Decoupling control method for bistable permanent magnet switch opening and closing air gap flux linkage

Abstract

The application provides a bistable permanent magnet switch opening and closing air gap flux linkage decoupling control method, including the following steps: step S1, constructing a real-time flux linkage observer in the operation process, calculating the flux linkage of the opening and closing magnetic circuit by collecting the voltage and current signals of the opening and closing coil in real time; step S2, constructing a switch state table according to the driving circuit topology, and designing a flux linkage prediction model based on a limited set model prediction, which is used to traverse the opening and closing air gap flux linkage values of different switch states at the next moment; step S3, designing a cost function, and optimizing the traversed flux linkage values according to the cost function to obtain the optimal solution of the next switch period, and outputting the switch state corresponding to the optimal solution to control the driving circuit in the next switch period; the application can control the air gap flux linkage of the opening and closing magnetic circuit of the bistable permanent magnet switch by using the limited set model prediction method, and realizes the decoupling control of the opening and closing air gap flux linkage.

Description

Technical Field

[0001] This invention relates to the field of intelligent control technology for switching electrical appliances, and in particular to a decoupling control method for the air gap flux linkage of a bistable permanent magnet switch during opening and closing. Background Technology

[0002] Switchgear is one of the fundamental components of a power system, responsible for switching on and off normal and fault loads. It is widely used in power generation, transmission, distribution, and consumption systems, and its performance directly affects the safety and reliability of the entire power system. Bistable permanent magnet switches have significant advantages such as simple structure, low operational dispersion, and ease of control. Compared to traditional mechanical switches, bistable permanent magnet switches utilize permanent magnets to maintain the opening and closing states, consuming no energy and thus saving energy and reducing carbon emissions. However, during operation, the electromagnetic coupling between the opening and closing magnetic circuits is complex, making it difficult to flexibly and precisely control the operating mechanism's characteristics.

[0003] In recent years, the control schemes for bistable permanent magnet switches proposed by scholars both domestically and internationally have become increasingly complex. However, they essentially all control the coil current of the switch, and the opening and closing processes only control a single coil, without coordinating the excitation state of the opening and closing coils. In bistable permanent magnet switches, the opening and closing coils are wound on the same stationary iron core, sharing a magnetic circuit. The excitation states of the opening and closing coils are mutually coupled, and the movement of the moving iron core and magnetic circuit saturation phenomena generate more complex nonlinear dynamic couplings in the opening and closing magnetic circuit. Therefore, controlling only a single coil cannot achieve decoupling of the opening and closing magnetic circuit, leading to mutual influence of the magnetic flux linkages of the opening and closing coils, further affecting the operating characteristics of the moving iron core, and making it difficult to achieve precise control of the operating mechanism. Summary of the Invention

[0004] This invention proposes a decoupling control method for the air gap flux linkage of a bistable permanent magnet switch during opening and closing. It can use a finite set model prediction method to control the air gap flux linkage of the opening and closing magnetic circuits of the bistable permanent magnet switch separately, thereby achieving decoupling control of the air gap flux linkage during opening and closing.

[0005] The present invention adopts the following technical solution.

[0006] A decoupling control method for the air gap flux linkage of a bistable permanent magnet switch includes the following steps;

[0007] Step S1: Construct a real-time flux linkage observer during the operation process. By collecting the voltage and current signals of the opening and closing coils in real time, calculate the flux linkage of the opening and closing magnetic circuits respectively.

[0008] Step S2: Construct a switch state table based on the drive circuit topology, and design a flux prediction model based on a finite set model to traverse the opening and closing air gap flux values ​​under different switch states at the next moment.

[0009] Step S3: Design a cost function, optimize the flux linkage value of the traversal based on the cost function to obtain the optimal solution for the next switching cycle, and output the switching state corresponding to the optimal solution in the next switching cycle to control the drive circuit.

[0010] In step S3, different reference values ​​for the opening and closing air gap flux are set so that the predicted opening and closing air gap fluxes track the set opening and closing air gap reference fluxes respectively, thereby achieving decoupled control of the opening and closing air gap fluxes.

[0011] The opening and closing coils of the bistable permanent magnet switch both adopt a full-bridge structure in their driving topology, specifically: U dc The input voltage is DC. S1 to S8 are switching transistors, forming four bridge arms, namely B1, B2, B3 and B4. Among them, bridge arms B1 and B2 are used to control the excitation state of the closing coil, and B3 and B4 are used to control the excitation state of the opening coil, thus defining the state of the bridge arm.

[0012] When B1 performs control, the bridge arm status is "1" when the upper bridge arm S1 is turned on and the lower bridge arm S3 is turned off; the bridge arm status is "0" when the lower bridge arm S3 is turned on and the upper bridge arm S1 is turned off.

[0013] In step S2, a switch state table is constructed by mapping the switch state of the drive circuit to the voltage state of the coil to construct a switch state table. The switch state table is used to directly provide the corresponding switch drive signal based on the predicted voltage state, thereby controlling the excitation.

[0014] The switch state table in step S2 includes a switch state combination table, which is constructed as follows:

[0015] Table 1 shows the changes in coil voltage and air gap flux linkage for different bridge arm states in a bistable permanent magnet switch belonging to the closing group.

[0016] Table 1: Status Table of Closing Group Switches

[0017]

[0018] In the table, u h This is the voltage of the closing coil;

[0019] Table 2 shows the changes in coil voltage and air gap flux corresponding to different bridge arm states of the tripping group:

[0020] Table 2: Status Table of Tripping Group Switches

[0021]

[0022] u f This is the voltage of the trip coil;

[0023] Since the excitation conditions of bridge arm states (1,1) and (0,0) are the same during the opening and closing operations of the bistable permanent magnet switch, state (1,1) is discarded from the table above, and only state (0,0) is retained. The bridge arm states of the closing group and the opening group are combined to simplify the 16 bridge arm states into 9 bridge arm states, forming a switch state combination table, as shown in Table 3 below.

[0024] Table 3: Switch State Combination Table

[0025] <![CDATA[(B1,B2,B3,B4)]]> <![CDATA[u h ]]> <![CDATA[u f ]]> <![CDATA[S1~S8]]> (0，0，0，0) 0 0 (0，0，1,1，0，0，1，1) (0，0,0,1) 0 <![CDATA[-U dc ]]> (0，0，1,1，0，1，1，0) (0，0,1，0) 0 <![CDATA[+U dc ]]> (0，0，1，1，1，0，0，1) (0，1，0，0) <![CDATA[-U dc ]]> 0 (0，1，1，0，0，0，1，1) (0，1，0，1) <![CDATA[-U dc ]]> <![CDATA[-U dc ]]> (0，1，1,0,0,1，1，0) (0，1，1，0) <![CDATA[-U dc ]]> <![CDATA[+U dc ]]> (0，1，1，0，1，0，0，1) (1，0，0，0) <![CDATA[+U dc ]]> 0 (1，0,0,1，0，0，1，1) (1，0，0,1) <![CDATA[+U dc ]]> <![CDATA[-U dc ]]> (1，0,0,1，0，1，1，0) (1，0,1，0) <![CDATA[+U dc ]]> <![CDATA[+U dc ]]> (1，0,0,1，1，0，0，1)

[0026] Table 3 clearly establishes the mapping relationship between the bridge arm state of the drive circuit and the voltage states of the two coils. Then, using the definition of the bridge arm state, the bridge arm state is converted into a switching state, thus constructing the mapping relationship between the switching state of the drive circuit and the voltage states of the two coils, and finally completing the construction of the switching state table.

[0027] In step S2, the flux linkage prediction model based on the finite set model is obtained by discretizing the magnetic circuit voltage balance equation in Formula 1 below.

[0028]

[0029] In the formula: R coil Let ψ be the coil resistance, ψ be the magnetic flux linkage, and u be the magnetic flux density. coil i is the coil voltage. coil Coil current. Discretizing Equation 1 using the Euler method yields:

[0030] ψ (k+1) =ψ (k) +T(u (k+1) -i (k+1) R coil Formula 2;

[0031] In the formula: ψ (k+1) For the predicted flux linkage of the next control cycle, ψ (k) The calculated flux linkage for the current period is given by u, where T is the control period of the discrete system. (k+1) i is the coil voltage applied at the next moment. (k+1) Let i be the coil current at the next moment; the magnetic circuit of the bistable permanent magnet switch coil is strongly inductive, and the change in its current within one control cycle is negligible, then i (k+1) Use i (k) After substitution, Formula 2 transforms into

[0032] ψ (k+1) =ψ (k) +T(u (k+1) -i (k) R coil Formula 3;

[0033] A flux linkage prediction model is constructed using Formula 3 and the methods of flux linkage accumulation and digital integration. Specifically, it is based on the coil current i acquired during the current control cycle. (k) Coil voltage u (k) Calculate the flux linkage ψ by accumulation (k) After i (k) , ψ (k) As input, the coil voltage states u in the switch state table are iterated through according to formula three times. (k+1) This allows us to obtain all possible flux linkage outputs ψ in the next control cycle. (k+1) To achieve flux linkage prediction.

[0034] In step S3, the cost function is used as the core of the finite set model predictive control. Specifically, to achieve decoupling of the air gap flux linkage during opening and closing: during the closing process, the flux linkage of the opening air gap needs to be controlled to 0, while the flux linkage of the closing air gap is maintained at the reference value. Therefore, adjusting only the reference value of the closing air gap flux linkage can accurately control the operating characteristics of the bistable permanent magnet switch during the closing process. Similarly, during the opening process, the flux linkage of the closing air gap needs to be controlled to 0, while the flux linkage of the opening air gap is maintained at the reference value. Adjusting only the reference value of the opening air gap flux linkage can accurately control the operating characteristics of the bistable permanent magnet switch during the opening process. Therefore, the following cost functions for the closing process and the opening process are constructed respectively.

[0035] Cost function of closing process:

[0036]

[0037] Cost function of the circuit breaker tripping process:

[0038]

[0039] In the formula: ψ href Indicates the closing flux reference value, ψ fref Indicates the reference value of the tripping flux, ψ h(k+1) ψ represents the predicted flux linkage of the closing coil. f(k+1) This represents the predicted value of the trip coil flux.

[0040] Based on the flux linkage prediction model and the possible coil voltage states listed in Table 3, the predicted flux linkage value ψ of the closing coil is calculated iteratively. h(k+1) Predicted value of magnetic flux linkage ψ of the trip coil f(k+1)Depending on whether the current process is a tripping or closing operation, the predicted flux obtained through the traversal is substituted into the cost function of Formula 4 or Formula 5 for calculation, and the coil voltage state corresponding to the minimum value of the cost function is selected as the optimal state. Then, according to the mapping relationship in Table 3, the optimal coil voltage state is converted into a switching state to drive the two full-bridge topologies in the next control cycle T. This allows one air gap flux to track the reference value, while the other air gap flux remains at 0, thus achieving decoupled control of the tripping and closing air gap flux.

[0041] The decoupling control method is based on finite set model prediction and includes the use of drive circuits and embedded control systems;

[0042] The driving circuit is used as follows: The input voltage charges the filter capacitor C1 through the rectifier bridge D1, outputting a relatively stable DC current; S1, S2, S3, S4, S5, S6, S7, and S8 are power electronic switches, forming four bridge arms B1, B2, B3, and B4, which control the voltage of the opening and closing coils, thereby controlling the speed and direction of change of the air gap flux linkage during opening and closing. Taking closing as an example, the closing circuit is driven by controlling the state of bridge arms B1 and B2: When S1 and S4 are on, the voltage across the closing coil is positive, and the coil current rises rapidly, achieving rapid magnetization of the coil; when S2 and S3 are on, a negative voltage is applied across the closing coil, and the coil current drops rapidly, achieving rapid demagnetization; when S2 and S4 are on, the voltage across the closing coil is 0, and the current drops slowly, achieving a slow demagnetization effect.

[0043] The usage of an embedded control system includes the following steps:

[0044] Step A1: The first current sensor and the first voltage sensor collect the closing coil voltage u. h(k) Current i h(k) Combined with the closing coil resistance R hcoil And the switch state combination table, traversing the possible closing drive circuit coil voltage states, as u h(k+1) ;

[0045] Step A2: Construct a closing air gap flux prediction model based on the principle of flux prediction model to predict the closing air gap flux ψ in the next cycle. h(k+1) ;

[0046] Step A3: The second current sensor and the second voltage sensor collect the voltage u on the trip coil. f(k) Current i f(k) Combined with the trip coil resistance R fcoil And the switch state combination table, traversing the possible tripping drive circuit coil voltage states, as u f(k+1) ,

[0047] Step A4: Construct a tripping air gap flux prediction model based on the flux prediction model principle to predict the tripping air gap flux ψ for the next cycle. f(k+1) Step A5: Determine whether the current operation is opening or closing based on the opening and closing process control. When it is determined that the current operation is closing, set the closing flux reference value ψ. href Substituting into Formula 4, we find the minimum cost function g. min Then, the switching states of S1 to S8 are mapped according to the switching state combination table 3. Finally, the switching state is output through the output module in the next control cycle to control the on / off state of the switching transistor in the drive circuit, thereby controlling the closing air gap flux linkage ψ. h Tracking reference value ψ href And the air gap flux linkage ψ f Always set to 0, achieving decoupled control of the closing process;

[0048] When the current operation process is determined to be a tripping process, the tripping flux reference value ψ is set. fref Substituting into Formula 5, we find the minimum cost function g. min Then, the switching states of S1 to S8 are mapped according to the switching state combination table 3. Finally, the switching state is output through the output module in the next control cycle to control the on / off state of the switching transistor in the drive circuit, thereby opening the air gap flux linkage ψ. f Tracking reference value ψ fref And the closing air gap flux ψ h It is always 0, thus achieving decoupled control of the tripping process.

[0049] In the decoupling control method, the coil current of the bistable permanent magnet switch is protected by a current limiting module. The current limiting module includes two protections: one protection is to limit the current amplitude cycle by cycle, and the other protection is to block the current maximum value.

[0050] During the operation of the embedded system, the opening and closing process control determines whether the current process is opening or closing, and sets different maximum values ​​of the opening and closing coil current i. fmax i hmax With current amplitude i fF i hF ;

[0051] When the current reaches the amplitude i fF or i hF When the current control cycle is in a state of "0", the corresponding bridge arm state is forcibly switched to "0" to turn off the excitation of the current cycle and reduce the current. In the next control cycle, this state is re-evaluated until the current drops below the current amplitude. Then, the switch state operation is restarted according to the switch state combination table output.

[0052] When the current rises too quickly, it is considered an output short circuit, and the detected current exceeds the maximum value i of the opening and closing coil currents. fmax i hmax When this occurs, the second level of protection is activated, immediately locking the output of all switches to prevent damage caused by excessive current.

[0053] This invention addresses the challenge of inaccurate control of operating characteristics caused by the mutual coupling of the opening and closing magnetic circuits during the operation of bistable permanent magnet switches. Based on the finite set model prediction method, a decoupling control method for the air gap flux linkage of bistable permanent magnet switches is proposed. This method achieves independent and accurate control of the air gap flux linkage during opening and closing, reduces the impact of magnetic circuit coupling on the switch operating characteristics, improves the control accuracy of the switch operating characteristics, and thus improves the opening and closing performance. Attached Figure Description

[0054] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0055] Appendix Figure 1 This is a schematic diagram of the magnetic flux prediction model in this invention;

[0056] Appendix Figure 2 This is a schematic diagram of the topology of the bistable permanent magnet switch opening and closing drive circuit in this invention;

[0057] Appendix Figure 3 This is a schematic diagram of the principle circuit for controlling the magnetic flux predicted by the finite set model (in the figure, the first current sensor is current sensor 1, the first voltage sensor is voltage sensor 1, the second current sensor is current sensor 2, and the second voltage sensor is voltage sensor 2). Detailed Implementation

[0058] As shown in the figure, a decoupling control method for the air gap flux linkage of a bistable permanent magnet switch includes the following steps;

[0059] Step S1: Construct a real-time flux linkage observer during the operation process. By collecting the voltage and current signals of the opening and closing coils in real time, calculate the flux linkage of the opening and closing magnetic circuits respectively.

[0060] Step S2: Construct a switch state table based on the drive circuit topology, and design a flux prediction model based on a finite set model to traverse the opening and closing air gap flux values ​​under different switch states at the next moment.

[0061] Step S3: Design a cost function, optimize the flux linkage value of the traversal based on the cost function to obtain the optimal solution for the next switching cycle, and output the switching state corresponding to the optimal solution in the next switching cycle to control the drive circuit.

[0062] In step S3, different reference values ​​for the opening and closing air gap flux are set so that the predicted opening and closing air gap fluxes track the set opening and closing air gap reference fluxes respectively, thereby achieving decoupled control of the opening and closing air gap fluxes.

[0063] like Figure 2 As shown, the opening and closing coils of the bistable permanent magnet switch both adopt a full-bridge structure in their driving topology, specifically: U dc The input voltage is DC. S1 to S8 are switching transistors, forming four bridge arms, namely B1, B2, B3 and B4. Among them, bridge arms B1 and B2 are used to control the excitation state of the closing coil, and B3 and B4 are used to control the excitation state of the opening coil, thus defining the state of the bridge arm.

[0064] When B1 performs control, the bridge arm status is "1" when the upper bridge arm S1 is turned on and the lower bridge arm S3 is turned off; the bridge arm status is "0" when the lower bridge arm S3 is turned on and the upper bridge arm S1 is turned off.

[0065] In step S2, a switch state table is constructed by mapping the switch state of the drive circuit to the voltage state of the coil to construct a switch state table. The switch state table is used to directly provide the corresponding switch drive signal based on the predicted voltage state, thereby controlling the excitation.

[0066] The switch state table in step S2 includes a switch state combination table, which is constructed as follows:

[0067] Table 1 shows the changes in coil voltage and air gap flux linkage for different bridge arm states in a bistable permanent magnet switch belonging to the closing group.

[0068] Table 1: Status Table of Closing Group Switches

[0069]

[0070] In the table, u h This is the voltage of the closing coil;

[0071] Table 2 shows the changes in coil voltage and air gap flux corresponding to different bridge arm states of the tripping group:

[0072] Table 2: Status Table of Tripping Group Switches

[0073]

[0074] u f This is the voltage of the trip coil;

[0075] Since the excitation conditions of bridge arm states (1,1) and (0,0) are the same during the opening and closing operations of the bistable permanent magnet switch, state (1,1) is discarded from the table above, and only state (0,0) is retained. The bridge arm states of the closing group and the opening group are combined to simplify the 16 bridge arm states into 9 bridge arm states, forming a switch state combination table, as shown in Table 3 below.

[0076] Table 3: Switch State Combination Table

[0077] <![CDATA[(B1,B2,B3,B4)]]> <![CDATA[u h ]]> <![CDATA[u f ]]> <![CDATA[S1~S8]]> (0，0，0，0) 0 0 (0，0，1，1，0，0，1，1) (0，0，0，1) 0 <![CDATA[-U dc ]]> (0，0，1，1，0，1，1，0) (0，0，1，0) 0 <![CDATA[+U dc ]]> (0，0，1，1，1，0，0，1) (0，1，0，0) <![CDATA[-U dc ]]> 0 (0，1，1，0，0，0，1，1) (0，1，0，1) <![CDATA[-U dc ]]> <![CDATA[-U dc ]]> (0，1，1，0，0，1，1，0) (0，1，1，0) <![CDATA[-U dc ]]> <![CDATA[+U dc ]]> (0，1，1，0，1，0，0，1) (1，0，0，0) <![CDATA[+U dc ]]> 0 (1，0，0，1，0，0，1，1) (1，0，0，1) <![CDATA[+U dc ]]> <![CDATA[-U dc ]]> (1，0，0，1，0，1，1，0) (1，0，1，0) <![CDATA[+U dc ]]> <![CDATA[+U dc ]]> (1，0,0,1，1,0,0，1)

[0078] Table 3 clearly establishes the mapping relationship between the bridge arm state of the drive circuit and the voltage states of the two coils. Then, using the definition of the bridge arm state, the bridge arm state is converted into a switching state, thus constructing the mapping relationship between the switching state of the drive circuit and the voltage states of the two coils, and finally completing the construction of the switching state table.

[0079] In step S2, the flux linkage prediction model based on the finite set model is obtained by discretizing the magnetic circuit voltage balance equation in Formula 1 below.

[0080]

[0081] In the formula: R coil Let ψ be the coil resistance, ψ be the magnetic flux linkage, and u be the magnetic flux density. coil i is the coil voltage. coil Coil current. Discretizing Equation 1 using the Euler method yields:

[0082] ψ (k+1) =ψ (k) +T(u (k+1) -i (k+1) R coil Formula 2;

[0083] In the formula: ψ (k+1) For the predicted flux linkage of the next control cycle, ψ (k) The calculated flux linkage for the current period is given by u, where T is the control period of the discrete system. (k+1) i is the coil voltage applied at the next moment. (k+1) Let i be the coil current at the next moment; the magnetic circuit of the bistable permanent magnet switch coil is strongly inductive, and the change in its current within one control cycle is negligible, then i (k+1) Use i (k) After substitution, Formula 2 transforms into

[0084] ψ (k+1) =ψ (k) +T(u (k+1) -i (k) R coil Formula 3;

[0085] like Figure 1 As shown, a flux linkage prediction model is constructed using Formula 3 and the methods of flux linkage accumulation and digital integration. Specifically, the model is based on the coil current i acquired during the current control cycle. (k) Coil voltage u (k) Calculate the flux linkage ψ by accumulation (k) After i (k) , ψ (k) As input, the coil voltage states u in the switch state table are iterated through according to formula three times. (k+1) This allows us to obtain all possible flux linkage outputs ψ in the next control cycle. (k+1) To achieve flux linkage prediction.

[0086] In step S3, the cost function is used as the core of the finite set model predictive control. Specifically, to achieve decoupling of the air gap flux linkage during opening and closing: during the closing process, the flux linkage of the opening air gap needs to be controlled to 0, while the flux linkage of the closing air gap is maintained at the reference value. Therefore, adjusting only the reference value of the closing air gap flux linkage can accurately control the operating characteristics of the bistable permanent magnet switch during the closing process. Similarly, during the opening process, the flux linkage of the closing air gap needs to be controlled to 0, while the flux linkage of the opening air gap is maintained at the reference value. Adjusting only the reference value of the opening air gap flux linkage can accurately control the operating characteristics of the bistable permanent magnet switch during the opening process. Therefore, the following cost functions for the closing process and the opening process are constructed respectively.

[0087] Cost function of closing process:

[0088]

[0089] Cost function of the circuit breaker tripping process:

[0090]

[0091] In the formula: ψ href Indicates the closing flux reference value, ψ fref Indicates the reference value of the tripping flux, ψ h(k+1) ψ represents the predicted flux linkage of the closing coil. f(k+1) This represents the predicted value of the trip coil flux.

[0092] Based on the flux linkage prediction model and the possible coil voltage states listed in Table 3, the predicted flux linkage value ψ of the closing coil is calculated iteratively. h(k+1) Predicted value of magnetic flux linkage ψ of the trip coil f(k+1)Depending on whether the current process is a tripping or closing operation, the predicted flux obtained through the traversal is substituted into the cost function of Formula 4 or Formula 5 for calculation, and the coil voltage state corresponding to the minimum value of the cost function is selected as the optimal state. Then, according to the mapping relationship in Table 3, the optimal coil voltage state is converted into a switching state to drive the two full-bridge topologies in the next control cycle T. This allows one air gap flux to track the reference value, while the other air gap flux remains at 0, thus achieving decoupled control of the tripping and closing air gap flux.

[0093] like Figure 3 As shown, the decoupling control method is based on finite set model prediction and includes the use of drive circuits and embedded control systems;

[0094] The driving circuit is used as follows: The input voltage charges the filter capacitor C1 through the rectifier bridge D1, outputting a relatively stable DC current; S1, S2, S3, S4, S5, S6, S7, and S8 are power electronic switches, forming four bridge arms B1, B2, B3, and B4, which control the voltage of the opening and closing coils, thereby controlling the speed and direction of change of the air gap flux linkage during opening and closing. Taking closing as an example, the closing circuit is driven by controlling the state of bridge arms B1 and B2: When S1 and S4 are on, the voltage across the closing coil is positive, and the coil current rises rapidly, achieving rapid magnetization of the coil; when S2 and S3 are on, a negative voltage is applied across the closing coil, and the coil current drops rapidly, achieving rapid demagnetization; when S2 and S4 are on, the voltage across the closing coil is 0, and the current drops slowly, achieving a slow demagnetization effect.

[0095] The usage of an embedded control system includes the following steps:

[0096] Step A1: The first current sensor and the first voltage sensor collect the closing coil voltage u. h(k) Current i h(k) Combined with the closing coil resistance R hcoil And the switch state combination table, traversing the possible closing drive circuit coil voltage states, as u h(k+1) ;

[0097] Step A2: Construct a closing air gap flux prediction model based on the principle of flux prediction model to predict the closing air gap flux ψ in the next cycle. h(k+1) ;

[0098] Step A3: The second current sensor and the second voltage sensor collect the voltage u on the trip coil. f(k) Current i f(k) Combined with the trip coil resistance R fcoil And the switch state combination table, traversing the possible tripping drive circuit coil voltage states, as u f(k+1) ,

[0099] Step A4: Construct a tripping air gap flux prediction model based on the flux prediction model principle to predict the tripping air gap flux ψ for the next cycle. f(k+1) Step A5: Determine whether the current operation is opening or closing based on the opening and closing process control. When it is determined that the current operation is closing, set the closing flux reference value ψ. href Substituting into Formula 4, we find the minimum cost function g. min Then, the switching states of S1 to S8 are mapped according to the switching state combination table 3. Finally, the switching state is output through the output module in the next control cycle to control the on / off state of the switching transistor in the drive circuit, thereby controlling the closing air gap flux linkage ψ. h Tracking reference value ψ href And the air gap flux linkage ψ f Always set to 0, achieving decoupled control of the closing process;

[0100] When the current operation process is determined to be a tripping process, the tripping flux reference value ψ is set. fref Substituting into Formula 5, we find the minimum cost function g. min Then, the switching states of S1 to S8 are mapped according to the switching state combination table 3. Finally, the switching state is output through the output module in the next control cycle to control the on / off state of the switching transistor in the drive circuit, thereby opening the air gap flux linkage ψ. f Tracking reference value ψ fref And the closing air gap flux ψ h It is always 0, thus achieving decoupled control of the tripping process.

[0101] In the decoupling control method, the coil current of the bistable permanent magnet switch is protected by a current limiting module. The current limiting module includes two protections: one protection is to limit the current amplitude cycle by cycle, and the other protection is to block the current maximum value.

[0102] During the operation of the embedded system, the opening and closing process control determines whether the current process is opening or closing, and sets different maximum values ​​of the opening and closing coil current i. fmax i hmax With current amplitude i fF i hF ;

[0103] When the current reaches the amplitude i fF or i hF When the current control cycle is in a state of "0", the corresponding bridge arm state is forcibly switched to "0" to turn off the excitation of the current cycle and reduce the current. In the next control cycle, this state is re-evaluated until the current drops below the current amplitude. Then, the switch state operation is restarted according to the switch state combination table output.

[0104] When the current rises too quickly, it is considered an output short circuit, and the detected current exceeds the maximum value i of the opening and closing coil currents. fmax i hmax When this occurs, the second level of protection is activated, immediately locking the output of all switches to prevent damage caused by excessive current.

Claims

1. A decoupling control method for the air gap flux linkage during the opening and closing of a bistable permanent magnet switch, characterized in that: Includes the following steps; Step S1: Construct a real-time flux linkage observer during the operation process. By collecting the voltage and current signals of the opening and closing coils in real time, calculate the flux linkage of the opening and closing magnetic circuits respectively. Step S2: Construct a switch state table based on the drive circuit topology, and design a flux prediction model based on a finite set model to traverse the opening and closing air gap flux values ​​under different switch states at the next moment. Step S3: Design a cost function, optimize the flux linkage value of the traversal based on the cost function to obtain the optimal solution for the next switching cycle, and output the switching state corresponding to the optimal solution in the next switching cycle to control the drive circuit. In step S2, the flux linkage prediction model based on the finite set model is obtained by discretizing the magnetic circuit voltage balance equation in Formula 1 below. In the formula: R coil Let ψ be the coil resistance, ψ be the magnetic flux linkage, and u be the magnetic flux density. coil Let i be the coil voltage. coil Let the coil current be the current; discretizing Equation 1 using the Euler method yields: ψ (k+1) =ψ (k) +T(u (k+1) -i (k+1) R coil Formula 2; In the formula: ψ (k+1) For the predicted flux linkage of the next control cycle, ψ (k) The calculated flux linkage for the current period is given by u, where T is the control period of the discrete system. (k+1) i is the coil voltage applied at the next moment. (k+1) Let i be the coil current at the next moment; the magnetic circuit of the bistable permanent magnet switch coil is strongly inductive, and the change in its current within one control cycle is negligible. (k+1) Use i (k) After substitution, Formula 2 transforms into ψ (k+1) = ψ (k) + T(u (k+1) - i (k) R coil ) Equation 3; A flux linkage prediction model is constructed using Formula 3 and the methods of flux linkage accumulation and digital integration. Specifically, it is based on the coil current i acquired during the current control cycle. (k) Coil voltage u (k) Calculate the flux linkage ψ by accumulation (k) After i (k) ψ (k) As input, the coil voltage states u in the switch state table are iterated through according to formula three times. (k+1) This yields all possible flux linkage outputs ψ in the next control cycle. (k+1) To achieve flux linkage prediction; The following cost functions are constructed for the closing process and the opening process, respectively; Cost function of closing process: Cost function of the circuit breaker tripping process: In the formula: ψ href Indicates the closing flux reference value, ψ fref Indicates the reference value of the tripping flux, ψ h(k+1) ψ represents the predicted flux linkage of the closing coil. f(k+1) This represents the predicted value of the trip coil flux linkage.

2. The decoupling control method for the air gap flux linkage of a bistable permanent magnet switch according to claim 1, characterized in that: In step S3, different reference values ​​for the opening and closing air gap flux are set so that the predicted opening and closing air gap fluxes track the set opening and closing air gap reference fluxes respectively, thereby achieving decoupled control of the opening and closing air gap fluxes.

3. The decoupling control method for the air gap flux linkage of a bistable permanent magnet switch according to claim 1, characterized in that: The opening and closing coils of the bistable permanent magnet switch both adopt a full-bridge structure in their driving topology, specifically: U dc The input voltage is DC. S1 to S8 are switching transistors, forming four bridge arms, namely B1, B2, B3 and B4. Among them, bridge arms B1 and B2 are used to control the excitation state of the closing coil, and B3 and B4 are used to control the excitation state of the opening coil, thus defining the state of the bridge arm. When B1 performs control, the bridge arm status is "1" when the upper bridge arm S1 is turned on and the lower bridge arm S3 is turned off; the bridge arm status is "0" when the lower bridge arm S3 is turned on and the upper bridge arm S1 is turned off.

4. The decoupling control method for the opening and closing air gap flux of a bistable permanent magnet switch according to claim 3, characterized in that: In step S2, a switch state table is constructed by mapping the switch state of the drive circuit to the voltage state of the coil to construct a switch state table. The switch state table is used to directly provide the corresponding switch drive signal based on the predicted voltage state, thereby controlling the excitation. The switch state table in step S2 includes a switch state combination table, which is constructed as follows: Table 1 shows the changes in coil voltage and air gap flux linkage for different bridge arm states in a bistable permanent magnet switch belonging to the closing group. Table 1: Status Table of Closing Group Switches In the table, u h This is the voltage of the closing coil; Table 2 shows the changes in coil voltage and air gap flux corresponding to different bridge arm states of the tripping group: Table 2: Status Table of Tripping Group Switches u f This is the voltage of the trip coil; Since the excitation conditions of bridge arm states (1,1) and (0,0) are the same during the opening and closing operations of the bistable permanent magnet switch, state (1,1) is discarded from the table above, and only state (0,0) is retained. The bridge arm states of the closing group and the opening group are combined to simplify the 16 bridge arm states into 9 bridge arm states, forming a switch state combination table, as shown in Table 3 below. Table 3: Switch Status Combination Table Table 3 is used to clearly establish the mapping relationship between the bridge arm state of the drive circuit and the voltage state of the two coils. Then, using the definition of the bridge arm state, the bridge arm state is converted into a switching state, and the mapping relationship between the switching state of the drive circuit and the voltage state of the two coils is constructed, thereby completing the construction of the switching state table.

5. The decoupling control method for the opening and closing air gap flux of a bistable permanent magnet switch according to claim 4, characterized in that: In step S3, the cost function is used as the core of the finite set model predictive control. Specifically, to achieve decoupling of the air gap flux linkage during opening and closing, the flux linkage of the opening air gap needs to be controlled to 0 during the closing process, while the flux linkage of the closing air gap is maintained at the reference value. Therefore, adjusting only the reference value of the closing air gap flux linkage can accurately control the operating characteristics of the bistable permanent magnet switch during the closing process. Similarly, during the opening process, the flux linkage of the closing air gap needs to be controlled to 0, while the flux linkage of the opening air gap is maintained at the reference value. Adjusting only the reference value of the opening air gap flux linkage can accurately control the operating characteristics of the bistable permanent magnet switch during the opening process. Based on the flux linkage prediction model and the possible coil voltage states listed in Table 3, the predicted value ψ of the closing coil flux linkage is calculated iteratively. h(k+1) Predicted value of magnetic flux linkage ψ of trip coil f(k+1) Depending on whether the current process is a tripping or closing operation, the predicted flux obtained through the traversal is substituted into the cost function of Formula 4 or Formula 5 for calculation, and the coil voltage state corresponding to the minimum value of the cost function is selected as the optimal state. Then, according to the mapping relationship in Table 3, the optimal coil voltage state is converted into a switching state to drive the two full-bridge topologies in the next control cycle T. This enables one air gap flux to track the reference value, while the other air gap flux is always 0, thus achieving decoupled control of the tripping and closing air gap flux.

6. The decoupling control method for the opening and closing air gap flux of a bistable permanent magnet switch according to claim 4, characterized in that: The decoupling control method is based on finite set model prediction and includes the use of drive circuits and embedded control systems; The driving circuit is used as follows: The input voltage charges the filter capacitor C1 through the rectifier bridge D1, outputting a relatively stable DC current; S1, S2, S3, S4, S5, S6, S7, and S8 are power electronic switches, forming four bridge arms B1, B2, B3, and B4, which control the voltage of the opening and closing coils, thereby controlling the speed and direction of change of the air gap flux linkage during opening and closing; When closing, the closing circuit is driven by controlling the state of bridge arms B1 and B2: When S1 and S4 are on, the voltage across the closing coil is positive, and the coil current rises rapidly, achieving rapid excitation of the coil; when S2 and S3 are on, a negative voltage is applied across the closing coil, and the coil current drops rapidly, achieving rapid demagnetization; when S2 and S4 are on, the voltage across the closing coil is 0, and the current drops slowly, achieving a slow demagnetization effect; The usage of an embedded control system includes the following steps: Step A1: The first voltage sensor and the first current sensor respectively collect the closing coil voltage u. h(k) Current i h(k) Combined with the closing coil resistance R hcoil And the switch state combination table, traversing the possible closing drive circuit coil voltage states, as u h(k+1) ; Step A2: Construct a closing air gap flux prediction model based on the principle of flux prediction model to predict the closing air gap flux ψ in the next cycle. h(k+1) ; Step A3: The second voltage sensor and the second current sensor respectively collect the voltage u on the trip coil. f(k) Current i f(k) Combined with the trip coil resistance R fcoil And the switch state combination table, traversing the possible tripping drive circuit coil voltage states, as u f(k+1) , Step A4: Construct a tripping air gap flux prediction model based on the flux prediction model principle to predict the tripping air gap flux ψ for the next cycle. f(k+1) , Step A5: Determine whether the current operation is opening or closing based on the opening and closing process control. When the current operation is determined to be closing, adjust the closing flux reference value ψ. href Substituting into Formula 4, we find the minimum cost function g. min1 Then, the switching states of S1 to S8 are mapped according to the switching state combination table 3. Finally, the switching state is output through the output module in the next control cycle to control the on / off state of the switching transistor in the drive circuit, thereby controlling the closing air gap flux linkage ψ. h Tracking reference value ψ href And the air gap flux linkage ψ f Always set to 0, achieving decoupled control of the closing process; When the current operation process is determined to be a tripping process, the tripping flux reference value ψ is set. fref Substituting into Formula 5, we find the minimum cost function g. min2 Then, the switching states of S1 to S8 are mapped according to the switching state combination table 3. Finally, the switching state is output through the output module in the next control cycle to control the on / off state of the switching transistor in the drive circuit, thereby opening the air gap flux linkage ψ. f Tracking reference value ψ fref And the closing air gap flux ψ h It is always 0, thus achieving decoupled control of the tripping process.

7. The decoupling control method for the opening and closing air gap flux of a bistable permanent magnet switch according to claim 6, characterized in that: In the decoupling control method, the coil current of the bistable permanent magnet switch is protected by a current limiting module. The current limiting module includes two protections: one protection is to limit the current amplitude cycle by cycle, and the other protection is to block the current maximum value. During the operation of the embedded system, the opening and closing process control determines whether the current process is opening or closing, and sets different maximum values ​​of the opening and closing coil current i. fmax i hmax With current amplitude i fF i hF ; When the current reaches the amplitude i fF or i hF When the current control cycle is in a state of "0", the corresponding bridge arm state is forcibly switched to "0" to turn off the excitation of the current cycle and reduce the current. In the next control cycle, this state is re-evaluated until the current drops below the current amplitude. Then, the switching state operation is restarted according to the switching state combination table output. When the current rises too quickly, it is considered an output short circuit, and the detected current exceeds the maximum value i of the opening and closing coil currents. fmax i hmax When this occurs, the second level of protection is activated, immediately locking the output of all switches to prevent damage caused by excessive current.

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