Permanent magnet mechanism and bypass switch structure

Abstract

This application relates to a permanent magnet mechanism and a bypass switch structure. The permanent magnet mechanism includes a permanent magnet mechanism body and a control circuit. The permanent magnet mechanism body includes a moving iron core, a permanent magnet, a stationary iron core, a pull rod, a compression spring, an iron core shaft, a first coil, a second coil, and a power supply. When the circuit is open, the moving iron core, the permanent magnet, and the stationary iron core generate magnetic flux in a first direction, causing the moving iron core and the stationary iron core to attract each other and compressing the compression spring. The control circuit controls the power supply to alternately power the first coil and the second coil, so that the energized first coil or the energized second coil generates magnetic flux in a second direction, eliminating the magnetic force between the moving iron core and the stationary iron core. The second direction is opposite to the first direction. Thus, by using the control circuit to alternately energize the first coil and the second coil, it can be ensured that at least one set of coils is energized at any given time, while effectively reducing the possibility of coil thermal failure, thereby improving the reliability of the bypass switch during use.

Description

Technical Field

[0001] This application relates to the field of flexible DC transmission technology, and in particular to permanent magnet mechanisms and bypass switch structures. Background Technology

[0002] With the rapid development of renewable energy power generation and flexible DC transmission technology, flexible DC converter valves are being used more and more widely in power systems. During operation, flexible DC converter valves may gradually age due to factors such as electrochemical corrosion and capacitance decay. To ensure the stable operation of the power system, it is often necessary to equip flexible DC converter valves with bypass switches, which are used to quickly short-circuit and bypass the submodules in the flexible DC converter valve when a failure occurs.

[0003] In related technologies, the bypass switches widely used in flexible DC converter valve submodules are mostly single-coil permanent magnet mechanisms. Their working principle is as follows: upon receiving a fault signal, current is supplied to the coil, generating a magnetic field opposite to that of the permanent magnet mechanism. This counteracts the permanent magnet's attraction, causing the moving and stationary contacts to close, thus achieving bypass closing and enabling bypass operation of the faulty submodule in the flexible DC converter valve. However, because the single coil continuously carries current during the closing process, prolonged energization leads to severe coil heating, which may cause coil failure, thereby causing the bypass switch to fail. Summary of the Invention

[0004] Therefore, it is necessary to provide a permanent magnet mechanism and a bypass switch structure to address the problem of coil failure caused by prolonged energization, which in turn leads to bypass switch failure.

[0005] In a first aspect, this application provides a permanent magnet mechanism, comprising:

[0006] The permanent magnet mechanism body includes a moving iron core, a permanent magnet, a stationary iron core, a pull rod, a compression spring, an iron core shaft, a first coil, a second coil, and a power supply. The moving iron core passes through the pull rod, and the permanent magnet is coaxially arranged around the moving iron core. The stationary iron core passes through the iron core shaft and is arranged opposite to the moving iron core. The compression spring is located between the moving and stationary iron cores, with one end connected to the iron core shaft and the other end connected to the pull rod. The end of the pull rod away from the compression spring is connected to the driving end of the moving copper busbar. When the circuit is open, the moving iron core, the permanent magnet, and the stationary iron core generate magnetic flux along a first direction, causing the moving and stationary iron cores to attract each other and compressing the compression spring. The first and second coils are sleeved around the permanent magnet.

[0007] The control circuit is used to control the power supply to alternately supply power to the first coil and the second coil, so that the first coil or the second coil after being energized generates a magnetic flux in a second direction, thereby eliminating the magnetic force between the moving iron core and the stationary iron core. The second direction is opposite to the first direction.

[0008] In one embodiment, the control circuit includes:

[0009] The first control sub-circuit is connected to the power supply and is also connected to the charging terminal of the first coil.

[0010] The second control sub-circuit is connected to the power supply and is also connected to the charging terminal of the second coil.

[0011] The power-on control sub-circuit includes a first output terminal and a second output terminal. The first output terminal is connected to a first control sub-circuit, and the second output terminal is connected to a second control sub-circuit. The first output terminal is used to output a first pulse width modulation signal, and the second output terminal is used to output a second pulse width modulation signal. The first level signal in the first pulse width modulation signal and the first level signal in the second pulse width modulation signal appear alternately.

[0012] When the first control subcircuit receives a first level signal in the first pulse width modulation signal, the first coil is turned on; when the first control subcircuit receives a second level signal in the first pulse width modulation signal, the second coil is turned on.

[0013] In one embodiment, there is a time delay between the first pulse width modulation signal and the second pulse width modulation signal. The time delay is determined based on the duration during which the second pulse width modulation signal remains at the first level when the first pulse width modulation signal switches from the second level to the first level, or when the first pulse width modulation signal switches from the first level to the second level.

[0014] In one embodiment, both the first control sub-circuit and the second control sub-circuit include:

[0015] Switching unit;

[0016] An energy storage unit is connected to a power supply and a switching unit. The energy storage unit, the coil, and the switching unit form a charging and discharging control circuit. The coil includes a first coil and a second coil.

[0017] The bleeder unit has its first end connected to the switch unit and its second end connected to the output of the power-on control sub-circuit, and is used to receive pulse width modulation signals; the pulse width modulation signals include a first pulse width modulation signal and a second pulse width modulation signal.

[0018] In one embodiment, the switching unit includes an IGBT switch, a first terminal of which is connected to the energy storage unit, and a second terminal of which is connected to the coil; the discharge unit includes:

[0019] The first bleed resistor has its first end connected to the third end of the IGBT switch, and its second end connected to the output end of the power-on control sub-circuit. The output end of the power-on control sub-circuit includes a first output end and a second output end.

[0020] The second bleeder resistor is connected in parallel with the first bleeder resistor, and the first end of the second bleeder resistor is connected to the output end of the power-on control sub-circuit.

[0021] The diode's cathode is connected to the second terminal of the second bleeder resistor, and the diode's anode is connected to the third terminal of the IGBT switch.

[0022] In one embodiment, the first control sub-circuit and the second control sub-circuit further include a current-limiting resistor, with a first end of the current-limiting resistor connected to the switching unit and a second end of the current-limiting resistor connected to the coil.

[0023] In one embodiment, the permanent magnet mechanism is applicable to multiple sub-modules connected in series in a flexible DC converter valve. The power supply includes an energy harvesting power supply and a first redundant power supply. The energy harvesting power supply is connected to a first control sub-circuit and a second control sub-circuit. The energy harvesting power supply is connected to a power-on control sub-circuit through a converter. The first redundant power supply is connected to a control sub-circuit in an adjacent sub-module.

[0024] In one embodiment, the power supply further includes a second redundant power supply connected to a power-on control sub-circuit in an adjacent sub-module.

[0025] In one embodiment, the permanent magnet mechanism further includes a bypass drive board and a module control board, with the first control sub-circuit and the second control sub-circuit both disposed on the bypass drive board; the power-on control sub-circuit is disposed on the module control board.

[0026] The first redundant power supply includes a first redundant sub-power supply and a second redundant sub-power supply. The first redundant sub-power supply is connected to the first control sub-circuit in the control sub-circuit of the adjacent sub-module; the second redundant sub-power supply is connected to the second control sub-circuit in the control sub-circuit of the adjacent sub-module.

[0027] Secondly, this application provides a bypass switch structure applicable to any of the permanent magnet mechanisms provided in the first aspect. The bypass switch structure further includes a housing, a stationary copper busbar and a moving copper busbar disposed within the housing, and an overtravel insulator connected to the driving end of the moving copper busbar. The end of the overtravel insulator away from the moving copper busbar is connected to the end of the pull rod away from the compression spring.

[0028] The aforementioned permanent magnet mechanism includes a permanent magnet mechanism body and a control circuit. The permanent magnet mechanism body includes a moving iron core, a permanent magnet, a stationary iron core, a pull rod, a compression spring, an iron core shaft, a first coil, a second coil, and a power supply. The moving iron core passes through the pull rod, and the permanent magnet is coaxially arranged around the moving iron core. The stationary iron core passes through the iron core shaft, and the stationary iron core is arranged opposite to the moving iron core. The compression spring is located between the moving iron core and the stationary iron core, with one end of the compression spring connected to the iron core shaft and the other end connected to the pull rod. The end of the pull rod away from the compression spring is connected to the driving end of the moving copper busbar. When the circuit is open, the moving iron core, the permanent magnet, and the stationary iron core generate magnetic flux in a first direction, causing the moving iron core and the stationary iron core to attract each other and the compression spring to be in a compressed state. The first coil and the second coil are sleeved around the permanent magnet. The control circuit is used to control the power supply to alternately supply power to the first coil and the second coil, so that the energized first coil or the energized second coil generates magnetic flux in a second direction, eliminating the magnetic force between the moving iron core and the stationary iron core. The second direction is opposite to the first direction. In this way, by controlling the circuit, the first coil and the second coil are alternately energized, ensuring that at least one set of coils is energized at any given time, while also reducing the average heating power of the coils and the temperature of the coils when they reach steady state, thereby effectively reducing the possibility of coil thermal failure and improving the reliability of the bypass switch. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the permanent magnet mechanism in some embodiments of this application;

[0031] Figure 2 The following are structural schematic diagrams illustrating the bypass switch structure in some embodiments of this application;

[0032] Figure 3 The following are schematic diagrams illustrating the structure of the control circuit in some embodiments of this application;

[0033] Figure 4 This is a schematic diagram of PWM pulse waveforms used in some embodiments of this application to illustrate the alternating operation of the first coil and the second coil;

[0034] Figure 5 This is a schematic diagram illustrating the connection relationship between the control sub-circuit, the power-on control sub-circuit, and the power supply in some embodiments of this application;

[0035] Figure 6This is a schematic diagram illustrating the connection relationship between two adjacent control circuits and the power supply in some embodiments of this application;

[0036] Figure 7 This is a schematic diagram illustrating a redundant power supply structure in some embodiments of this application.

[0037] Explanation of icon numbers:

[0038] 100. Permanent magnet mechanism body; 101. Moving iron core; 102. Permanent magnet; 103. Stationary iron core; 104. Pull rod; 105. Compression spring; 106. Iron core shaft; 107. First coil; 108. Second coil; 109. Power supply; 1091. Energy harvesting power supply; 1092. First redundant power supply; 1093. Second redundant power supply; 110. Magnetic cylinder; 111. Magnetic shielding sheet; 112. Magnetic ring; 200. Control circuit; 210. First control sub-circuit; 220. Second control sub-circuit; 212. Switching unit; 214. Energy storage unit; 216. Discharge unit; 230. Power-on control sub-circuit; 300. Bypass drive board; 400. Module control board; 500. Housing; 600. Stationary copper busbar; 700. Moving copper busbar; 800. Overtravel insulator; 900. Vacuum interrupter. Detailed Implementation

[0039] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0040] In the description of this application, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," "vertical," and "horizontal," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0042] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixation," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction between two elements, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. It should be noted that when an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element present.

[0043] With the rapid development of renewable energy power generation and flexible DC transmission technology, flexible DC converter valves are being used more and more widely in power systems. During operation, flexible DC converter valves may gradually age due to factors such as electrochemical corrosion and capacitance decay. To ensure the stable operation of the power system, it is often necessary to equip flexible DC converter valves with bypass switches, which are used to quickly short-circuit and bypass the submodules in the flexible DC converter valve when a failure occurs.

[0044] In related technologies, the bypass switches widely used in flexible DC converter valve submodules are mostly single-coil permanent magnet mechanisms. Their working principle is as follows: upon receiving a fault signal, current is supplied to the coil, generating a magnetic field opposite to that of the permanent magnet mechanism. This counteracts the permanent magnet's attraction, causing the moving and stationary contacts to close, thus achieving bypass closing and enabling bypass operation of the faulty submodule in the flexible DC converter valve. However, because the single coil continuously carries current during the closing process, prolonged energization leads to severe coil heating, which may cause coil failure, thereby causing the bypass switch to fail.

[0045] To solve the aforementioned technical problems, firstly, referring to... Figures 1 to 6One embodiment of this application provides a permanent magnet mechanism, including a permanent magnet mechanism body 100 and a control circuit 200. The permanent magnet mechanism body 100 includes a moving iron core 101, a permanent magnet 102, a stationary iron core 103, a pull rod 104, a compression spring 105, an iron core shaft 106, a first coil 107, a second coil 108, and a power supply 109. The moving iron core 101 passes through the pull rod 104, and the permanent magnet 102 is coaxially arranged around the moving iron core 101. The stationary iron core 103 passes through the iron core shaft 106, and the stationary iron core 103 is arranged opposite to the moving iron core 101. The compression spring 105 is located between the moving iron core 101 and the stationary iron core 103, and one end of the compression spring 105 is connected to the iron core shaft 106, while the other end of the compression spring 105... The lever 104 is connected to the drive end of the moving copper busbar 700. The moving iron core 101, the permanent magnet 102, and the stationary iron core 103 generate magnetic flux in the first direction when the circuit is open, causing the moving iron core 101 and the stationary iron core 103 to attract each other and the compression spring 105 to be in a compressed state. The first coil 107 and the second coil 108 are sleeved around the permanent magnet 102. The control circuit 200 is used to control the power supply 109 to alternately supply power to the first coil 107 and the second coil 108, so that the first coil 107 or the second coil 108 after being energized generates magnetic flux in the second direction, eliminating the magnetic force between the moving iron core 101 and the stationary iron core 103. The second direction is opposite to the first direction.

[0046] The moving iron core 101 is inserted through and coaxially fixed on the pull rod 104, and the permanent magnet 102 is coaxially arranged around the moving iron core 101 and fixed on the stationary iron core 103.

[0047] Specifically, in the open state, the magnetic flux in the first direction is excited by the permanent magnet 102 and passes through the pole face of the stationary iron core 103, through the air gap, and into the pole face of the moving iron core 101. This generates an axial magnetic flux that causes the moving iron core 101 to tend to fit against the stationary iron core 103. The first direction is specifically the direction of the axial magnetic attraction force established between the opposing pole faces of the stationary iron core 103 and the moving iron core 101. The direction of this axial magnetic attraction force is opposite to the direction of the spring force of the compression spring 105, and is used to overcome the spring force to keep the moving iron core 101 in the open position. When the first coil 107 or the second coil 108 is energized, a magnetic flux in the second direction is generated. Since the second direction is opposite to the first direction, the magnetic attraction force generated by the magnetic flux in the second direction will cancel out the magnetic attraction force generated in the first direction, thereby causing the compression spring 105, which is in a compressed state, to release energy to drive the moving end copper busbar 700 to close.

[0048] In this embodiment, by controlling the circuit 200, the first coil 107 and the second coil 108 are alternately energized. This ensures that at least one set of coils is energized at any given time, while also reducing the average heating power of the coils and the temperature of the coils when they reach a steady state. This effectively reduces the possibility of coil thermal failure and improves the reliability of the bypass switch.

[0049] Reference Figures 1 to 3 In some embodiments, the control circuit 200 includes a first control sub-circuit 210, a second control sub-circuit 220, and a power-on control sub-circuit 230. The first control sub-circuit 210 is connected to the power supply 109 and is also connected to the charging terminal of the first coil 107. The second control sub-circuit 220 is connected to the power supply 109 and is also connected to the charging terminal of the second coil 108. The power-on control sub-circuit 230 includes a first output terminal and a second output terminal. The first output terminal is connected to the first control sub-circuit 210, and the second output terminal is connected to the second control sub-circuit 220. The first output terminal is used to output a first pulse width modulation signal, and the second output terminal is used to output a second pulse width modulation signal. The first level signal in the first pulse width modulation signal and the first level signal in the second pulse width modulation signal appear alternately. When the first control sub-circuit 210 receives the first level signal in the first pulse width modulation signal, the first coil 107 is turned on. When the first control sub-circuit 210 receives the second level signal in the first pulse width modulation signal, the second coil 108 is turned on.

[0050] The first pulse width modulation signal is a square wave signal used to control the on / off state of the first control sub-circuit 210. When the signal is high, the first control sub-circuit 210 is on, and the first coil 107 is energized; when the signal is low, the first control sub-circuit 210 is off, and the first coil 107 is not energized. The second pulse width modulation signal is a square wave signal used to control the on / off state of the second control sub-circuit 220. When the signal is high, the second control sub-circuit 220 is on, and the second coil 108 is energized; when the signal is low, the second control sub-circuit 220 is off, and the second coil 108 is not energized.

[0051] The alternation of the first level signal in the first pulse width modulation signal and the first level signal in the second pulse width modulation signal means that when the first pulse width modulation signal is high, the second pulse width modulation signal is low; and when the first pulse width modulation signal is low, the second pulse width modulation signal is high. When the closing is detected to be complete, the energizing control subcircuit 230 will no longer output pulse width modulation signals, both signals will be low, the first coil 107 and the second coil 108 will be de-energized, and the moving copper busbar 700 will be mechanically kept closed.

[0052] In this embodiment, by alternating the appearance of the first level signal, the first coil 107 and the second coil 108 are in a time-sharing operation and rest state. That is, when the first coil 107 is working, the second coil 108 is in a power-off dormant period, and the heat is naturally dissipated, thereby reducing the possibility of thermal failure of the coil.

[0053] Reference Figure 4 In some embodiments, there is a time delay between the first pulse width modulation signal and the second pulse width modulation signal. The time delay is determined based on the duration during which the second pulse width modulation signal remains at the first level when the first pulse width modulation signal switches from the second level to the first level, or when the first pulse width modulation signal switches from the first level to the second level.

[0054] in, Figure 4 In this context, PWM1 is the first pulse width modulation signal, and PWM2 is the second pulse width modulation signal. Figure 4 The width of the gray bar between PWM1 and PWM2 represents the time delay.

[0055] It is understandable that during the process of controlling the alternating energization of the first coil 107 and the second coil 108, it is necessary to ensure that one of the coils is energized when switching states to ensure the stability and reliability of closing. In other words, when the first pulse width modulation signal switches from the second level to the first level, or from the first level to the second level, the second pulse width modulation signal must maintain its current level and wait for a period of time before switching its own state. This waiting time is called the delay, also known as the dead time.

[0056] For example, such as Figure 4 As shown, when the first pulse width modulation signal PWM1 changes from low level to high level, the second pulse width modulation signal PWM2 does not immediately change from high level to low level, but continues to remain at high level for a period of time, that is, wait for a time delay. After the time delay ends, the second pulse width modulation signal PWM2 changes from high level to low level. During the switching process, there is a very short time when both coils are energized to ensure the stability and reliability of closing.

[0057] In this embodiment, by setting a time delay, it can be ensured that at least one coil is energized at any time, avoiding the simultaneous de-energization of the two coils due to the turn-off delay of the control sub-circuit, thereby ensuring the continuity of the reverse magnetic field during the closing process and improving the reliability of the bypass switch operation.

[0058] Reference Figure 3 and Figure 5In some embodiments, both the first control sub-circuit 210 and the second control sub-circuit 220 include a switching unit 212, an energy storage unit 214, and a discharge unit 216. The energy storage unit 214 is connected to the power supply 109 and the switching unit 212. The energy storage unit 214, the coil, and the switching unit 212 form a charging and discharging control loop. The coil includes a first coil 107 and a second coil 108. The first end of the discharge unit 216 is connected to the switching unit 212, and the second end of the discharge unit 216 is connected to the output end of the power-on control sub-circuit 230 for receiving pulse width modulation signals. The pulse width modulation signals include a first pulse width modulation signal and a second pulse width modulation signal.

[0059] Since the circuit structures of the first control sub-circuit 210 and the second control sub-circuit 220 in this embodiment are identical, to avoid repeating the function of the energy storage unit 214, the first control sub-circuit 210 is used as an example. The energy storage unit 214 in the first control sub-circuit 210 supplies power to the first coil 107 when the first control sub-circuit 210 is on. When the first control sub-circuit 210 is not on, the power supply 109 supplies power to the energy storage unit 214 to prepare for the next coil charging process. The switching unit 212 in the first control sub-circuit 210 controls the on / off state of the first control sub-circuit 210, i.e., the on / off state of the first coil 107. The discharge unit 216 in the first control sub-circuit 210 accelerates the discharge of charge in the first control sub-circuit 210 when the switching unit 212 is off, thereby achieving rapid turn-off and reducing turn-off losses.

[0060] For example, when the first pulse width modulation signal is low, the switching unit 212 in the first control sub-circuit 210 is turned off, and the power supply 109 supplies power to the energy storage unit 214. At this time, there is no current in the first coil 107. When the first pulse width modulation signal switches from low to high, the switching unit 212 in the first control sub-circuit 210 is turned on, and the energy storage unit 214 discharges, i.e., supplies power to the first coil 107, and the first coil 107 generates magnetic flux in the second direction. When the first pulse width modulation signal switches from high to low, the switching unit 212 in the first control sub-circuit 210 is turned off, and the discharge unit 216 begins to rapidly discharge the charge in the first control sub-circuit 210. When the first control sub-circuit 210 is turned off, i.e., when it enters the dead time, the discharge in the second control sub-circuit 220 is waiting to receive a high-level signal. After the dead time ends, the switching unit 212 of the second control sub-circuit 220 is turned on, and the above discharge process is repeated, so that the second coil 108 can take over the work.

[0061] In this embodiment, through the cooperation of the power-on control sub-circuit 230, power supply 109, energy storage unit 214, and switching unit 212, the duty cycle and dead time of the first pulse width modulation signal and the second pulse width modulation signal can be precisely controlled. With the cooperation of the discharge unit 216, it can be ensured that the switching unit 212 can accurately follow the control command of the power-on control sub-circuit 230 and respond quickly when it is necessary to turn off, thereby ensuring the accuracy of switching between the two coils and thus ensuring the reliability of closing.

[0062] Reference Figure 6 In some embodiments, the switching unit 212 includes an IGBT switch, the first terminal of which is connected to the energy storage unit 214, which may be an energy storage capacitor, and the second terminal of the IGBT switch is connected to the coil; the discharge unit 216 includes a first discharge resistor. Second bleed resistor and diode; first bleeder resistor The first terminal is connected to the third terminal of the IGBT switch, and the first bleed resistor... The second terminal is connected to the output terminal of the power-on control sub-circuit 230; the output terminal of the power-on control sub-circuit 230 includes a first output terminal and a second output terminal; the second bleeder resistor With the first bleed resistor Parallel connection, second bleeder resistor The first terminal is connected to the output terminal of the power-on control sub-circuit 230; the cathode of the diode is connected to the second bleeder resistor. The second terminal is connected, and the anode of the diode is connected to the third terminal of the IGBT switch.

[0063] Since IGBT switches are bipolar devices with conductivity modulation effects, their on-state voltage drop remains very low even under high voltage, resulting in low conduction losses. In addition, IGBT switches have good short-circuit withstand time and pulse current carrying capacity. Therefore, in this embodiment, the switching unit 212 adopts an IGBT switch.

[0064] Specifically, the first bleed resistor The first terminal is connected to the first output terminal of the power-on control sub-circuit 230, and the first bleeder resistor The second terminal is connected to the gate of the IGBT switch. When the IGBT switch is turned on, the first bleeder resistor... It can be used as a current-limiting resistor to limit the gate charging current and prevent overshoot and oscillation. Second bleeder resistor. The first terminal is connected to the first output terminal of the power-on control sub-circuit 230, and the second bleeder resistor The second terminal is connected to the cathode of the diode. When the IGBT switch is turned off, the second bleeder resistor... Connected in parallel with the first bleeder resistor, it provides a low-resistance discharge path for the gate charge, thereby enabling rapid discharge of charge in the first control sub-circuit 210 when it is off. The anode of the diode is connected to the gate of the IGBT switch. In this embodiment, the unidirectional conductivity of the diode is utilized to block the second bleeder resistor when the IGBT switch is on. The path is such that the second bleeder resistor is turned on when the IGBT switch is turned off. The path is such that when the IGBT switch is turned off, the second bleeder resistor... With the first bleed resistor Parallel connection provides a low-resistance discharge path for gate charge.

[0065] In this embodiment, through the first bleeder resistor Second bleed resistor The discharge unit 216, composed of diodes, constructs an asymmetric drive circuit structure that turns off quickly and turns on slowly. In cooperation with the power-on control sub-circuit 230, it can reliably and accurately control the alternating energization of the first coil 107 and the second coil 108. At the same time, the simple structure of the discharge unit 216 can reduce the manufacturing cost of the permanent magnet mechanism.

[0066] Reference Figure 6 In some embodiments, the first control sub-circuit 210 and the second control sub-circuit 220 further include current-limiting resistors. Current limiting resistor The first terminal is connected to the switching unit 212, and the current limiting resistor is... The second end is connected to the coil.

[0067] Understandably, during the discharge instant, energy storage unit 214 acts as a low-impedance voltage source, without a current-limiting resistor. The coil's impedance is primarily a small DC resistance in the initial stage, which causes a sharp increase in discharge current. Therefore, a current-limiting resistor is required. This limits the peak current to a safe range, ensuring that the current does not exceed the rated pulse current withstand capability of the switching unit 212 and the coil. In other words, the current-limiting resistor... Used to convert the output current of the IGBT switch into the rated current of the coil. Additionally, the energization control sub-circuit 230 can be... Figure 6 The FPGA control chip in the process.

[0068] Specifically, when the power-on control sub-circuit 230 outputs a high level, the first bleeder resistor... Controlling the IGBT switch to turn on, the first bleeder resistor This eliminates LC oscillations caused by parasitic inductance and gate capacitance, preventing IGBT switch gate breakdown. When the IGBT switch is turned on, the energy storage unit 214 discharges to the coil through the IGBT switch and current-limiting resistor. The magnetic field generated by the coil cancels out the magnetic field generated by the permanent magnet mechanism, thereby closing the bypass switch. Second discharge resistor Its function is to connect with the first bleeder resistor during the IGBT turn-off process. Parallel connection reduces the gate resistance, thereby accelerating the turn-off speed and reducing turn-off losses. The diode is cut off when the IGBT is turned on and turns on when it is turned off, thus reducing the first bleeder resistor. Second bleed resistor When the IGBT is turned off, a parallel structure is formed. Under the drive of the PWM signal, coil 1 and coil 2 receive periodic current.

[0069] Reference Figure 6 and Figure 7 In some embodiments, the permanent magnet mechanism is suitable for multiple sub-modules connected in series in a flexible DC converter valve, such as... Figure 6 As shown, Figure 6 Taking two adjacent sub-modules, namely module 1 and module 2, as an example, the power supply 109 includes a power source 1091 and a first redundant power source 1092. The power source 1091 is connected to the first control sub-circuit 210 and the second control sub-circuit 220, and the first redundant power source 1092 is connected to the control sub-circuit in the other adjacent sub-module.

[0070] The power source 1091 draws power primarily from the capacitor in its submodule. Under normal circumstances, it provides energy for driving the two coils. However, considering the possibility that the capacitor in the submodule containing power source 109 may be faulty or damaged and unable to supply power to the control subcircuit, a redundant power source 109 is provided in this embodiment to supply power to the control subcircuit, providing the energy required for closing the bypass switch. In other words, in addition to being normally powered by the power source 1091 in its own submodule, the first control subcircuit 210 and the second control subcircuit 220 in each submodule are also powered by the first redundant power source 1092 in the adjacent submodule in the event of a failure of the power source 1091. This ensures the normal operation of the first control subcircuit 210 and the second control subcircuit 220, thereby guaranteeing the reliability of the alternating operation of the two coils.

[0071] Specifically, due to the fluctuation of capacitor voltage, the power supply 1091 should have a wide voltage input range. The power supply 1091 outputs four 200V channels, two of which charge the two energy storage capacitors in this submodule. The other two 200V channels serve as redundant power supplies for adjacent modules, acting as the first redundant power supply 1092. When the capacitors or power supply 1091 of an adjacent module fail, they charge the two energy storage capacitors of the paired module. Similarly, when the capacitors or power supply 1091 of this module fail, the energy storage capacitors can be charged by the two 200V channels from the adjacent modules, thereby improving the reliability of the bypass switch. One of the 200V channels is converted to 13V by a DC-DC converter in the bypass driver board 300 to power the bypass driver board 300. By using the power supply 109 of the adjacent module as redundancy, compared with the traditional method, on the one hand, the number of power supply 1091 in the module is reduced, avoiding the need to configure redundant power supply 109 inside the module, reducing cost and module complexity. On the other hand, even in the event of capacitor failure, the bypass drive board 300 can still be operated normally, covering a wider range of fault conditions, and further improving the reliability of the bypass switch.

[0072] In this embodiment, by setting up the redundant power supply 109, it can be ensured that the two coils can still obtain energy normally when the power supply 1091 is lost, thereby maintaining the alternating operation mode of the two coils.

[0073] Reference Figure 6 and Figure 7 In some embodiments, the power supply 109 further includes a second redundant power supply 1093, which is connected to a power-on control sub-circuit 230 in an adjacent sub-module.

[0074] The power supply 1091 can be connected to the power-on control sub-circuit 230 via a DC-DC converter to power the power-on control sub-circuit 230. Alternatively, it can be powered independently by an external power supply. Considering manufacturing costs, this embodiment uses the power supply 1091 to power the power-on control sub-circuit 230 via a DC-DC converter. If the power supply 1091 fails or is damaged and cannot provide power, the power supply 230 is powered by the second redundant power supply 1093. In other words, in addition to being powered by the power supply 1091 in its own sub-module, the power supply 230 in each sub-module is also powered by the second redundant power supply 1093 in the adjacent sub-module if the power supply 1091 fails.

[0075] Specifically, the power supply 1091 outputs two 15V channels, one of which supplies power to the module control board 400 of this module, and the other serves as redundancy to supply power to the module control board 400 of the adjacent module.

[0076] In this embodiment, the setting of the second redundant power supply 1093 can ensure the normal operation of the power-on control sub-circuit 230, thereby further ensuring the reliability and stability of the closing.

[0077] Reference Figure 6 and Figure 7 In some embodiments, the permanent magnet mechanism further includes a bypass drive board 300 and a module control board 400. The first control sub-circuit 210 and the second control sub-circuit 220 are both disposed on the bypass drive board 300. The power-on control sub-circuit 230 is disposed on the module control board 400. The first redundant power supply 1092 includes a first redundant sub-power supply and a second redundant sub-power supply. The first redundant sub-power supply is connected to the first control sub-circuit 210 in the control sub-circuit of an adjacent sub-module. The second redundant sub-power supply is connected to the second control sub-circuit 220 in the control sub-circuit of an adjacent sub-module.

[0078] Understandably, since the failure modes and power requirements of the bypass drive board 300 and the module control board 400 are completely different in fault scenarios, two different redundant power supplies 109 are needed to power the bypass drive board 300 and the module control board 400 separately. For example, the drive voltage of the bypass drive board 300 is 200V, and the drive voltage of the module control board 400 is 15V, that is, the voltage provided by the first redundant power supply 1092 is 200V, and the voltage provided by the second redundant power supply 1093 is 15V.

[0079] Furthermore, in order to ensure the normal operation of the first control sub-circuit 210 and the second control sub-circuit 220, the first redundant sub-power supply is used as the backup power supply for the first control sub-circuit 210, and the second redundant sub-power supply is used as the backup power supply for the second control sub-circuit 220.

[0080] In this embodiment, the bypass drive board 300 is powered by the first redundant power supply 1092, which ensures that the two coils can still obtain energy normally when the capacitors of their respective submodules cannot be powered, thereby maintaining the alternating operation mode of the two coils; while the module control board 400 is powered by the second redundant power supply 1093, which ensures the normal operation of the power-on control subcircuit 230.

[0081] Secondly, such as Figure 2As shown, one embodiment of this application provides a bypass switch structure, which is applied to any of the permanent magnet mechanisms provided in the first aspect above. The bypass switch structure includes a housing 500, a stationary copper busbar 600 and a moving copper busbar 700 disposed in the housing 500. The driving end of the moving copper busbar 700 is connected to an overtravel insulator 800. The end of the overtravel insulator 800 away from the moving copper busbar 700 is connected to the end of the pull rod 104 away from the compression spring 105.

[0082] The permanent magnet mechanism body 100 also includes a magnetic cylinder 110, a magnetic shielding sheet 111, and a magnetic guide ring 112. The magnetic cylinder 110 is fixed on the inner wall of the housing 500. The magnetic shielding sheet 111 is fixedly connected to the end wall of the magnetic cylinder 110 near the stationary copper sheet. The magnetic guide ring 112 is connected to the magnetic shielding sheet 111 and is arranged around the moving iron core 101. The magnetic cylinder 110, permanent magnet 102, magnetic guide ring 112, and moving iron core 101 are all coaxially arranged. A vacuum interrupter 900 is provided between the stationary copper busbar 600 and the moving copper busbar 700. When the moving copper busbar 700 is closed with the stationary copper busbar 600 under the drive of the permanent magnet mechanism, the moving and stationary contacts inside the vacuum interrupter 900 close, short-circuiting the fault submodule and allowing the current to bypass the fault module and flow through the bypass switch. When it is necessary to disconnect, the contacts inside the vacuum interrupter separate in the vacuum environment, which can quickly extinguish any possible arc.

[0083] Specifically, when the bypass switch is in the open state, the permanent magnet mechanism inside the magnetic cylinder 110, including the permanent magnet 102, stationary iron core 103, moving iron core 101, and magnetic ring 112, forms a magnetic circuit with the permanent magnet 102. The attraction force between the stationary iron core 103 and the moving iron core 101 is greater than the reaction force generated by the compression of the spring when the switch is closed, causing the moving copper busbar 700 of the bypass switch to separate from the stationary copper busbar 600, thus putting it in the open state. When the converter valve submodule malfunctions, the FPGA generates two sets of PWM waves (PWM1 and PWM2) and sends them to the coil charging module. The two sets of PWM are complementary and contain dead time, ensuring that at least one coil is energized during the bypass switch closing process. After the coil is charged, it generates a magnetic field opposite to that of the permanent magnet 102 to counteract the attraction force formed by the stationary iron core 103 and the moving iron core 101. When the attraction force of the stationary and moving iron cores 103 is less than the reaction force of the spring, the moving iron core 101 moves towards the vacuum tube, causing the moving and stationary contacts in the vacuum interrupter 900 to come into contact, completing the closing operation. The overtravel insulator 800, located between the magnetic cylinder 110 and the vacuum interrupter 900, serves two purposes: firstly, it provides insulation between the permanent magnet mechanism and the vacuum chamber; secondly, it provides contact pressure to ensure reliable contact between the moving and stationary contacts within the vacuum chamber.

[0084] In this embodiment, the bypass switch structure, having incorporated any of the permanent magnet mechanisms provided in the first aspect, also correspondingly possesses the capability to control the alternating energization of the first coil 107 and the second coil 108 via the control circuit 200. This ensures that at least one set of coils is energized at any given time, while also reducing the average heating power of the coils and the temperature at steady state, thereby effectively reducing the possibility of coil thermal failure and improving the reliability of the bypass switch. Furthermore, by using redundant power supplies from adjacent modules, the possibility of bypass switch failure due to capacitor failure or power supply 1091 malfunction can be effectively reduced, and the increased cost caused by setting up redundant power supplies 109 within the module can also be reduced.

[0085] In the description of this specification, references to terms such as "some embodiments," "other embodiments," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0086] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A permanent magnet mechanism, characterized in that, The permanent magnet mechanism includes: The permanent magnet mechanism body includes a moving iron core, a permanent magnet, a stationary iron core, a pull rod, a compression spring, an iron core shaft, a first coil, a second coil, and a power supply. The moving iron core passes through the pull rod, and the permanent magnet is coaxially arranged around the moving iron core. The stationary iron core passes through the iron core shaft and is arranged opposite to the moving iron core. The compression spring is located between the moving iron core and the stationary iron core, with one end connected to the iron core shaft and the other end connected to the pull rod. The end of the pull rod away from the compression spring is connected to the driving end of the moving copper busbar. When the circuit is open, the moving iron core, the permanent magnet, and the stationary iron core generate magnetic flux along a first direction, causing the moving iron core and the stationary iron core to attract each other and the compression spring to be in a compressed state. The first coil and the second coil are sleeved around the permanent magnet. A control circuit is used to control the power supply to alternately supply power to the first coil and the second coil, so that the first coil or the second coil after being energized generates a magnetic flux in a second direction, thereby eliminating the magnetic force between the moving iron core and the stationary iron core, wherein the second direction is opposite to the first direction.

2. The permanent magnet mechanism according to claim 1, characterized in that, The control circuit includes: A first control sub-circuit is connected to the power supply, and the first control sub-circuit is connected to the charging terminal of the first coil; The second control sub-circuit is connected to the power supply, and the second control sub-circuit is connected to the charging terminal of the second coil; The power-on control sub-circuit includes a first output terminal and a second output terminal. The first output terminal is connected to the first control sub-circuit, and the second output terminal is connected to the second control sub-circuit. The first output terminal is used to output a first pulse width modulation signal, and the second output terminal is used to output a second pulse width modulation signal. The first level signal in the first pulse width modulation signal and the first level signal in the second pulse width modulation signal appear alternately. When the first control sub-circuit receives a first level signal in the first pulse width modulation signal, the first coil is turned on; when the first control sub-circuit receives a second level signal in the first pulse width modulation signal, the second coil is turned on.

3. The permanent magnet mechanism according to claim 2, characterized in that, There is a time delay between the first pulse width modulation signal and the second pulse width modulation signal. The time delay is determined based on the duration during which the second pulse width modulation signal remains at the first level when the first pulse width modulation signal switches from the second level to the first level, or when the first pulse width modulation signal switches from the first level to the second level.

4. The permanent magnet mechanism according to claim 2, characterized in that, Both the first control sub-circuit and the second control sub-circuit include: Switching unit; An energy storage unit is connected to the power supply and the switching unit, and the energy storage unit, the coil, and the switching unit form a charging and discharging control circuit; the coil includes a first coil and a second coil. A discharge unit, the first end of which is connected to the switching unit, and the second end of which is connected to the output end of the power-on control sub-circuit, are used to receive pulse width modulation signals; the pulse width modulation signals include the first pulse width modulation signal and the second pulse width modulation signal.

5. The permanent magnet mechanism according to claim 4, characterized in that, The switching unit includes an IGBT switch, the first terminal of which is connected to the energy storage unit, and the second terminal of which is connected to the coil; the discharge unit includes: A first bleed resistor, the first end of which is connected to the third terminal of the IGBT switch, and the second end of which is connected to the output terminal of the power-on control sub-circuit; the output terminal of the power-on control sub-circuit includes the first output terminal and the second output terminal; The second bleed resistor is connected in parallel with the first bleed resistor, and the first end of the second bleed resistor is connected to the output end of the power-on control sub-circuit. The diode has its cathode connected to the second terminal of the second bleeder resistor, and its anode connected to the third terminal of the IGBT switch.

6. The permanent magnet mechanism according to claim 4, characterized in that, The first control sub-circuit and the second control sub-circuit also include a current-limiting resistor, the first end of which is connected to the switching unit and the second end of which is connected to the coil.

7. The permanent magnet mechanism according to claim 2, characterized in that, The permanent magnet mechanism is applicable to multiple sub-modules connected in series in a flexible DC converter valve. The power supply includes an energy harvesting power supply and a first redundant power supply. The energy harvesting power supply is connected to the first control sub-circuit and the second control sub-circuit. The energy harvesting power supply is connected to the power-on control sub-circuit through a converter. The first redundant power supply is connected to the control sub-circuit in an adjacent sub-module.

8. The permanent magnet mechanism according to claim 7, characterized in that, The power supply also includes a second redundant power supply, which is connected to the power-on control sub-circuit in the adjacent sub-module.

9. The permanent magnet mechanism according to claim 8, characterized in that, The permanent magnet mechanism further includes a bypass drive board and a module control board, with the first control sub-circuit and the second control sub-circuit both disposed on the bypass drive board; the power-on control sub-circuit is disposed on the module control board. The first redundant power supply includes a first redundant sub-power supply and a second redundant sub-power supply. The first redundant sub-power supply is connected to a first control sub-circuit in the control sub-circuit of the adjacent sub-module. The second redundant sub-power supply is connected to a second control sub-circuit in the control sub-circuit of the adjacent sub-module.

10. A bypass switch structure, characterized in that, The bypass switch structure, comprising any one of claims 1-9, further includes a housing, a stationary copper busbar and a moving copper busbar disposed within the housing, wherein the driving end of the moving copper busbar is connected to an overtravel insulator, and the end of the overtravel insulator away from the moving copper busbar is connected to the end of the pull rod away from the compression spring.

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