Electromagnetic buffer circuit of rapid vacuum switch

Abstract

The invention discloses an electromagnetic buffer circuit of a rapid vacuum switch. The electromagnetic buffer circuit comprises a capacitor, a turn-off power electronic device, a first diode, a second diode, a coil and a resistor, the collector of the turn-off power electronic device is connected with the anode of the capacitor, the emitter is connected with the wire inlet end of the coil, and the base receives a switch control signal; the coil outlet end is connected with the cathode of the capacitor; the anode of the first diode is connected with the cathode of the capacitor, and the cathode of the first diode is connected with the anode of the capacitor; the anode of the second diode is connected with the coil leading-out terminal, and the cathode is connected with the resistor in series and then connected with the coil leading-in terminal; the switch control signal is used for adjusting the starting time and the duration of electromagnetic buffering. By controlling the turn-on and turn-off of the turn-off power electronic device, the turn-on of the main discharge loop of the electromagnetic buffer circuit and the switching of the first-stage or second-stage follow current loop are realized, and the buffer intervention time and the buffer duration are controlled.

Description

Technical Field

[0001] The invention relates to the technical field of power switch equipment, and in particular to an electromagnetic buffer circuit of a fast vacuum switch. Background Art

[0002] The fast vacuum switch has an extremely fast operating speed. If an effective buffer is not added, the high speed at the end of the switch operation will cause severe switch bounce, shorten its service life, and even cause the switch to fail to open or close. Therefore, the design of a reasonable buffer device is of great significance to the development of fast vacuum switches.

[0003] The electromagnetic buffering of the fast vacuum switch is a buffering solution based on a bidirectional electromagnetic repulsion mechanism. The principle is to generate a reverse electromagnetic force by discharging the coil in the buffer circuit to slow down the switch, thereby achieving the buffering effect. Since the buffering design of the fast vacuum switch needs to match the switch driving characteristics, and the existing electromagnetic buffering solution cannot freely adjust the buffering strength, when the motion characteristics of the fast vacuum switch change, it may cause the buffering design to be mismatched with the motion characteristics of the switch, resulting in the buffering effect not being able to function normally. Summary of the invention

[0004] The purpose of an embodiment of the present invention is to provide an electromagnetic buffer circuit for a fast vacuum switch. By controlling the on and off of a switchable power electronic device, the main discharge circuit of the electromagnetic buffer circuit can be turned on and the primary freewheeling circuit and the secondary freewheeling circuit can be switched, thereby controlling the intervention time and duration of the buffer.

[0005] To solve the above technical problems, a first aspect of an embodiment of the present invention provides an electromagnetic buffer circuit, including: a capacitor, a turn-off power electronic device, a first diode, a second diode, a coil and a resistor;

[0006] The collector of the switchable power electronic device is connected to the positive electrode of the capacitor, the emitter is connected to the inlet terminal of the coil, and the base receives a switch control signal;

[0007] The coil outlet terminal is connected to the negative electrode of the capacitor;

[0008] The first diode is connected in parallel with the capacitor, with its positive electrode connected to the negative electrode of the capacitor and its negative electrode connected to the positive electrode of the capacitor;

[0009] The anode of the second diode is connected to the coil outlet, and the cathode of the second diode is connected in series with the resistor and then connected to the coil inlet;

[0010] The capacitor, the turn-off power electronic device and the coil constitute a main discharge circuit, the first diode, the turn-off power electronic device and the coil constitute a primary freewheeling circuit, and the second diode, the coil and the resistor constitute a secondary freewheeling circuit;

[0011] The switch control signal is used to adjust the start time and duration of the electromagnetic buffer.

[0012] Further, the switch control signal includes: an on control signal and an off control signal;

[0013] The sending time of the conduction control signal corresponds to the start time of the electromagnetic buffer;

[0014] The interval duration between the on control signal and the off control signal corresponds to the duration of the current of the coil and the duration of the electromagnetic buffering.

[0015] Furthermore, the capacitor is in a pre-charge state before receiving the switch control signal.

[0016] Furthermore, the switchable power electronic device is a fully controlled power electronic device.

[0017] Furthermore, the resistance value of the resistor is greater than a first preset multiple of the resistance value of the coil.

[0018] Furthermore, the time constant of the primary freewheeling loop is greater than a second preset multiple of the time constant of the secondary freewheeling loop.

[0019] Further, after the switchable power electronic device is turned on and before the capacitor voltage value drops to 0, the main discharge circuit of the electromagnetic buffer circuit is an RLC discharge circuit;

[0020] When the capacitor voltage value drops to 0 and before the turn-off power electronic device is turned off, the primary freewheeling circuit of the electromagnetic buffer circuit is an RL discharge circuit.

[0021] Accordingly, a second aspect of an embodiment of the present invention provides an electromagnetic buffer circuit control method for controlling the electromagnetic buffer circuit, comprising the following steps:

[0022] Receiving a conduction control signal to control the conduction of a power electronic device that can be turned off;

[0023] Control the capacitor in the main discharge circuit to discharge to the coil;

[0024] When the voltage value of the capacitor drops to 0, the first diode in the primary freewheeling loop, the turn-off power electronic device and the coil are turned on, and the coil current begins to decay;

[0025] When a shutdown control signal is received, the second diode, the resistor and the coil in the secondary freewheeling loop are turned on, the coil current decays to 0, and the electromagnetic buffering process ends.

[0026] Furthermore, the electromagnetic buffer circuit control method further includes:

[0027] By adjusting the sending time of the conduction control signal, the start time of the electromagnetic buffer is correspondingly adjusted;

[0028] By adjusting the interval between the on control signal and the off control signal, the duration of the current in the coil and the duration of the electromagnetic buffer are adjusted accordingly.

[0029] Accordingly, a third aspect of an embodiment of the present invention provides a fast vacuum switch, comprising the above-mentioned electromagnetic buffer circuit,

[0030] It also includes: a vacuum interrupter, an insulating pull rod, an electromagnetic repulsion mechanism, a holding device and a buffer device;

[0031] The vacuum interrupter, the insulating pull rod, the holding device, the electromagnetic repulsion mechanism and the buffer device are connected in sequence;

[0032] When the fast vacuum switch performs a closing action, the coil of the electromagnetic buffer circuit is the opening coil of the electromagnetic repulsion mechanism, the capacitor in the electromagnetic buffer circuit is the opening capacitor of the electromagnetic repulsion mechanism, and the buffering effect is achieved by the opening coil of the electromagnetic repulsion mechanism;

[0033] When the fast vacuum switch performs the opening action, the coil of the electromagnetic buffer circuit is the closing coil of the electromagnetic repulsion mechanism, the capacitor in the electromagnetic buffer circuit is the closing capacitor of the electromagnetic repulsion mechanism, and the buffering effect is achieved by the closing coil of the electromagnetic repulsion mechanism;

[0034] When the fast vacuum switch performs a closing action, the capacitor of the electromagnetic buffer circuit discharges to the closing coil, and an electromagnetic repulsion force is generated between the repulsion disk of the electromagnetic repulsion mechanism and the closing coil to push the repulsion disk to move and drive the moving contact in the vacuum interrupter to move, thereby realizing the closing action of the fast vacuum switch. After a first preset time, the turnable power electronic device in the electromagnetic buffer circuit connected to the opening coil of the electromagnetic repulsion mechanism is turned on, and the capacitor discharges to the opening coil and generates an electromagnetic repulsion force in the opposite direction of the closing movement, thereby decelerating the repulsion disk and realizing buffering.

[0035] When the fast vacuum switch performs an opening action, the capacitor discharges to the opening coil, and an electromagnetic repulsive force is generated between the repulsion disk and the opening coil to push the repulsion disk to move and drive the moving contact in the vacuum interrupter to move, thereby realizing the opening action of the fast vacuum switch. After a second preset time, the turnable power electronic device connected to the closing coil is turned on, and the capacitor discharges to the closing coil and generates an electromagnetic repulsive force in the opposite direction of the opening movement, thereby decelerating the repulsion disk and realizing buffering.

[0036] The above technical solution of the embodiment of the present invention has the following beneficial technical effects:

[0037] 1. Through the on and off control signals of the power electronic device that can be turned off, the start time and duration of the electromagnetic snubber circuit can be accurately controlled, so that the electromagnetic snubber circuit can intervene at a specific time as needed and provide buffering force within an appropriate period of time, thereby protecting the fast vacuum switch from mechanical shock and electrical stress and extending its service life;

[0038] 2. By reducing the speed of the fast vacuum switch at the end of the movement and reducing the bounce of the switch, the wear and failure rate of the switch are effectively reduced, which helps to reduce the risk of switch opening and closing failure, improve the reliability of the switch, and ensure the stable operation of the power system;

[0039] 3. The control method of the electromagnetic snubber circuit allows the fast vacuum switch to switch between different working states to adapt to different snubber requirements, so that the snubber design can match the motion characteristics of the switch, which is beneficial to the design optimization of the fast vacuum switch. By controlling the on and off of the switchable power electronic device, the intervention time and duration of the snubber can be freely adjusted, making the switch design more flexible and meeting the needs of different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a schematic diagram of the structure of an electromagnetic buffer circuit provided by an embodiment of the present invention;

[0041] Figure 2 is a schematic diagram of an electromagnetic buffer circuit provided by an embodiment of the present invention working in a discharge loop state;

[0042] Figure 3 is a schematic diagram of an electromagnetic snubber circuit provided by an embodiment of the present invention working in a primary freewheeling loop state;

[0043] Figure 4 It is a schematic diagram of the electromagnetic snubber circuit provided by an embodiment of the present invention working in a secondary freewheeling loop state. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0045] Please refer to Figure 1 The first aspect of the embodiment of the present invention provides an electromagnetic buffer circuit, including: a capacitor, a turn-off power electronic device, a first diode, a second diode, a coil and a resistor. The collector of the turn-off power electronic device is connected to the positive electrode of the capacitor, the emitter is connected to the coil input terminal, and the base receives a switch control signal; the coil output terminal is connected to the negative electrode of the capacitor; the first diode is connected in parallel with the capacitor, the positive electrode is connected to the negative electrode of the capacitor, and the negative electrode is connected to the positive electrode of the capacitor; the positive electrode of the second diode is connected to the coil output terminal, and the negative electrode is connected in series with the resistor and then connected to the coil input terminal; the capacitor, the turn-off power electronic device and the coil constitute a main discharge circuit, the first diode, the turn-off power electronic device and the coil constitute a primary freewheeling circuit, and the second diode, the coil and the resistor constitute a secondary freewheeling circuit; the switch control signal is used to adjust the start time and duration of the electromagnetic buffer.

[0046] The switchable power electronic device has a controllable switch-off current. By controlling the on and off of the switchable power electronic device, the main discharge circuit of the electromagnetic buffer circuit can be turned on and the primary freewheeling circuit and the secondary freewheeling circuit can be switched, thereby controlling the buffering intervention time and buffering duration.

[0047] Specifically, the switch control signal includes: an on-control signal and an off-control signal; the sending time of the on-control signal corresponds to the start time of the electromagnetic buffer; the interval between the on-control signal and the off-control signal corresponds to the current duration of the coil and the electromagnetic buffer duration, and the current duration is synchronized with the electromagnetic buffer duration.

[0048] The buffer force generated by the electromagnetic buffer circuit can reduce the speed of the fast vacuum switch at the end of its movement and reduce the bounce of the switch, thereby extending the service life of the switch and reducing the failure rate of the switch opening and closing. By controlling the on and off of the turn-off power electronic device, the electromagnetic buffer circuit can switch between three different working states, and then freely adjust the intervention time and duration of the buffer, so that the buffer design is easy to match the movement characteristics of the switch, which is beneficial to the design of the fast vacuum switch.

[0049] Optionally, the type of coil can be: solenoid coil, rectangular coil, Helmholtz coil or superconducting coil. In the electromagnetic buffer circuit of the fast vacuum switch, the solenoid coil can generate a magnetic field through the current, interact with the moving parts of the switch, and generate a buffer force; the rectangular coil can better adapt to the structure and space limitations of the switch, and is convenient for installation and integration; the Helmholtz coil can generate a wider uniform magnetic field near the midpoint of its common axis, and the current and the magnetic field have a good linear relationship. The Helmholtz coil can provide a stable and uniform magnetic field, and accurately buffer the movement of the switch, which is especially suitable for occasions with high requirements for buffering effects; the superconducting coil can provide a strong buffer force, which can effectively reduce the speed of the switch at the end of the movement and reduce the bounce of the switch.

[0050] like Figure 1 As shown, the resistance R and inductance L in the coil are the equivalent resistance and equivalent inductance of the coil respectively.

[0051] Furthermore, the capacitor is in a pre-charged state before receiving the switch control signal. The pre-charged state of the capacitor in the electromagnetic buffer circuit means that the capacitor has been charged to a certain voltage level before the circuit starts working. In the electromagnetic buffer circuit, the pre-charged state of the capacitor ensures that when the switchable power electronic device is turned on, the capacitor can quickly release the stored energy, generate electromagnetic force through the coil, and achieve a buffering effect on the fast vacuum switch. This pre-charged state helps to reduce the speed of the switch at the end of the movement, reduce the bounce of the switch, thereby extending the service life of the switch and reducing the failure rate of the switch opening and closing.

[0052] Furthermore, the switchable power electronic device is a fully controlled power electronic device, and specifically, an IGBT (insulated gate bipolar transistor) or a GTR (power transistor) can be selected.

[0053] IGBT is a composite fully controlled voltage-driven power semiconductor device that combines the advantages of MOSFET's high input impedance and GTR's low on-state voltage drop. IGBT consists of an N-channel MOSFET and a PNP bipolar transistor, and its on and off states are achieved by controlling the gate voltage. Under the action of the forward gate voltage, the MOSFET forms a channel, allowing the current between the P+ base and the N- layer to flow, thereby providing the base current for the PNP transistor and turning on the IGBT. When the gate voltage is zero or reverse, the channel disappears, the base current of the PNP transistor is cut off, and the IGBT is turned off. IGBT is widely used in inverters, electric vehicles, power transmission and other fields, especially in converter systems with DC voltages of 600V and above.

[0054] GTR, also known as giant transistor, is a bipolar junction transistor (BJT) that can withstand high voltage and high current. The structure and working principle of GTR are the same as those of ordinary bipolar junction transistors, but its most important characteristics are high voltage resistance, high current, and good switching characteristics. GTR is a bipolar device with high current gain and high voltage blocking capability, which can achieve fast switching through gate signals. The applications of GTR include motor control, high-voltage switching power supply and other fields.

[0055] In the electromagnetic snubber circuit, both IGBT and GTR are turnable power electronic devices, which control the current in the circuit by controlling their on and off. IGBT is particularly suitable for applications that require high input impedance and low on-state voltage drop because it combines the advantages of MOSFET and GTR, while GTR has unique advantages in high voltage and high current applications due to its high withstand voltage and high current characteristics. By accurately controlling these devices, the electromagnetic snubber circuit can be accurately controlled to achieve the desired buffering effect.

[0056] Furthermore, the resistance value is greater than the first preset multiple of the coil resistance value; the time constant of the primary freewheeling circuit is greater than the second preset multiple of the time constant of the secondary freewheeling circuit. The resistor R1 is much greater than the resistance value R of the coil, and the turn-off power electronic device is turned off. Under the action of the second diode, the electromagnetic buffer circuit switches from the primary freewheeling circuit to the secondary freewheeling circuit. The time constant τ1 of the secondary freewheeling circuit is much smaller than the time constant τ of the primary freewheeling circuit. The coil current decays rapidly to 0, and the electromagnetic buffer ends.

[0057] By precisely designing the resistance values ​​of the resistor and coil as well as their time constants, the electromagnetic snubber circuit can achieve more precise control of the timing and duration of the buffering intervention, which not only helps protect the circuit from damage caused by excessive current, but also allows the circuit state to be quickly switched as needed to achieve effective electromagnetic snubbering.

[0058] Furthermore, after the turn-off power electronic device is turned on and before the voltage value of the capacitor drops to 0, the main discharge circuit of the electromagnetic buffer circuit is an RLC discharge circuit, wherein R is the equivalent resistance of the coil, L is the equivalent inductance of the coil, and C is the capacitor; and when the voltage value of the capacitor drops to 0 and before the turn-off power electronic device is turned off, the primary freewheeling circuit of the electromagnetic buffer circuit is an RL discharge circuit, wherein R is the equivalent resistance of the coil, and L is the equivalent inductance of the coil.

[0059] The RLC discharge circuit is a circuit composed of the equivalent resistance R of the coil, the equivalent inductance L and the capacitor C. In the electromagnetic buffer circuit, when the capacitor is charged to a certain voltage, the power electronic device can be turned off and the capacitor begins to discharge through the coil. During the discharge process, the voltage of the capacitor gradually decreases, the current passes through the coil to generate a magnetic field, and the resistor consumes electrical energy and converts it into heat energy. The RLC circuit has the characteristics of oscillating discharge. When the capacitor is discharged, an oscillating current will be generated, and the interaction between the inductance and capacitance will cause electromagnetic oscillation.

[0060] In the RL discharge circuit, when the capacitor voltage drops to 0, the power electronic device can be turned off, and the circuit is transformed into an RL discharge circuit, which only contains resistors and coils. In the RL discharge circuit, the magnetic field energy in the coil begins to be released through the resistor, and the current gradually decays. Since there is no capacitor involved, the circuit no longer has the characteristics of oscillating discharge, but shows a monotonic decay of current. The discharge process of the RL discharge circuit is usually a non-periodic decay process. The inductance of the coil will drop rapidly under the action of the DC voltage, causing the current to decay rapidly.

[0061] Please refer to Figure 2 At the preset time, the switchable power electronic device is controlled to be turned on, the electromagnetic buffer circuit starts working, and the pre-charged capacitor starts to discharge. The current path in the circuit is from the capacitor through the switchable power electronic device, into the coil, and finally back to the capacitor. Both diodes are reversely cut off. At this time, the working circuit is the RLC discharge circuit, the coil current continues to increase, and the reverse electromagnetic force generated by this continues to increase, which begins to play a buffering role for the fast vacuum switch.

[0062] Please refer to Figure 3 , the capacitor in the electromagnetic snubber circuit is continuously discharged, and the voltage gradually drops to 0, and no current flows. At this time, the first diode begins to conduct, forming a primary freewheeling loop with the turn-off power electronic device and the coil. The coil current begins to decay, and the decay rate is related to the time constant τ of the loop. The buffering effect of the electromagnetic snubber circuit on the fast vacuum switch is still continuing, but gradually weakening.

[0063] Please refer to Figure 4 , the turn-off power electronic device is controlled to be turned off at the appropriate time, the working state of the electromagnetic buffer circuit is switched, the second diode starts to conduct, and forms a secondary freewheeling circuit with the resistor and coil in series with the freewheeling circuit. Because the serial resistor R1 is much larger than the resistance R of the coil, the time constant τ1 of the secondary freewheeling circuit is much smaller than the time constant τ of the primary freewheeling circuit. The coil current decays rapidly in the secondary freewheeling circuit and drops to 0. The buffering effect of the electromagnetic buffer circuit on the fast vacuum switch is rapidly weakened until it disappears.

[0064] By controlling the on and off of the switchable power electronic device, in conjunction with the first diode and the second diode, the electromagnetic buffer circuit can be switched between different working states. The longer the switchable power electronic device is on, the longer the coil current lasts in the buffer circuit, and the longer the corresponding electromagnetic buffer force action time is. The electromagnetic buffer circuit of the present invention can freely adjust the buffer intervention time and buffer duration, so that the buffer characteristics can effectively match the fast vacuum switch motion characteristics.

[0065] Accordingly, a second aspect of an embodiment of the present invention provides an electromagnetic buffer circuit control method for controlling the electromagnetic buffer circuit, comprising the following steps:

[0066] Step S100, receiving a conduction control signal, and controlling a switchable power electronic device to conduct.

[0067] By receiving and responding to the turn-on control signal of the shut-off power electronic device, the start-up timing of the electromagnetic snubber circuit can be accurately controlled to ensure that the snubber force is provided when needed.

[0068] Step S200, controlling the capacitor in the main discharge circuit to discharge to the coil.

[0069] The capacitor in the main discharge circuit is controlled to discharge into the coil, so that the energy stored in the capacitor can be effectively converted into electromagnetic energy in the coil to drive the load or provide buffering force.

[0070] Step S300, when the voltage value of the capacitor drops to 0, the first diode, the turn-off power electronic device and the coil in the primary freewheeling loop are turned on, and the coil current begins to decay.

[0071] When the capacitor voltage drops to 0, the conduction of the primary freewheeling circuit achieves a smooth transition from capacitor discharge to coil current maintenance, which helps reduce current shock and electromagnetic interference in the circuit.

[0072] Step S400, receiving a shutdown control signal, the second diode, the resistor and the coil in the secondary freewheeling loop are turned on, the coil current decays to 0, and the electromagnetic buffering process ends.

[0073] By receiving the shutdown control signal of the shutoff power electronic device, the secondary freewheeling loop is quickly activated, so that the coil current decays quickly to 0, thereby quickly ending the electromagnetic buffering process, reducing energy loss and improving response speed.

[0074] Furthermore, the electromagnetic buffer circuit control method further includes:

[0075] Step S510, adjusting the sending time of the conduction control signal to correspondingly adjust the electromagnetic buffering start time.

[0076] Step S520, by adjusting the interval between the on control signal and the off control signal, the current duration of the coil and the electromagnetic buffer duration are correspondingly adjusted.

[0077] The above control method can reduce the speed of the fast vacuum switch at the end of its movement and reduce the bounce of the switch by controlling the electromagnetic buffer circuit, thereby extending the service life of the switch and reducing the failure rate of the switch opening and closing; the electromagnetic buffer circuit can be switched between three different working states (main discharge, primary freewheeling, and secondary freewheeling) to adapt to different buffering requirements, making the buffer design easy to match the movement characteristics of the switch; by accurately controlling the conduction and shutdown of the switchable power electronic devices, the electromagnetic buffer circuit can provide necessary protection at critical moments to avoid damage to circuit components due to current shock or overvoltage, thereby improving the safety of the entire system.

[0078] Correspondingly, a third aspect of an embodiment of the present invention provides a fast vacuum switch, including the above-mentioned electromagnetic buffer circuit, and also including: a vacuum arc chamber, an insulating pull rod, an electromagnetic repulsion mechanism, a retaining device and a buffer device; the vacuum arc chamber, the insulating pull rod, the retaining device, the electromagnetic repulsion mechanism and the buffer device are connected in sequence.

[0079] When the fast vacuum switch performs the closing action, the coil of the electromagnetic buffer circuit is the opening coil of the electromagnetic repulsion mechanism, and the capacitor in the electromagnetic buffer circuit is the opening capacitor of the electromagnetic repulsion mechanism. The buffering effect is achieved by the opening coil of the electromagnetic repulsion mechanism. When the fast vacuum switch performs the closing action, the capacitor of the electromagnetic buffer circuit discharges to the closing coil, and the electromagnetic repulsion force is generated between the repulsion disk of the electromagnetic repulsion mechanism and the closing coil to push the repulsion disk to move and drive the moving contact in the vacuum interrupter to move, so as to achieve the closing action of the fast vacuum switch. After the first preset time, the turn-off power electronic device in the electromagnetic buffer circuit connected to the opening coil of the electromagnetic repulsion mechanism is turned on, and the capacitor discharges to the opening coil and generates an electromagnetic repulsion force in the opposite direction of the closing movement, which decelerates the repulsion disk and achieves buffering.

[0080] When the fast vacuum switch performs the opening action, the coil of the electromagnetic buffer circuit is the closing coil of the electromagnetic repulsion mechanism, and the capacitor in the electromagnetic buffer circuit is the closing capacitor of the electromagnetic repulsion mechanism. The buffering effect is achieved by the closing coil of the electromagnetic repulsion mechanism. When the fast vacuum switch performs the opening action, the capacitor discharges to the opening coil, and the electromagnetic repulsion force generated between the repulsion disk and the opening coil pushes the repulsion disk to move and drives the moving contact in the vacuum interrupter to move, so as to realize the opening action of the fast vacuum switch. After the second preset time, the turn-off power electronic device connected to the closing coil is turned on, and the capacitor discharges to the closing coil and generates an electromagnetic repulsion force in the opposite direction of the opening movement, which decelerates the repulsion disk and realizes buffering.

[0081] The insulating pull rod connects the vacuum interrupter and the electromagnetic repulsion mechanism and plays an insulating role; the holding device provides a holding force to stabilize the fast vacuum switch in the open state or the closed state; the buffer device can reduce the terminal speed of the opening action of the fast vacuum switch, and cooperate with the electromagnetic buffer circuit to buffer the opening action of the fast vacuum switch.

[0082] Fast vacuum switches can achieve higher breaking capacity through the application of electromagnetic buffer circuits. Their rated short-circuit breaking current can reach up to 100kA and their rated voltage can reach up to 242kV. At the same time, the development of operating mechanism technology has shortened the breaking time of vacuum circuit breakers. Vacuum circuit breakers using electromagnetic repulsion mechanisms can shorten the breaking time of short-circuit fault currents to within half a cycle. The buffering problem in fast vacuum switches is solved through electromagnetic buffer circuits. Electromagnetic buffering is the most suitable buffering method for fast switches. It can ensure the "soft landing" of moving parts in fast vacuum switches, thereby obtaining a smooth stroke characteristic curve and avoiding strong mechanical impact during the operation of high-voltage fast switches.

[0083] The embodiment of the present invention aims to protect an electromagnetic buffer circuit and its control method, and a fast vacuum switch, wherein the electromagnetic buffer circuit includes: a capacitor, a turn-off power electronic device, a first diode, a second diode, a coil and a resistor; the collector of the turn-off power electronic device is connected to the positive electrode of the capacitor, its emitter is connected to the coil input terminal, and its base receives a switch control signal; the coil output terminal is connected to the negative electrode of the capacitor; the first diode is connected in parallel with the capacitor, its positive electrode is connected to the negative electrode of the capacitor, and its negative electrode is connected to the positive electrode of the capacitor; the positive electrode of the second diode is connected to the coil output terminal, and its negative electrode is connected in series with the resistor and then connected to the coil input terminal; the capacitor, the turn-off power electronic device and the coil constitute a main discharge circuit, the first diode, the turn-off power electronic device and the coil constitute a primary freewheeling circuit, and the second diode, the coil and the resistor constitute a secondary freewheeling circuit; the switch control signal is used to adjust the start time and duration of the electromagnetic buffer. The above technical solution has the following effects:

[0084] 1. Through the on and off control signals of the power electronic device that can be turned off, the start time and duration of the electromagnetic snubber circuit can be accurately controlled, so that the electromagnetic snubber circuit can intervene at a specific time as needed and provide buffering force within an appropriate period of time, thereby protecting the fast vacuum switch from mechanical shock and electrical stress and extending its service life;

[0085] 2. By reducing the speed of the fast vacuum switch at the end of the movement and reducing the bounce of the switch, the wear and failure rate of the switch are effectively reduced, which helps to reduce the risk of switch opening and closing failure, improve the reliability of the switch, and ensure the stable operation of the power system;

[0086] 3. The control method of the electromagnetic snubber circuit allows the fast vacuum switch to switch between different working states to adapt to different snubber requirements, so that the snubber design can match the motion characteristics of the switch, which is beneficial to the design optimization of the fast vacuum switch. By controlling the on and off of the switchable power electronic device, the intervention time and duration of the snubber can be freely adjusted, making the switch design more flexible and meeting the needs of different application scenarios.

[0087] It should be understood that the above specific embodiments of the present invention are only used to illustrate or explain the principles of the present invention, and do not constitute a limitation of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or the equivalent forms of such scope and boundaries.

Claims

1. An electromagnetic buffer circuit, characterized in that: include: A capacitor, a turn-off power electronic device, a first diode, a second diode, a coil and a resistor; The collector of the switchable power electronic device is connected to the positive electrode of the capacitor, the emitter is connected to the inlet terminal of the coil, and the base receives a switch control signal; The coil outlet terminal is connected to the negative electrode of the capacitor; The first diode is connected in parallel with the capacitor, with its positive electrode connected to the negative electrode of the capacitor and its negative electrode connected to the positive electrode of the capacitor; The anode of the second diode is connected to the coil outlet, and the cathode of the second diode is connected in series with the resistor and then connected to the coil inlet; The capacitor, the turn-off power electronic device and the coil constitute a main discharge circuit, the first diode, the turn-off power electronic device and the coil constitute a primary freewheeling circuit, and the second diode, the coil and the resistor constitute a secondary freewheeling circuit; The switch control signal is used to adjust the start time and duration of the electromagnetic buffer.

2. The electromagnetic buffer circuit according to claim 1, characterized in that: The switch control signal includes: a turn-on control signal and a turn-off control signal; The sending time of the conduction control signal corresponds to the start time of the electromagnetic buffer; The interval duration between the on control signal and the off control signal corresponds to the duration of the current of the coil and the duration of the electromagnetic buffering.

3. The electromagnetic buffer circuit according to claim 1, characterized in that: The capacitor is in a pre-charge state before receiving the switch control signal.

4. The electromagnetic buffer circuit according to claim 1, characterized in that: The switchable power electronic device is a fully controlled power electronic device.

5. The electromagnetic buffer circuit according to claim 1, characterized in that: The resistance value of the resistor is greater than a first preset multiple of the resistance value of the coil.

6. The electromagnetic buffer circuit according to claim 1, characterized in that: The time constant of the primary freewheeling loop is greater than a second preset multiple of the time constant of the secondary freewheeling loop.

7. The electromagnetic buffer circuit according to any one of claims 1 to 6, characterized in that: When the switchable power electronic device is turned on and before the capacitor voltage drops to 0, the main discharge circuit of the electromagnetic buffer circuit is an RLC discharge circuit; When the capacitor voltage value drops to 0 and before the turn-off power electronic device is turned off, the primary freewheeling circuit of the electromagnetic buffer circuit is an RL discharge circuit.

8. A method for controlling an electromagnetic buffer circuit, characterized in that: Used to control the electromagnetic buffer circuit as claimed in any one of claims 1 to 7, comprising the following steps: Receiving a conduction control signal to control the conduction of a power electronic device that can be turned off; Control the capacitor in the main discharge circuit to discharge to the coil; When the voltage value of the capacitor drops to 0, the first diode in the primary freewheeling loop, the turn-off power electronic device and the coil are turned on, and the coil current begins to decay; When a shutdown control signal is received, the second diode, the resistor and the coil in the secondary freewheeling loop are turned on, the coil current decays to 0, and the electromagnetic buffering process ends.

9. The electromagnetic buffer circuit control method according to claim 8, characterized in that: Also includes: By adjusting the sending time of the conduction control signal, the start time of the electromagnetic buffer is correspondingly adjusted; By adjusting the interval between the on control signal and the off control signal, the duration of the current in the coil and the duration of the electromagnetic buffer are adjusted accordingly.

10. A fast vacuum switch, characterized in that: The electromagnetic buffer circuit comprises any one of claims 1 to 7, further comprising: a vacuum interrupter, an insulating pull rod, an electromagnetic repulsion mechanism, a holding device and a buffer device; The vacuum interrupter, the insulating pull rod, the holding device, the electromagnetic repulsion mechanism and the buffer device are connected in sequence; When the fast vacuum switch performs a closing action, the coil of the electromagnetic buffer circuit is the opening coil of the electromagnetic repulsion mechanism, the capacitor in the electromagnetic buffer circuit is the opening capacitor of the electromagnetic repulsion mechanism, and the buffering effect is achieved by the opening coil of the electromagnetic repulsion mechanism; When the fast vacuum switch performs the opening action, the coil of the electromagnetic buffer circuit is the closing coil of the electromagnetic repulsion mechanism, the capacitor in the electromagnetic buffer circuit is the closing capacitor of the electromagnetic repulsion mechanism, and the buffering effect is achieved by the closing coil of the electromagnetic repulsion mechanism; When the fast vacuum switch performs a closing action, the capacitor of the electromagnetic buffer circuit discharges to the closing coil, and an electromagnetic repulsion force is generated between the repulsion disk of the electromagnetic repulsion mechanism and the closing coil to push the repulsion disk to move and drive the moving contact in the vacuum interrupter to move, thereby realizing the closing action of the fast vacuum switch. After a first preset time, the turnable power electronic device in the electromagnetic buffer circuit connected to the opening coil of the electromagnetic repulsion mechanism is turned on, and the capacitor discharges to the opening coil and generates an electromagnetic repulsion force in the opposite direction of the closing movement, thereby decelerating the repulsion disk and realizing buffering. When the fast vacuum switch performs an opening action, the capacitor discharges to the opening coil, and an electromagnetic repulsive force is generated between the repulsion disk and the opening coil to push the repulsion disk to move and drive the moving contact in the vacuum interrupter to move, thereby realizing the opening action of the fast vacuum switch. After a second preset time, the turnable power electronic device connected to the closing coil is turned on, and the capacitor discharges to the closing coil and generates an electromagnetic repulsive force in the opposite direction of the opening movement, thereby decelerating the repulsion disk and realizing buffering.

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