Monostable magnetic control operating mechanism control method suitable for intelligent switch

Abstract

The invention relates to a monostable magnetic control operation mechanism control method suitable for an intelligent switch, and the method comprises the steps: monitoring the current change of a mechanism coil in real time in a switching-on process and a switching-off process, determining the voltage loop disconnection time points in the switching-on process and the switching-off process based on the corresponding current change characteristics, and controlling the voltage loop of the coil to be disconnected; performing release time optimization operation of the residual current based on the optimal release function, and changing the dynamic condition release current time and the static condition release current time according to the optimal release time obtained by operation on the premise of satisfying the magnetic retention force; and detecting the magnetic field intensity of the magnetic control mechanism in a closing holding state in real time, and magnetizing a magnet of the magnetic control mechanism under the condition that the magnetic field intensity is smaller than a set magnetizing threshold value. According to the invention, energy consumption can be reduced on the premise of maintaining switching-on and switching-off reliability of the switch, loss of switch equipment is reduced, the service life of the equipment is prolonged, and switch cost is reduced.

Description

Technical Field

[0001] This invention relates to intelligent drive control of a monostable magnetic control operating mechanism for high-voltage switches, which effectively improves the reliability of opening and closing while reducing energy loss, and belongs to the field of high-voltage switches and power electronics applications in power distribution systems. Background Technology

[0002] High-voltage switches employing magnetic control mechanisms are a new type of switch developed in China in recent years, with the operating mechanism being a monostable magnetic control mechanism. Compared to existing traditional spring-operated mechanisms, which suffer from drawbacks such as large size, high energy consumption, numerous mechanical parts, short mechanical life, and frequent maintenance, the monostable magnetic control mechanism is gradually gaining widespread application due to its small size, low energy consumption for closing and opening, and longer mechanical life. In particular, the monostable magnetic control mechanism uses reversible magnetization and demagnetization materials, allowing for rapid switching of the magnetization state under external excitation. By reflecting the change in current, it reflects the application of electromagnetic force and the motion state of the mechanism, enabling precise control of closing and opening characteristics. This makes it the preferred operating structure for intelligent switches and phase-controlled switches.

[0003] However, this type of magnetic switch also has the following problems in application, which affect its further promotion and application, mainly in the following aspects:

[0004] 1) The control method of the monostable magnetic control mechanism usually adopts an open-loop mode. The fixed closing and opening control pulse width time is set according to the mechanical characteristic parameters of the magnetic control switch. However, the energizing time of the closing coil in the magnetic control parameters is set based on the test or theoretical calculation under the worst conditions (maximum load, lowest ambient temperature, etc.). Although it ensures reliable closing under the worst conditions, in most actual operating conditions, this parameter setting far exceeds the actual needs. Therefore, a larger energy storage capacitor and driving power are required, resulting in energy consumption and waste of components.

[0005] 2) After the magnetic control material is energized and attracted, it relies on the residual magnetic holding force (the force remaining after subtracting the reverse force of the tripping spring and contact pressure spring, etc., from the static magnetic holding force of the magnetic control mechanism) to maintain the closed state of the mechanism. Therefore, sufficient residual magnetic holding force of the magnetic control mechanism is the guarantee for the reliable operation of the circuit breaker. If the residual magnetic holding force of the magnetic control mechanism is insufficient, it will cause the circuit breaker to automatically trip during operation, resulting in a power outage. The residual holding force of the magnetic control mechanism is greatly affected by external factors. For example, different closing operation strategies can have a 20% to 30% impact on the holding force.

[0006] 3) The timing of the tripping operation will affect the reliability of the next closing operation. This is mainly because an excessively long tripping pulse width will lead to a decrease in the closing holding force, or even prevent reliable closing.

[0007] 4) When the magnetic control material is in the closed state, the magnetic properties may decrease due to temperature, aging, humidity, corrosion, etc., which may lead to insufficient closing holding force. If it is further affected by external factors such as vibration, the phenomenon of false tripping may occur. Summary of the Invention

[0008] The purpose of this invention is to reduce energy consumption while maintaining the reliability of switch opening and closing.

[0009] The technical solution of the present invention is: a control method for a monostable magnetic control operating mechanism adapted to an intelligent switch, wherein during the closing process, the current of the mechanism coil is monitored in real time, and the voltage circuit disconnection time point during the closing process is determined based on the current change characteristic point, and the coil voltage circuit is controlled to disconnect.

[0010] A closing pulse current can be injected into the mechanism coil through an IGBT bridge circuit.

[0011] Once the voltage circuit disconnection time point during the closing process is determined, a coil voltage circuit disconnection command can be generated and sent to control the IGBT bridge circuit to disconnect the coil voltage circuit.

[0012] Preferably, when the rate of change of current di / dt is detected to change from a negative zero-crossing point to a positive value, and for a certain period of time after di / dt crosses zero (this period of time can be expressed as Δt2, see below) it is continuously greater than the minimum current value when di / dt is zero, a coil voltage loop disconnection command is sent, where i is the coil current and t is time.

[0013] Preferably, the following conditions are used as the main criteria for disconnecting the control coil voltage circuit during the closing process:

[0014]

[0015] For the moment t when all the above conditions are met for the first time, t+Δt2 is taken as the voltage loop disconnection time point (that is, after the above judgment is completed at time t+Δt2, the coil voltage loop disconnection command is generated and sent out), where I min Let t be the nearest current minimum value before time t, and let Δt1 and Δt2 be the first and second time constants, respectively.

[0016] Preferably, a third time constant Δt3 is set, and the judgment is made on whether the closing time reaches the third time constant. When the closing time reaches the third time constant, a command to disconnect the coil voltage circuit is sent.

[0017] Preferably, during the tripping process, the current in the mechanism coil is monitored in real time, and the timing of the voltage circuit disconnection during the tripping process is determined based on the current change characteristics, thereby controlling the coil voltage circuit to disconnect.

[0018] A tripping pulse current can be injected into the mechanism coil through an IGBT bridge circuit. The direction of the tripping pulse current is opposite to the direction of the closing pulse current.

[0019] Once the voltage circuit disconnection time point during the tripping process is determined, a coil voltage circuit disconnection command can be generated and sent to control the IGBT bridge circuit to disconnect the coil voltage circuit.

[0020] Preferably, when a short-term rapid rise followed by a drop in coil current is detected, a coil voltage circuit disconnection command is sent.

[0021] Preferably, the following conditions are used as the main criteria for disconnecting the control coil voltage circuit during the tripping process:

[0022]

[0023] For the moment t when all the above conditions are met for the first time, t+Δt5 is taken as the voltage loop disconnection time point. That is, after the above judgment is completed at time t+Δt5, a coil voltage loop disconnection command is generated and sent out, where i is the coil current and t is time. △t4 and △t5 are the set fourth and fifth time constants, respectively.

[0024] Preferably, a sixth time constant Δt3 is set, and the determination of whether the opening time reaches the sixth time constant is implemented. When the opening time reaches the sixth time constant, a command to disconnect the coil voltage circuit is sent.

[0025] Preferably, the magnetic field strength of the magnetic control mechanism in the closed-hold state is detected in real time, and the detected magnetic field strength is compared with a set magnetization threshold. If it is less than the magnetization threshold, the magnet of the magnetic control mechanism is magnetized.

[0026] Preferably, the release time optimization calculation of the residual current is performed based on the following optimal release function:

[0027]

[0028] or

[0029]

[0030] The release time t is minimized when the optimal release function J is minimized. d To determine the optimal release time, the dynamic condition release current time and the static condition release current time are adjusted based on the calculated optimal release time, where Hr is the residual magnetic holding force, and Hr∝t. d α and β are the set weights for discharge time and residual magnetic retention force, respectively.

[0031] The optimal release function can be dynamically adjusted according to the operating conditions.

[0032] The beneficial effects of this invention are as follows: By deeply analyzing the relationship between the mechanism coil current, electromagnetic force, and contact movement during the closing and opening processes, this invention reveals the relevant change characteristics of the coil current. Based on the analysis of these relevant characteristics, it is possible to more reasonably determine the disconnection time point of the mechanism coil voltage circuit during the closing and opening processes, thereby forming a drive control method that can improve the reliability of magnetic switch operation, reduce energy consumption, and maintain the reliability of closing.

[0033] This invention can reduce energy consumption, reduce switch equipment losses, extend equipment service life, and reduce switch costs while maintaining the reliability of switch opening and closing. It can be directly used in ordinary circuit breakers and load switches with magnetic control mechanisms, and can also be extended to intelligent phase control switches or other related applications. Attached Figure Description

[0034] Figure 1 This is a diagram illustrating the composition of the intelligent magnetic control system involved in this invention;

[0035] Figure 2 This invention relates to a diagram showing the change of closing coil current with displacement;

[0036] Figure 3 This invention relates to a flowchart of the coil voltage circuit disconnection criterion during the closing process;

[0037] Figure 4 This invention relates to current variation diagrams under capacitor-charged freewheeling and diode freewheeling conditions;

[0038] Figure 5 This invention relates to a curve diagram showing the change of current under constant inductance and variable inductance conditions during the circuit breaker tripping process;

[0039] Figure 6 This invention relates to the curves of the first and second derivatives of current under constant and variable inductance conditions. Detailed Implementation

[0040] This invention relates to an intelligent control method for a magnetically controlled switch. During the closing process, the method monitors the change in current value of the mechanism coil (the coil of the monostable magnetically controlled operating mechanism, hereinafter referred to as the coil) in real time. Based on the characteristic points of the corresponding current change, the method controls the timing (or time point) when the coil voltage circuit (the voltage circuit of the mechanism coil) is disconnected during the closing process. The coil voltage is cut off at the optimal time, thereby reducing energy consumption and IGBT power while ensuring reliable closing.

[0041] By controlling the coil freewheeling current, the duration of the current after the coil voltage circuit of the mechanism is cut off can be appropriately controlled, which can effectively enhance the residual magnetism after closing, improve the magnetic holding force after closing, and avoid the phenomenon of the closing mechanism rebounding due to external interference.

[0042] During the tripping process, the change in coil current value is detected in real time. The timing of the coil voltage circuit disconnection is determined based on the characteristic points of the corresponding current change. While ensuring reliable tripping, the energizing time is reduced to ensure the reliability of the next closing.

[0043] With the switch closed, the mechanism is dynamically magnetized according to environmental conditions to reduce the probability of demagnetization, ensure reliability when the switch is closed, and avoid abnormal tripping.

[0044] Figure 1 A schematic diagram of the circuit structure for implementing the control method of this patent is shown, comprising six parts: a main control circuit, a magnetic field detection circuit, a charging circuit, an energy storage capacitor, a current sampling circuit, an IGBT drive circuit, and an IGBT bridge circuit. The magnetic field detection circuit detects the magnetic field strength at the closing and holding point of the magnetic control mechanism. The energy storage capacitor serves as the power source for the mechanism coil (referred to as the coil), is charged through the charging circuit, and connected to the power supply side of the IGBT bridge circuit. The coil is connected to the load side of the IGBT bridge circuit. The current sampling circuit is used to collect the current output of the energy storage capacitor to the mechanism coil. It can be set in the current loop of the energy storage capacitor discharge, for example, between the capacitor and the power supply connection terminal of the IGBT bridge circuit. The current sampling signal is sent to the main control circuit, which analyzes and processes the current sampling signal to control the operation of the other parts, thus realizing the control method of this invention. Compared to conventional magnetic control drive control circuits, the control circuit of this invention adds a current sampling circuit and a magnetic field detection circuit for collecting the current and magnetic field strength of the mechanism coil. The main control circuit implements corresponding control based on the collected coil current to realize the intelligent drive control logic of the magnetic switch described in this patent.

[0045] The control process or working principle of this invention is as follows:

[0046] 1. Adaptive Cut-off Method for Closing Current

[0047] See Figure 3 During the closing operation control of the monostable magnetic control mechanism, a closing pulse current is injected into the mechanism coil through an IGBT bridge control circuit, and the current in the coil is collected in real time through a current sampling circuit. When the magnetic force generated by the current in the coil reaches the point of overcoming the spring force and friction, the moving iron core begins to move towards the stationary iron core, and at the same time, the air gap δ begins to decrease. Since the air gap reluctance Rm∝δ and the inductance L∝N, 2 / Rm, where N is the number of turns in the coil. Therefore, the rate of change of inductance increases, leading to a greater back electromotive force generated by the inductor. This suppresses the increase in current in the coil, causing the current to decrease. The maximum value I of the coil current during this time period is collected (obtained through calculation). max .

[0048] At this point, the coil circuit can be simplified to a voltage equation:

[0049]

[0050] Where U is the energy storage capacitor voltage, i is the coil current, which can vary with time and can also be expressed as i(t), R is the coil circuit resistance, ω is the magnetic flux linkage, which is closely coupled with L and i, and t is time.

[0051] When the contacts close, the contact spring is compressed. Due to the spring force, the speed of the moving iron core decreases sharply, and the coil current rises again. As the air gap gradually decreases, the current decreases again. This process is the result of the deep coupling between the circuit breaker's "sudden change in mechanical load" and "electromagnetic transient response." When the contact spring is fully compressed, the air gap in the main magnetic circuit between the moving and stationary iron cores is basically closed. At this moment, the air gap δ decreases to its minimum value, the air gap magnetic reluctance decreases to its minimum value, and the inductance reaches its maximum value L. max And it hardly changes anymore, at which point dL / dt≈0, while due to the back electromotive force generated earlier, the coil current is at a minimum (valley) I. min .

[0052] If the voltage across the energy storage capacitor is still applied across the coil, the voltage equation for the coil loop is a standard RL circuit equation:

[0053]

[0054] like Figure 2 As shown, at time t0, since the moving iron core has reached its travel position, the inductance no longer changes, the back electromotive force disappears, and the coil current i begins to rise under the drive of the energy storage capacitor voltage U. At this time, the voltage applied to the coil by the energy storage capacitor begins to do useless work; therefore, the coil voltage circuit can be cut off at this time. Before this moment, the current experiences a large peak (main peak value) and then drops after a small peak value to the trough value at this moment. Since the main peak value is significantly higher than other peak values, it can be determined whether the detected peak value is the main peak value based on experience or theoretical calculations of the main peak value.

[0055] An overcurrent protection value I can be set. set When the real-time current is greater than I set When the value is reached, the control coil voltage circuit is disconnected.

[0056] A specific implementation method can be as follows: when the rate of change of the current di / dt at the above-mentioned moment changes from a negative value to a positive value, and the current remains greater than I for a certain fixed time period (set time) Δt2. min At that time (to avoid misjudging the first minimum point before that moment), a command to disconnect the coil voltage circuit is sent.

[0057] When the current change simultaneously satisfies the following formulas (conditions), a coil voltage loop disconnection command can be issued to disconnect the coil power supply:

[0058]

[0059] The above criteria serve as the primary criteria for disconnecting the control coil voltage circuit.

[0060] To prevent the failure to detect the above coil voltage circuit disconnection command due to various reasons, an engineering time constant Δt3 can be introduced. When the closing process time exceeds this time, the coil voltage circuit disconnection command will be sent again as a backup criterion for the forced disconnection of the control coil voltage circuit.

[0061] Among them, △t1 and △t2 are both engineering experience time parameters, which can be called the first time constant and the second time constant. They are generally set between 1ms and 10ms. △t3 can be called the third time constant. It is dynamically adjusted according to different working conditions so that the time when the coil voltage circuit disconnection command is issued based on the backup criterion is appropriately later than the time when the coil voltage circuit disconnection command should be issued based on the main criterion under the corresponding working conditions.

[0062] II. Adaptive Tripping Current Method

[0063] When the mechanism performs a tripping operation, the moving and stationary iron cores are magnetically attracted to each other. A reverse tripping pulse current is injected into the mechanism coil via the IGBT bridge control circuit. The magnetic field lines generated by this current are in the opposite direction to the magnetic field lines generated by the closing pulse current at the upper end of the stationary iron core. The magnetic material rapidly demagnetizes, the residual magnetism weakens, and the current change is:

[0064]

[0065] Where U is the energy storage capacitor voltage, R is the coil circuit resistance, the time constant τ = L / R, and L is the coil inductance.

[0066] When the magnetic force generated by the current in the coil in the tripping circuit, the repulsive force of the built-in tripping spring, and the contact pressure spring are sufficient to overcome the residual magnetic holding force, the moving iron core begins to separate from the stationary iron core, the air gap δ begins to increase, the magnetic reluctance Rm begins to increase, and the inductance L begins to decrease.

[0067] According to the circuit equations:

[0068]

[0069] It can be seen that a decrease in inductance L will lead to an increase in current.

[0070] After the moving iron core separates from the stationary iron core, the main energy for the tripping operation comes from the release of the spring's kinetic energy. The main function of the coil has been completed (counteracting the residual magnetic holding force). However, the coil is still energized at this time. In order to avoid the coil from overheating due to continuous energization while ensuring reliable tripping, it is necessary to find a suitable time to cut off the coil voltage.

[0071] Figure 5 The diagram shows the curves of coil current variation under constant inductance (dashed line) and variable inductance (solid line) conditions when the control coil voltage loop is not disconnected in a simulated circuit tripping circuit.

[0072] In the context of this invention, displacement of the moving iron core can cause a change in inductance. Displacement of the moving iron core leads to an increase in the air gap of the coil, an increase in magnetic reluctance, and consequently a decrease in the coil inductance. Figure 5 As shown, the moving iron core begins to accelerate at time t3. Therefore, there is a significant abrupt change at time t3 when the inductance changes. This is because the decrease in inductance L at this time causes the coil current to rise at a significantly faster rate. Based on this current characteristic, the abrupt change is detected in real time. When a sudden change in the coil current characteristic parameter is detected, it is determined that the moving and stationary iron cores have separated, and a command to disconnect the control coil voltage circuit is executed.

[0073] See Figure 6 At the point of abrupt change in the current curve, both the first derivative and the second derivative are maximized. In this figure, the solid line corresponds to the variable inductance, and the dashed line corresponds to the constant inductance.

[0074] Define a function:

[0075]

[0076] Where di(t) is the first derivative of the current at time t, representing the slope of the current curve at that point; d 2 i(t) represents the second derivative of the current at time t, and represents the rate of change of the slope of the current curve at that point.

[0077] When the curve is smooth, di(t)≈di(t-Δt) and d 2 i(t)≈0, therefore Di(t)≈0.

[0078] At the point of abrupt change, di(t) and di(t-Δt) differ significantly and the second derivative of the current curve changes considerably. Therefore, Di(t) exhibits a local maximum value at this point.

[0079] Criteria for determining the sudden change point (the point at which the voltage circuit is disconnected during the tripping process):

[0080]

[0081] In the above judgment conditions, △t4 and △t5 are both engineering experience time parameters, which can be called the fourth time constant and the fifth time constant, respectively, and can generally be set between 1ms and 5ms.

[0082] The current satisfying the above formula (11) is used as the main criterion for executing the de-energizing command of the circuit breaker opening operation coil.

[0083] To prevent the failure to detect and receive the aforementioned coil voltage cutoff command due to various reasons, an engineering empirical time parameter Δt6 is set as a backup criterion. When executing the forced cutoff command for the control tripping operation coil voltage, the tripping coil voltage is forcibly shut off after the tripping time exceeds Δt6. Because the engineering empirical time parameter is usually set based on the worst-case operating conditions, this setting time lags behind the time determined by the main criterion. Δt6 can be called the sixth time constant, and is generally set between 10ms and 15ms.

[0084] 3. Methods to adjust the rate of change of freewheeling current

[0085] After the coil voltage circuit is disconnected, there is a residual current I0 in the circuit. Since the inductor current on the coil cannot change abruptly, a path for releasing (or discharging) the residual current needs to be provided.

[0086] The rate of decrease of the coil current i corresponds to the rate of change of the magnetic field strength H, which conforms to the following formula:

[0087]

[0088] Where N is the number of coil turns, l m This represents the length of the magnetic circuit.

[0089] Based on existing theories, the magnetized material in a magnetic control mechanism consists of many small magnetic regions called magnetic domains. Each magnetic domain is equivalent to a small magnet. When subjected to an external magnetic field, the magnetic domains align and form an additional magnetic field, thus significantly enhancing the magnetic field. According to the hysteresis loop phenomenon, the change in magnetization lags behind the change in the magnetic field. The magnetic flux density B decreases as the current i decreases. Therefore, when the current i decreases to 0, the magnetic flux density B is not zero, meaning there is remanence, which generates a residual magnetic holding force.

[0090] Under static conditions, i.e. dH / dt≈0, the magnetic flux evolves along the principal hysteresis loop, the magnetic domains stabilize in the magnetization direction, and the magnetic domains have more time to relax. At this time, it is characterized by high remanence, and the magnitude of the remanence is determined by the inherent magnetic field characteristics of the material.

[0091] Under dynamic conditions, rapid changes in current can cause changes in magnetic field strength, which in turn generates eddy currents. This generates a reverse magnetic field that cancels out the remaining magnetic field, causing some magnetic domains to lose their ordered state and reducing remanence.

[0092] like Figure 4 As shown, commonly used residual current release circuits employ freewheeling diodes or capacitor charging to allow current to flow. This invention can utilize any suitable existing residual current release circuit to achieve residual current release. However, as a preferred embodiment, an optimized release time can be used to control the residual current release while ensuring the residual magnetic holding force.

[0093] When the freewheeling diode connected in parallel with the coil is released, the diode provides a low-impedance path, clamping the coil voltage near the diode's voltage drop (typically 0.7V). From the inductor voltage formula:

[0094] (5)

[0095] It can be seen that the rate of change of current is very small, and the current decreases slowly. This type of discharge is close to a static condition.

[0096] When the coil uses capacitor charging for freewheeling, the current decay equation in the coil is:

[0097]

[0098] Where I0 is the initial value of the residual current, L is the coil inductance, and C is the capacitance. As shown in the above equation, the current decays rapidly according to a cosine law; this type of discharge is approximately under dynamic conditions.

[0099] Figure 4 In the example, time t1 indicates that the moving iron core has reached its travel position, and time t2 indicates that the coil voltage control circuit is disconnected at this time, requiring the release of residual current. The solid line in the diagram represents the residual current freewheeling through the diode. This method results in a very slow discharge rate due to the diode voltage drop, which may cause a delay in tripping and affect the next operation. The dashed line represents the freewheeling through capacitor charging. Although this method releases the current quickly, it leads to a relative reduction in residual magnetism and a decrease in the residual magnetism holding force.

[0100] As can be seen from the above, the residual magnetic holding force Hr is related to the current fall time (freewheeling time, or current release time) t. d Positive correlation, Hr∝t d Slow current decrease (high t) d This is beneficial for domain adjustment and increases Hr, but the release time is long; the current drops rapidly (low t). dThis reduces discharge time but lowers Hr. To maintain sufficient residual magnetic holding force while rapidly releasing the current, the following algorithm is used to find the optimal fall time that balances both factors, such that t d Achieving balance with HR:

[0101]

[0102] Where J is the optimal release function, α and β are the set release time weights and residual magnetic holding force weights, respectively, and the optimal release time t is obtained through the optimization function. d * Under the premise that the residual magnetic holding force meets the requirements, the dynamic condition release current mode time and the static condition release current mode time are dynamically changed, that is, the conduction time of the capacitor charging mode discharge circuit and the conduction time of the freewheeling diode discharge circuit are changed to obtain the optimal solution.

[0103] α and β can be determined based on experience or experimental data.

[0104] It can record historical release current data and residual magnetic holding force, and optimize and update α and β through historical data to optimize subsequent releases.

[0105] IV. Dynamically Adjusting the Magnetization Method

[0106] This method employs closed-loop control based on magnetic field detection. A Hall effect sensor continuously monitors the magnetic field strength at the closing and holding point of the magnetic control mechanism. The acquired magnetic field strength signal is converted by an ADC and sent to a processor. The processor analyzes and compares the signal with a set magnetic field strength threshold. If the current magnetic field strength value is less than the threshold, a pulse magnetization command is issued. This threshold value is determined based on actual needs and can be dynamically adjusted according to changes in various environmental and operating conditions, such as temperature, humidity, and the service life of materials.

[0107] The principle of pulse magnetization is the same as that of the closing operation. It generates current through capacitor discharge to the mechanism coil, which in turn generates a magnetic field, rapidly magnetizing the magnet. The pulse magnetization method allows for dynamic adjustment of the magnetization time based on actual needs or operational requirements. During the magnetization process, the difference between the current and set magnetic field strength can be calculated. This method offers advantages such as fast magnetization speed and high efficiency, while avoiding problems like coil overheating or aging of the magnetic control material caused by overcharging.

[0108] The preferred and optional technical means disclosed in this invention can be arbitrarily combined to form several different specific embodiments, unless otherwise specified or one technical means is a further limitation of another.

Claims

1. A control method for a monostable magnetically controlled operating mechanism adapted to intelligent switches, characterized in that... During the closing process, the current of the mechanism coil is monitored in real time, and the voltage circuit disconnection time point is determined based on the current change characteristics, thereby controlling the coil voltage circuit to disconnect.

2. The control method for the monostable magnetically controlled operating mechanism as described in claim 1, characterized in that... When the rate of change of current di / dt is detected to change from a negative zero-crossing point to a positive value, and remains greater than the minimum current value when di / dt is zero for a certain period of time after di / dt crosses zero, a command to disconnect the coil voltage circuit is sent, where i is the coil current and t is time.

3. The control method for the monostable magnetically controlled operating mechanism as described in claim 2, characterized in that... The following conditions are the main criteria for determining whether the control coil voltage circuit is disconnected during the closing process: ， For the moment t when all the above conditions are met for the first time, t+Δt2 is taken as the point at which the voltage loop is disconnected, where I min Let t be the nearest current minimum value before time t, and let Δt1 and Δt2 be the first and second time constants, respectively.

4. The control method for a monostable magnetically controlled operating mechanism as described in any one of claims 1-3, characterized in that... Set a third time constant Δt3, and determine whether the closing time reaches the third time constant. When the closing time reaches the third time constant, send a command to disconnect the coil voltage circuit.

5. The control method for the monostable magnetically controlled operating mechanism as described in claim 1, characterized in that... During the tripping process, the current in the mechanism coil is monitored in real time. Based on the current change characteristics, the timing of the voltage circuit disconnection during the tripping process is determined, and the coil voltage circuit is controlled to disconnect.

6. The control method for the monostable magnetically controlled operating mechanism as described in claim 5, characterized in that... When a short-term rapid rise and subsequent fall in coil current is detected, a command to disconnect the coil voltage circuit is sent.

7. The control method for the monostable magnetically controlled operating mechanism as described in claim 6, characterized in that... The following conditions are the main criteria for determining whether the control coil voltage circuit is disconnected during the tripping process: ， For the moment t when all the above conditions are first met, t+Δt5 is taken as the point at which the voltage loop is disconnected, where i is the coil current and t is time. △t4 and △t5 are the set fourth and fifth time constants, respectively.

8. The control method for a monostable magnetically controlled operating mechanism as described in any one of claims 5-7, characterized in that... Set a sixth time constant Δt3, and determine whether the opening time has reached the sixth time constant. When the opening time reaches the sixth time constant, send a command to disconnect the coil voltage circuit.

9. The control method for a monostable magnetically controlled operating mechanism as described in any one of claims 1-8, characterized in that... The magnetic field strength of the magnetic control mechanism in the closed holding state is detected in real time. The detected magnetic field strength is compared with the set magnetization threshold. If it is less than the magnetization threshold, the magnet of the magnetic control mechanism is magnetized.

10. The control method for a monostable magnetically controlled operating mechanism as described in any one of claims 1-8, characterized in that... The residual current release time is optimized based on the following optimal release function: ， or ， With the optimal release function J and release time t d To determine the optimal release time, the dynamic condition release current time and the static condition release current time are adjusted based on the optimal release time obtained from the calculation. Here, Hr is the residual magnetic holding force, and α and β are the set weights for the discharge time and the residual magnetic holding force, respectively.

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