Electronic expansion valve flow high-precision control method and system

Abstract

This invention discloses a method and system for high-precision flow control of an electronic expansion valve. The method includes: acquiring the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period; determining the calculated opening output of the electronic expansion valve controller in the current sampling period based on the calculated opening increment and the opening output of the electronic expansion valve controller in the previous sampling period; determining the proportional adjustment duty cycle based on the calculated opening output of the electronic expansion valve controller in the current sampling period; determining the actual opening output of the electronic expansion valve based on the proportional adjustment duty cycle, and sending the actual opening output of the electronic expansion valve to the electronic expansion valve. By proportionally oscillating and adjusting the actual opening output of the electronic expansion valve using the proportional adjustment duty cycle, a more precise flow regulation capability can be obtained, thereby improving the performance of the refrigeration system and equipment.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and in particular to a method and system for high-precision flow control of an electronic expansion valve. Background Technology

[0002] Due to the limitations of stepper motors, the minimum change in the opening of an electronic expansion valve is one step. For electronic expansion valves with a small opening adjustment range (e.g., 0 to 500 steps), traditional flow adjustment methods can meet this small-range requirement. However, for applications requiring more precise flow control, traditional flow adjustment methods are constrained.

[0003] Existing technologies typically employ electronic expansion valves with a wider opening range (e.g., 0 to 2000 steps) to further improve control accuracy, but this not only significantly increases system costs but also hinders the generalization and standardization of refrigeration system components. Summary of the Invention

[0004] This invention provides a method and system for high-precision flow control of electronic expansion valves, which eliminates the limitation of the minimum stepper motor step in flow regulation and enables more precise flow regulation capabilities.

[0005] According to one aspect of the present invention, a method for high-precision flow control of an electronic expansion valve is provided, the method comprising:

[0006] Obtain the calculation amount of the opening increment of the electronic expansion valve and the opening output amount of the electronic expansion valve controller in the previous sampling period;

[0007] The calculation of the opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period are used to determine the calculation of the opening output of the electronic expansion valve controller in the current sampling period.

[0008] The proportional adjustment duty cycle is determined based on the calculated amount of the opening output of the electronic expansion valve controller during the current sampling period.

[0009] The actual opening output of the electronic expansion valve is determined according to the proportional adjustment duty cycle, and the actual opening output of the electronic expansion valve is sent to the electronic expansion valve.

[0010] Optionally, determining the calculated opening output of the electronic expansion valve controller for the current sampling period based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period includes:

[0011] The calculated opening output of the electronic expansion valve controller in the current sampling period is obtained by summing the calculated opening increment of the electronic expansion valve with the opening output of the electronic expansion valve controller in the previous sampling period.

[0012] Optionally, the formula for calculating the opening increment of the electronic expansion valve is as follows:

[0013] ΔD eev,k =K p Δe(k)+K i e(k)+K d [Δe(k)-Δe(k-1)]

[0014] Where, ΔD eev,k K represents the computational cost of the opening increment. p K is the proportionality coefficient. i K is the integral coefficient; d denoted as the differential coefficient; e(k) is the evaporator outlet superheat deviation value input at the k-th sampling time; Δe(k) is the difference between the deviation value input at the k-th sampling time and the evaporator outlet superheat deviation value input at the (k-1)-th sampling time; Δe(k-1) is the difference between the deviation value input at the (k-1)-th sampling time and the evaporator outlet superheat deviation value input at the (k-2)-th sampling time.

[0015] Optionally, determining the proportional adjustment duty cycle based on the calculated opening output of the electronic expansion valve controller during the current sampling period includes:

[0016] The proportional adjustment duty cycle is calculated based on the difference between the calculated opening output of the electronic expansion valve controller in the current sampling period and the rounded value of the calculated opening output of the electronic expansion valve controller in the current sampling period.

[0017] Optionally, determining the actual opening output of the electronic expansion valve based on the proportional adjustment of the duty cycle includes:

[0018] Determine the range of preset duty cycle conditions that the proportional adjustment duty cycle must satisfy;

[0019] Based on the preset duty cycle range conditions satisfied by the proportional adjustment duty cycle, the calculation algorithm for the actual opening output of the electronic expansion valve is determined; and the actual opening output of the electronic expansion valve is calculated according to the corresponding calculation algorithm.

[0020] Optionally, the range conditions for the preset duty cycle include a first preset range condition, a second preset range condition, a third preset range condition, and a fourth preset range condition;

[0021] The algorithm for determining the actual opening output of the electronic expansion valve based on the preset duty cycle range condition satisfied by the proportional adjustment duty cycle includes:

[0022] When the proportional adjustment duty cycle satisfies any one of the first preset range condition, the second preset range condition, and the third preset range condition, the calculation algorithm for determining the actual opening output of the electronic expansion valve is based on the opening output calculation of the electronic expansion valve controller in the current sampling period.

[0023] When the proportional adjustment duty cycle meets the fourth preset range condition, the calculation algorithm for determining the actual opening output of the electronic expansion valve is based on the opening output calculation of the electronic expansion valve controller in the current sampling period, the first proportional adjustment enable factor, the second proportional adjustment enable factor, and the third proportional adjustment enable factor.

[0024] Optionally, the formula for calculating the first proportional adjustment enabling factor is:

[0025]

[0026] Among them, F bl T is the first proportional adjustment enabling factor. pv_err Temperature deviation in the temperature control chamber of the environmental test chamber;

[0027] Among them, T pv_err =T sv -T pv

[0028] Among them, T sv The target temperature for the temperature control chamber of the environmental test chamber, T pv The measured temperature of the temperature-controlled chamber in the environmental test chamber.

[0029] Optionally, the formula for calculating the second proportional adjustment enabling factor is:

[0030]

[0031] Among them, F eev,emv D is the second proportional adjustment enabling factor. eev,max D represents the maximum opening value of the electronic expansion valve. eev,k This is the calculated output value of the electronic expansion valve controller for the current sampling period.

[0032] Optionally, the formula for calculating the third proportional adjustment enabling factor is:

[0033]

[0034] Among them, F lp This is the third proportional adjustment enabling factor.

[0035] According to another aspect of the present invention, a high-precision flow control system for an electronic expansion valve is provided, the high-precision flow control system for an electronic expansion valve comprising:

[0036] The first acquisition module is used to acquire the calculation amount of the opening increment of the electronic expansion valve;

[0037] The second acquisition module is used to acquire the opening output of the electronic expansion valve controller in the previous sampling period;

[0038] The first determining module is used to determine the calculated opening output of the electronic expansion valve controller in the current sampling period based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period.

[0039] The second determining module is used to determine the proportional adjustment duty cycle based on the calculated amount of the opening output of the electronic expansion valve controller in the current sampling period.

[0040] The third determining module is used to determine the actual opening output of the electronic expansion valve according to the duty cycle adjusted by the ratio;

[0041] The actual opening output quantity sending module is used to send the actual opening output quantity of the electronic expansion valve to the electronic expansion valve.

[0042] The technical solution of this invention provides a high-precision flow control method and system for an electronic expansion valve. The method includes: acquiring the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period; determining the calculated opening output of the electronic expansion valve controller in the current sampling period based on the calculated opening increment and the opening output of the electronic expansion valve controller in the previous sampling period; determining the proportional adjustment duty cycle based on the calculated opening output of the electronic expansion valve controller in the current sampling period; determining the actual opening output of the electronic expansion valve based on the proportional adjustment duty cycle, and sending the actual opening output of the electronic expansion valve to the electronic expansion valve. This method enables proportional oscillation adjustment of the actual opening output of the electronic expansion valve through the proportional adjustment duty cycle, achieving fractional-level adjustment of the actual opening output. This removes the constraint of the minimum stepper motor step on the flow regulation of the electronic expansion valve, resulting in more precise flow regulation capabilities and thus improving the performance of the refrigeration system and equipment.

[0043] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of the application structure of the electronic expansion valve in a refrigeration system provided in this embodiment of the invention;

[0046] Figure 2 This is a flowchart of a high-precision flow control method for an electronic expansion valve provided in an embodiment of the present invention;

[0047] Figure 3 This is a flowchart of another high-precision flow control method for an electronic expansion valve provided in this embodiment of the invention;

[0048] Figure 4 This is a structural block diagram of a high-precision flow control system for an electronic expansion valve provided in an embodiment of the present invention. Detailed Implementation

[0049] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. 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 should fall within the scope of protection of the present invention.

[0050] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0051] The inventors discovered that the electronic expansion valve is a refrigerant flow regulating device driven by a stepper motor. This device controls the movement of the valve needle by providing a logic digital signal to the stepper motor, thereby controlling the valve's flow rate and area. In applications with drastic load changes, high temperature control accuracy, or a wide operating range, such as environmental test chambers, traditional throttling elements (such as capillary tubes and thermostatic expansion valves) can no longer meet the requirements for temperature control accuracy and energy saving. Therefore, the application of electronic expansion valves is becoming increasingly widespread.

[0052] An electronic expansion valve mainly consists of four parts: 1. Rotor: equivalent to the rotor of a synchronous motor, it connects to the valve stem and controls the valve orifice opening. 2. Stator: equivalent to the stator of a synchronous motor; it converts electrical energy into a magnetic field to drive the rotor to rotate. 3. Valve needle (core): driven by the rotor, its end is tapered, and it moves up and down to regulate flow. 4. Valve body: generally made of brass.

[0053] Figure 1 This is a schematic diagram illustrating the application structure of the electronic expansion valve provided in an embodiment of the present invention within a refrigeration system. (Reference) Figure 1 The flow control system of the refrigeration system consists of an electronic expansion valve, a pressure sensor P, a temperature sensor T, a controller, a condenser, and a compressor. During operation, the pressure sensor transmits the evaporator outlet pressure to the controller, and the temperature sensor transmits the compressor suction superheat to the controller. The controller processes the signals and then outputs a command to the stepper motor of the electronic expansion valve, opening the valve to the desired position. The typical adjustment range for the opening is 0–500 steps; some electronic expansion valves used for precision flow control can have an adjustment range of 0–2000 steps.

[0054] Due to the limitations of stepper motor principles, the minimum change in opening of an electronic expansion valve is one step. For electronic expansion valves with a small opening adjustment range (e.g., 0–500 steps), the minimum flow rate change is: in, This represents the maximum operating flow rate of the refrigeration system. Traditional electronic expansion valve flow adjustment methods can meet this small-range requirement. However, for applications requiring more precise flow rate adjustment, traditional electronic expansion valve flow adjustment methods are limited. Existing technologies typically use electronic expansion valves with a wider opening range (e.g., 0-2000 steps) to further improve control accuracy, but this not only significantly increases system costs but also hinders the generalization and standardization of refrigeration system components.

[0055] Therefore, the present invention provides a high-precision flow control method and system for electronic expansion valves, which eliminates the limitation of the minimum stepper motor step in the flow regulation of electronic expansion valves, and enables more precise flow regulation capabilities, thereby improving the performance of refrigeration systems and equipment.

[0056] Figure 2 This is a flowchart of a high-precision flow control method for an electronic expansion valve provided in an embodiment of the present invention. Figure 2 As shown, the method includes the following steps:

[0057] S110: Obtain the calculation amount of the opening increment of the electronic expansion valve and the opening output amount of the electronic expansion valve controller in the previous sampling period.

[0058] The opening output of the electronic expansion valve controller in the previous sampling period can be directly obtained from the calculation results of the previous sampling period.

[0059] The formula for calculating the opening increment of the electronic expansion valve is as follows:

[0060] ΔD eev,k =K p Δe(k)+K i e(k)+K d [Δe(k)-Δe(k-1)]

[0061] Where, ΔD eev,k K represents the computational cost of the opening increment. p K is the proportionality coefficient. i K is the integral coefficient; d denoted as the differential coefficient; e(k) is the evaporator outlet superheat deviation value input at the k-th sampling time; Δe(k) is the difference between the deviation value input at the k-th sampling time and the evaporator outlet superheat deviation value input at the (k-1)-th sampling time; Δe(k-1) is the difference between the deviation value input at the (k-1)-th sampling time and the evaporator outlet superheat deviation value input at the (k-2)-th sampling time.

[0062] Where, Δe(k)=e(k)-e(k-1)

[0063] Where, Δe(k-1)=e(k-1)-e(k-2)

[0064] Where e(k-1) is the evaporator outlet superheat deviation value input at the (k-1)th sampling time, and e(k-2) is the evaporator outlet superheat deviation value input at the (k-2)th sampling time.

[0065] The calculation process for e(k) is as follows:

[0066] In a refrigeration system, let T eva,out T is the refrigerant temperature at the evaporator outlet. sa Let VT be the temperature of the saturated refrigerant gas at the evaporator outlet pressure. Then, the superheat VT at the evaporator outlet is... sh The calculation formula is:

[0067] VTsh =T eva,out -T sa

[0068] Let VT sh,target If the setpoint for the superheat at the evaporator outlet is given, then the formula for calculating the superheat deviation e(k) is:

[0069] e(k) = VT sh -VT sh,target

[0070] S120. Determine the calculated opening increment of the electronic expansion valve controller for the current sampling period based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period.

[0071] S130. Determine the proportional adjustment duty cycle based on the calculated amount of the opening output of the electronic expansion valve controller during the current sampling period.

[0072] The opening degree of the electronic expansion valve is controlled by a stepper motor. The proportional adjustment duty cycle is used to adjust the number of steps taken by the stepper motor, thereby adjusting the opening degree of the electronic expansion valve.

[0073] S140. Determine the actual opening output of the electronic expansion valve based on the proportional adjustment duty cycle, and send the actual opening output of the electronic expansion valve to the electronic expansion valve.

[0074] Among them, the proportional adjustment duty cycle adjusts the number of steps of the stepper motor by adjusting the duty cycle proportional oscillation, thereby enabling precise adjustment of the actual opening output of the electronic expansion valve.

[0075] In this embodiment, the working principle of the high-precision flow control method for the electronic expansion valve is as follows: First, the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period are obtained. Then, the calculated opening output of the electronic expansion valve controller in the current sampling period is determined based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period. The proportional adjustment duty cycle is determined based on the calculated opening output of the electronic expansion valve controller in the current sampling period. Finally, the actual opening output of the electronic expansion valve is determined based on the proportional adjustment duty cycle, and the actual opening output of the electronic expansion valve is sent to the electronic expansion valve. Therefore, this method can achieve proportional oscillation adjustment of the actual opening output of the electronic expansion valve through the proportional adjustment duty cycle, realizing fractional-level adjustment of the actual opening output of the electronic expansion valve. This eliminates the constraint of the minimum stepper motor step on the flow regulation of the electronic expansion valve, achieving more precise flow regulation capabilities and thus improving the performance of the refrigeration system and equipment.

[0076] Figure 3This is a flowchart of another high-precision flow control method for an electronic expansion valve provided in an embodiment of the present invention. Based on the above embodiments, as follows... Figure 3 As shown, the method includes the following steps:

[0077] S210, Obtain the calculation amount of the opening increment of the electronic expansion valve and the opening output amount of the electronic expansion valve controller in the previous sampling period.

[0078] S220. The calculated opening output of the electronic expansion valve controller in the current sampling period is obtained by summing the calculated opening increment of the electronic expansion valve with the opening output of the electronic expansion valve controller in the previous sampling period.

[0079] Let the opening output of the electronic expansion valve controller in the previous sampling period be D. eev,k-1 The calculation quantity D of the opening output of the electronic expansion valve controller during the current sampling period. eev,k The calculation formula is:

[0080] D eev,k =D eev,k-1 +ΔD eev,k

[0081] =D eev,k-1 +K p Δe(k)+K i e(k)+K d [Δe(k)-Δe(k-1)]

[0082] Among them, D eev,k and D eev,k-1 The value can be a decimal.

[0083] S230. The proportional control duty cycle is calculated based on the difference between the calculated opening output of the electronic expansion valve controller in the current sampling period and the rounded value of the calculated opening output of the electronic expansion valve controller in the current sampling period.

[0084] Let the proportional adjustment duty cycle be k, then the calculation formula is:

[0085] k = D eev,k -INT(D eev,k )

[0086] The duty cycle k for proportional adjustment ranges from 0 to 1.

[0087] S240. Determine the range of preset duty cycle conditions that the proportional adjustment duty cycle must satisfy.

[0088] Optionally, the preset duty cycle range conditions include a first preset range condition, a second preset range condition, a third preset range condition, and a fourth preset range condition.

[0089] The first preset range condition is: k < 0.2; the second preset range condition is: k > 0.8.

[0090] The third preset range condition is: 0.2≤k≤0.8 and T1≤(1-k)*T2;

[0091] The fourth preset range condition is: 0.2≤k≤0.8 and T1>(1-k)*T2;

[0092] Where T1 is the proportional adjustment duration of the proportional duty cycle k, and T1 is reset and restarted every time interval T2. Wherein the third preset range condition and the fourth preset range condition are the dead zone of the proportional adjustment duty cycle.

[0093] S250. Based on the range of the preset duty cycle satisfied by the proportional adjustment duty cycle, determine the calculation algorithm for the actual opening output of the electronic expansion valve; and calculate the actual opening output of the electronic expansion valve according to the corresponding calculation algorithm.

[0094] The calculation algorithm for the actual opening output of the electronic expansion valve varies depending on the range of preset duty cycle conditions satisfied by the proportional adjustment duty cycle. Therefore, the actual opening output of the electronic expansion valve is calculated based on the calculation algorithm for the actual opening output of the electronic expansion valve corresponding to the range of preset duty cycle conditions satisfied by the proportional adjustment duty cycle.

[0095] Optionally, the preset duty cycle range conditions include a first preset range condition, a second preset range condition, a third preset range condition, and a fourth preset range condition. The algorithm for calculating the actual opening output of the electronic expansion valve is determined based on the preset duty cycle range conditions satisfied by the proportional adjustment duty cycle. This includes: when the proportional adjustment duty cycle satisfies any one of the first, second, and third preset range conditions, determining the calculation algorithm for the actual opening output of the electronic expansion valve based on the calculated opening output of the electronic expansion valve controller in the current sampling period; and when the proportional adjustment duty cycle satisfies the fourth preset range condition, determining the calculation algorithm for the actual opening output of the electronic expansion valve based on the calculated opening output of the electronic expansion valve controller in the current sampling period, the first proportional adjustment enable factor, the second proportional adjustment enable factor, and the third proportional adjustment enable factor.

[0096] Specifically, when the proportional control duty cycle meets either the first or third preset range condition, the calculation algorithm for the actual opening output of the electronic expansion valve is determined based on the rounded value of the calculated opening output of the electronic expansion valve controller in the current sampling period. When the proportional control duty cycle meets the second preset range condition, the calculation algorithm for the actual opening output of the electronic expansion valve is determined by adding one to the rounded value of the calculated opening output of the electronic expansion valve controller in the current sampling period.

[0097] Specifically, the actual opening output D of the electronic expansion valve eev,op The calculation formula is:

[0098] D eev,op =

[0099]

[0100] Wherein, T1 is the proportional adjustment duration of the proportional adjustment duty cycle k. Every time interval T2, T1 is reset to zero and the timer is restarted.

[0101] Optionally, the formula for calculating the first proportional adjustment enabling factor is:

[0102]

[0103] Among them, F bl T is the first proportional adjustment enabling factor. pv_err Temperature deviation in the temperature control chamber of the environmental test chamber;

[0104] Among them, T pv_err =T sv -T pv

[0105] Among them, T sv The target temperature for the temperature control chamber of the environmental test chamber, T pv The measured temperature of the temperature-controlled chamber in the environmental test chamber.

[0106] Optionally, the formula for calculating the second proportional adjustment enabling factor is:

[0107]

[0108] Among them, F eev,emv D is the second proportional adjustment enabling factor. eev,max D represents the maximum opening value of the electronic expansion valve. eev,k This is the calculated output value of the electronic expansion valve controller for the current sampling period.

[0109] Optionally, the formula for calculating the third proportional adjustment enabling factor is:

[0110]

[0111] Among them, F lp This is the third proportional adjustment enabling factor.

[0112] In this embodiment, the working principle of the high-precision flow control method for the electronic expansion valve is as follows: First, the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period are obtained. Then, the calculated opening output of the electronic expansion valve controller in the current sampling period is calculated based on the sum of the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period. The proportional control duty cycle is calculated based on the difference between the calculated opening output of the electronic expansion valve controller in the current sampling period and the rounded value of the calculated opening output of the electronic expansion valve controller in the current sampling period. The range condition of the preset duty cycle that the proportional control duty cycle satisfies is determined. Finally, based on the range condition of the preset duty cycle that the proportional control duty cycle satisfies, the calculation algorithm for the actual opening output of the electronic expansion valve is determined; and the actual opening output of the electronic expansion valve is calculated based on the corresponding calculation algorithm. Therefore, this method can achieve the following: by proportionally adjusting the duty cycle, the actual opening output of the electronic expansion valve can be oscillated and adjusted in fractional increments. This allows the flow regulation of the electronic expansion valve to no longer be constrained by the minimum stepper motor step, thus achieving more precise flow regulation capabilities and improving the performance of the refrigeration system and equipment.

[0113] Figure 4 This is a structural block diagram of a high-precision flow control system for an electronic expansion valve provided in an embodiment of the present invention. The present invention provides a high-precision flow control system for an electronic expansion valve, see reference. Figure 4 The high-precision flow control system 100 for the electronic expansion valve includes: a first acquisition module 10 for acquiring the calculated opening increment of the electronic expansion valve; a second acquisition module 20 for acquiring the opening output of the electronic expansion valve controller in the previous sampling period; a first determination module 30 for determining the calculated opening output of the electronic expansion valve controller in the current sampling period based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period; a second determination module 40 for determining the proportional adjustment duty cycle based on the calculated opening output of the electronic expansion valve controller in the current sampling period; a third determination module 50 for determining the actual opening output of the electronic expansion valve based on the proportional adjustment duty cycle; and an actual opening output sending module 60 for sending the actual opening output of the electronic expansion valve to the electronic expansion valve.

[0114] The technical solution of this embodiment provides a high-precision control system for the flow rate of an electronic expansion valve. This system includes: a first acquisition module for acquiring the calculated opening increment of the electronic expansion valve; a second acquisition module for acquiring the opening output of the electronic expansion valve controller in the previous sampling period; a first determination module for determining the calculated opening output of the electronic expansion valve controller in the current sampling period based on the calculated opening increment and the opening output of the electronic expansion valve controller in the previous sampling period; a second determination module for determining the proportional adjustment duty cycle based on the calculated opening output of the electronic expansion valve controller in the current sampling period; a third determination module for determining the actual opening output of the electronic expansion valve based on the proportional adjustment duty cycle; and an actual opening output transmission module for transmitting the actual opening output of the electronic expansion valve to the electronic expansion valve. Therefore, this system can achieve the following: by proportionally adjusting the duty cycle, the actual opening output of the electronic expansion valve can be oscillated and adjusted in fractional increments. This allows the flow regulation of the electronic expansion valve to no longer be limited by the minimum stepper motor step, thus achieving more precise flow regulation capabilities and improving the performance of the refrigeration system and equipment.

[0115] Optionally, the first determining module 30 includes: a calculation unit for the opening output of the electronic expansion valve controller in the current sampling period, used to calculate the opening output of the electronic expansion valve controller in the current sampling period based on the sum of the opening increment calculation of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period.

[0116] Optionally, the formula for calculating the opening increment of the electronic expansion valve is:

[0117] ΔD eev,k =K p Δe(k)+K i e(k)+K d [Δe(k)-Δe(k-1)]

[0118] Where, ΔD eev,k K represents the computational cost of the opening increment. p K is the proportionality coefficient. i K is the integral coefficient; d denoted as the differential coefficient; e(k) is the evaporator outlet superheat deviation value input at the k-th sampling time; Δe(k) is the difference between the deviation value input at the k-th sampling time and the evaporator outlet superheat deviation value input at the (k-1)-th sampling time; Δe(k-1) is the difference between the deviation value input at the (k-1)-th sampling time and the evaporator outlet superheat deviation value input at the (k-2)-th sampling time.

[0119] Optionally, the second determining module 40 includes: a proportional adjustment duty cycle determining unit, used to calculate the proportional adjustment duty cycle based on the difference between the calculated amount of the opening output of the electronic expansion valve controller in the current sampling period and the rounded value of the calculated amount of the opening output of the electronic expansion valve controller in the current sampling period.

[0120] Optionally, the third determining module 50 includes: a range determining unit, used to determine the range conditions of the preset duty cycle satisfied by the proportional adjustment duty cycle.

[0121] The actual opening output calculation algorithm determination unit is used to determine the calculation algorithm of the actual opening output of the electronic expansion valve based on the range conditions of the preset duty cycle satisfied by the proportional adjustment duty cycle.

[0122] The actual opening output calculation unit is used to calculate the actual opening output of the electronic expansion valve according to the corresponding calculation algorithm.

[0123] Optionally, the preset duty cycle range conditions include a first preset range condition, a second preset range condition, a third preset range condition, and a fourth preset range condition; the calculation algorithm for determining the actual opening output of the electronic expansion valve based on the preset duty cycle range conditions satisfied by the proportional adjustment duty cycle includes: when the proportional adjustment duty cycle satisfies any one of the first preset range condition, the second preset range condition, and the third preset range condition, the calculation algorithm for determining the actual opening output of the electronic expansion valve based on the opening output calculation of the electronic expansion valve controller in the current sampling period;

[0124] When the proportional adjustment duty cycle meets the fourth preset range condition, the calculation algorithm for the actual opening output of the electronic expansion valve is determined based on the opening output calculation of the electronic expansion valve controller in the current sampling period, the first proportional adjustment enable factor, the second proportional adjustment enable factor, and the third proportional adjustment enable factor.

[0125] Optionally, the formula for calculating the first proportional adjustment enabling factor is:

[0126]

[0127] Among them, F bl T is the first proportional adjustment enabling factor. pv_err Temperature deviation in the temperature control chamber of the environmental test chamber;

[0128] Among them, T pv_err =T sv -T pv

[0129] Among them, T sv The target temperature for the temperature control chamber of the environmental test chamber, T pv The measured temperature of the temperature-controlled chamber in the environmental test chamber.

[0130] Optionally, the formula for calculating the second proportional adjustment enabling factor is:

[0131]

[0132] Among them, F eev,emv D is the second proportional adjustment enabling factor. eev,max D represents the maximum opening value of the electronic expansion valve. eev,k This is the calculated output value of the electronic expansion valve controller for the current sampling period.

[0133] Optionally, the formula for calculating the third proportional adjustment enabling factor is:

[0134]

[0135] Among them, F lp This is the third proportional adjustment enabling factor.

[0136] The high-precision flow control system for electronic expansion valves provided in this embodiment of the invention can execute the high-precision flow control method for electronic expansion valves provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0137] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0138] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for high-precision flow control of an electronic expansion valve, characterized in that, include: Obtain the calculation amount of the opening increment of the electronic expansion valve and the opening output amount of the electronic expansion valve controller in the previous sampling period; The calculation of the opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period are used to determine the calculation of the opening output of the electronic expansion valve controller in the current sampling period. The proportional adjustment duty cycle is determined based on the calculated amount of the opening output of the electronic expansion valve controller during the current sampling period. The actual opening output of the electronic expansion valve is determined according to the proportional adjustment duty cycle, and the actual opening output of the electronic expansion valve is sent to the electronic expansion valve. The step of determining the proportional adjustment duty cycle based on the calculated opening output of the electronic expansion valve controller during the current sampling period includes: The proportional adjustment duty cycle is calculated based on the difference between the calculated opening output of the electronic expansion valve controller in the current sampling period and the rounded value of the calculated opening output of the electronic expansion valve controller in the current sampling period. The step of determining the actual opening output of the electronic expansion valve based on the proportional adjustment duty cycle includes: Determine the range of preset duty cycle conditions that the proportional adjustment duty cycle must satisfy; Based on the preset duty cycle range conditions satisfied by the proportional adjustment duty cycle, the calculation algorithm for the actual opening output of the electronic expansion valve is determined; and the actual opening output of the electronic expansion valve is calculated according to the corresponding calculation algorithm. The preset duty cycle range conditions include a first preset range condition, a second preset range condition, a third preset range condition, and a fourth preset range condition. The first preset range condition is: ; The second preset range condition is: ; The third preset range condition is: ; The fourth preset range condition is: ; in, To adjust the duty cycle proportionally, The duration of proportional adjustment of the duty cycle. The interval time period; The algorithm for determining the actual opening output of the electronic expansion valve based on the preset duty cycle range condition satisfied by the proportional adjustment duty cycle includes: When the proportional adjustment duty cycle satisfies any one of the first preset range condition, the second preset range condition, and the third preset range condition, the calculation algorithm is to round down the calculated opening output of the electronic expansion valve controller in the current sampling period to obtain the actual opening output. When the proportional adjustment duty cycle meets the fourth preset range condition, the calculation algorithm calculates the actual opening output by combining the opening output of the electronic expansion valve controller in the current sampling period, the first proportional adjustment enable factor, the second proportional adjustment enable factor, and the third proportional adjustment enable factor.

2. The high-precision flow control method for an electronic expansion valve according to claim 1, characterized in that, The step of determining the opening output calculation of the electronic expansion valve controller in the current sampling period based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period includes: The calculated opening output of the electronic expansion valve controller in the current sampling period is obtained by summing the calculated opening increment of the electronic expansion valve with the opening output of the electronic expansion valve controller in the previous sampling period.

3. The high-precision flow control method for an electronic expansion valve according to claim 1, characterized in that, The formula for calculating the opening increment of the electronic expansion valve is as follows: in, This is the calculation amount for the opening increment; This is the proportionality coefficient; The integral coefficient; These are the differential coefficients; The evaporator outlet superheat deviation value is input at the k-th sampling time. This is the difference between the deviation value input at the k-th sampling time and the evaporator outlet superheat deviation value input at the (k-1)-th sampling time. This is the difference between the deviation value input at the (k-1)th sampling time and the evaporator outlet superheat deviation value input at the (k-2)th sampling time.

4. The high-precision flow control method for an electronic expansion valve according to claim 1, characterized in that, The formula for calculating the first proportional adjustment enabling factor is: in, The first proportional adjustment enabling factor, Temperature deviation in the temperature control chamber of the environmental test chamber; in, in, The target temperature for the temperature control chamber of the environmental test chamber. The measured temperature of the temperature-controlled chamber in the environmental test chamber.

5. The high-precision flow control method for an electronic expansion valve according to claim 1, characterized in that, The formula for calculating the second proportional adjustment enabling factor is as follows: in, This is the second proportional adjustment enabling factor. This represents the maximum opening value of the electronic expansion valve. This is the calculated output value of the electronic expansion valve controller for the current sampling period.

6. The high-precision flow control method for an electronic expansion valve according to claim 1, characterized in that, The formula for calculating the third proportional adjustment enabling factor is as follows: in, This is the third proportional adjustment enabling factor.

7. A high-precision flow control system for an electronic expansion valve, characterized in that, include: The first acquisition module is used to acquire the calculation amount of the opening increment of the electronic expansion valve; The second acquisition module is used to acquire the opening output of the electronic expansion valve controller in the previous sampling period; The first determining module is used to determine the calculated opening output of the electronic expansion valve controller in the current sampling period based on the calculated opening increment of the electronic expansion valve and the opening output of the electronic expansion valve controller in the previous sampling period. The second determining module is used to determine the proportional adjustment duty cycle based on the calculated amount of the opening output of the electronic expansion valve controller in the current sampling period. The third determining module is used to determine the actual opening output of the electronic expansion valve according to the duty cycle adjusted by the ratio; The actual opening output quantity sending module is used to send the actual opening output quantity of the electronic expansion valve to the electronic expansion valve; The second determining module includes: The proportional adjustment duty cycle determination unit is used to calculate the proportional adjustment duty cycle based on the difference between the calculated amount of the opening output of the electronic expansion valve controller in the current sampling period and the rounded value of the calculated amount of the opening output of the electronic expansion valve controller in the current sampling period. The third determining module includes: The range determination unit is used to determine the range conditions of the preset duty cycle that the proportional adjustment duty cycle satisfies; The actual opening output calculation algorithm determination unit is used to determine the calculation algorithm of the actual opening output of the electronic expansion valve based on the range conditions of the preset duty cycle satisfied by the proportional adjustment duty cycle. The actual opening output calculation unit is used to calculate the actual opening output of the electronic expansion valve according to the corresponding calculation algorithm. The preset duty cycle range conditions include a first preset range condition, a second preset range condition, a third preset range condition, and a fourth preset range condition. The first preset range condition is: ; The second preset range condition is: ; The third preset range condition is: ; The fourth preset range condition is: ; in, To adjust the duty cycle proportionally, The duration of proportional adjustment of the duty cycle. The interval time period; The algorithm for determining the actual opening output of the electronic expansion valve based on the preset duty cycle range condition satisfied by the proportional adjustment duty cycle includes: When the proportional adjustment duty cycle satisfies any one of the first preset range condition, the second preset range condition, and the third preset range condition, the calculation algorithm is to round down the calculated opening output of the electronic expansion valve controller in the current sampling period to obtain the actual opening output. When the proportional adjustment duty cycle meets the fourth preset range condition, the calculation algorithm calculates the actual opening output by combining the opening output of the electronic expansion valve controller in the current sampling period, the first proportional adjustment enable factor, the second proportional adjustment enable factor, and the third proportional adjustment enable factor.

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