CN111580436B - Contactor flux linkage closed-loop control method based on state observer - Google Patents

Abstract

The present invention proposes a contactor flux linkage closed-loop control method based on a state observer. The control method observes the contactor flux linkage data through the flux linkage state observer during the contactor starting process and the contactor holding process, and uses the observation results The contactor current is controlled; the invention adopts the double closed-loop control structure of the flux linkage outer loop to control the current inner loop, which not only overcomes the defect of the single current closed-loop holding process, but also further improves the flexibility of the optimal control of the contactor starting process.

Description

Closed-loop control method of contactor flux linkage based on state observer

technical field

The invention relates to the technical field of electromagnetic control, in particular to a contactor flux linkage closed-loop control method based on a state observer.

Background technique

As a common electromagnetic switch, the contactor is used in a large amount in industrial systems and power distribution systems, and its performance indicators directly affect the safety and stability of the entire control system. There are many problems in the operation of traditional contactors, such as: they are more sensitive to voltage drops, and they are easily affected by power grid voltage fluctuations and cause contacts to break off incorrectly, which affects the reliability of contactors in continuous production systems such as oil; the working voltage range is narrow. , Under the critical pull-in voltage, the iron core will generate continuous vibration, resulting in contact welding; the temperature rise of the contactor coil is too high under frequent operation, which affects the coil life and the performance of the contactor.

In recent years, scholars at home and abroad have proposed various contactor intelligent control schemes. Compared with the current control schemes, the direct closed-loop control of the contactor coil current has the following advantages: the coil current is directly used as the feedback control quantity, which has the characteristics of natural current limiting. Especially when used in large-capacity contactors with small coil resistance, the starting excitation ampere-turn can be flexibly adjusted to avoid coil overcurrent and short circuit; during the starting process, the optimal control of the starting process can be realized by flexibly adjusting the starting current curve; the coil current is always Continuously controllable, there will be no sudden cut-off of current, avoiding overvoltage of coil operation. Although the current closed loop has many advantages, it has a major defect in the holding process: when the energy-saving silent hold is performed, once the air gap between the moving and static iron cores is suddenly increased slightly due to the influence of external vibration or shock, the coil holding current will be forced to Rising, is greater than the holding reference current, at this time the current closed loop enters a "vicious circle", quickly adjusting the holding current duty cycle to 0, but aggravating the breaking of the contactor, seriously affecting the intelligent contactor in harsh application environments such as locomotives and ships. Maintain reliability.

In view of the defects of the current closed-loop control of the contactor, the present invention proposes a flux linkage closed-loop control. In the process of starting and holding, a flux linkage state observer is constructed to observe the flux linkage value, and then the flux linkage outer loop is used to control the current inner loop. Double closed-loop control structure , which not only overcomes the defect of the single current closed-loop holding process, but also further improves the flexibility of the optimal control of the contactor starting process.

SUMMARY OF THE INVENTION

The invention proposes a contactor flux closed-loop control method based on a state observer, and adopts a double closed-loop control structure in which the flux linkage outer loop controls the current inner loop, which not only overcomes the defect of the single current closed-loop holding process, but also further improves the contactor starting process. Flexibility for process optimization control.

The present invention adopts the following technical solutions.

A contactor flux linkage closed-loop control method based on a state observer. The control method observes the flux linkage data of the contactor through the flux linkage state observer during the contactor starting process and the contactor holding process, and uses the observation results to monitor the contactor's flux linkage data. current is controlled.

During the starting process of the contactor, the flux linkage state observer adopts the open-loop observation method based on the voltage integral flux linkage observer to obtain the flux linkage data; in the stable contactor holding process, the flux linkage state observer adopts the closed-loop state based on the flux linkage state. The closed-loop observation method of the observer is used to obtain the flux linkage data; in the control method, the open-loop observation method and the closed-loop observation method are smoothly switched according to the progress of the contactor control process; in the control method, by controlling the current of the contactor coil , to control the excitation state of the contactor coil to optimize the dynamic work of the contactor.

The contactor starting time is less than 100ms; in the open-loop observation method for the contactor starting process, formula (1) is used to calculate the data of the flux linkage;

In formula (1), the data ψ of the flux linkage in the starting process can be obtained by detecting the coil voltage u _coil and the coil current i _coil and then integrating with the contactor coil resistance R _coil for integral calculation; t ₀ is the starting time of the contactor, ψ, u The initial states of _coil and i _coil at time t ₀ are all 0; the starting flux linkage can be recorded as

In the closed-loop observation method for the stable contactor holding process, the flux linkage of the contactor coil magnetic circuit satisfies the following formula (2):

ψ=Li _coil (2)

The magnetic circuit voltage balance equation of the contactor is expressed by formula (3) as:

Combining formula (2) and formula (3), formula (4) is derived

In formula (4), the coil magnetic circuit of the contactor during the stable maintenance process is regarded as a constant resistance-inductive load to calculate; u _coil is the coil current, R _coil is the coil resistance, ψ is the magnetic circuit flux linkage, and L is the magnetic circuit inductance. ;

The state space expression of the contactor's stable holding process is derived

为磁链的微分。where:

is the differential of the flux linkage.

In the state space expression of the contactor's stable holding process, with u _coil as the input, i _coil as the output, and ψ as the state variable, it can be seen that the same A=-R _coil /L, B=1, C=1/ L's one-dimensional linear steady-state system with single input and single output, and use this one-dimensional linear steady system for real-time solution application, and use input variables and output variables to construct a closed-loop flux linkage state observer applied to the process of contactor stability;

与实际值i_coil的误差来闭环修正状态变量观测值

以改善观测器的性能。The closed-loop flux linkage state observer applied to the contactor stable maintaining process utilizes the system output parameter i _coil , and adopts the coil current observation value

The error from the actual value i _coil is used to close the loop to correct the observed value of the state variable

to improve the performance of the observer.

与i_coil的误差为输入，对保持过程中的观测磁链

进行闭环修正，使

能够迅速趋近实际值。The flux-linkage closed-loop state observer applied to the contactor's stable holding process takes the measured u _coil and i _coil as the observer inputs, and adds a feedback matrix E on the basis of the open-loop state observer, to obtain

The error with the i _coil is the input, and the observed flux linkage during the holding process is

A closed-loop correction is made so that

The actual value can be approached quickly.

The device used in the contactor flux linkage closed-loop control method includes a coil drive circuit and an embedded control system;

The coil drive circuit includes a rectifier bridge D ₁ and a rectifier module which is a filter capacitor C ₁ ; the rectifier module is connected to the input power supply, and the input voltage is changed into a relatively stable DC voltage and output to the contactor coil, so that the contactor coil Work;

The coil driving circuit further includes electronic switches S ₁ , S ₄ , as well as fast recovery diodes D ₂ , D ₃ ; the electronic switches perform PWM control on the rectified and filtered DC voltage to control the polarity of the voltage applied to the contactor coil ;

The coil driving circuit makes the contactor coil circuit work in +1 state, -1 state and 0 state by controlling the polarity of the voltage applied to the contactor coil;

When the contactor coil circuit works in the +1 state, S ₁ and S ₄ are turned on at the same time, and the forward voltage after rectification and filtering is applied to both ends of the coil, so that the current of the contactor coil rises rapidly and the flux linkage is rapidly strengthened;

When the contactor coil circuit works in -1 state, the coil current is not zero at this time, S ₁ and S ₄ are turned off at the same time, the coil current feeds back energy to the filter capacitor C ₁ through D ₂ and D ₃ , and the negative voltage of the capacitor Applied to both ends of the coil, forcing the coil to demagnetize quickly;

When the contactor coil circuit works in the 0 state, the two ends of the coil are subjected to negative _D3 and S4 tube voltage drop close to 0V, the electronic switch only S4 is turned _on , the coil current flows through _D3 and _S4 , and the coil current flows _. decline slowly;

The embedded control system detects the contactor coil current through the current sensor, and detects the contactor coil voltage through the voltage sensor.

The embedded control system includes a process control module, a topology control module and an observer switch, and also includes a flux linkage outer loop control module using the hysteresis control principle and a current inner loop control module using the hysteresis control principle; the process control module It is connected with the flux linkage outer loop control module; the flux linkage outer loop control module is connected with the current inner loop control module; the input end of the observer switch is connected with the flux linkage outer loop control module and the current inner loop control module, and the output end is connected with the current inner loop control module. The flux linkage outer loop control module is connected; the current inner loop control module outputs _a PWM signal to the electronic switch S1 and the topology control module, and the output end of the topology control module is connected to the electronic switch S4 _;

及保持过程中的磁链

When the embedded control system is working, the detected coil voltage u _coil and coil current i _coil are simultaneously fed into the voltage integral flux linkage observer and the flux linkage closed-loop state observer, which are respectively used to observe the flux linkage in the starting process

and the flux linkage during the hold

The process control module of the embedded control system controls the contactor to enter the starting, holding and breaking processes according to the sequence requirements, and different flux linkage reference values ψ _ref can be set in these different processes;

The observer switch of the embedded control system is responsible for the switching of the two observers to synthesize the flux linkage observations of the whole process

The topology control module decides whether to set the switch S4 to a normally _- on state according to the action signal of the observer switching switch.

ψ_ref与

经过磁链外环控制模块的滞环比较来控制电流内环控制模块的参考值i_ref，使其在电流最大值i_max与0之间变化，之后i_ref与i_coil经过电流内环控制模块的滞环比较作用，输出信号PWM1及PWM4，PWM1控制S₁的通断状态，在起动过程中拓扑控制模块直接采用PWM4信号来控制S₄的通断状态，使电路状态在+1态和-1态间切换来快速达到参考电流，从而使接触器线圈磁路磁链等于起动磁链参考值；The software strategy of the embedded control system is divided into a starting process, a holding process and a breaking process according to the control sequence; the process control module makes the embedded control system work according to different software strategies according to the control instructions; when the embedded control system executes When starting the software strategy of the process, the observer toggle switch selects

ψ _ref and

Through the hysteresis comparison of the flux linkage outer loop control module, the reference value i _ref of the current inner loop control module is controlled to change between the current maximum value i _max and 0, and then i _ref and i _coil pass through the current inner loop control module The hysteresis comparison function of the output signal PWM1 and PWM4, PWM1 controls the on-off state of S _1. During the starting process, the topology control module directly uses the PWM4 signal to control the on-off state of S ₄ , so that the circuit state is in the +1 state and - Switch between 1 states to quickly reach the reference current, so that the magnetic flux of the contactor coil is equal to the reference value of the starting flux;

并与ψ_ref滞环比较来控制i_ref，i_ref与i_coil滞环比较，控制电路状态在+1态和-1态间切换来快速达到ψ_ref，磁路磁链等于保持磁链参考值后观测器切换开关选择

将磁链闭环状态观测器接入磁链外环控制模块，进行保持磁链的观测器的平稳衔接，同时拓扑控制模块检测到观测器切换开关的切换信号，将S₄置为常通，使接触器线圈电路状态仅在+1态和0态间切换来维持保持线圈电流动态恒定，降低电子开关的导通周期数，减小损耗，进行更好的节能保持；When the embedded control system executes the software strategy of the hold process, ψ _ref is set as the hold value, and the observer switch is still selected

And compare with ψ _ref hysteresis loop to control i _ref , compare i _ref with i _coil hysteresis loop, control circuit state to switch between +1 state and -1 state to quickly reach ψ _ref , the magnetic flux linkage is equal to maintaining the reference value of flux linkage Rear Observer toggle switch selection

The flux linkage closed-loop state observer is connected to the flux linkage outer loop control module to maintain the smooth connection of the flux linkage observer. At the same time, the topology control module detects the switching signal of the observer switching switch, and sets S4 to be normally _on , so that the The circuit state of the contactor coil is only switched between the +1 state and the 0 state to maintain the dynamic constant of the coil current, reduce the number of conduction cycles of the electronic switch, reduce the loss, and achieve better energy conservation;

When the embedded control system executes the software strategy of the breaking process, the process control module directly controls the current inner loop to set PWM1 and PWM4 to 0, and cooperates with the topology control module to quickly set the circuit state to -1 state, so that the electromagnetic coil of the contactor is quickly demagnetized , the contactor breaks.

The invention overcomes the defect of the single current closed-loop holding process, and also further improves the flexibility of the optimal control of the contactor starting process.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments:

Accompanying drawing 1 is the schematic diagram of the principle of the voltage integral type flux linkage state observer in the starting process;

Accompanying drawing 2 is the principle schematic diagram of the closed-loop flux linkage state observer during the contactor coil holding process;

FIG. 3 is a schematic diagram of the principle of the closed-loop control of the contactor flux linkage.

Detailed ways

As shown in Figure 1-3, the closed-loop control method of the contactor flux linkage based on the state observer, the control method observes the flux linkage data of the contactor through the flux linkage state observer during the contactor starting process and the contactor holding process. , and control the contactor current based on the observation results.

During the starting process of the contactor, the flux linkage state observer adopts the open-loop observation method based on the voltage integral flux linkage observer to obtain the flux linkage data; in the stable contactor holding process, the flux linkage state observer adopts the closed-loop state based on the flux linkage state. The closed-loop observation method of the observer is used to obtain the flux linkage data; in the control method, the open-loop observation method and the closed-loop observation method are smoothly switched according to the progress of the contactor control process; in the control method, by controlling the current of the contactor coil , to control the excitation state of the contactor coil to optimize the dynamic work of the contactor.

The contactor starting time is less than 100ms; in the open-loop observation method for the contactor starting process, formula (1) is used to calculate the data of the flux linkage;

As shown in Figure 1, in formula (1), by detecting the coil voltage u _coil and the coil current i _coil and then integrating with the contactor coil resistance R _coil , the data ψ of the flux linkage during the starting process can be obtained; t ₀ is the contactor At the starting time, the initial states of ψ, u _coil and i _coil at time t ₀ are all 0; the starting flux linkage can be recorded as

In the closed-loop observation method for the stable contactor holding process, the flux linkage of the contactor coil magnetic circuit satisfies the following formula (2):

ψ=Li _coil (2)

The magnetic circuit voltage balance equation of the contactor is expressed by formula (3) as:

Combining formula (2) and formula (3), formula (4) is derived

As shown in Figure 2, in formula (4), the coil magnetic circuit of the contactor during the stable maintenance process is regarded as a constant resistance-inductive load to calculate; u _coil is the coil current, R _coil is the coil resistance, and ψ is the magnetic circuit flux linkage , L is the magnetic circuit inductance; the state space expression of the contactor's stable holding process is obtained by deriving

为磁链的微分。where:

is the differential of the flux linkage.

In the state space expression of the contactor's stable holding process, with u _coil as the input, i _coil as the output, and ψ as the state variable, it can be seen that the same A=-R _coil /L, B=1, C=1/ L's one-dimensional linear steady-state system with single input and single output, and use this one-dimensional linear steady system for real-time solution application, and use input variables and output variables to construct a closed-loop flux linkage state observer applied to the process of contactor stability;

与实际值i_coil的误差来闭环修正状态变量观测值

以改善观测器的性能。The closed-loop flux linkage state observer applied to the contactor stable maintaining process utilizes the system output parameter i _coil , and adopts the coil current observation value

The error from the actual value i _coil is used to close the loop to correct the observed value of the state variable

to improve the performance of the observer.

与i_coil的误差为输入，对保持过程中的观测磁链

进行闭环修正，使

能够迅速趋近实际值。The magnetic flux closed-loop state observer applied to the contactor's stable holding process takes the measured u _coil and i _coil as the observer inputs, and adds a feedback matrix E on the basis of the open-loop state observer to obtain

The error with the i _coil is the input, and the observed flux linkage during the holding process is

A closed-loop correction is made so that

The actual value can be approached quickly.

As shown in FIG. 3 , the device used in the contactor flux linkage closed-loop control method includes a coil drive circuit and an embedded control system;

The coil drive circuit includes a rectifier bridge D ₁ and a rectifier module which is a filter capacitor C ₁ ; the rectifier module is connected to the input power supply, and the input voltage is changed into a relatively stable DC voltage and output to the contactor coil, so that the contactor coil Work;

The coil driving circuit further includes electronic switches S ₁ , S ₄ , as well as fast recovery diodes D ₂ , D ₃ ; the electronic switches perform PWM control on the rectified and filtered DC voltage to control the polarity of the voltage applied to the contactor coil ;

The coil driving circuit makes the contactor coil circuit work in +1 state, -1 state and 0 state by controlling the polarity of the voltage applied to the contactor coil;

When the contactor coil circuit works in the +1 state, S ₁ and S ₄ are turned on at the same time, and the forward voltage after rectification and filtering is applied to both ends of the coil, so that the current of the contactor coil rises rapidly, and the flux linkage is rapidly strengthened;

When the contactor coil circuit works in -1 state, the coil current is not zero at this time, S ₁ and S ₄ are turned off at the same time, the coil current feeds back energy to the filter capacitor C ₁ through D ₂ and D ₃ , and the negative voltage of the capacitor Applied to both ends of the coil, forcing the coil to demagnetize quickly;

When the contactor coil circuit works in the 0 state, the two ends of the coil are subjected to negative _D3 and S4 tube voltage drop close to 0V, the electronic switch only S4 is turned _on , the coil current flows through _D3 and _S4 , and the coil current flows _. decline slowly;

The embedded control system detects the contactor coil current through the current sensor, and detects the contactor coil voltage through the voltage sensor.

The embedded control system includes a process control module, a topology control module and an observer switch, and also includes a flux linkage outer loop control module using the hysteresis control principle and a current inner loop control module using the hysteresis control principle; the process control module It is connected with the flux linkage outer loop control module; the flux linkage outer loop control module is connected with the current inner loop control module; the input end of the observer switch is connected with the flux linkage outer loop control module and the current inner loop control module, and the output end is connected with the current inner loop control module. The flux linkage outer loop control module is connected; the current inner loop control module outputs _a PWM signal to the electronic switch S1 and the topology control module, and the output end of the topology control module is connected to the electronic switch S4 _;

及保持过程中的磁链

When the embedded control system is working, the detected coil voltage u _coil and coil current i _coil are simultaneously fed into the voltage integral flux linkage observer and the flux linkage closed-loop state observer, which are respectively used to observe the flux linkage in the starting process

and the flux linkage during the hold

The process control module of the embedded control system controls the contactor to enter the starting, holding and breaking processes according to the sequence requirements, and different flux linkage reference values ψ _ref can be set in these different processes;

The observer switch of the embedded control system is responsible for the switching of the two observers to synthesize the flux linkage observations of the whole process

The topology control module decides whether to set the switch S4 to a normally _- on state according to the action signal of the observer switching switch.

ψ_ref与

经过磁链外环控制模块的滞环比较来控制电流内环控制模块的参考值i_ref，使其在电流最大值i_max与0之间变化，之后i_ref与i_coil经过电流内环控制模块的滞环比较作用，输出信号PWM1及PWM4，PWM1控制S₁的通断状态，在起动过程中拓扑控制模块直接采用PWM4信号来控制S₄的通断状态，使电路状态在+1态和-1态间切换来快速达到参考电流，从而使接触器线圈磁路磁链等于起动磁链参考值；The software strategy of the embedded control system is divided into a starting process, a holding process and a breaking process according to the control sequence; the process control module makes the embedded control system work according to different software strategies according to the control instructions; when the embedded control system executes When starting the software strategy of the process, the observer toggle switch selects

ψ _ref and

Through the hysteresis comparison of the flux linkage outer loop control module, the reference value i _ref of the current inner loop control module is controlled to change between the current maximum value i _max and 0, and then i _ref and i _coil pass through the current inner loop control module The hysteresis comparison function of the output signal PWM1 and PWM4, PWM1 controls the on-off state of S ₁ , and the topology control module directly uses the PWM4 signal to control the on-off state of S ₄ during the startup process, so that the circuit state is in the +1 state and - Switch between 1 states to quickly reach the reference current, so that the magnetic flux of the contactor coil is equal to the reference value of the starting flux;

并与ψ_ref滞环比较来控制i_ref，i_ref与i_coil滞环比较，控制电路状态在+1态和-1态间切换来快速达到ψ_ref，磁路磁链等于保持磁链参考值后观测器切换开关选择

将磁链闭环状态观测器接入磁链外环控制模块，进行保持磁链的观测器的平稳衔接，同时拓扑控制模块检测到观测器切换开关的切换信号，将S₄置为常通，使接触器线圈电路状态仅在+1态和0态间切换来维持保持线圈电流动态恒定，降低电子开关的导通周期数，减小损耗，进行更好的节能保持；When the embedded control system executes the software strategy of the hold process, ψ _ref is set as the hold value, and the observer switch is still selected

And compare with ψ _ref hysteresis loop to control i _ref , compare i _ref with i _coil hysteresis loop, control circuit state to switch between +1 state and -1 state to quickly reach ψ _ref , the magnetic flux linkage is equal to maintaining the reference value of flux linkage Rear Observer toggle switch selection

The flux linkage closed-loop state observer is connected to the flux linkage outer loop control module to maintain the smooth connection of the flux linkage observer. At the same time, the topology control module detects the switching signal of the observer switching switch, and sets S4 to be normally _on , so that the The circuit state of the contactor coil is only switched between the +1 state and the 0 state to maintain the dynamic constant of the coil current, reduce the number of conduction cycles of the electronic switch, reduce the loss, and achieve better energy conservation;

When the embedded control system executes the software strategy of the breaking process, the process control module directly controls the current inner loop to set PWM1 and PWM4 to 0, and cooperates with the topology control module to quickly set the circuit state to -1 state, so that the electromagnetic coil of the contactor is quickly demagnetized , the contactor breaks.

In this example, the external controller sends the contactor starting, holding or breaking control instructions to the process control module, so that the embedded control system works according to different software strategies, and the magnetic link closed-loop control of the contactor starting and holding process can be realized. And the rapid demagnetization control of the breaking process.

Claims (8)

1. The contactor flux linkage closed-loop control method based on the state observer is characterized in that: the control method observes the flux linkage data of the contactor through the flux linkage state observer during the contactor starting process and the contactor holding process, and Control the contactor current based on the observation results; During the starting process of the contactor, the flux linkage state observer adopts the open-loop observation method based on the voltage integral flux linkage observer to obtain the flux linkage data; in the stable contactor holding process, the flux linkage state observer adopts the closed-loop state based on the flux linkage state. The closed-loop observation method of the observer is used to obtain the flux linkage data; in the control method, the open-loop observation method and the closed-loop observation method are smoothly switched according to the progress of the contactor control process; in the control method, by controlling the current of the contactor coil , to control the excitation state of the contactor coil to optimize the dynamic work of the contactor. 2 . The state observer-based contactor flux linkage closed-loop control method according to claim 1 , wherein the contactor start-up time is less than 100ms; in the open-loop observation method for the contactor start-up process, the formula (1) Calculate the data of the flux linkage;

In formula (1), the data ψ of the flux linkage in the starting process can be obtained by detecting the coil voltage u _coil and the coil current i _coil and then integrating the contactor coil resistance R _coil to calculate the data ψ; t ₀ is the starting time of the contactor, ψ, u The initial states of _coil and i _coil at time t ₀ are all 0; the starting flux linkage can be recorded as

3. The state observer-based contactor flux linkage closed-loop control method according to claim 2, characterized in that: in the closed-loop observation method for a stable contactor holding process, the flux linkage of the contactor coil magnetic circuit satisfies the following Formula (2): ψ=Li _coil (2) The magnetic circuit voltage balance equation of the contactor is expressed by formula (3) as:

Combining formula (2) and formula (3), formula (4) is derived

In formula (4), the coil magnetic circuit of the contactor during the stable maintenance process is regarded as a constant resistance-inductive load to calculate; u _coil is the coil current, R _coil is the coil resistance, ψ is the magnetic circuit flux linkage, and L is the magnetic circuit inductance. ; The state space expression of the contactor's stable holding process is derived

where:

is the differential of the flux linkage. 4. The state observer-based contactor flux linkage closed-loop control method according to claim 3, characterized in that: in the state space expression of the contactor stable holding process, u _coil is used as input, i _coil is used as output, Taking ψ as the state variable, the same one-dimensional linear steady system with single input and single output with A=-R _coil /L, B=1, C=1/L can be seen, and the one-dimensional linear steady system can be solved in real time. Application, using the input variables and output variables to construct a closed-loop flux linkage state observer applied to the contactor's stable holding process; The closed-loop flux linkage state observer applied to the contactor stable maintaining process utilizes the system output parameter i _coil , and adopts the coil current observation value

The error from the actual value i _coil is used to close the loop to correct the observed value of the state variable

to improve the performance of the observer. 5. The contactor flux closed-loop control method based on a state observer according to claim 4, characterized in that: the flux closed-loop state observer applied to the contactor stable holding process is based on the measured u _coil , i _coil is the input of the observer, and the feedback matrix E is added on the basis of the open-loop state observer, so as to

The error with the i _coil is the input, and the observed flux linkage during the holding process is

A closed-loop correction is made so that

The actual value can be approached quickly. 6. The state observer-based contactor flux closed-loop control method according to claim 5, wherein the device used in the contactor flux closed-loop control method comprises a coil drive circuit and an embedded control system; The coil drive circuit includes a rectifier bridge D ₁ and a rectifier module which is a filter capacitor C ₁ ; the rectifier module is connected to the input power supply, and the input voltage is changed into a relatively stable DC voltage and output to the contactor coil, so that the contactor coil Work; The coil driving circuit further includes electronic switches S ₁ , S ₄ , as well as fast recovery diodes D ₂ , D ₃ ; the electronic switches perform PWM control on the rectified and filtered DC voltage to control the polarity of the voltage applied to the contactor coil ; The coil driving circuit makes the contactor coil circuit work in +1 state, -1 state and 0 state by controlling the polarity of the voltage applied to the contactor coil; When the contactor coil circuit works in the +1 state, S ₁ and S ₄ are turned on at the same time, and the forward voltage after rectification and filtering is applied to both ends of the coil, so that the current of the contactor coil rises rapidly and the flux linkage is rapidly strengthened; When the contactor coil circuit works in -1 state, the coil current is not zero at this time, S ₁ and S ₄ are turned off at the same time, the coil current feeds back energy to the filter capacitor C ₁ through D ₂ and D ₃ , and the negative voltage of the capacitor Applied to both ends of the coil, forcing the coil to demagnetize quickly; When the contactor coil circuit works in the 0 state, the two ends of the coil are subjected to negative _D3 and S4 tube voltage drop close to 0V, the electronic switch only S4 is turned _on , the coil current flows through _D3 and _S4 , and the coil current flows _. decline slowly; The embedded control system detects the contactor coil current through the current sensor, and detects the contactor coil voltage through the voltage sensor. 7 . The state observer-based contactor flux linkage closed-loop control method according to claim 6 , wherein the embedded control system comprises a process control module, a topology control module and an observer switch, and also includes a hysteresis switch. 8 . The flux linkage outer loop control module based on the loop control principle and the current inner loop control module using the hysteresis control principle; the process control module is connected with the flux linkage outer loop control module; the flux linkage outer loop control module is connected with the current inner loop control module; The input end of the observer switch is connected with the flux linkage outer loop control module and the current inner loop control module, and the output end is connected with the flux linkage outer loop control module; the current inner loop control module is connected to the electronic switch S ₁ , the topology control module Output PWM signal, the output end of described topology control module is connected with electronic switch S4 _; When the embedded control system is working, the detected coil voltage u _coil and coil current i _coil are simultaneously fed into the voltage integral flux linkage observer and the flux linkage closed-loop state observer, which are respectively used to observe the flux linkage in the starting process

and the flux linkage during the hold

The process control module of the embedded control system controls the contactor to enter the starting, holding and breaking processes according to the sequence requirements, and different flux linkage reference values ψ _ref can be set in these different processes; The observer switch of the embedded control system is responsible for the switching of the two observers to synthesize the flux linkage observations of the whole process

The topology control module decides whether to set the switch S4 to a normally _- on state according to the action signal of the observer switching switch. 8. The state observer-based contactor flux closed-loop control method according to claim 7, wherein the software strategy of the embedded control system is divided into a starting process, a holding process and a breaking process according to the control sequence; The process control module can make the embedded control system work according to different software strategies according to the control instructions; When the embedded control system executes the software strategy of the startup process, the observer toggle switch selects

ψ _ref and

Through the hysteresis comparison of the flux linkage outer loop control module, the reference value i _ref of the current inner loop control module is controlled to change between the current maximum value i _max and 0, and then i _ref and i _coil pass through the current inner loop control module The hysteresis comparison function of the output signal PWM1 and PWM4, PWM1 controls the on-off state of S _1. During the starting process, the topology control module directly uses the PWM4 signal to control the on-off state of S ₄ , so that the circuit state is in the +1 state and - Switch between 1 states to quickly reach the reference current, so that the magnetic flux of the contactor coil is equal to the reference value of the starting flux; When the embedded control system executes the software strategy of the hold process, ψ _ref is set as the hold value, and the observer switch is still selected

And compare with ψ _ref hysteresis loop to control i _ref , compare i _ref with i _coil hysteresis loop, control circuit state to switch between +1 state and -1 state to quickly reach ψ _ref , the magnetic flux linkage is equal to maintaining the reference value of flux linkage Rear Observer toggle switch selection

The flux linkage closed-loop state observer is connected to the flux linkage outer loop control module to maintain the smooth connection of the flux linkage observer. At the same time, the topology control module detects the switching signal of the observer switching switch, and sets S4 to be normally _on , so that the The circuit state of the contactor coil is only switched between the +1 state and the 0 state to maintain the dynamic constant of the coil current, reduce the number of conduction cycles of the electronic switch, reduce the loss, and achieve better energy conservation; When the embedded control system executes the software strategy of the breaking process, the process control module directly controls the current inner loop to set PWM1 and PWM4 to 0, and cooperates with the topology control module to quickly set the circuit state to -1 state, so that the electromagnetic coil of the contactor is quickly demagnetized , the contactor breaks.

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