Rapid mechanical switch based on coil type electromagnetic driving mechanism and control method

Abstract

The invention discloses a quick mechanical switch based on a coil type electromagnetic driving mechanism, which comprises a vacuum arc extinguish chamber, a static contact, a moving contact, a transmission connecting rod, an electromagnetic driving mechanism, a discharge circuit, a holding mechanism and a buffer mechanism. According to the three-coil type electromagnetic driving mechanism, rapid opening and closing operation of the rapid mechanical switch with the electromagnetic buffering function can be achieved, at the last stage of opening action, the three-coil type electromagnetic driving mechanism can also use electromagnetic force to restrain opening rebound, the opening rebound displacement and rebound time are reduced, the instantaneous output requirement for a maintaining mechanism in the opening rebound restraining process can be lowered, and the reliability of the maintaining mechanism is improved. The size of the buffer mechanism and the holding mechanism can be reduced, so that the application range of the quick mechanical switch is wider.

Description

Technical Field

[0001] The present invention relates to the technical field of fast mechanical switches for circuit breakers, and in particular to a fast mechanical switch based on a coil-type electromagnetic drive mechanism and a control method thereof. Background Art

[0002] High-voltage DC grid disconnection refers to the process of cutting off the current from the DC grid through specific equipment and methods. This process is crucial to protecting the safety and stable operation of the grid. In the prior art, the preferred solutions for high-voltage DC grid disconnection are mechanical DC circuit breakers and hybrid DC circuit breakers, each of which has its own characteristics and applicable scenarios. As the core components of the two, fast mechanical switches undertake the important tasks of steady-state current carrying and transient pressure bearing. Electromagnetic drive mechanisms have significant advantages over other drive mechanisms in starting time, initial acceleration and opening and closing speed. Fast mechanical switches based on electromagnetic drive mechanisms are the key technologies for the development of mechanical DC circuit breakers and hybrid DC circuit breakers.

[0003] The coil-type electromagnetic drive mechanism has a high power conversion efficiency and is often used in long-stroke, high-voltage mechanical switches. Due to its high opening and closing speed, it places high demands on the mechanical buffer mechanism and holding mechanism of the mechanical switch. For example, the invention patent CN202110705514.7 discloses a technical method for electromagnetic buffering of opening and closing, which uses the electromagnetic force generated by the electromagnetic drive mechanism as an active buffer, thereby reducing the output requirements of the mechanical buffer mechanism. However, at the end of the opening action, the opening rebounds due to elastic collision between mechanical parts, and it still relies only on the mechanical holding mechanism to provide instantaneous holding force. At the end of the opening action, due to insufficient instantaneous holding force, the opening rebound displacement is too long, and in severe cases, it even causes the opening to fail. In the prior art, the mechanical buffer mechanism and holding mechanism used have problems such as large size, prone to mechanical failure, and insufficient instantaneous output.

[0004] The disclosure of the above background technology content is only used to assist in understanding the concept and technical solution of the present invention. It does not necessarily belong to the prior art of this patent application. In the absence of clear evidence that the above content has been disclosed on the filing date of this patent application, the above background technology should not be used to evaluate the novelty and creativity of the present application. Summary of the invention

[0005] The purpose of the present invention is to propose a fast mechanical switch and control method based on a coil-type electromagnetic drive mechanism, so as to solve the technical problems existing in the above-mentioned prior art that the mechanical buffer mechanism and the holding mechanism in the fast mechanical switch are insufficient in instantaneous output, resulting in too long rebound displacement of the opening switch, and even causing opening failure in severe cases.

[0006] To this end, the present invention proposes a fast mechanical switch and a control method based on a coil-type electromagnetic drive mechanism.

[0007] Preferably, the present invention may also have the following technical features:

[0008] A fast mechanical switch based on a coil-type electromagnetic drive mechanism, comprising a vacuum interrupter, a static contact, a moving contact, a transmission connecting rod, an electromagnetic drive mechanism, a discharge circuit, a holding mechanism and a buffer mechanism;

[0009] The static contact is arranged in the vacuum interrupter and fixedly arranged on the top of the vacuum interrupter;

[0010] The moving contact is arranged directly below the static contact, the lower end of the moving contact passes through the bottom surface of the vacuum interrupter and is fixedly connected to the upper end of the transmission connecting rod, and the moving contact can move up and down with the transmission connecting rod to realize closing or opening;

[0011] The electromagnetic drive mechanism is arranged below the vacuum interrupter, and comprises an opening coil, a moving coil and a closing coil. The opening coil, the moving coil and the closing coil have the same winding direction and are all wound around the transmission connecting rod, and can provide electromagnetic driving force and electromagnetic buffering force during the opening or closing process, and provide instantaneous electromagnetic holding force at the end of the opening action; the moving coil is arranged on the transmission connecting rod and can move up and down with the transmission connecting rod, the moving coil is connected in reverse series with the opening coil, and the positive and reverse series relationship between the moving coil and the closing coil is determined by the current direction of the discharge circuit; the opening coil and the closing coil are fixed in position and are respectively arranged above and below the moving coil;

[0012] The holding mechanism is arranged between the vacuum interrupter and the electromagnetic drive mechanism. When the moving contact and the moving coil are in the closing or opening position, the holding mechanism can provide a steady-state holding force through the transmission connecting rod; at the end of the closing or opening action, the holding mechanism can provide an instantaneous holding force through the transmission connecting rod;

[0013] The buffer mechanism is arranged directly below the transmission connecting rod and provides a buffer force for the transmission connecting rod at the end of the opening action.

[0014] Preferably, the transmission connecting rod is made of insulating material.

[0015] Preferably, the opening coil, the moving coil and the closing coil all have two inner and outer outlet ports; the closing coil and four diodes form an H-bridge branch, so that the closing coil current flows in from the inside and out from the outside.

[0016] Preferably, the discharge circuit comprises a driving discharge branch, a buffer discharge branch and a holding discharge branch, each of which comprises a group of discharge capacitors and a group of thyristor control devices, and the buffer discharge branch is connected in parallel with the holding discharge branch in opposite directions.

[0017] Preferably, the discharge circuit includes a driving capacitor C1, a buffer capacitor C2, a holding capacitor C3, a thyristor T1, a thyristor T2, and a thyristor T3;

[0018] The driving capacitor C1 and the thyristor T1 are connected in series to form the driving discharge branch, the positive terminal of the driving discharge branch is connected to the inner terminal of the opening coil, the negative terminal of the driving discharge branch is connected to the inner terminal of the moving coil, and the outer terminal of the opening coil is connected to the outer terminal of the moving coil;

[0019] The buffer capacitor C2 and the thyristor T2 are connected in series to form the buffer discharge branch, the positive terminal of the buffer discharge branch is connected to the diode and the upper terminal of the H-bridge branch, the negative terminal of the buffer discharge branch is connected to the inner terminal of the moving coil, and the outer terminal of the moving coil is connected to the lower terminal of the H-bridge branch;

[0020] The holding capacitor C3 and the thyristor T3 are connected in series to form the holding discharge branch, the positive terminal of the holding discharge branch is connected to the inner terminal of the moving coil, the negative terminal of the holding discharge branch is connected to the upper terminal of the H-bridge branch, and the outer terminal of the moving coil is connected to the lower terminal of the H-bridge branch.

[0021] Preferably, the retaining mechanism includes two fixed ends and two movable ends, one end of the movable end is connected to the fixed end, and the other end is connected to the transmission connecting rod, and can move up and down with the transmission connecting rod, the two fixed ends are symmetrically arranged about the transmission connecting rod, and the two movable ends are symmetrically arranged about the transmission connecting rod.

[0022] Preferably, the fixed end is provided with a bistable spring, and the movable end is a plurality of interconnected connecting rods.

[0023] Preferably, in the closing position, the distance between the buffer mechanism and the transmission connecting rod is smaller than the rated opening distance, so as to provide a buffer space for the end of the opening action.

[0024] According to the control method of the fast mechanical switch based on the coil type electromagnetic drive mechanism, the opening action process includes the following steps:

[0025] (1) In the opening drive stage, the thyristor T1 is turned on, the driving capacitor C1 is discharged, and the opening coil and the moving coil pass through excitation currents in opposite directions. The opening coil and the moving coil generate magnetic fields in opposite directions. The electromagnetic repulsion force on the moving coil is directed downward, and the holding force of the holding mechanism in the closing direction is overcome by the transmission connecting rod, so that the moving contact, the transmission connecting rod and the moving coil move downward;

[0026] (2) During the opening buffer stage, the thyristor T2 is turned on, the buffer capacitor C2 is discharged, and excitation currents in opposite directions flow through the moving coil and the closing coil. The moving coil and the closing coil generate magnetic fields in opposite directions. The electromagnetic repulsion force on the moving coil is directed upward, and the holding force of the holding mechanism in the opening direction is overcome by the transmission connecting rod, and the movement speed of the moving contact, the transmission connecting rod and the moving coil in the opening direction is reduced;

[0027] (3) During the opening and holding stage, the thyristor T3 is turned on, the holding capacitor C3 is discharged, and the moving coil and the closing coil are passed through an excitation current in the same direction. The moving coil and the closing coil generate magnetic fields in the same direction, and the electromagnetic attraction force on the moving coil is downward. Under the joint action of the opening holding force of the transmission connecting rod and the holding mechanism, the moving contact, the transmission connecting rod and the moving coil are kept in the opening position, eliminating the rebound of the moving contact, the transmission connecting rod and the moving coil.

[0028] Preferably, the closing action process includes the following steps: the thyristor T2 is turned on, the buffer capacitor C2 serves as a closing drive capacitor, the moving coil and the closing coil generate magnetic fields in opposite directions, and the moving coil is subjected to an electromagnetic repulsive force in an upward direction, thereby overcoming the holding force of the holding mechanism in the opening direction through the transmission connecting rod, so that the moving contact, the transmission connecting rod and the moving coil move upward.

[0029] The beneficial effects of the present invention compared with the prior art include:

[0030] Compared with traditional unidirectional electromagnetic drive mechanisms, bidirectional electromagnetic drive mechanisms, and bidirectional electromagnetic drive mechanisms with electromagnetic buffering, the three-coil electromagnetic drive mechanism proposed in the present invention can realize the rapid opening and closing operations of a fast mechanical switch with electromagnetic buffering function. At the end of the opening action, the three-coil electromagnetic drive mechanism of the present invention can also use electromagnetic force to suppress the rebound of the opening gate, reduce the rebound displacement and rebound time of the opening gate, and reduce the instantaneous output requirements of the holding mechanism when suppressing the rebound of the opening gate. The volume of the buffer mechanism and the holding mechanism can be reduced, making this type of fast mechanical switch more applicable. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the fast mechanical switch provided by the present invention.

[0032] Figure 2a A schematic diagram of the operation of the fast mechanical switch opening drive stage provided by an embodiment of the present invention.

[0033] Figure 2b A schematic diagram of the action of the fast mechanical switch opening buffer stage provided by an embodiment of the present invention.

[0034] Figure 2c A schematic diagram of the operation of the fast mechanical switch opening and holding phase provided by an embodiment of the present invention.

[0035] Figure 3a for Figure 2a The current path diagram of the discharge circuit during the operation shown.

[0036] Figure 3b for Figure 2b The current path diagram of the discharge circuit during the operation shown.

[0037] Figure 3c for Figure 2c The current path diagram of the discharge circuit during the operation shown.

[0038] 1- vacuum interrupter; 11- static contact; 12- moving contact; 2- transmission connecting rod; 3- holding mechanism; 31- bistable spring; 32- connecting rod; 4- buffer mechanism; 5- electromagnetic drive mechanism; 51- opening coil; 52- moving coil; 53- closing coil; 6- discharge circuit. DETAILED DESCRIPTION

[0039] The present invention will be further described in detail below in conjunction with specific implementations and with reference to the accompanying drawings. It should be emphasized that the following description is merely exemplary and is not intended to limit the scope of the present invention and its application.

[0040] Non-limiting and non-exclusive embodiments will be described with reference to the following figures, wherein like reference numerals refer to like parts unless otherwise specifically stated.

[0041] Embodiment 1:

[0042] A fast mechanical switch based on a coil-type electromagnetic drive mechanism, such as Figure 1As shown, it includes a vacuum interrupter 1, a static contact 11, a moving contact 12, a transmission connecting rod 2, an electromagnetic drive mechanism 5, a discharge circuit 6, a holding mechanism 3 and a buffer mechanism 4. It can be understood that the transmission connecting rod 2 is made of insulating material. The static contact 11 is arranged in the vacuum arc extinguishing chamber 1 and is fixedly arranged on the top of the vacuum arc extinguishing chamber 1; the moving contact 12 is arranged directly below the static contact 11, and the lower end of the moving contact 12 passes through the bottom surface of the vacuum arc extinguishing chamber 1 and is fixedly connected to the upper end of the transmission connecting rod 2, and the moving contact 12 can move up and down with the transmission connecting rod 2 to realize closing or opening. It can be understood that closing means that the moving contact 12 is close to the static contact 11, and opening means that the moving contact 12 is away from the static contact 11; the electromagnetic drive mechanism 5 is arranged below the vacuum arc extinguishing chamber 1, and includes an opening coil 51, a moving coil 52 and a closing coil 53. The opening coil 51, the moving coil 52 and the closing coil 53 have the same winding direction and are all wound around the transmission connecting rod 2 as the axis. They can provide electromagnetic driving force and electromagnetic buffering force during the opening or closing process, and provide electromagnetic buffering force at the end of the opening action. Provide instantaneous electromagnetic holding force; the moving coil 52 is arranged on the transmission connecting rod 2, and can move up and down with the transmission connecting rod 2. The moving coil 52 is reversely connected in series with the opening coil 51, and the positive and negative series relationship between the moving coil 52 and the closing coil 53 is determined by the current direction of the discharge circuit 6; the opening coil 51 and the closing coil 52 are fixed in position and are respectively arranged above and below the moving coil 52; the holding mechanism 3 is arranged between the vacuum interrupter 1 and the electromagnetic drive mechanism 5, when the moving contact 12 and the moving coil 52 are in the closing or opening position, the holding mechanism 3 can provide a steady-state holding force through the transmission connecting rod 2; at the end of the closing or opening action, the holding mechanism 3 can provide an instantaneous holding force through the transmission connecting rod 2; the buffer mechanism 4 is arranged directly below the transmission connecting rod 2, and provides a buffer force for the transmission connecting rod 2 at the end of the opening action. When in the closing position, the distance between the buffer mechanism 4 and the transmission connecting rod 2 is smaller than the rated opening distance, so as to provide a buffer space for the final stage of the opening action.

[0043] Specifically, the opening coil 51, the moving coil 52 and the closing coil 53 all have two inner and outer outlet ports; the closing coil 53 and four diodes form an H-bridge branch, so that the current of the closing coil 53 flows into the inner side and flows out from the outer side.

[0044] Specifically, the discharge circuit 6 includes a driving discharge branch, a buffer discharge branch, and a holding discharge branch, each of which includes a group of discharge capacitors and a group of thyristor control devices. The buffer discharge branch is connected in parallel with the holding discharge branch and in opposite directions.

[0045] like Figure 2a , 2b As shown in , 2c, 3a, 3b and 3c, the discharge circuit includes a driving capacitor C1, a buffer capacitor C2, a holding capacitor C3, a thyristor T1, a thyristor T2 and a thyristor T3. Specifically, the driving capacitor C1 is connected in series with the thyristor T1 to form the driving discharge branch, the positive terminal of the driving discharge branch is connected to the inner port of the opening coil 51, the negative terminal of the driving discharge branch is connected to the inner port of the moving coil 52, and the outer port of the opening coil 51 is connected to the outer port of the moving coil 52; the buffer capacitor C2 is connected in series with the thyristor T2 to form the buffer discharge branch, the positive terminal of the buffer discharge branch is connected to the upper port of the diode and the H-bridge branch, the negative terminal of the buffer discharge branch is connected to the inner port of the moving coil 52, and the outer port of the moving coil 52 is connected to the lower port of the H-bridge branch; the holding capacitor C3 is connected in series with the thyristor T3 to form the holding discharge branch, the positive terminal of the holding discharge branch is connected to the inner port of the moving coil 52, the negative terminal of the holding discharge branch is connected to the upper port of the H-bridge branch, and the outer port of the moving coil 52 is connected to the lower port of the H-bridge branch.

[0046] like Figure 1 As shown, in some examples of this embodiment, the holding mechanism includes two fixed ends and two movable ends, one end of the movable end is connected to the fixed end, and the other end is connected to the transmission connecting rod and can move up and down with the transmission connecting rod, the two fixed ends are symmetrically arranged about the transmission connecting rod, and the two movable ends are symmetrically arranged about the transmission connecting rod. Specifically, the fixed end is provided with a bistable spring 31, and the movable end is a plurality of interconnected connecting rods 32.

[0047] Embodiment 2:

[0048] A control method for a fast mechanical switch based on a coil-type electromagnetic drive mechanism includes three stages in the opening and closing action process:

[0049] (1) Opening drive stage, such as Figure 2a and 3a As shown, after the control system issues a trip command, the thyristor T1 is turned on, the drive capacitor C1 is discharged, and the trip coil and the moving coil pass through excitation currents in opposite directions. The trip coil and the moving coil generate magnetic fields in opposite directions, and the moving coil is subjected to an electromagnetic repulsive force in a downward direction. The driving connecting rod overcomes the holding force of the holding mechanism in the closing direction, so that the moving contact, the driving connecting rod and the moving coil move downward until the thyristor T1 is turned off, and the moving contact, the driving connecting rod and the moving coil enter the inertia stage. The current path of the electromagnetic drive mechanism and the discharge circuit in the trip drive stage is shown in FIG. Figure 3a shown.

[0050] (2) Disconnection buffer stage, such as Figure 2b and 3b As shown, the thyristor T2 is turned on, the buffer capacitor C2 is discharged, and the moving coil and the closing coil pass through the excitation current in opposite directions. The moving coil and the closing coil generate magnetic fields in opposite directions. The electromagnetic repulsion force on the moving coil is upward, and the holding force of the holding mechanism in the opening direction is overcome by the transmission connecting rod, and the movement speed of the moving contact, the transmission connecting rod and the moving coil in the opening direction is reduced. The parameter design of the discharge circuit in the buffer stage should enable the buffer capacitor to complete the discharge before reaching the opening position to prevent the opening rebound from being aggravated. The current path of the electromagnetic drive mechanism and the discharge circuit in the opening buffer stage is shown as follows: Figure 3b shown.

[0051] (3) Opening and holding stage, such as Figure 2c and 3c As shown, the thyristor T3 is turned on, the holding capacitor C3 is discharged, the moving coil and the closing coil pass through the excitation current in the same direction, the moving coil and the closing coil generate magnetic fields in the same direction, and the electromagnetic attraction force on the moving coil is downward. Under the joint action of the driving connecting rod and the opening holding force of the holding mechanism, the moving contact, the driving connecting rod and the moving coil are kept in the opening position, eliminating the rebound of the moving contact, the driving connecting rod and the moving coil. The holding mechanism provides the maximum opening position holding force to the driving connecting rod, the control system issues an electromagnetic holding command, the thyristor T3 is turned on, and the holding capacitor C3 generates a current through the closing coil and the moving coil connected in series in the forward direction and generates an electromagnetic attraction force. The moving coil is again subjected to the electromagnetic attraction force in the "opening direction", and this electromagnetic force and the holding mechanism form a composite holding mechanism to suppress the opening rebound. The design of the discharge circuit parameters in the holding stage should be based on factors such as the opening rebound technical indicators, the output curve of the holding mechanism, and the capacity of the buffer mechanism. The current path of the electromagnetic drive mechanism and the discharge circuit in the opening holding stage is shown as follows Figure 3c shown.

[0052] According to the control method of the fast mechanical switch based on the coil-type electromagnetic drive mechanism, the closing action process includes the following steps: the thyristor T2 is turned on, the buffer capacitor C2 is used as the closing drive capacitor, the moving coil and the closing coil generate magnetic fields in opposite directions, and the moving coil is subjected to the electromagnetic repulsion force in an upward direction, so that the holding force of the holding mechanism in the opening direction is overcome by the transmission connecting rod, so that the moving contact, the transmission connecting rod and the moving coil move upward until the moving contact reaches the specified closing position, and the closing action is completed. Since the average closing speed is low, there is no need to design a buffer device with too large a capacity, and buffer materials such as polyurethane can be used.

[0053] Compared with the traditional unidirectional electromagnetic drive mechanism, the bidirectional electromagnetic drive mechanism and the bidirectional electromagnetic drive mechanism with electromagnetic buffering, the above-mentioned fast mechanical switch and control method based on the coil-type electromagnetic drive mechanism can use electromagnetic force to complete the three functions of electromagnetic drive, electromagnetic buffering and electromagnetic holding during the opening process, which can improve the opening reliability and provide important reference value for the multifunctionalization of the electromagnetic drive mechanism; the instantaneous output requirements of the holding mechanism and the buffer mechanism are reduced by electromagnetic force, which helps to reduce the capacity of the mechanical mechanism and provide certain help for the miniaturization design of the electromagnetic drive mechanism.

[0054] Those skilled in the art will appreciate that numerous variations to the above description are possible, and that the examples and figures are intended only to describe one or more specific implementations.

[0055] Although what is considered as exemplary embodiments of the present invention has been described and described, it will be understood by those skilled in the art that various changes and substitutions may be made thereto without departing from the spirit of the present invention. In addition, many modifications may be made to adapt specific situations to the teachings of the present invention without departing from the central concept of the present invention described herein. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but the present invention may also include all embodiments and their equivalents that fall within the scope of the present invention.

Claims

1. A fast mechanical switch based on a coil-type electromagnetic drive mechanism, characterized in that: It includes a vacuum interrupter, a static contact, a moving contact, a transmission connecting rod, an electromagnetic drive mechanism, a discharge circuit, a holding mechanism and a buffer mechanism; The static contact is arranged in the vacuum interrupter and fixedly arranged on the top of the vacuum interrupter; The moving contact is arranged directly below the static contact, the lower end of the moving contact passes through the bottom surface of the vacuum interrupter and is fixedly connected to the upper end of the transmission connecting rod, and the moving contact can move up and down with the transmission connecting rod to realize closing or opening; The electromagnetic drive mechanism is arranged below the vacuum interrupter, and comprises an opening coil, a moving coil and a closing coil. The opening coil, the moving coil and the closing coil have the same winding direction and are all wound around the transmission connecting rod, and can provide electromagnetic driving force and electromagnetic buffering force during the opening or closing process, and provide instantaneous electromagnetic holding force at the end of the opening action; the moving coil is arranged on the transmission connecting rod and can move up and down with the transmission connecting rod, the moving coil is connected in reverse series with the opening coil, and the positive and reverse series relationship between the moving coil and the closing coil is determined by the current direction of the discharge circuit; the opening coil and the closing coil are fixed in position and are respectively arranged above and below the moving coil; The holding mechanism is arranged between the vacuum interrupter and the electromagnetic drive mechanism. When the moving contact and the moving coil are in the closing or opening position, the holding mechanism can provide a steady-state holding force through the transmission connecting rod; at the end of the closing or opening action, the holding mechanism can provide an instantaneous holding force through the transmission connecting rod; The buffer mechanism is arranged directly below the transmission connecting rod and provides a buffer force for the transmission connecting rod at the end of the opening action.

2. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 1, characterized in that: The transmission connecting rod is made of insulating material.

3. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 1, characterized in that: The opening coil, the moving coil and the closing coil all have two inner and outer outlet ports; the closing coil and four diodes form an H-bridge branch circuit, so that the closing coil current flows in from the inner side and flows out from the outer side.

4. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 3, characterized in that: The discharge circuit comprises a driving discharge branch, a buffer discharge branch and a holding discharge branch, each of which comprises a group of discharge capacitors and a group of thyristor control devices. The buffer discharge branch is connected in parallel with the holding discharge branch and in opposite directions.

5. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 4, characterized in that: The discharge circuit includes a driving capacitor C1, a buffer capacitor C2, a holding capacitor C3, a thyristor T1, a thyristor T2, and a thyristor T3; The driving capacitor C1 and the thyristor T1 are connected in series to form the driving discharge branch, the positive terminal of the driving discharge branch is connected to the inner terminal of the opening coil, the negative terminal of the driving discharge branch is connected to the inner terminal of the moving coil, and the outer terminal of the opening coil is connected to the outer terminal of the moving coil; The buffer capacitor C2 and the thyristor T2 are connected in series to form the buffer discharge branch, the positive terminal of the buffer discharge branch is connected to the diode and the upper terminal of the H-bridge branch, the negative terminal of the buffer discharge branch is connected to the inner terminal of the moving coil, and the outer terminal of the moving coil is connected to the lower terminal of the H-bridge branch; The holding capacitor C3 and the thyristor T3 are connected in series to form the holding discharge branch, the positive terminal of the holding discharge branch is connected to the inner terminal of the moving coil, the negative terminal of the holding discharge branch is connected to the upper terminal of the H-bridge branch, and the outer terminal of the moving coil is connected to the lower terminal of the H-bridge branch.

6. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 1, characterized in that: The retaining mechanism includes two fixed ends and two movable ends, one end of the movable end is connected to the fixed end, and the other end is connected to the transmission connecting rod, and can move up and down with the transmission connecting rod. The two fixed ends are symmetrically arranged with respect to the transmission connecting rod, and the two movable ends are symmetrically arranged with respect to the transmission connecting rod.

7. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 6, characterized in that: The fixed end is provided with a bistable spring, and the movable end is a plurality of connecting rods connected to each other.

8. The fast mechanical switch based on the coil type electromagnetic drive mechanism according to claim 1, characterized in that: When in the closing position, the distance between the buffer mechanism and the transmission connecting rod is less than the rated opening distance, so as to provide a buffer space for the final stage of the opening action.

9. A control method for a fast mechanical switch based on a coil-type electromagnetic drive mechanism according to claim 5, characterized in that: The opening action process includes the following steps: (1) In the opening drive stage, the thyristor T1 is turned on, the driving capacitor C1 is discharged, and the opening coil and the moving coil pass through excitation currents in opposite directions. The opening coil and the moving coil generate magnetic fields in opposite directions. The electromagnetic repulsion force on the moving coil is directed downward, and the holding force of the holding mechanism in the closing direction is overcome by the transmission connecting rod, so that the moving contact, the transmission connecting rod and the moving coil move downward; (2) During the opening buffer stage, the thyristor T2 is turned on, the buffer capacitor C2 is discharged, and excitation currents in opposite directions flow through the moving coil and the closing coil. The moving coil and the closing coil generate magnetic fields in opposite directions. The electromagnetic repulsion force on the moving coil is directed upward, and the holding force of the holding mechanism in the opening direction is overcome by the transmission connecting rod, and the movement speed of the moving contact, the transmission connecting rod and the moving coil in the opening direction is reduced; (3) During the opening and holding stage, the thyristor T3 is turned on, the holding capacitor C3 is discharged, and the moving coil and the closing coil are passed through an excitation current in the same direction. The moving coil and the closing coil generate magnetic fields in the same direction, and the electromagnetic attraction force on the moving coil is downward. Under the joint action of the opening holding force of the transmission connecting rod and the holding mechanism, the moving contact, the transmission connecting rod and the moving coil are kept in the opening position, eliminating the rebound of the moving contact, the transmission connecting rod and the moving coil.

10. The control method of a fast mechanical switch based on a coil-type electromagnetic drive mechanism according to claim 9, characterized in that: The closing action process includes the following steps: the thyristor T2 is turned on, the buffer capacitor C2 is used as the closing drive capacitor, the moving coil and the closing coil generate magnetic fields in opposite directions, and the moving coil is subjected to an electromagnetic repulsive force in an upward direction, thereby overcoming the holding force of the holding mechanism in the opening direction through the transmission connecting rod, so that the moving contact, the transmission connecting rod and the moving coil move upward.

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