnitude of the electromagnetic force on the projectile is inversely correlated with the distance from the coil, and is the region on both sides.

[0025] Furthermore, during the acceleration phase, the first region is located in the region where the magnitude of the electromagnetic force on the projectile is inversely related to the distance from the coil, and overlaps with the region where the force exerted by the coil's magnetic field on the projectile is positive.

[0026] Furthermore, during the deceleration phase, the first region is located in the region where the magnitude of the electromagnetic force on the projectile is inversely related to the distance from the coil, and overlaps with the region where the force exerted by the coil's magnetic field on the projectile is negative.

[0027] The present invention also provides a first control system for the above-mentioned projectile magnetic levitation method of a reluctance coilgun, which includes at least one sensor, a control circuit, and a power circuit, wherein the control circuit is connected to the sensor and the power circuit respectively; wherein:

[0028] The sensor is used to detect the position of the projectile;

[0029] The power circuit is used to provide pulsed power current to the coil;

[0030] The control circuit controls the power circuit to energize the coil at the corresponding time based on the position information of the projectile provided by the sensor.

[0031] Furthermore, the control circuit is configured as follows:

[0032] The control circuit is pre-configured with the expected conduction time of each coil, and the control circuit continuously receives information provided by the sensor;

[0033] During the acceleration phase, when the information provided by the sensors indicates that the expected turn-on time will result in the projectile and the current coil being closer than expected, the control circuit advances the turn-on time of the current coil; when the information provided by the sensors indicates that the expected turn-on time will result in the projectile and the current coil being farther than expected, the control circuit delays the turn-on time of the current coil.

[0034] During the deceleration phase, if the sensor information indicates that the expected turn-on time will bring the projectile and the current coil closer than expected, the control circuit will delay the turn-on time of the current coil; if the sensor information indicates that the expected turn-on time will bring the projectile and the current coil farther than expected, the control circuit will advance the turn-on time of the current coil.

[0035] Furthermore, the control circuit is configured as follows:

[0036] The control circuit is pre-configured with the conduction positions corresponding to each coil. When the information provided by the sensor shows that the positional relationship between the projectile and the current coil reaches the conduction position, or when the projectile is in the conduction position, the control circuit turns on the current coil.

[0037] The present invention also provides a second control system for the above-mentioned projectile magnetic levitation method of a reluctance coilgun, which includes a control circuit and a power circuit, wherein the control circuit is connected to the power circuit; wherein:

[0038] The power circuit is used to provide pulsed power current to the coil;

[0039] The control circuit pre-configures the expected conduction period for each coil, and conducts the current coil through the power circuit during the expected conduction period.

[0040] The present invention also provides a magnetically levitated reluctance coil gun, which includes an acceleration section and a magnetic levitation section. The acceleration section is used to accelerate the projectile, and the magnetic levitation section includes the first control system described above. Furthermore, the power circuit of the control system is connected to at least one stage coil at the outlet of the acceleration section.

[0041] The present invention also provides another magnetically levitated reluctance coil gun, which includes an acceleration section and a magnetic levitation section. The acceleration section is used to accelerate the projectile, and the magnetic levitation section includes the second control system described above. Furthermore, the power circuit of the control system is connected to at least one stage coil at the exit of the acceleration section.

[0042] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0043] 1. Improved firing accuracy. With magnetic levitation, the projectile is suspended in the middle of the barrel, resulting in significantly smaller radial random errors. Simultaneously, the absence of friction also reduces axial velocity errors.

[0044] 2. Reduced requirements for material strength. Magnetic levitation eliminates barrel wear, allowing the use of lower-strength materials for the barrel. Insulators, such as plastics, can be used to completely eliminate the effects of eddy currents and completely prevent arcing between the barrel and the coil. Furthermore, it offers advantages unique to low-strength materials; for example, some plastics are transparent, facilitating the mounting of optical sensors.

[0045] 3. Reduced requirements for mechanical precision. Magnetic levitation allows for the use of less precise mechanical components without significantly impacting shooting accuracy. Therefore, costs can be significantly reduced.

[0046] 4. Achieve "inertial stability" of the projectile. If magnetic levitation can be achieved, the disturbance to the projectile caused by the launcher itself can be largely eliminated. At this point, even without spin and tail fins, the projectile can remain stable for a long time after leaving the barrel and will not tumble. Attached Figure Description

[0047] The present invention will be described by way of example and with reference to the accompanying drawings, wherein:

[0048] Figure 1 This is a schematic diagram of four motion states of a projectile moving inside the barrel of a magnetic reluctance gun. 1(a) is the projectile magnetically levitated, 1(b) is the projectile adhering to the barrel wall, 1(c) is the projectile self-restoring stability, and 1(d) is the projectile tumbling.

[0049] Figure 2This is a schematic diagram showing the conduction of one coil at a time.

[0050] Figure 3 It corresponds to Figure 2 The example shows the relationship between the acceleration force on the projectile and the projectile's position, along with a corresponding diagram of the zones.

[0051] Figure 4 This is a schematic diagram showing the conduction of two coils at one time, along with the corresponding forces and partitions.

[0052] Figure 5 This is a hardware schematic diagram for a closed-loop system.

[0053] Figure 6 This is a physical image of the experiment in Example 5.

[0054] Figure 7 yes Figure 6 A schematic diagram showing the relationship between the current of each stage of the coil and the position of the projectile head during the experiment.

[0055] Figure 8 , Figure 9 These are the scattering diagrams of the projectiles in the non-magnetic levitation section and the magnetic levitation section, respectively.

[0056] Figure 10 The diagram shows the bullet hole (No. 8) when the bullet tumbles and the bullet hole (No. 7) when it does not tumble.

[0057] In the diagram, 1 represents the projectile, 2 represents the center of the projectile, 3 represents the coil, 4 represents the center of the coil, 5 represents the barrel wall, 6 represents the barrel axis, and 7 represents the projectile's path of motion. Detailed Implementation

[0058] All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.

[0059] Any feature disclosed in this specification (including any appended claims and abstract) may be replaced by other equivalent or similar features, unless specifically stated otherwise. That is, unless specifically stated otherwise, each feature is merely one example of a series of equivalent or similar features.

[0060] Definitions:

[0061] The neutralizing force refers to the force exerted on the projectile in the direction of the barrel axis (away from the barrel wall).

[0062] Edge force, as defined opposite to centering force, refers to the force acting on the projectile that points towards the barrel wall (away from the barrel axis).

[0063] Stabilizing torque refers to the torque that maintains the projectile in a stable state under any working condition. It is the torque that automatically appears after the projectile is disturbed and deviates from its original equilibrium state, and its direction always points to the original equilibrium position.

[0064] Instability torque, as defined opposite to stability torque, refers to the torque that changes the projectile's stable state, that is, the torque that disturbs the projectile from its original smooth state and deviates from its original equilibrium position.

[0065] Note: In this invention, the projectile's direction of motion is from the "barrel" to the "muzzle". The accelerating force acts on the projectile, pointing towards the muzzle; that is, the direction towards the muzzle is positive, and the direction towards the barrel is negative. The direction closer to the barrel is "rear", and the direction closer to the muzzle is "forward".

[0066] Example 1

[0067] This embodiment discloses a method for magnetic levitation of projectiles in a reluctance coilgun, the method comprising:

[0068] Control the conduction time of the current coil 3 so that (i.e., the conduction time corresponds to):

[0069] Condition 1: The total impulse of the centering force on projectile 1 in the first region is greater than the total impulse of the edge-moving force on it in the second region; and

[0070] Condition 2: The total angular impulse of the stabilizing torque experienced by projectile 1 in the first region is greater than the total angular impulse of the buckling torque experienced by projectile 1 in the second region.

[0071] The term "coil" here refers to all the accelerating coils that are turned on at one time. That is, the "current coil" can be a single coil 3 or multiple coils 3. When there are multiple coils 3, the magnetic field generated is the result of the superposition of the magnetic fields of these coils 3.

[0072] The so-called first region, referred to in this application as the "axial unstable region" or simply the "unstable region", is characterized as the region where the magnitude of the electromagnetic force on the projectile 1 is inversely related to its distance from the coil 3. In this region, the farther (closer) the projectile 1 is from the coil 3, the smaller (larger) the electromagnetic force it experiences.

[0073] The second region, in contrast to the first region, is referred to in this application as the "axial stability region" or simply the "stability region". It refers to the region where the magnitude of the electromagnetic force on the projectile 1 is positively correlated with the distance from the coil 3. In this region, the farther (closer) the projectile 1 is from the coil 3, the greater (smaller) the electromagnetic force it experiences.

[0074] For example, such as Figure 2The simplified case shown uses a uniform cylindrical coil 3 and a uniform cylindrical projectile 1 as an example, with the center 4 of the coil as the origin. The relationship between the accelerating force (with direction) on the projectile 1 and the position of the projectile 1 is as follows: Figure 3 As shown.

[0075] exist Figure 3 In the equation, the region where the derivative of the accelerating force with respect to the projectile's coordinates (dF / dz) is less than zero is the stable region, and conversely, the region where it is greater than zero is the unstable region.

[0076] For a single coil 3, the stable region consists of only one segment (or can be considered as two consecutive segments), located where the center of the projectile 1 and the center of the coil 4 are relatively close. Within this region, the farther (closer) the projectile 1 is from coil 3, the greater (smaller) the electromagnetic force it experiences. When a disturbance causes the projectile 1 to move closer (away) from coil 3, the electromagnetic force on the projectile 1 decreases (increases), and relatively speaking, there is a tendency for the projectile 1 to return to its original position. At this point, the axial position of the projectile 1 is stable; therefore, this region is called the stable region.

[0077] Unlike the stable region, for the case of a single coil 3, the unstable region is divided into two discontinuous segments, both located at a considerable distance between the projectile center 2 and the coil center 4. Within the unstable region, the farther (closer) the projectile 1 is from coil 3, the smaller (larger) the electromagnetic force it experiences. When a disturbance causes the projectile 1 to move closer (away) from coil 3, the electromagnetic force on the projectile 1 increases (decreases), causing it to move even closer (away) from coil 3. At this point, the axial position of the projectile 1 is unstable; it will either move further away from coil 3 until it completely escapes its influence, or it will move closer to coil 3 and eventually fall into the stable region.

[0078] From this perspective, it seems that having the projectile 1 in the stable region is more conducive to stabilizing its axial position and launching it. However, this is not conducive to achieving magnetic levitation. In fact, when the magnetic reluctance projectile 1 is in the unstable region of the magnetic field, although its axial position is unstable, its radial position tends to be stably suspended at the center of the magnetic field. Therefore, the key design point of this invention is to control the conduction time of the coil 3 so that the projectile 1 is in the unstable region of the magnetic field of the coil 3 for a sufficiently long time. This requirement of "sufficiently long time" is the two requirements mentioned at the beginning.

[0079] When multiple (two or more) coils 3 are simultaneously activated, since the total magnetic field is the superposition of the magnetic fields of multiple coils 3, multiple stable and unstable regions may appear. In this case, the preferred solution is to place the projectile 1 in the unstable regions at the outermost edges (i.e., furthest from the coils 3), that is, to control the activation time of the multiple coils 3 so that the projectile 1 is in the unstable regions at the outermost edges of the superimposed magnetic field of the multiple coils 3 for a sufficient period of time.

[0080] like Figure 4 The figure shows an example of simultaneously conducting two coils 3. As can be seen from the figure, between the two most unstable regions, there are two alternating stable regions and one unstable region. The unstable region is relatively short, so this part of the unstable region can be excluded from the control of the magnetic levitation of the projectile 1.

[0081] As mentioned earlier, projectile 1 is subject to random disturbances such as friction from the gun barrel and impact, making it difficult to maintain a stable attitude. Projectile 1 is extremely prone to tumbling, such as... Figure 1 As shown in (d), the expected result is that the projectile can automatically return to a stable state, as... Figure 1 As shown in (c). The stability of projectile 1's attitude can also be achieved by controlling the conduction time of coil 3, placing projectile 1 in the unstable region. The total torque on projectile 1 is equal to the sum of the torques on each part. When projectile 1 is in the axially unstable region, each part of projectile 1 will experience a restoring force. The superposition of these restoring forces manifests as a "stabilizing torque" that restores projectile 1's attitude to the expected state.

[0082] Based on the above, the optimal approach to achieve magnetic levitation and attitude stability for projectile 1 is clearly to keep it constantly within the unstable region of the magnetic field of coil 3. However, this would result in a smaller acceleration force and lower efficiency. Therefore, for other performance considerations (such as launch power and electromagnetic gun efficiency), the conduction time of coil 3 can be controlled, so that projectile 1 spends part of its time in the unstable region of the currently conducting coil 3 and another part in the stable region. Although projectile 1 will experience side-pulling forces and instability torques in the stable region, as long as the total impulse of the restoring force and the total angular impulse of the stabilizing torque are smaller than those experienced in the unstable region (i.e., satisfying the initial two conditions), projectile 1 can still achieve magnetic levitation and attitude stability.

[0083] Furthermore, when accelerating projectile 1, the conduction time of the current coil 3 is controlled so that:

[0084] The total impulse of the centering force experienced by projectile 1 in the third region is greater than the total impulse of the edge-moving force experienced in the second region; and

[0085] The total angular impulse of the stabilizing torque experienced by projectile 1 in the third region is greater than the total angular impulse of the buckling torque experienced in the second region.

[0086] During deceleration, the conduction time of the current coil 3 is controlled so that:

[0087] The total impulse of the centering force experienced by projectile 1 in the fourth region is greater than the total impulse of the edge-moving force experienced in the second region; and

[0088] The total angular impulse of the stabilizing torque experienced by projectile 1 in the fourth region is greater than the total angular impulse of the buckling torque experienced in the second region.

[0089] The third region is the overlap between the unstable region and the acceleration region. The "acceleration region" is where the force exerted by the coil's magnetic field on projectile 1 is positive (manifested as attraction), while the opposite is the "deceleration region," where the force exerted by the coil's magnetic field on projectile 1 is negative (manifested as repulsion). See appendix. Figure 3 or Figure 4 The region where the acceleration force F is positive is the acceleration zone, and the region where the acceleration force F is negative is the deceleration zone. The fourth region is the overlapping area of ​​the unstable zone and the deceleration zone.

[0090] There are two control systems for controlling the conduction time of coil 3, i.e., controlling projectile 1 to remain in the unstable region for a sufficiently long time: open-loop and closed-loop.

[0091] 1. Closed-loop method:

[0092] The closed-loop method uses negative feedback provided by an external control circuit to counteract the positive feedback in the axial unstable region, so that the projectile 1 can be stably located in the unstable region.

[0093] For the hardware basis for implementing this method, please refer to [link / reference]. Figure 5 A closed-loop control system includes at least one (several) sensors, control circuitry, and a power loop.

[0094] The sensor is used to detect the position of projectile 1. The sensor needs to be able to continuously detect the position of projectile 1, or detect it at many discrete points. The sensor can be a single sensor capable of continuously detecting the position of projectile 1, such as a laser rangefinder or microwave radar. It can also be multiple sensors that can only detect the position of projectile 1 within a small area, such as photoelectric switches, Hall effect sensors, or coils. Alternatively, it can be a combination of the above sensors.

[0095] The power circuit is used to provide pulsed power current to coil 3 to generate sufficient electromagnetic force to accelerate / decelerate projectile 1.

[0096] The control circuit controls the power circuit to energize the coil 3 at the corresponding time based on the position information of the projectile 1 provided by the sensor, thereby controlling the relative positional relationship between the magnetic field of the coil 3 and the projectile 1.

[0097] The control circuit is pre-configured with the expected conduction time (time point or time period) for each coil 3, and the control circuit continuously receives information provided by the sensor.

[0098] Taking the magnetic levitation control of projectile 1 during the acceleration phase as an example: when the information provided by the sensor indicates that the "expected conduction time" will cause the positional relationship between projectile 1 and the current coil 3 to be closer than expected, the control circuit advances the conduction time of the current coil 3. This increases the distance between the current coil 3 and projectile 1 when energized, thereby causing the positional relationship between projectile 1 and the magnetic field to return to the expected state, that is, projectile 1 is located at a certain position in the overlapping area of ​​the unstable region and the acceleration region.

[0099] Conversely, when the sensor indicates that the projectile 1 will travel further than expected, the control circuit will delay the energization of coil 3 (i.e., delay the conduction time), reducing the distance between coil 3 and projectile 1 when energized, so that the position of projectile 1 is closer to the position of the magnetic field, and it returns to the expected position.

[0100] Conversely, when controlling the magnetic levitation deceleration of projectile 1, the control circuit turns on the current coil 3 in advance when the information provided by the sensor shows that the position of projectile 1 is farther than expected, and turns on the current coil 3 later when the position of projectile 1 is closer than expected.

[0101] The relationship between the advance or delay time, the current distance between projectile 1 and coil 3 (calculated by the position detected by the sensor), and the expected distance is determined so that when the coil is turned on, the projectile is in the unstable region of the coil's magnetic field.

[0102] Alternatively, from another perspective, the control circuit has pre-configured conduction positions corresponding to each coil 3. Whether accelerating or decelerating, when the sensor indicates that the projectile 1 is in a conduction position (meaning the distance from the projectile 1 to the current coil 3 reaches the corresponding conduction distance, or the physical position of the projectile 1 is in a conduction position), the control circuit activates the current coil 3, placing the projectile 1 at a certain position within the unstable region. This conduction position is a specific location within the unstable region of the current coil 3's magnetic field. More specifically, during acceleration, it is a location within the overlapping region of the unstable region and the acceleration region of the current coil 3's magnetic field; during deceleration, it is a location within the overlapping region of the unstable region and the deceleration region of the current coil 3's magnetic field. Preferably, the aforementioned unstable region, when multiple coils 3 are simultaneously activated, refers to the unstable regions on both sides.

[0103] 2. Open-loop method

[0104] The hardware difference between open-loop and closed-loop methods is that there are no sensors; otherwise, they are the same.

[0105] The open-loop scheme involves pre-configuring the expected conduction period for each coil 3 in the control circuit. This conduction period is fixed and is configured before launching the projectile 1. Determining this conduction period requires that the projectile 1 spend a sufficiently long time within the unstable region of the coil 3's magnetic field during the expected conduction time. The control circuit then activates the current coil via a power loop during the expected conduction period.

[0106] Because the open-loop design lacks negative feedback, when projectile 1 is in the unstable region, as described above, its axial position is unstable; it will either completely detach from the magnetic field or be attracted into the stable region. However, this detachment or attraction takes time; projectile 1 will not immediately leave the unstable region. Even with a fully open-loop design, projectile 1 can be kept in the unstable region within a relatively short distance. By achieving magnetic levitation of projectile 1 before axial instability occurs, some of the advantages of magnetic levitation can be obtained.

[0107] Example 2

[0108] This embodiment discloses a control system for controlling the conduction time of coils. This system can be applied to the projectile magnetic levitation method of a reluctance coil gun. The system includes several stages of coils 3, several sensors, a power circuit, and a control circuit (the coils can be reused, that is, the control system of this invention can only include sensors, power circuits, and control circuits, and then be used in an existing coil gun). Each stage of coil 3 is arranged sequentially along the barrel axis 6, and each sensor is arranged sequentially along the barrel axis 6. The power circuits are connected to each stage of coil 3, and the control circuits are connected to each sensor and the power circuit.

[0109] The sensor is used to detect the position of projectile 1. The sensor needs to be able to continuously detect the position of projectile 1, or detect it at many discrete points. The sensor can be a single sensor capable of continuously detecting the position of projectile 1, such as a laser rangefinder or microwave radar. It can also be multiple sensors that can only detect the position of projectile 1 within a small area, such as a photoelectric switch, a Hall sensor, or coil 3. Alternatively, it can be a combination of the above sensors.

[0110] The power circuit is used to provide pulsed power current to coil 3 to generate sufficient electromagnetic force to accelerate / decelerate projectile 1.

[0111] The control circuit controls the power circuit to energize the coil 3 at a set time based on the position information of the projectile 1 provided by the sensor, thereby controlling the relative positional relationship between the magnetic field of the coil 3 and the projectile 1.

[0112] In some embodiments, the control circuit is pre-configured with the expected conduction period for each coil 3. The control circuit continuously receives information from the sensor. When the sensor information indicates that the "expected conduction time" would cause the positional relationship between the projectile 1 and the current coil 3 to be closer than expected, the control circuit advances the conduction period of the current coil 3. This increases the distance between the current coil 3 and the projectile 1 when energized, thereby causing the positional relationship between the projectile 1 and the magnetic field to return to the expected state, that is, the projectile 1 is located at a position in the overlapping region of the unstable region and the acceleration region.

[0113] Conversely, when the information provided by the sensor indicates that the projectile 1 will travel farther than expected, the control circuit will delay the energization of the coil 3, reducing the distance between the coil 3 and the projectile 1 when energized, so that the position of the projectile 1 is closer to the position of the magnetic field, and it returns to the expected position.

[0114] Conversely, when controlling the magnetic levitation deceleration of projectile 1, the control circuit turns on the current coil 3 in advance when the information provided by the sensor shows that the position of projectile 1 is farther than expected, and turns on the current coil 3 later when the position of projectile 1 is closer than expected.

[0115] The relationship between the advance or delay time, the current distance between projectile 1 and coil 3 (calculated by the position detected by the sensor), and the expected distance is determined.

[0116] In other embodiments, the control circuit is pre-configured with corresponding conduction positions for each coil 3. When the information provided by the sensor indicates that the projectile 1 has reached the relevant conduction position, the control circuit activates the corresponding coil 3. This conduction position is a location within the unstable region of the current coil 3's magnetic field. More specifically, during the acceleration phase, it is a location within the overlapping region of the unstable region and the acceleration region of the current coil 3's magnetic field; during the deceleration phase, it is a location within the overlapping region of the unstable region and the deceleration region of the current coil 3's magnetic field. Preferably, the aforementioned unstable region, when multiple coils 3 are activated simultaneously, refers to the unstable regions on both sides.

[0117] In this embodiment, the control circuit must ultimately control the coil to conduct for the time that the two conditions mentioned at the beginning are met, or meet the two conditions limited by the acceleration or deceleration phases.

[0118] Example 3

[0119] This embodiment discloses another control system that can be applied to the projectile magnetic levitation method of a reluctance coil gun. The electromagnetic gun includes several stages of coils 3, a power circuit, and a control circuit (the coils can be reused, that is, the control system of this invention can include only the power circuit and the control circuit, and then be used in an existing coil gun). Each stage of coil 3 is arranged sequentially along the barrel axis 6, and the power circuit is connected to each stage of coil 3 respectively, and the control circuit is connected to the power circuit.

[0120] In some implementations, the control circuit is pre-configured with a predetermined conduction period for each coil 3, and the corresponding coil 3 is turned on when the corresponding conduction period is reached. During this conduction period, the projectile 1 has a sufficiently long time to be in the unstable region of the magnetic field of the coil 3.

[0121] Similarly, the period during which the control circuit turns on the coil needs to meet the two conditions mentioned at the beginning, or the two conditions of the acceleration or deceleration phase.

[0122] Example 4

[0123] This embodiment provides an overall description of the method for controlling the magnetic levitation of a projectile using the control system described in Embodiment 2 or Embodiment 3 above.

[0124] The control circuit in the control system controls the conduction time of the current coil through the power loop, so that (see Example 1):

[0125] The total impulse of the centering force on projectile 1 in the first region is greater than the total impulse of the edge-moving force on it in the second region; and

[0126] The total angular impulse of the stabilizing torque experienced by projectile 1 in the first region is greater than the total angular impulse of the buckling torque experienced by projectile 1 in the second region.

[0127] Furthermore, when accelerating projectile 1, the conduction time of the current coil 3 is controlled so that:

[0128] The total impulse of the centering force experienced by projectile 1 in the third region is greater than the total impulse of the edge-moving force experienced in the second region; and

[0129] The total angular impulse of the stabilizing moment experienced by projectile 1 in the third region is greater than the total angular impulse of the buckling moment experienced in the second region.

[0130] During deceleration, the conduction time of the current coil 3 is controlled so that:

[0131] The total impulse of the centering force experienced by projectile 1 in the fourth region is greater than the total impulse of the edge-moving force experienced in the second region; and

[0132] The total angular impulse of the stabilizing torque experienced by projectile 1 in the fourth region is greater than the total angular impulse of the buckling torque experienced in the second region.

[0133] Example 5

[0134] This embodiment discloses a magnetically levitated reluctance coilgun. The electromagnetic gun includes an acceleration section and a magnetic levitation section. The acceleration section accelerates the projectile 1 and can theoretically be any structure capable of accelerating the projectile 1, such as an air gun, a gunpowder gun, a conventional reluctance electromagnetic gun, an induction electromagnetic gun, or even the magnetically levitated reluctance coilgun designed in this invention. The magnetic levitation section includes the control system described in embodiments two and three above. At least one stage coil 3 is located at the exit of the acceleration section, i.e., at the muzzle of the electromagnetic gun, or the power circuit of the control system is connected to at least one stage coil at the exit of the acceleration section. Thus, after the projectile 1 is accelerated by the acceleration section, regardless of whether the projectile 1 is in a magnetically levitated state or attached to the barrel wall 5, the magnetic levitation section magnetically levitates the projectile 1 to stabilize its launch attitude and improve firing accuracy.

[0135] This embodiment uses a multi-stage reluctance coil as the acceleration segment for the experiment. The configuration of this embodiment is as follows:

[0136] Actual photographs of the embodiments are as follows Figure 6 As shown. This embodiment is a multi-stage magnetoresistive coilgun, including an acceleration section and a magnetic levitation section. Figure 6 In the middle section, the acceleration phase is on the left, and the magnetic levitation phase is on the right. During launch, the projectile moves from left to right.

[0137] Electrolytic capacitors are used as energy storage elements in both the acceleration and magnetic levitation phases of the power circuit, with a storage voltage of 390V. The switching elements in the power circuits are all IGBTs. The projectile launched in this embodiment is made of carbon steel and is cylindrical in shape, with a diameter of 8mm and a length of 20mm.

[0138] The acceleration section consists of 12 coil stages with a total length of 25.9 cm. This acceleration section is a standard magnetic reluctance gun and does not have magnetic levitation capabilities. The magnetic levitation section consists of only one coil stage.

[0139] The control method in this embodiment is an "open-loop method" (as described in Embodiments 1 and 3). That is, no sensors are used, the conduction periods of each coil are fixed, and this is pre-programmed into the control circuit before launch. The relative positions of each coil, and the relationship between the coil current and the projectile head position, are as follows: Figure 7As shown, the current curves are for illustrative purposes only and do not represent the actual current waveforms and amplitudes. For simplicity, only stages 10 to 13 are shown (coils before stage 10 are shown in stage 10). It can be seen that in the acceleration phase (stages 10-12 in the diagram), the control circuit energizes the coil when the projectile and coil are relatively close, at which point the projectile is in a stable region. However, in the magnetic levitation phase (stage 13 in the diagram), the coil is energized when the projectile and coil are relatively far apart, at which point the projectile is in an unstable region.

[0140] Test results of this embodiment:

[0141] When only the acceleration section is operational (i.e., the magnetic levitation section is removed), the projectile's exit velocity is 100 m / s, and its exit kinetic energy is 39.0 J. Adding the magnetic levitation section slightly increases both the projectile's velocity and kinetic energy, raising the exit velocity to 102 m / s and the kinetic energy to 40.6 J. It also provides a statistically significant improvement in dispersion and projectile stability.

[0142] Figure 8 and Figure 9 The projectile dispersion was demonstrated with and without magnetic levitation. During the experiment, the launcher was fixed in place, the target paper was placed 5 meters away, and the projectiles were fired 10 times. The results showed that without magnetic levitation, the dispersion circle diameter was approximately 6.5 cm, while with magnetic levitation, the dispersion circle diameter decreased to approximately 5 cm. A more concentrated distribution of projectile holes indicates better performance.

[0143] Tables 1 and 2 show the tumbling behavior of the projectiles in the "no magnetic levitation section" and "with magnetic levitation section," respectively. The criteria for determining whether tumbling occurs are as follows: Figure 10 As shown, if the bullet hole is approximately rectangular (as shown in bullet hole number 8 in the figure), it is determined that a rollover has occurred; if the bullet hole is approximately circular (as shown in bullet hole number 7 in the figure), it is determined that a rollover has not occurred. For practical applications, the more "no" results, the better. Experimental results show that without the magnetic levitation section, in 100 launches conducted under the same experimental conditions, 9 did not result in a rollover, while with the magnetic levitation section, 38 did not result in a rollover. Therefore, the solution proposed in this invention can reduce the probability of rollover occurring.

[0144] Table 1 shows the experimental results regarding whether rollover occurred in the absence of magnetic levitation.

[0145]

[0146] Table 2 shows the experimental results regarding whether rollover occurred when the magnetic levitation section was present.

[0147]

[0148] In this embodiment, the magnetic levitation segment has only one level of coil, so the effect of reducing the probability of dispersion and tumbling is not very obvious. However, it is foreseeable that if a "closed-loop scheme" (as described in Embodiment 1 and Embodiment 2) is used, and multi-level coils are used for magnetic levitation, better results can be achieved.

[0149] Figure 1 The example shown uses a cylindrical gun barrel and a projectile as examples. This invention is not limited to this embodiment; the gun barrel or projectile can be square or other shapes.

[0150] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. A method for magnetic levitation of projectiles in a reluctance coilgun, the reluctance coilgun comprising at least one coil, characterized in that the method... include: Control the current conduction time of the coil so that: The total impulse of the centering force on the projectile in the first region is greater than the total impulse of the side force on the projectile in the second region; the centering force is the force on the projectile directed towards the barrel axis, and the side force is the force on the projectile directed towards the barrel wall. as well as The total angular impulse of the stabilizing moment experienced by the projectile in the first region is greater than the total angular impulse of the buckling moment experienced by the projectile in the second region. The first region is located in a region where the magnitude of the electromagnetic force on the projectile is inversely correlated with the distance from the coil, and the second region is located in a region where the magnitude of the electromagnetic force on the projectile is positively correlated with the distance from the coil.

2. The projectile magnetic levitation method for a reluctance coilgun as described in claim 1, characterized in that, The first region is located in the region where the magnitude of the electromagnetic force on the projectile is inversely related to the distance from the coil, and is the region on both sides.

3. The projectile magnetic levitation method for a reluctance coilgun as described in claim 1 or 2, characterized in that, The first region is located in the region where the magnitude of the electromagnetic force on the projectile is inversely related to the distance from the coil, and overlaps with the region where the force exerted by the coil's magnetic field on the projectile is positive.

4. The projectile magnetic levitation method for a reluctance coilgun as described in claim 1 or 2, characterized in that, The first region is located in the region where the magnitude of the electromagnetic force on the projectile is inversely related to the distance from the coil, and overlaps with the region where the force exerted by the coil's magnetic field on the projectile is negative.

5. The control system for the projectile magnetic levitation method of a reluctance coilgun as described in any one of claims 1-4, characterized in that, It includes at least one sensor, a control circuit, and a power circuit, wherein the control circuit is connected to both the sensor and the power circuit; wherein: The sensor is used to detect the position of the projectile; The power circuit is used to provide pulsed power current to the coil; The control circuit controls the power circuit to energize the coil at the corresponding time based on the position information of the projectile provided by the sensor.

6. The control system as described in claim 5, characterized in that, The control circuit is configured as follows: The control circuit is pre-configured with the expected conduction time of each coil, and the control circuit continuously receives information provided by the sensor; During the acceleration phase, when the information provided by the sensors indicates that the expected turn-on time will result in the projectile and the current coil being closer than expected, the control circuit advances the turn-on time of the current coil; when the information provided by the sensors indicates that the expected turn-on time will result in the projectile and the current coil being farther than expected, the control circuit delays the turn-on time of the current coil. During the deceleration phase, if the sensor information indicates that the expected turn-on time will bring the projectile and the current coil closer than expected, the control circuit will delay the turn-on time of the current coil; if the sensor information indicates that the expected turn-on time will bring the projectile and the current coil farther than expected, the control circuit will advance the turn-on time of the current coil.

7. The control system as described in claim 5, characterized in that, The control circuit is configured as follows: The control circuit is pre-configured with the conduction positions corresponding to each coil. When the information provided by the sensor shows that the projectile is in the conduction position, the control circuit turns on the current coil.

8. The control system for the projectile magnetic levitation method of a reluctance coilgun as described in any one of claims 1-4, characterized in that, It includes a control circuit and a power circuit, wherein the control circuit is connected to the power circuit; wherein: The power circuit is used to provide pulsed power current to the coil; The control circuit pre-configures the expected conduction period for each coil, and conducts the current coil through the power circuit during the expected conduction period.

9. A magnetically levitated reluctance coilgun, characterized in that, It includes an acceleration section and a magnetic levitation section, the acceleration section being used to accelerate the projectile, and the magnetic levitation section including a control system as described in any one of claims 5-7, wherein the power loop of the control system is connected to at least one stage coil at the outlet of the acceleration section.

10. A magnetically levitated reluctance coilgun, characterized in that, It includes an acceleration section and a magnetic levitation section, the acceleration section being used to accelerate the projectile, the magnetic levitation section including the control system as described in claim 8, and the power loop of the control system being connected to at least one stage coil at the outlet of the acceleration section.

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