An electronic expansion valve control method and heat pump system based on return gas superheat

Abstract

This invention relates to an electronic expansion valve control method and a heat pump system based on return gas superheat. The control method calculates the change in return gas superheat between the current and previous valve control cycles, and the deviation from the target return gas superheat. Based on the return gas superheat deviation and change in return gas superheat, the corresponding valve control percentage is determined. Based on the current valve opening and valve control percentage, the target opening for the next valve control cycle is obtained, and the opening of the electronic expansion valve is adjusted accordingly. This ensures that the opening of the electronic expansion valve meets the refrigerant mass flow requirements when the heat pump operates at high or low ambient temperatures, achieving efficient and safe operation of the heat pump system and avoiding problems such as decreased evaporation performance, decreased system stability, and compressor liquid slugging.

Description

Technical Field

[0001] This invention relates to the field of heat pump control technology, and in particular to an electronic expansion valve control method and heat pump system based on return gas superheat. Background Technology

[0002] Heat pump systems are a highly efficient and environmentally friendly energy utilization technology. Their core working principle is the reverse Carnot cycle, which uses a small amount of electricity or other energy to transfer heat energy from a low-temperature heat source to a high-temperature environment, achieving heating or cooling. Air source heat pump systems, as a type of heat pump system, absorb low-temperature heat energy from the air with minimal electricity, compress it into high-temperature heat energy, and then transfer it to the location requiring heating or cooling. They are highly favored by consumers and users and are widely used for cooling and hot water supply in hotels, schools, hospitals, saunas, beauty salons, swimming pools, laundries, and other places.

[0003] The refrigerant mass flow rate required for safe and efficient operation of the same heat pump system differs under high and low ambient temperature conditions. Current technology adjusts the opening of the electronic expansion valve using a PID controller based on the deviation between the return gas superheat and the target return gas superheat. When the difference between the return gas superheat and the target superheat is constant, the number of adjustment steps for the PID-controlled electronic expansion valve is also constant. However, the impact of the same number of adjustment steps differs significantly between systems operating at high and low ambient temperatures. For example, if the number of adjustment steps calculated by the PID controller based on the return gas superheat deviation is 10 steps, the impact on a refrigerant system operating at high ambient temperatures is negligible, resulting in a low adjustment rate and long processing time. However, the impact on a refrigerant system operating at low ambient temperatures is significant, potentially leading to liquid slugging problems.

[0004] Existing technologies use a combination of the deviation between the return gas superheat and the target return gas superheat, as well as the change in the return gas superheat, to adjust the electronic expansion valve of the heat pump system. However, this still involves calculating the number of steps for each deviation and change, and then adding the two together. This results in the same valve adjustment steps for the same heat pump system operating under both high and low ambient temperature conditions, leading to valve adjustment problems at high and low ambient temperatures.

[0005] The above adjustment method does not take into account the significant difference in the impact of the same valve adjustment step of the electronic expansion valve on the system under high and low ambient temperature conditions. Therefore, it cannot accurately control the opening of the electronic expansion valve to match the mass flow rate of the refrigerant with the frequency requirements of the compressor, resulting in problems such as decreased evaporation performance, decreased system stability, and compressor liquid slugging under low or high ambient temperature conditions. Summary of the Invention

[0006] Based on this, the purpose of this invention is to provide an electronic expansion valve control method based on return gas superheat, so as to solve the problem of mismatch between the opening adjustment of the electronic expansion valve and the refrigerant mass flow rate requirements of the heat pump system under low ambient temperature and high ambient temperature conditions.

[0007] An electronic expansion valve control method based on return gas superheat includes the following steps:

[0008] S10: Collect several return gas temperatures and several low-pressure values ​​of the refrigerant at several moments during the current valve control cycle, and calculate the average return gas superheat value of the current valve control cycle.

[0009] S20: Calculate the difference between the average return gas superheat value of the current valve control cycle and the average return gas superheat value of the previous valve control cycle to obtain the change value of return gas superheat.

[0010] S30: Obtain the target return gas superheat, calculate the difference between the target return gas superheat and the average return gas superheat of the current valve control cycle, and obtain the return gas superheat deviation.

[0011] S40: Determine the valve control percentage for the next valve control cycle based on the return gas superheat change value and return gas superheat deviation in the valve control percentage lookup table;

[0012] S50: Obtain the opening degree of the electronic expansion valve in the current valve adjustment cycle, and calculate the target opening degree of the electronic expansion valve in the next valve adjustment cycle based on the valve adjustment percentage.

[0013] Furthermore, the average return gas superheat value of the current valve control cycle satisfies:

[0014]

[0015] In the formula, This indicates the average return gas superheat during the current valve control cycle. This represents the return air temperature collected at the k-th sampling point. This represents the evaporation temperature corresponding to the low pressure collected at the k-th sampling point, and n represents the total number of sampling points in the current valve control cycle.

[0016] Furthermore, the change in the return gas superheat satisfies:

[0017]

[0018] in,

[0019] In the formula, Δ(SSH) t-1～t This indicates the change in return gas superheat. This represents the average superheat of the return gas in the previous valve control cycle. This represents the return gas temperature collected at the k-th sampling point in the previous valve control cycle. This indicates the evaporation temperature corresponding to the low-pressure sampled at the k-th sampling point in the previous valve control cycle;

[0020] The return gas superheat deviation satisfies:

[0021]

[0022] In the formula: Δ(SSH) t ) indicates the deviation of return gas superheat, SSH target This indicates the target return gas superheat.

[0023] Furthermore, the valve percentage lookup table is an N*M dimensional percentage value p ij matrix:

[0024]

[0025] Where i represents the change in return gas superheat Δ(SSH) t-1～t The i-th value range of ) where i∈(1,N), is the change in return gas superheat Δ(SSH). t-1～t There are N value ranges; j represents the return gas superheat deviation Δ(SSH). t The j-th value range of ) is given by j∈(1,M), where Δ(SSH) is the return gas superheat deviation. t There are M value ranges.

[0026] Furthermore, the target opening K for the next valve control cycle t+1 satisfy:

[0027] K t+1 =K t *(100%-p) ij )

[0028] In the formula, K t This indicates the opening degree of the electronic expansion valve during the current valve adjustment cycle.

[0029] Furthermore, it also includes correcting the valve percentage using a differential pressure correction factor, wherein the target opening K for the next valve control cycle is... t+1 satisfy:

[0030] K t+1 =K t *(100%-p) ij *R)

[0031] in,

[0032] In the formula, This indicates the high pressure during the current valve control cycle. This indicates the low-pressure setting for the current valve control cycle. R represents the atmospheric pressure of the current valve control cycle, and R represents the differential pressure correction factor.

[0033] Furthermore, it also includes correcting the pressure regulation percentage using an empirical constant, wherein the target opening K for the next valve control cycle is... t+1 satisfy:

[0034] K t+1 =K t *(100%-p) ij *R*α)

[0035] In the formula, α represents an empirical constant.

[0036] Compared with existing technologies, this invention calculates the change in return gas superheat between the current and previous valve control cycles, and the deviation between the current and target return gas superheat. Based on the return gas superheat deviation and change, it finds the corresponding valve control percentage. Based on the current valve opening and valve control percentage of the electronic expansion valve, it obtains the target opening for the next valve control cycle and adjusts the opening of the electronic expansion valve. This ensures that the opening of the electronic expansion valve meets the refrigerant mass flow requirements when the heat pump operates at high and low ambient temperatures, achieving efficient and safe operation of the heat pump system and avoiding problems such as decreased evaporation performance, decreased system stability, and compressor liquid slugging. At the same time, by using a differential pressure correction factor and empirical constant to correct the valve control percentage, it can further improve the adjustment accuracy of the electronic expansion valve under high and low ambient temperature conditions, and achieve better matching with the refrigerant mass flow required by the system.

[0037] In addition, the present invention also provides a heat pump system.

[0038] A heat pump system includes a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, and an air-side heat exchanger, sequentially connected via refrigerant circulation piping, and a sensor module, and a controller electrically and / or communicatively connected to the electronic expansion valve and the sensor module. The controller includes: a return gas superheat average calculation unit, a return gas superheat variation calculation unit, a return gas superheat deviation calculation unit, a valve percentage query unit, and a valve opening calculation unit.

[0039] The return gas superheat average calculation unit is used to collect several return gas temperatures and several low-pressure values ​​of the refrigerant at several moments during the current valve control cycle, and calculate the return gas superheat average value of the current valve control cycle.

[0040] The return gas superheat change value calculation unit is used to calculate the difference between the average return gas superheat value of the current valve control cycle and the average return gas superheat value of the previous valve control cycle, and obtain the return gas superheat change value.

[0041] The return gas superheat deviation calculation unit is used to calculate the difference between the target return gas superheat and the average return gas superheat of the current valve control cycle, and obtain the return gas superheat deviation.

[0042] The valve control percentage query unit is used to determine the valve control percentage for the next valve control cycle based on the return gas superheat change value and return gas superheat deviation in the valve control percentage query table.

[0043] The valve opening calculation unit is used to obtain the opening of the electronic expansion valve in the current valve adjustment cycle and calculate the target opening of the electronic expansion valve in the next valve adjustment cycle based on the valve adjustment percentage.

[0044] Furthermore, the controller also includes a differential pressure correction unit:

[0045] The differential pressure correction unit is used to obtain the high pressure during the current valve control cycle. Calculate the differential pressure correction factor R, and apply the differential pressure correction factor to the valve percentage p. ij Make corrections.

[0046] Furthermore, the controller also includes an empirical constant correction unit:

[0047] The empirical constant correction unit is used to obtain the empirical constant α of the system and to adjust the valve percentage p using the empirical constant α. ij Make corrections.

[0048] The beneficial effects of the heat pump system proposed in this invention are the same as those of the above-mentioned electronic expansion valve control method based on return gas superheat, and will not be repeated here.

[0049] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the system structure according to an embodiment of the present invention;

[0051] Figure 2 This is a flowchart of an electronic expansion valve control method according to an embodiment of the present invention. Detailed Implementation

[0052] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings of the embodiments of the present invention.

[0053] To address the issue that existing technologies, which adjust the opening of the electronic expansion valve using the deviation between the return gas superheat and the target return gas superheat, and / or the change in return gas superheat, cannot simultaneously account for the impact of low and high ambient temperatures on the refrigerant mass flow rate in the system under low and high ambient temperature conditions, resulting in inaccurate control of the electronic expansion valve opening to match the refrigerant mass flow rate with the compressor frequency requirements, and consequently causing problems such as decreased evaporation performance, reduced system stability, and compressor liquid slugging under low or high ambient temperature conditions, this invention proposes an electronic expansion valve control method based on return gas superheat. The control method calculates the change in return gas superheat between the current and previous valve control cycles, as well as the deviation from the target return gas superheat. Based on the return gas superheat deviation and change, the corresponding valve control percentage is determined. Then, based on the current valve opening and valve control percentage of the electronic expansion valve, the target opening for the next valve control cycle is obtained, and the opening of the electronic expansion valve is adjusted. This ensures that the opening of the electronic expansion valve meets the refrigerant mass flow requirements when the heat pump operates at high or low ambient temperatures, achieving efficient and safe operation of the heat pump system and avoiding problems such as decreased evaporation performance, decreased system stability, and compressor liquid slugging.

[0054] For specific implementation details, please refer to [link / reference]. Figure 1 The heat pump system proposed in this invention includes a compressor 10, a four-way valve 20, a water-side heat exchanger 30, an electronic expansion valve 40, an air-side heat exchanger 50, a sensor module 60, a controller (not shown), and other auxiliary pipes, all connected via refrigerant piping. The controller is electrically and / or communicatively connected to the electronic expansion valve 40 and the sensor module 60.

[0055] The sensor module 60 includes a temperature sensor 61, a first pressure sensor 62, a second pressure sensor 63, and a third pressure sensor 64.

[0056] Temperature sensor 61 is installed at the return port of compressor 10 to collect the return gas temperature of refrigerant. and the measured return gas temperature Transmitted to the controller.

[0057] The first pressure sensor 61 is installed at the discharge port of the compressor 10 to collect the high-pressure reading of the refrigerant. And the measured high pressure Transmitted to the controller.

[0058] The second pressure sensor 62 is installed at the return port of the compressor 10 to collect the low-pressure reading of the refrigerant. And measure the low pressure Transmitted to the controller.

[0059] The controller includes a return gas superheat average calculation unit 100, a return gas superheat change value calculation unit 200, a return gas superheat deviation calculation unit 300, a valve percentage query unit 400, and a valve opening calculation unit 500.

[0060] The return gas superheat average calculation unit 100 is used to execute step S10: collecting several return gas temperatures of the refrigerant at several moments within the current valve regulating cycle. and several low pressure Based on several low-pressure Determine the corresponding evaporation temperatures of the refrigerant. Based on several return gas temperatures and several evaporation temperatures The average return gas superheat value of the current valve control cycle is calculated.

[0061]

[0062] In the formula, k represents the kth sampling point in the current valve control cycle, n represents the total number of sampling points in the current valve control cycle, and t is the valve control cycle, such as 10 seconds, 20 seconds, 30 seconds, etc.

[0063] The duration of the valve control cycle and the number of sampling points within the valve control cycle can be set as needed. The time interval between sampling points can be set to be equal, have a trend, or be random. This application does not impose any restrictions.

[0064] Example 1: The valve control cycle is set to 30 seconds, meaning the average return gas superheat is calculated every 30 seconds within that valve control cycle; the return gas temperature and low-pressure are collected every 3 seconds, with a total of 10 sampling points, meaning the average return gas superheat is equal to the average value calculated from the data of the 10 sampling points.

[0065] Based on several low-pressure Determine the corresponding evaporation temperatures of the refrigerant. The method can be the lookup table method or the formula calculation method, and this application does not impose any restrictions.

[0066] The return gas superheat variation calculation unit 200 is used to execute step S20: calculate the average return gas superheat value of the current valve control cycle. Average return gas superheat compared to the previous valve control cycle The difference is used to obtain the change in return gas superheat Δ(SSH). t-1～t ).

[0067] Average superheat of return gas (SSH) in the previous valve control cycle t-1 Calculated by the return gas superheat average calculation unit 100:

[0068]

[0069] Change in return gas superheat satisfy:

[0070]

[0071] The return gas superheat deviation calculation unit 300 is used to perform step S30: obtain the target return gas superheat SSH. target Calculate the target return gas superheat SSH target Average return gas superheat compared to the current valve control cycle The difference is used to obtain the return gas superheat deviation Δ(SSH). t ).

[0072] Return gas superheat deviation Δ(SSH) t )satisfy:

[0073]

[0074] The valve control percentage lookup unit 400 is used to execute step S40: In the valve control percentage lookup table, based on the return gas superheat change value Δ(SSH)... t-1～t ) and return gas superheat deviation Δ(SSH) t Determine the valve control percentage p for the next valve control cycle. ij , where i represents the i-th value range of the return gas superheat change value, j represents the j-th value range of the return gas superheat deviation, i∈(1,N), j∈(1,M).

[0075] The valve percentage lookup table P is an N*M dimensional percentage value p. ij The matrix consists of N rows labeled with the range of values ​​for the change in return gas superheat and M columns labeled with the range of values ​​for the deviation in return gas superheat.

[0076] The valve percentage lookup table P is represented as follows:

[0077]

[0078] The valve adjustment percentage lookup table is based on the valve adjustment percentage corresponding to the change in return gas superheat and the deviation in return gas superheat, which are measured when the heat pump is running at high and low ambient temperatures and the refrigerant mass flow rate of the heat pump system meets the requirements of efficient and safe operation of the system.

[0079] Example 2: Change in return gas superheat Δ(SSH) t-1～t The range of values ​​for ) is 5, namely, [, -2], (-2, -1), [-1, 1], (1, 2), [2, ); the return gas superheat deviation Δ(SSH tThe value range of ) has 5 intervals, namely (,-2], (-2,-1), [-1,1], (1,2), [2,). Therefore, the corresponding valve percentage lookup table has 5*5=25 percentage values ​​p, as shown in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] Valve opening calculation unit 500 is used to execute step S50: obtain the opening K of the electronic expansion valve in the current valve adjustment cycle. t According to the valve percentage p ij Calculate the target opening K of the electronic expansion valve in the next valve control cycle. t+1 .

[0084] The target opening K for the next valve control cycle t+1 satisfy:

[0085] K t+1 =K t *(100%-p) ij ).

[0086] Since different water temperatures will have a certain impact even at the same ambient temperature, the higher the water temperature, the greater the system pressure difference. With the same opening degree of the electronic expansion valve, a greater system pressure difference results in a greater refrigerant mass flow rate. Therefore, to improve the adjustment accuracy of the electronic expansion valve under high and low ambient temperature conditions, in one embodiment, the system pressure difference is used to adjust the valve percentage p. ij Make corrections.

[0087] The controller also includes a differential pressure correction unit 600, used to execute step S60: obtain the high pressure during the current valve control cycle. Calculate the differential pressure correction factor R, and apply the differential pressure correction factor to the valve percentage p. ij Make corrections.

[0088] The differential pressure correction factor R satisfies:

[0089]

[0090] in, This indicates the atmospheric pressure during the current valve control cycle.

[0091] The target valve opening K for the next control cycle after differential pressure correction is then... t+1 satisfy:

[0092] K t+1 =K t *(100%-p) ij *R).

[0093] Since other factors, such as the components of the system, also have a certain influence under the same ambient temperature and water temperature, in one embodiment, a correction coefficient is used to characterize the influence of factors other than ambient temperature and water temperature on the opening degree of the electronic expansion valve.

[0094] The controller also includes an empirical constant correction unit 700, used to perform step S70: obtaining the system's empirical constant α, and using the empirical constant α to adjust the valve percentage p. ij Make corrections.

[0095] The target valve opening K for the next control cycle, after pressure difference correction and empirical constant correction, is then... t+1 satisfy:

[0096] K t+1 =K t *(100%-p) ij *R*α).

[0097] Example 3: When a heat pump system operates at high ambient temperatures, it requires a large refrigerant mass flow rate. Therefore, the electronic expansion valve needs to be opened more fully. According to Table 1, a 2% valve opening is required. Assuming the current ambient temperature is 20 degrees Celsius, with an electronic expansion valve opening of 400 pulses, a differential pressure correction factor R = 1, and an empirical constant α = 1, opening the valve at the current 2% opening would result in 8 valve opening steps. When the heat pump system operates at low ambient temperatures, it requires a smaller refrigerant mass flow rate. Therefore, the electronic expansion valve needs to be opened less fully. Assuming the current ambient temperature is -20 degrees Celsius, with an electronic expansion valve opening of 100 pulses, a differential pressure correction factor R = 1, and an empirical constant α = 1, opening the valve at the current 2% opening would result in 2 valve opening steps. This demonstrates that adjusting the valve based on its own opening degree and a percentage of that opening degree better balances the valve opening requirements at both high and low ambient temperatures.

[0098] By using differential pressure correction factors and empirical constants to correct the valve percentage, the adjustment accuracy of the electronic expansion valve under high and low ambient temperature conditions can be further improved, resulting in better matching with the refrigerant mass flow rate required by the system.

[0099] In practice, the controller is an electronic device, which includes, but is not limited to, a memory, a processor, and a network interface that can communicate with each other via a system bus.

[0100] Among them, electronic devices can be computing devices such as rack servers, blade servers, tower servers, or cabinet servers.

[0101] 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 can also include both internal storage units and external storage devices of the electronic device.

[0102] The processor can be a central processing unit (CPU), a microcontroller, a 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 aforementioned electronic expansion valve control method based on return gas superheat.

[0103] 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.

[0104] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” and “several” refer to two or more; “and / or” refers to and includes any or all possible combinations of one or more associated listed items; “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0105] 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 method for controlling an electronic expansion valve based on return gas superheat, characterized in that, include: S10: Collect several return gas temperatures and several low-pressure values ​​of the refrigerant at several moments during the current valve control cycle, and calculate the average return gas superheat value of the current valve control cycle. S20: Calculate the difference between the average return gas superheat value of the current valve control cycle and the average return gas superheat value of the previous valve control cycle to obtain the change value of return gas superheat. S30: Obtain the target return gas superheat, calculate the difference between the target return gas superheat and the average return gas superheat of the current valve control cycle, and obtain the return gas superheat deviation. S40: Determine the valve control percentage value for the next valve control cycle based on the return gas superheat change value and return gas superheat deviation in the valve control percentage lookup table. ; S50: Obtain the opening degree of the electronic expansion valve during the current valve control cycle. According to the valve percentage value Calculate the target opening degree of the electronic expansion valve in the next valve control cycle. , satisfy: in, In the formula, This represents the differential pressure correction factor. This indicates the high pressure during the current valve control cycle. This indicates the low-pressure setting for the current valve control cycle. This indicates the atmospheric pressure during the current valve control cycle.

2. The electronic expansion valve control method according to claim 1, characterized in that, The average return gas superheat value of the current valve control cycle satisfies: In the formula, This indicates the average return gas superheat during the current valve control cycle. This represents the return air temperature collected at the k-th sampling point. This represents the evaporation temperature corresponding to the low pressure collected at the k-th sampling point, and n represents the total number of sampling points in the current valve control cycle.

3. The electronic expansion valve control method according to claim 2, characterized in that, The change value of the return gas superheat satisfies: in, , In the formula, This indicates the change in return gas superheat. This represents the average superheat of the return gas in the previous valve control cycle. This represents the return gas temperature collected at the k-th sampling point in the previous valve control cycle. This indicates the evaporation temperature corresponding to the low-pressure sampled at the k-th sampling point in the previous valve control cycle; The return gas superheat deviation satisfies: In the formula: This indicates the deviation in return gas superheat. This indicates the target return gas superheat.

4. The electronic expansion valve control method according to claim 3, characterized in that, The valve percentage lookup table is an N*M dimensional percentage value table. matrix: Where i represents the change in return gas superheat. The i-th value range, i∈(1,N), represents the change in return gas superheat. There are N value ranges; j represents the deviation of return gas superheat. The j-th value range, j∈(1,M), is the return gas superheat deviation. There are a total of M value ranges.

5. The electronic expansion valve control method according to claim 1, characterized in that, This also includes using empirical constants to adjust the percentage value of the regulating valve. The correction is made to determine the target opening degree for the next valve control cycle. satisfy: In the formula, This represents an empirical constant.

6. A heat pump system, comprising a compressor, a four-way valve, a water-side heat exchanger, an electronic expansion valve, an air-side heat exchanger, and a sensor module connected sequentially via a refrigerant circulation pipeline, and a controller electrically and / or communicatively connected to the electronic expansion valve and the sensor module, characterized in that, The controller includes: a return gas superheat average calculation unit, a return gas superheat variation calculation unit, a return gas superheat deviation calculation unit, a valve percentage query unit, and a valve opening calculation unit. The return gas superheat average calculation unit is used to collect several return gas temperatures and several low-pressure values ​​of the refrigerant at several moments during the current valve control cycle, and calculate the return gas superheat average value of the current valve control cycle. The return gas superheat change value calculation unit is used to calculate the difference between the average return gas superheat value of the current valve control cycle and the average return gas superheat value of the previous valve control cycle, and obtain the return gas superheat change value. The return gas superheat deviation calculation unit is used to calculate the difference between the target return gas superheat and the average return gas superheat of the current valve control cycle, and obtain the return gas superheat deviation. The valve control percentage query unit is used to determine the valve control percentage value for the next valve control cycle based on the return gas superheat change value and the return gas superheat deviation in the valve control percentage query table. ; The valve opening calculation unit is used to obtain the opening degree of the electronic expansion valve in the current valve adjustment cycle. According to the valve percentage value Calculate the target opening degree of the electronic expansion valve in the next valve control cycle. , satisfy: in, In the formula, This represents the differential pressure correction factor. This indicates the high pressure during the current valve control cycle. This indicates the low-pressure setting for the current valve control cycle. This indicates the atmospheric pressure during the current valve control cycle.

7. The heat pump system according to claim 6, characterized in that, The controller also includes an empirical constant correction unit: The empirical constant correction unit is used to obtain the empirical constants of the system. And using empirical constants Percentage value of regulating valve Make corrections.

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