PID (Proportion Integration Differentiation) adjusting method of three-fold-line type electronic expansion valve and air source heat pump

Abstract

The invention relates to a PID (Proportion Integration Differentiation) adjusting method of a three-fold-line type electronic expansion valve and an air source heat pump, the adjusting method adopts the three-fold-line type electronic expansion valve which has small flow change in a low-flow adjusting interval, has large flow change in a large-flow adjusting interval and has medium flow change in a medium-flow interval; in combination with the operation condition, the deviation between the actual superheat degree and the predicted optimal target superheat degree and the deviation between the environment temperature and the target water outlet temperature, the opening degree of the three-fold-line type electronic expansion valve is accurately controlled and adjusted through a PID algorithm; the requirements of low-flow long-range adjustment during low-temperature heating and large-flow short-range adjustment during high-temperature refrigeration can be well met, and the problem of flow adjustment of an existing electronic expansion valve in a wide temperature area is solved; the unit can achieve efficient and stable heating and refrigeration in a wide temperature area of-35 DEG C to 53 DEG C, and the operation efficiency and stability of the unit are improved.

Description

Technical Field

[0001] This invention relates to the field of heat pump control technology, and in particular to a PID control method for a three-segment electronic expansion valve and an air source heat pump. Background Technology

[0002] Air source heat pumps, as a highly efficient and clean heating and cooling technology, have been widely used in the building sector in recent years.

[0003] During the operation of an air source heat pump, the unit needs to achieve efficient and stable heating and cooling within a wide temperature range of -35℃ to 53℃.

[0004] However, the electronic expansion valves of existing air source heat pumps have significant drawbacks in flow regulation when facing different operating conditions:

[0005] Under low-temperature heating conditions, heat pumps require low flow rates and long-range regulation to ensure that the unit can effectively heat in extreme low-temperature environments. However, the flow regulation characteristics of existing electronic expansion valves are difficult to meet the needs of such low flow rates and long-range regulation, resulting in low heating efficiency and even unstable operation.

[0006] In high-temperature cooling conditions, heat pumps require large flow rates and short-range adjustments to quickly achieve cooling effects. Existing electronic expansion valves are also unable to adapt well to this requirement of large flow rates and short-range adjustments, resulting in poor cooling efficiency and difficulty in meeting the cooling needs of high-temperature environments. Summary of the Invention

[0007] Therefore, the purpose of this invention is to provide a PID control method for a three-segment electronic expansion valve. This method employs a three-segment electronic expansion valve with small flow rate changes in the low flow rate regulation range, large flow rate changes in the large flow rate regulation range, and medium flow rate changes in the medium flow rate range. The method uses PID control to adjust the opening of the electronic expansion valve based on ambient temperature and superheat deviation. This addresses the problem that existing electronic expansion valves cannot meet the requirements of low-flow, long-range regulation during low-temperature heating and large-flow, short-range regulation during high-temperature cooling in a wide temperature range of -35℃ to 53℃ for air source heat pumps, resulting in low unit operating efficiency and poor stability.

[0008] A PID control method for a three-segmented electronic expansion valve includes the following steps: S1A: Obtain the actual overheat level at the current moment. ; S1B: Get the current ambient temperature Target water temperature and operating conditions, including ambient temperature Target water temperature The optimal target overheating is obtained by pre-training the optimal target overheating model based on the operating conditions input. ; S2: Calculate the actual superheat at the current moment. With the optimal target superheat superheat deviation and ambient temperature With target water temperature temperature difference ; S3: Combining superheat deviation Temperature difference Calculate the opening adjustment of the three-segmented electronic expansion valve based on the PID parameters corresponding to the operating conditions. ; The operating conditions are divided into low-temperature heating mode, high-temperature cooling mode and other operating modes, each corresponding to different PID parameter values.

[0009] Furthermore, the adjustment increment of the current fan speed satisfy:

[0010] in, This indicates the current degree of overheating deviation. This indicates the superheat deviation at the previous moment. This represents the superheat deviation at time i. This indicates the time difference between the current moment and the previous moment. This represents the proportionality coefficient. Represents the integration time constant. denoted by ; K represents the compensation coefficient.

[0011] Furthermore, the value range of the PID parameters corresponding to the low-temperature heating operation mode is as follows: Kp∈[0.8-1.2), Ti∈(100s,150s], Td∈(20s,30s]; The value range of the PID parameters corresponding to the high-temperature cooling operation mode is as follows: Kp∈(1.5-1.2], Ti∈[50s,80s), Td∈[10s,20s).

[0012] Furthermore, the value ranges of the PID parameters for the other operating modes are as follows: Kp∈[1.2-1.5], Ti∈[80s,100s], Td∈[20s,25s].

[0013] Furthermore, the compensation coefficient K is used to adjust the degree of influence of the difference between the ambient temperature and the target outlet water temperature on the opening adjustment amount, and the value range is 0.1-0.3.

[0014] Furthermore, the actual overheat at the current moment Obtain it through the following methods: S1A1: Obtain the current exhaust temperature Exhaust pressure ; S1A2: Based on refrigerant type and exhaust pressure Find the saturation temperature of the refrigerant at the current exhaust pressure. ; S1A3: Calculate the exhaust temperature at the current moment. With saturation temperature The difference yields the actual superheat. : = - .

[0015] Furthermore, the optimal target superheat model is composed of the XGBoost algorithm. By establishing a mapping relationship between the feature list [ambient temperature, target water temperature, operating condition, heating capacity, cooling capacity, power consumption] and the label [optimal target superheat], it predicts the optimal target superheat in low-temperature heating mode, high-temperature cooling mode, and other operating modes.

[0016] Furthermore, the current superheat deviation satisfy: = - .

[0017] Furthermore, the temperature difference satisfy: - .

[0018] Compared to existing technologies, this invention employs a three-segment electronic expansion valve with small flow rate changes in the low flow rate regulation range, large flow rate changes in the large flow rate regulation range, and medium flow rate changes in the medium flow rate range. By combining operating conditions, the deviation between actual superheat and the predicted optimal target superheat, and the deviation between ambient temperature and target outlet water temperature, a PID algorithm is used to precisely control and regulate the opening of the three-segment electronic expansion valve. This effectively meets the needs of low-flow, long-range regulation during low-temperature heating and large-flow, short-range regulation during high-temperature cooling, solving the pain point of existing electronic expansion valves in flow rate regulation over a wide temperature range. This enables the unit to achieve efficient and stable heating and cooling within a wide temperature range of -35℃ to 53℃, improving the unit's operating efficiency and stability.

[0019] Meanwhile, the present invention also provides an air source heat pump, including a compressor, a four-way valve, a water-side heat exchanger, a three-fold electronic expansion valve, an air-side heat exchanger, and a parameter detection module connected in sequence through a refrigerant circulation pipeline, and a controller communicatively connected to the three-fold electronic expansion valve and the parameter detection module; wherein, the parameter detection module includes a first temperature sensor and a second temperature sensor, the first temperature sensor being used to measure the exhaust temperature of the compressor, and the second temperature sensor being used to measure the ambient temperature, and the controller implementing the PID regulation method of the three-fold electronic expansion valve.

[0020] Compared with the prior art, the beneficial effects of the air source heat pump provided by the present invention are the same as those of the PID regulation method of the three-fold electronic expansion valve described above, and will not be repeated here. Attached Figure Description

[0021] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings.

[0022] Figure 1 This is a flowchart of the PID control method for the three-segment electronic expansion valve of the present invention; Figure 2 This is an opening-flow diagram of the three-segment electronic expansion valve of the present invention. Detailed Implementation

[0023] The technical solutions of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention. The described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the protection scope of the present invention.

[0024] The air source heat pump of the present invention includes a compressor, a four-way valve, a water-side heat exchanger, a three-fold electronic expansion valve, an air-side heat exchanger, and a parameter detection module, which are circulated and connected through a refrigerant pipeline, and a controller that is communicatively connected to the three-fold electronic expansion valve and the parameter detection module.

[0025] The parameter detection module includes a first temperature sensor, a second temperature sensor, and a first pressure sensor.

[0026] The first temperature sensor is installed at the compressor's exhaust port and is used to measure the compressor's exhaust temperature. And the exhaust temperature is displayed in real time. Transmitted to the controller.

[0027] The second temperature sensor is used to measure the ambient temperature. And the ambient temperature is displayed in real time. Transmitted to the controller.

[0028] The first pressure sensor is installed at the compressor's exhaust port and is used to measure the compressor's exhaust pressure. And transmit exhaust pressure in real time Transmitted to the controller.

[0029] The controller, based on the received exhaust temperature Exhaust pressure Determine the actual superheat According to the received ambient temperature Target water temperature Calculate temperature difference And based on the optimal target superheat model, the optimal target superheat is obtained. Based on actual superheat With the optimal target superheat superheat deviation Temperature difference The opening-flow characteristic of the three-segment electronic expansion valve corresponding to the operating conditions was analyzed, and the opening adjustment amount of the three-segment electronic expansion valve was obtained using a PID control algorithm. .

[0030] Please see Figure 1 The controller implements PID regulation of the three-segment electronic expansion valve in the following manner, specifically including the following steps.

[0031] S1A: Obtain the actual overheat level at the current moment. .

[0032] In practice, the following sub-steps are included: S1A1: Obtain the current exhaust temperature Exhaust pressure ; S1A2: Based on refrigerant type and exhaust pressure Find the saturation temperature of the refrigerant at the current exhaust pressure. ; S1A3: Calculate the exhaust temperature at the current moment. With saturation temperature The difference yields the actual superheat. : = - .

[0033] S1B: Get the current ambient temperature Target water temperature and current operating conditions; ambient temperature Target water temperature By combining the current operating conditions with the pre-trained optimal target overheat model, the optimal target overheat is obtained. .

[0034] In practice, the operating conditions are divided into low-temperature heating mode, high-temperature cooling mode, and other operating modes.

[0035] The optimal target superheat model, composed of the XGBoost algorithm, obtains test datasets by conducting extensive target superheat debugging and actual operation on multiple units under different operating conditions. It establishes a mapping relationship between feature list [ambient temperature, target water temperature, operating condition, heating capacity, cooling capacity, power consumption] and label [optimal target superheat]. After training and testing, it can predict the optimal target superheat in low-temperature heating mode, high-temperature cooling mode, and other operating modes.

[0036] The XGBoost algorithm is not a limitation on the optimal target overheating model; other machine learning and deep learning models, such as LightGBM and SVR, can also be used to achieve target prediction.

[0037] S2: Calculate the actual superheat With the optimal target superheat The difference is used to obtain the superheat deviation at the current moment. and ambient temperature With target water temperature temperature difference .

[0038] The temperature difference satisfy: - .

[0039] The superheat deviation satisfy: = - .

[0040] S3: Combining superheat deviation Temperature difference Calculate the opening adjustment of the three-segmented electronic expansion valve based on the PID parameters corresponding to the operating conditions. .

[0041] The opening adjustment amount satisfy:

[0042] in: ΔU(t) represents the opening adjustment amount of the three-segment electronic expansion valve at the current moment, in steps; Kp represents the proportionality coefficient, the value of which is determined experimentally. Under low-temperature heating conditions, the value is usually in the range of 0.8-1.2, under high-temperature cooling conditions, the value is in the range of 1.5-2.0, and in the intermediate temperature range, the value is in the range of 1.2-1.5. It can be finely adjusted according to the actual operating effect of the unit. e(t) represents the superheat deviation at the current moment (unit: °C); Ts represents the sampling period, in seconds; it can be adjusted according to the system response speed requirements. A smaller value is used when the system response is required to be fast, and a larger value is used when the stability is required to be high. In this embodiment, the value is 1s to 5s. Ti represents the integral time constant, in seconds. It is 100s~150s for low-temperature heating, 50s~80s for high-temperature cooling, and 80s~100s for other conditions. It is used to eliminate static errors in the system. Td represents the differential time constant, with the unit being s. It is taken as 20s~30s for low-temperature heating, 10s~20s for high-temperature cooling, and 20s~25s for other conditions. It is used to predict the trend of deviation changes and reduce overshoot. e(t-1) represents the superheat deviation at the previous moment, in °C; K represents the compensation coefficient, which is determined experimentally and is used to adjust the degree of influence of the difference between the ambient temperature and the target outlet water temperature on the opening adjustment amount. In this embodiment, the value range is 0.1-0.3. This represents the difference between the ambient temperature and the target outlet water temperature, in °C.

[0043] Please see Figure 2 The application of the PID control algorithm to calculate the opening adjustment of the three-segmented electronic expansion valve under different operating conditions is as follows: In low-temperature heating mode, the ambient temperature is low, but the target outlet water temperature is high. A negative value provides negative compensation for the opening adjustment amount. Combined with a smaller Kp and a larger Ti and Td, this allows the tri-linear electronic expansion valve to perform slow, precise, and long-range adjustment in the low flow rate adjustment range, avoiding excessive flow fluctuations that could affect heating stability.

[0044] In high-temperature cooling mode, the ambient temperature is high, while the target outlet water temperature is low. When the value is positive, it provides positive compensation for the opening adjustment amount. Combined with a larger Kp and smaller Ti and Td, the three-fold electronic expansion valve can respond quickly in the large flow rate adjustment range, achieve efficient adjustment in a short range, and meet the needs of rapid cooling.

[0045] In other operating modes, all parameters are in a transitional state, and the formula can be automatically adjusted according to the actual operating conditions to ensure stable operation of the unit in this area.

[0046] S4: Adjust the amount of adjustment based on the opening degree The opening degree of the three-fold electronic expansion valve is controlled.

[0047] Compared to existing technologies, this invention employs a three-segment electronic expansion valve with small flow rate changes in the low flow rate regulation range, large flow rate changes in the large flow rate regulation range, and medium flow rate changes in the medium flow rate range. By combining operating conditions, the deviation between actual superheat and the predicted optimal target superheat, and the deviation between ambient temperature and target outlet water temperature, a PID algorithm is used to precisely control and regulate the opening of the three-segment electronic expansion valve. This effectively meets the needs of low-flow, long-range regulation during low-temperature heating and large-flow, short-range regulation during high-temperature cooling, solving the pain point of existing electronic expansion valves in flow rate regulation over a wide temperature range. This enables the unit to achieve efficient and stable heating and cooling within a wide temperature range of -35℃ to 53℃, improving the unit's operating efficiency and stability.

[0048] The PID control method for the aforementioned three-segment electronic expansion valve is stored in an electronic device and executed by this device to achieve variable slope speed regulation of the heat pump fan. The electronic device includes, but is not limited to, memory, processor, and network interface that can communicate with each other via a system bus.

[0049] The memory includes at least one type of readable storage medium, including flash memory, hard disk, multimedia card, card-type memory (e.g., SD or DX memory), random access memory (RAM), static random access memory (SRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), programmable read-only memory (PROM), magnetic memory, magnetic disk, optical disk, etc. The memory can be an internal storage unit of the electronic device, such as the hard disk or RAM of the electronic device. The memory can also be an external storage device of the electronic device, such as a plug-in hard disk, smart media card (SMC), secure digital card (SD), flash card, etc. The memory may also include both internal storage units and external storage devices of the electronic device.

[0050] The processor can be a central processing unit (CPU), controller, microcontroller, microprocessor, or other data processing chip. This processor is typically used to control the overall operation of the electronic device, such as performing control and processing related to data interaction or communication with the electronic device. The processor is used to run program code stored in the memory or process data, for example, to run the PID control method of the described three-segmented electronic expansion valve.

[0051] The network interface may include a wireless network interface or a wired network interface, which is typically used to establish communication connections between the electronic device and other electronic devices. For example, the network interface is used to connect the electronic device to an external data platform via a network, establishing a data transmission channel and communication connection between the electronic device and the external data platform. The network may be an intranet, the Internet, Global System for Mobile communication (GSM), Wideband Code Division Multiple Access (WCDMA), 4G network, 5G network, Bluetooth, Wi-Fi, or other wireless or wired networks.

[0052] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0053] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, features defined with "first" and "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0054] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A PID regulating method of a three-fold line type electronic expansion valve, characterized by, Includes the following steps: S1A: Acquire current actual superheat degree ; S1B: Obtain the ambient temperature at the current time , target water temperature and working condition, input the ambient temperature , target water temperature and working condition into the pre-trained optimal target superheat degree model to obtain the optimal target superheat degree ; S2: Calculate the actual superheat at the current moment. With the optimal target superheat superheat deviation and ambient temperature With target water temperature temperature difference ; S3: Combining superheat deviation Temperature difference Calculate the opening adjustment of the three-segmented electronic expansion valve based on the PID parameters corresponding to the operating conditions. ; The operating conditions are divided into low-temperature heating mode, high-temperature cooling mode and other operating modes, each corresponding to different PID parameter values.

2. The PID control method for the three-segment electronic expansion valve according to claim 1, characterized in that, Current fan speed adjustment increment satisfy: in, This indicates the current degree of overheating deviation. This indicates the superheat deviation at the previous moment. This represents the superheat deviation at time i. This indicates the time difference between the current moment and the previous moment. Represents the proportionality coefficient. Represents the integration time constant. denoted by ; K represents the compensation coefficient.

3. The PID control method for the three-segment electronic expansion valve according to claim 2, characterized in that, The value range of the PID parameters corresponding to the low-temperature heating operation mode is as follows: Kp∈[0.8-1.2), Ti∈(100s,150s], Td∈(20s,30s]; The value range of the PID parameters corresponding to the high-temperature cooling operation mode is as follows: Kp∈(1.5-1.2], Ti∈[50s,80s), Td∈[10s,20s).

4. The PID control method for the three-segment electronic expansion valve according to claim 3, characterized in that, The value ranges of the PID parameters for the other operating modes are as follows: Kp∈[1.2-1.5], Ti∈[80s,100s], Td∈[20s,25s].

5. The PID control method for the three-segment electronic expansion valve according to claim 2, characterized in that, The compensation coefficient K is used to adjust the degree of influence of the difference between the ambient temperature and the target outlet water temperature on the opening adjustment amount, and the value range is 0.1-0.

3.

6. The PID control method for the three-segment electronic expansion valve according to claim 1, characterized in that, The actual overheat at the current moment Obtain it through the following methods: S1A1: Obtain the current exhaust temperature Exhaust pressure ; S1A2: Based on refrigerant type and exhaust pressure Find the saturation temperature of the refrigerant at the current exhaust pressure. ; S1A3: Calculate the exhaust temperature at the current moment. With saturation temperature The difference yields the actual superheat. : = - 。 7. The PID control method for the three-segment electronic expansion valve according to claim 1, characterized in that, The optimal target superheat model is composed of the XGBoost algorithm. By establishing a mapping relationship between the feature list [ambient temperature, target water temperature, operating condition, heating capacity, cooling capacity, power consumption] and the label [optimal target superheat], it predicts the optimal target superheat in low-temperature heating mode, high-temperature cooling mode, and other operating modes.

8. The PID control method for the three-segment electronic expansion valve according to claim 1, characterized in that, The current superheat deviation satisfy: = - 。 9. The PID control method for the three-segment electronic expansion valve according to claim 1, characterized in that, The temperature difference satisfy: - 。 10. An air source heat pump, comprising a compressor, a four-way valve, a water-side heat exchanger, a three-fold electronic expansion valve, and an air-side heat exchanger connected sequentially via a refrigerant circulation pipeline, and a parameter detection module, and a controller communicatively connected to the three-fold electronic expansion valve and the parameter detection module; wherein, The parameter detection module includes a first temperature sensor and a second temperature sensor. The first temperature sensor is used to measure the exhaust temperature of the compressor, and the second temperature sensor is used to measure the ambient temperature. The controller implements the PID control method for the three-segment electronic expansion valve as described in any one of claims 1 to 9.

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