A new ventilator proportional valve impedance flow self-stable control method and system

Abstract

The application discloses a novel ventilator proportional valve impedance flow self-stable control method and system, and relates to the technical field of ventilators. The method comprises the following steps: acquiring a current force value of a moving armature in a proportional valve sealing cavity according to liquid flow through the proportional valve sealing cavity; acquiring a predicted force value of the moving armature in the proportional valve sealing cavity when a predicted output flow of the proportional valve is acquired; calculating a difference value between the predicted force value and the current force value of the moving armature; inputting the difference value into an impedance control model to solve a displacement value of the moving armature; and compensating an electromagnetic input current of the proportional valve according to the displacement value. The method and the system for running the method can improve the dynamic response speed, stability and anti-interference ability of the flow control of the ventilator proportional valve.

Description

Technical Field

[0001] This invention relates to the field of ventilator technology, and more specifically to a novel impedance flow self-stabilizing control method and system for a proportional valve in a ventilator. Background Technology

[0002] A ventilator is a vital medical device that can prevent and treat respiratory failure, reduce complications, and save and prolong patients' lives. As an effective means of artificially replacing spontaneous ventilation, it has been widely used in respiratory failure caused by various reasons, anesthetic respiratory management during major surgery, respiratory support therapy, and emergency resuscitation, and occupies a very important position in the field of modern medicine.

[0003] During the use of a ventilator, mechanical ventilation of the patient is essential. Ventilators have their own compressors, turbines, or other components to provide the gas supply; therefore, they require valves capable of proportional flow control to regulate gas flow. The key technical aspect of proportional valves for ventilators lies in achieving precise control of a small flow range under relatively high pressure. In everyday use, ventilator proportional valves often employ electromagnetic proportional valves. These valves use a proportional electromagnet as an electromechanical conversion element. The proportional electromagnet converts the input current signal into a force or displacement mechanical signal output, thereby controlling parameters such as pressure, flow rate, and direction.

[0004] Miniature proportional solenoid valves used in ventilators operate under complex conditions, and their flow characteristics are nonlinear and time-varying. Currently, a major research direction for proportional solenoid valves is products with fast dynamic frequency response, which can make the flow control of ventilators respond more quickly. However, products with fast dynamic frequency response often cannot take stability into account, that is, existing proportional solenoid valves generally have poor anti-interference capabilities.

[0005] Therefore, how to provide a self-stabilizing control method and system for the impedance flow of a ventilator proportional valve with fast dynamic frequency response, high stability, and strong anti-interference capability is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a novel impedance flow self-stabilizing control method and system for a proportional valve of a ventilator, which at least partially solves the above-mentioned problems existing in the background art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] First, this invention discloses a novel impedance flow self-stabilizing control method for a proportional valve of a ventilator, comprising the following steps:

[0009] The current force value of the moving armature in the proportional valve sealing cavity is obtained based on the liquid flow rate through the proportional valve sealing cavity.

[0010] When obtaining the expected output flow of the proportional valve, the expected force value corresponding to the moving armature in the sealing cavity of the proportional valve is obtained.

[0011] Calculate the difference between the expected force value and the current force value of the moving armature;

[0012] The difference between the expected force value and the current force value of the moving armature is input into the impedance control model to solve for the displacement value of the moving armature.

[0013] The electromagnetic input current of the proportional valve is compensated based on the displacement value of the moving armature.

[0014] Preferably, the current force value of the moving armature inside the proportional valve sealing cavity is obtained based on the liquid flow rate through the proportional valve sealing cavity, specifically using the following expression:

[0015] F e =Q×K×ΔP

[0016] Among them, F e Q represents the force exerted by the moving armature on the proportional valve core; K represents the flow rate through the proportional valve core; K represents the flow coefficient of the proportional valve, which is a constant; ΔP represents the pressure difference across the proportional valve orifice.

[0017] Preferably, the difference between the expected force value and the current force value of the moving armature is input into the impedance control model to solve for the displacement value of the moving armature, specifically including the following expression:

[0018]

[0019] In the formula, ΔF(t) is the difference between the expected force value and the current force value of the moving armature at time t, ΔX(t) is the displacement value of the moving armature at time t, and M... z For the quality coefficient of the impedance control model, B z For the damping coefficient of the impedance control model, K z t represents the stiffness coefficient of the impedance control model, and t is the time variable.

[0020] Preferably, the electromagnetic input current of the proportional valve is compensated based on the displacement value of the moving armature, specifically including:

[0021] When the displacement of the moving armature is positive, the electromagnetic input current of the proportional valve is reduced; when the displacement of the moving armature is negative, the electromagnetic input current of the proportional valve is increased; until the displacement of the moving armature is zero.

[0022] Secondly, the present invention also discloses a novel impedance flow self-stabilizing control system for a proportional valve of a ventilator, comprising: a current force value acquisition module, a predicted force value acquisition module, an impedance control model, and a current compensation module;

[0023] The current force value acquisition module is used to acquire the current force value of the moving armature in the proportional valve sealing cavity based on the liquid flow rate through the proportional valve sealing cavity.

[0024] The expected force value acquisition module is used to acquire the expected force value of the moving armature in the sealing cavity of the proportional valve when the expected output flow of the proportional valve is expected.

[0025] The impedance control model is used to calculate the displacement value of the moving armature based on the difference between the expected force value and the current force value of the moving armature.

[0026] The current compensation module is used to compensate the electromagnetic input current of the proportional valve based on the displacement value of the moving armature.

[0027] Preferably, the current force value acquisition module obtains the current force value of the moving armature inside the proportional valve sealing cavity using the following formula:

[0028] F e =Q×K×ΔP

[0029] Among them, F e Q represents the force exerted by the moving armature on the proportional valve core; K represents the flow rate through the proportional valve core; ΔP represents the flow coefficient of the proportional valve; and ΔP represents the pressure difference across the proportional valve orifice.

[0030] Preferably, the displacement value of the moving armature calculated by the impedance control model specifically includes the following formula:

[0031]

[0032] In the formula, ΔF(t) is the difference between the expected force value and the current force value of the moving armature at time t, ΔX(t) is the displacement value of the moving armature at time t, and M... z For the quality coefficient of the impedance control model, B z For the damping coefficient of the impedance control model, K z t represents the stiffness coefficient of the impedance control model, and t is the time variable.

[0033] Preferably, the current compensation module compensates the electromagnetic input current of the proportional valve based on the displacement value of the moving armature, specifically including the following methods:

[0034] When the displacement of the moving armature is positive, the electromagnetic input current of the proportional valve is reduced; when the displacement of the moving armature is negative, the electromagnetic input current of the proportional valve is increased; until the displacement of the moving armature is zero.

[0035] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a novel impedance flow self-stabilizing control method and system for a proportional valve of a ventilator, which has the following beneficial effects:

[0036] This invention correlates the output flow rate of the proportional valve of the ventilator with the fluid pressure in the cavity, ultimately transforming the complex flow control problem into a simple force control problem. This makes the problem more concrete, simplifies the calculation, and enables rapid dynamic response of the proportional valve control of the ventilator while ensuring system stability and improving the system's anti-interference capability. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the overall process of the method provided in the embodiments of the present invention;

[0039] Figure 2 This is a schematic diagram of a mass block-spring-damping model provided in an embodiment of the present invention;

[0040] Figure 3 The impedance flow self-stabilizing mechanical control block diagram provided in the embodiments of the present invention;

[0041] Figure 4 This is a schematic diagram of the impedance control model structure provided by the present invention. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] like Figure 1 As shown in the figure, this invention discloses a novel impedance flow self-stabilizing control method for a proportional valve of a ventilator, comprising the following steps:

[0045] The current force value of the moving armature in the proportional valve sealing cavity is obtained based on the liquid flow rate through the proportional valve sealing cavity.

[0046] When obtaining the expected output flow of the proportional valve, the expected force value corresponding to the moving armature in the sealing cavity of the proportional valve is obtained.

[0047] Calculate the difference between the expected force value and the current force value of the moving armature;

[0048] The difference between the expected force value and the current force value of the moving armature is input into the impedance control model to solve for the displacement value of the moving armature.

[0049] The electromagnetic input current of the proportional valve is compensated based on the displacement value of the moving armature.

[0050] Each step is described in further detail below.

[0051] First, obtain the current force F of the moving armature inside the proportional valve sealing cavity based on the liquid flow rate Q through the proportional valve sealing cavity. e ;

[0052] The current force F on the moving armature inside the sealing cavity of the proportional valve e The following expression is established between the liquid flow rate Q through the proportional valve's sealed cavity and the flow rate Q:

[0053] F e =Q×K×ΔP (1)

[0054] Among them, F e Q represents the force exerted by the moving armature on the proportional valve core; Q represents the flow rate through the proportional valve core; K represents the flow coefficient of the proportional valve, which is a constant; ΔP represents the pressure difference before and after the valve port. The current force value of the moving armature can be obtained through expression (1).

[0055] In addition, it is also necessary to obtain the expected force F corresponding to the moving armature in the sealing cavity of the proportional valve when the expected output flow rate is obtained. d (Expected force value, i.e. the desired contact force that the impedance control model is to track).

[0056] Then, the difference ΔF between the expected force value and the current force value of the moving armature is calculated, and the specific expression is as follows:

[0057] ΔF=F e -F d ;

[0058] Next, an impedance control model (impedance controller) is established, and the difference ΔF between the expected force value and the current force value of the moving armature is input into the impedance control model to solve for the displacement value ΔX of the moving armature.

[0059] In the impedance control model, the relationship between the force difference and the displacement difference can be expressed by the following expression:

[0060] In the formula, M z For the quality coefficient of the impedance control model, B z For the damping coefficient of the impedance control model, K z Here, t represents the stiffness coefficient of the impedance control model, and t is the time variable.

[0061] Where, x d Let x(t) represent the desired displacement of the moving armature, and x(t) represent the current displacement of the moving armature. Therefore, ΔX(t) = x d The relationship between the force difference and displacement difference can be expressed as: (t)-x(t)

[0062]

[0063] From this, we can obtain

[0064] Finally, the electromagnetic input current of the proportional valve is compensated based on the displacement value ΔX. Specifically, when the displacement value ΔX is positive, the electromagnetic input current of the proportional valve is reduced; when the displacement value ΔX is negative, the electromagnetic input current of the proportional valve is increased. The current remains stable until ΔX reaches 0; otherwise, it remains in a dynamic adjustment process until the current stabilizes.

[0065] By using the above method, this invention correlates the output flow rate of the ventilator proportional valve with the fluid pressure in the cavity, ultimately transforming the complex flow control problem into a simple force control problem. By utilizing an impedance control model, it achieves a rapid dynamic response for the ventilator proportional valve control, ensures system stability, and improves the system's anti-interference capability.

[0066] This invention transforms the flow control problem of a proportional valve into a dynamic force control problem of the force exerted by the fluid pressure in the cavity on the moving armature within the sealed cavity of the proportional valve.

[0067] When the size of the sealing cavity and the diameter of the inlet and outlet ports of the proportional valve are fixed, there is a fixed proportional relationship between the output flow rate and the magnitude of the effect of the gas in the cavity on the piston. Therefore, the flow control problem can be transformed into a force control problem.

[0068] like Figure 2 As shown, to achieve force control of the blocking piston, this invention adopts an impedance control scheme. The impedance model of the force system in contact between the moving armature and the gas can be represented by a system model composed of a mass block, a spring, and a damper, where M... z For the quality coefficient, B z For damping coefficient, Kz Let X be the stiffness coefficient and X be the current position of the moving armature. In impedance control, a position correction is generated by the deviation between the interaction force and the desired force. This position correction is appropriately converted and given to the position controller for adjustment, thereby achieving the purpose of controlling the contact force. In the principle of impedance controllers, the current force value F on the moving armature is... e Related to pressure changes and area, this is converted to the current force F of the moving armature in the ventilator proportional valve. e The current force value of the moving armature can be obtained from the liquid flow rate Q through the sealing cavity of the proportional valve using formula (1).

[0069] From this, we can obtain the following: Figure 3 The preliminary mechanical control block diagram is shown, and flow control is achieved based on this block diagram. The input current to the electromagnet is I. Under the action of this current, the electromagnet inside the proportional valve attracts the moving armature, controlling its movement according to the mathematical relationship of the mass-spring-damping system model, generating a desired displacement X'. At this point, the current force F on the moving armature is determined based on the return value from the flow sensor. e , will F e Force F on the moving armature corresponding to the expected output flow rate d The difference is compared and input into the set impedance controller to calculate the displacement magnitude ΔX corresponding to ΔF, and the input current I is compensated accordingly.

[0070] The basic structural block diagram of the impedance control compensator is as follows: Figure 4 As shown, the outer loop calculation formula for the power control system can be obtained after the Labras transformation:

[0071]

[0072] In other embodiments, the motion error controller in the inner loop of the force control system can also employ PID control, with the PID control equation being:

[0073] Where e(t) is the deviation signal of the desired motion error.

[0074] Example 2

[0075] This embodiment discloses a computer system for implementing an impedance flow self-stabilizing control method for a novel proportional valve in a ventilator, comprising: a current force value acquisition module, a predicted force value acquisition module, an impedance control model, and a current compensation module;

[0076] The current force value acquisition module is used to acquire the current force value of the moving armature in the proportional valve sealing cavity based on the liquid flow rate through the proportional valve sealing cavity; the expected force value acquisition module is used to acquire the expected force value of the moving armature in the proportional valve sealing cavity when the proportional valve is expected to output flow rate; the impedance control model is used to calculate the displacement value of the moving armature based on the difference between the expected force value and the current force value; and the current compensation module is used to compensate the electromagnetic input current of the proportional valve based on the displacement value of the moving armature.

[0077] The current force value acquisition module obtains the current force value of the moving armature in the proportional valve sealing cavity using formula (1) in Example 1. The specific method for calculating the displacement value of the moving armature using the impedance control model can also be found in Example 1, and will not be repeated here.

[0078] The current compensation module compensates the electromagnetic input current of the proportional valve based on the displacement value of the moving armature. Specifically: when the displacement value of the moving armature is positive, the electromagnetic input current of the proportional valve is reduced; when the displacement value of the moving armature is negative, the electromagnetic input current of the proportional valve is increased; until the displacement value of the moving armature is zero.

[0079] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0080] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for impedance-flow self-stabilizing control of a proportional valve in a ventilator, characterized in that, The method includes the following steps: The current force value of the moving armature inside the proportional valve sealing cavity is obtained based on the liquid flow rate through the proportional valve sealing cavity; specifically, the following expression is used: F e = Q×K ×ΔP Among them, F e Q represents the force exerted by the moving armature on the proportional valve core; K represents the flow rate through the proportional valve core; ΔP represents the flow coefficient of the proportional valve; and ΔP represents the pressure difference across the proportional valve orifice. When obtaining the expected output flow of the proportional valve, the expected force value corresponding to the moving armature in the sealing cavity of the proportional valve is obtained. Calculate the difference between the expected force value and the current force value of the moving armature; The difference between the expected force value and the current force value of the moving armature is input into the impedance control model to solve for the displacement value of the moving armature; specifically, it includes the following expressions. ； In the formula, ΔF(t) is the difference between the expected force value and the current force value of the moving armature at time t, ΔX(t) is the displacement value of the moving armature at time t, and M... z For the quality coefficient of the impedance control model, B z For the damping coefficient of the impedance control model, K z Here, t represents the stiffness coefficient of the impedance control model, and t is the time variable. The electromagnetic input current of the proportional valve is compensated based on the displacement value of the moving armature.

2. The impedance-flow self-stabilizing control method for a ventilator proportional valve according to claim 1, characterized in that, The electromagnetic input current of the proportional valve is compensated based on the displacement value of the moving armature, specifically including: When the displacement of the moving armature is positive, the electromagnetic input current of the proportional valve is reduced; when the displacement of the moving armature is negative, the electromagnetic input current of the proportional valve is increased; until the displacement of the moving armature is zero.

3. An impedance-flow self-stabilizing control system for a ventilator proportional valve, characterized in that, include: The module includes a current force value acquisition module, an expected force value acquisition module, an impedance control model, and a current compensation module. The current force value acquisition module is used to acquire the current force value of the moving armature inside the proportional valve sealing cavity based on the liquid flow rate through the proportional valve sealing cavity; specifically, it uses the following expression: F e = Q×K ×ΔP Among them, F e Q represents the force exerted by the moving armature on the proportional valve core; K represents the flow rate through the proportional valve core; ΔP represents the flow coefficient of the proportional valve; and ΔP represents the pressure difference across the proportional valve orifice. The expected force value acquisition module is used to acquire the expected force value of the moving armature in the sealing cavity of the proportional valve when the expected output flow of the proportional valve is expected. The impedance control model is used to calculate the displacement value of the moving armature based on the difference between the expected force value and the current force value; specifically, it includes the following expressions. ； In the formula, ΔF(t) is the difference between the expected force value and the current force value of the moving armature at time t, ΔX(t) is the displacement value of the moving armature at time t, and M... z For the quality coefficient of the impedance control model, B z For the damping coefficient of the impedance control model, K z Here, t represents the stiffness coefficient of the impedance control model, and t is the time variable. The current compensation module is used to compensate the electromagnetic input current of the proportional valve based on the displacement value of the moving armature.

4. The impedance-flow self-stabilizing control system for the proportional valve of a ventilator according to claim 3, characterized in that, The current compensation module compensates the electromagnetic input current of the proportional valve based on the displacement value of the moving armature, specifically including the following methods: When the displacement of the moving armature is positive, the electromagnetic input current of the proportional valve is reduced; when the displacement of the moving armature is negative, the electromagnetic input current of the proportional valve is increased; until the displacement of the moving armature is zero.

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