A variable frequency condensing unit compressor variable frequency control method, computer readable storage medium and variable frequency condensing unit

Abstract

The application discloses a variable frequency condensing unit compressor variable frequency control method, a computer readable storage medium and a variable frequency condensing unit. The method comprises the following steps: determining the adjustment direction of the compressor frequency according to the target refrigeration temperature and the current refrigeration temperature; setting the frequency adjustment speed of the compressor according to the current frequency of the compressor and the adjustment direction of the compressor frequency; if the current frequency of the compressor is located in the high-efficiency performance frequency interval of the compressor, the frequency of the compressor is adjusted at a set first adjustment speed; if the current frequency of the compressor is not located in the high-efficiency performance frequency interval of the compressor and the adjustment direction of the compressor frequency is close to the high-efficiency performance frequency interval of the compressor, the frequency of the compressor is adjusted at a set second adjustment speed, wherein the second adjustment speed is higher than the first adjustment speed. Compared with the prior art, the application can effectively reduce the energy consumption of the compressor and can be applied to energy-saving air conditioners.

Description

Technical Field

[0001] This invention relates to the field of refrigeration, and in particular to a compressor frequency conversion control method for a frequency conversion condensing unit, a computer-readable storage medium, and a frequency conversion condensing unit. Background Technology

[0002] Variable frequency condensing chillers are core equipment in cold chain warehousing, commercial refrigeration, and industrial refrigeration scenarios. They achieve adaptive load regulation by adjusting the compressor's operating frequency to match the real-time refrigeration load. Within the rated operating range, the coefficient of performance (COP) of a variable frequency compressor exhibits a single-peak characteristic, initially rising with the operating frequency, then continuously decreasing after reaching the high-efficiency performance frequency range. This characteristic has become a recognized fundamental performance law of compressors in the refrigeration industry. Figure 1 As shown, in the frequency-to-performance curve of the variable frequency condensing unit, there is a high-efficiency performance frequency range in the middle. When the compressor operates in this range, the coefficient of performance (COP) is at its peak level. When the frequency is below the lower limit of this range, the compressor suction efficiency is low, the oil return is not smooth, and both energy efficiency and cooling capacity are low. When the frequency is above the upper limit of this range, the compressor motor loss and mechanical loss increase significantly, the heat exchange system becomes unbalanced, and the COP drops rapidly.

[0003] Currently, the compressor control of commercial variable frequency condensing units in the industry uses the difference between the current cooling temperature and the target cooling temperature as the core basis for frequency adjustment, and performs adjustment actions with a fixed frequency increase / decrease rate, without taking into account the compressor's high-efficiency performance frequency range for targeted optimization. Although some high-end units attempt to identify the optimal operating frequency, they only use single-point optimal frequency control, that is, they try to control the compressor frequency at a set optimal frequency, without forming a continuous high-efficiency operating range. In actual operation, they are easily affected by load and ambient temperature fluctuations, and frequently deviate from the high-efficiency performance frequency range.

[0004] Meanwhile, in existing control schemes, the frequency increase and decrease logics are independent, lacking symmetrical energy efficiency optimization design. When decreasing frequency, a slower rate is often used to avoid overshoot, but when increasing frequency (especially when the current cooling temperature differs significantly from the set temperature), a full-band "rapid frequency increase" logic is used in pursuit of "rapid temperature rise." This causes the compressor to directly bypass the high-efficiency performance frequency range without hindrance, entering the high-frequency, high-energy-consumption, and low-efficiency zone, resulting in severe energy waste. The frequency decrease logic lacks a corresponding rapid fallback mechanism, causing the compressor to remain in the high-frequency, low-efficiency range for extended periods. These two sets of speed control rules and range determination logics are completely disconnected, prioritizing only temperature control response speed without simultaneously considering operational energy efficiency. The high-frequency range still uses the "rapid frequency increase" logic, directly entering the high-consumption, low-efficiency zone, resulting in energy waste. In contrast, after starting up, variable frequency condensing units spend most of their operating time maintaining temperature. Therefore, controlling the compressor frequency within the high-efficiency performance frequency range can significantly reduce operating energy consumption.

[0005] Therefore, how to design a compressor frequency conversion control method, a computer-readable storage medium, and a frequency conversion condensing unit to reduce operating energy consumption is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0006] To address the high energy consumption problem of existing variable frequency condensing unit compressor variable frequency control methods, this invention proposes a variable frequency control method for a variable frequency condensing unit compressor, a computer-readable storage medium, and a variable frequency condensing unit.

[0007] The technical solution of this invention is to propose a variable frequency control method for a compressor in a variable frequency condensing unit, which includes: The direction of compressor frequency adjustment is determined based on the target cooling temperature and the current cooling temperature; The compressor frequency adjustment speed is set according to the compressor's current frequency and the direction of frequency adjustment. If the compressor's current frequency is within the compressor's high-efficiency performance frequency range, then the compressor's frequency is adjusted at the set first adjustment speed; If the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the compressor frequency adjustment direction is closer to the compressor's high-efficiency performance frequency range, then the compressor frequency is adjusted at a set second adjustment speed, wherein the second adjustment speed is higher than the first adjustment speed.

[0008] This invention dynamically adjusts the frequency change rate based on the current compressor frequency range and adjustment direction, thereby achieving precise control over the compressor's operating frequency. When the compressor is in the high-efficiency performance frequency range, a slow adjustment is used to extend the compressor's operating time in the high-efficiency performance frequency range; when the compressor is in the low-efficiency range and the adjustment direction is close to the high-efficiency performance frequency range, a fast adjustment is used to shorten the compressor's operating time in the low-efficiency range, thereby maximizing the duration of the compressor's high-efficiency operation phase and reducing the duration of the high-energy-consumption operation phase.

[0009] In addition, based on the actual measured calibration performance curve of the compressor, the present invention calibrates two fixed frequency points: the lower limit of the peak frequency of high efficiency performance and the upper limit of the peak frequency of high efficiency performance, forming a continuous high efficiency operating range. This perfectly matches the actual performance characteristics of the compressor's high efficiency performance, which first increases and then decreases, thus solving the problem of easy fluctuation of single-point frequency and deviation from the high efficiency performance frequency range.

[0010] Furthermore, the method further includes setting the compressor frequency adjustment speed based on the compressor's current frequency and the compressor frequency adjustment direction, and also includes: If the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the compressor frequency adjustment direction is far from the compressor's high-efficiency performance frequency range, then the compressor frequency is kept unchanged for a set period of time before judging whether the current cooling temperature meets the requirements. If yes, the compressor frequency is kept unchanged; otherwise, the compressor frequency is adjusted at a set third adjustment speed, wherein the third adjustment speed is lower than the second adjustment speed.

[0011] When the compressor is in the low-efficiency zone and the adjustment direction is far from the high-efficiency performance frequency range, this invention first maintains the compressor frequency unchanged for a set period of time before judging whether the current cooling temperature meets the requirements. If the temperature requirements cannot be met, the frequency is slowly adjusted to keep the compressor operating frequency near the high-efficiency performance frequency range as much as possible, thus avoiding blind adjustment.

[0012] Furthermore, the method further includes setting the compressor frequency adjustment speed based on the compressor's current frequency and the compressor frequency adjustment direction, and also includes: If the current frequency of the compressor is not within the high-efficiency performance frequency range of the compressor and the adjustment direction of the compressor frequency is far away from the high-efficiency performance frequency range of the compressor, the frequency of the compressor is adjusted at a set third adjustment speed, wherein the third adjustment speed is lower than the second adjustment speed.

[0013] When the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the direction of the compressor frequency adjustment is far from the compressor's high-efficiency performance frequency range, directly adjusting the compressor's frequency at a slow speed can speed up the frequency adjustment and achieve the temperature control requirements more quickly.

[0014] Furthermore, the third adjustment speed is lower than the first adjustment speed.

[0015] When the compressor is in the inefficient zone and the adjustment direction is far from the high-efficiency performance frequency range, the present invention uses a slower third adjustment speed to slowly adjust the frequency, bringing the compressor operating frequency as close as possible to the high-efficiency performance frequency range, thus avoiding unnecessary energy consumption due to excessive adjustment.

[0016] Furthermore, the compressor frequency conversion control method for the aforementioned frequency conversion condensing unit also includes: The high-efficiency performance frequency range of the compressor is obtained based on the operating conditions of the variable frequency condensing unit.

[0017] This invention pre-tests the performance of the variable frequency condensing unit under various operating conditions to obtain the high-efficiency performance frequency range under various operating conditions, forming a mapping table between operating conditions and high-efficiency performance frequency ranges, which facilitates obtaining the optimal performance frequency range of the compressor based on the current operating conditions of the compressor.

[0018] Furthermore, based on the operating conditions of the variable frequency condensing unit, the high-efficiency performance frequency range of the compressor is obtained, including: The system searches a pre-established mapping table based on the compressor's operating conditions to determine if a matching operating condition exists. If there is an operating condition that matches the current operating condition of the compressor, then the high-efficiency performance frequency range corresponding to it shall be used as the high-efficiency performance frequency range of the current compressor. If no matching operating condition exists, the two closest operating conditions above and below the current operating condition and their corresponding high-efficiency performance frequency ranges are obtained. The upper and lower limits of the two obtained high-efficiency performance frequency ranges are linearly interpolated to obtain the upper and lower limits of the high-efficiency performance frequency range of the current compressor.

[0019] Since it is impossible to exhaust every operating condition when sampling to create a mapping table between operating conditions and high-efficiency frequency ranges, when searching, if no matching operating condition exists, the two closest operating conditions above and below the current operating condition and their corresponding high-efficiency frequency ranges are obtained. Linear interpolation is then used to calculate the high-efficiency frequency range of the current compressor, so that the corresponding high-efficiency frequency range can be estimated relatively accurately and quickly even when no matching operating condition exists.

[0020] Furthermore, the operating conditions of the variable frequency condensing unit include the condensing temperature and evaporation temperature of the variable frequency condensing unit.

[0021] Since the condensing and evaporating temperatures of the variable frequency condensing unit are usually constant when it is not individually set, and they affect the target cooling temperature together with the operating frequency of the compressor, in this embodiment of the invention, the operating conditions of the variable frequency condensing unit are set to the condensing and evaporating temperatures of the variable frequency condensing unit.

[0022] Furthermore, determining the direction of compressor frequency adjustment based on the target cooling temperature and the current cooling temperature includes: If the current cooling temperature is higher than the target cooling temperature, then the direction of compressor frequency adjustment is determined to be the direction of frequency increase; If the current cooling temperature is lower than the target cooling temperature, then the direction of compressor frequency adjustment is determined to be the direction of frequency reduction; If the current cooling temperature is equal to the target cooling temperature, then the compressor frequency remains unchanged.

[0023] In this invention, the direction of compressor frequency adjustment is determined by the target cooling temperature and the current cooling temperature. It is determined whether the compressor needs to increase or decrease its frequency. Then, the frequency is adjusted using the set speed regulation logic, which realizes energy efficiency optimization across the entire frequency band, with no control blind spots, and effectively reduces the operating energy consumption of the condensing unit.

[0024] Furthermore, if the compressor frequency is adjusted in the direction of frequency increase, then: When the current frequency of the compressor is lower than the lower limit of the high-efficiency performance frequency range, the frequency of the compressor is increased at the second adjustment speed until the current frequency of the compressor reaches the lower limit of the high-efficiency performance frequency range. When the compressor's current frequency is within the high-efficiency performance frequency range, the compressor's frequency is adjusted by increasing the frequency at the first adjustment speed. When the compressor's current frequency is higher than the upper limit of the high-efficiency performance frequency range, the frequency increase is stopped and the compressor's frequency is kept constant for a set period of time. Then, the current cooling temperature is monitored to see if it meets the requirements. If it does, the compressor's frequency is kept constant; otherwise, the compressor's frequency is increased and adjusted at the third adjustment speed.

[0025] When frequency increase is required, i.e., when the current temperature is higher than the target temperature and the cooling capacity needs to be increased, if the compressor's current frequency is lower than the lower limit of the high-efficiency performance frequency range, the compressor frequency is increased at a relatively fast adjustment speed, so that the compressor quickly runs into the high-efficiency performance frequency range. If the compressor's current frequency is within the high-efficiency performance frequency range, the compressor frequency is increased at a slower speed, so that the compressor stays in the high-efficiency performance frequency range for a longer period of time, and the temperature control target is achieved within the high-efficiency performance frequency range as much as possible. If the compressor's current frequency is higher than the upper limit of the high-efficiency performance frequency range, the compressor frequency is kept unchanged for a set period of time before judging whether the current cooling temperature meets the requirements. Frequency is increased slowly only when the temperature control requirements cannot be met, avoiding blind frequency increase and minimizing the high-frequency, high-energy-consumption operation time.

[0026] Furthermore, if the compressor frequency is adjusted in the direction of frequency reduction, then: When the current frequency of the compressor is higher than the upper limit of the high-efficiency performance frequency range, the frequency of the compressor is adjusted to be reduced at the second adjustment speed until the current frequency of the compressor is reduced to the upper limit of the high-efficiency performance frequency range. When the compressor's current frequency is within the high-efficiency performance frequency range, the compressor's frequency is adjusted by reducing the frequency at the first adjustment speed; When the compressor's current frequency is lower than the lower limit of the high-efficiency performance frequency range, the frequency reduction is stopped and the compressor's frequency is kept constant for a set period of time. Then, the current cooling temperature is monitored to see if it meets the requirements. If it does, the compressor's frequency is kept constant; otherwise, the compressor's frequency is reduced at the third adjustment speed.

[0027] When frequency reduction is needed, i.e., when the current temperature is lower than the target temperature and the cooling capacity needs to be reduced, if the compressor's current frequency is higher than the upper limit of the high-efficiency performance frequency range, the compressor frequency is reduced at a relatively fast adjustment speed, so that the compressor quickly runs into the high-efficiency performance frequency range, minimizing the high-frequency, high-energy-consumption operation time. If the compressor's current frequency is within the high-efficiency performance frequency range, the compressor frequency is reduced at a slower speed, so that the compressor stays in the high-efficiency performance frequency range for a longer period of time, making the compressor work in the high-efficiency performance frequency range as much as possible. If the compressor's current frequency is lower than the lower limit of the high-efficiency performance frequency range, the compressor frequency is kept unchanged for a set period of time before judging whether the current cooling temperature meets the requirements. The frequency is reduced slowly only when the temperature control requirements cannot be met, to prevent insufficient cooling capacity due to excessive frequency reduction, which would cause the current cooling temperature to rebound, trigger high-temperature frequency increase, and form a repeated frequency reduction and increase cycle, resulting in energy waste.

[0028] The present invention also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the above-described variable frequency control method for the compressor of a variable frequency condensing unit.

[0029] The present invention also provides a variable frequency condensing unit, comprising: Variable frequency compressor; The operating parameter detection module is used to detect the operating parameters of the variable frequency unit; The compressor controller is used to control the operating frequency of the compressor according to the operating parameters of the variable frequency unit and the parameters set by the user. When controlling the operating frequency of the compressor, the compressor controller executes the compressor variable frequency control method of the variable frequency condensing unit described above.

[0030] Compared with the prior art, the present invention has at least one of the following beneficial effects: 1. By dividing the compressor frequency into three regions—the high-efficiency performance frequency range, the lower high-efficiency performance frequency range, and the higher high-efficiency performance frequency range—and dynamically adjusting the frequency change rate according to the current frequency region and adjustment direction, fine-grained control of the compressor's operating frequency is achieved.

[0031] 2. When the compressor is in the high-efficiency frequency range, slow adjustment is used to extend the compressor's operating time in the high-efficiency frequency range; when the compressor is in the low-efficiency range and the adjustment direction is close to the high-efficiency frequency range, fast adjustment is used to shorten the compressor's operating time in the low-efficiency range; when the compressor is in the low-efficiency range and the adjustment direction is far from the high-efficiency frequency range, blind adjustment is avoided by delay judgment and slow frequency adjustment; through the above frequency adjustment methods, the compressor's operating frequency is kept as close as possible to the high-efficiency frequency range, thereby reducing the compressor's energy consumption. The variable frequency condensing unit and its compressor variable frequency control method of the present invention can be applied to energy-saving air conditioners to improve the energy efficiency of air conditioners. Attached Figure Description

[0032] The present invention will now be described in detail with reference to the embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram showing the relationship between the compressor frequency and energy efficiency of a variable frequency condensing unit. Figure 2 This is a schematic diagram of the variable frequency condensing unit of the present invention; Figure 3 This is a compressor frequency control process for a variable frequency condensing unit according to one embodiment of the present invention; Figure 4 The compressor frequency control process of a variable frequency condensing unit according to another embodiment of the present invention; Figure 5 This is the control process for obtaining the high-efficiency performance frequency range based on operating conditions in this invention; Figure 6 This is the process for determining the frequency adjustment direction in this invention; Figure 7 This is the compressor frequency control process in the frequency increase direction of the present invention; Figure 8 This is the compressor frequency control process in the frequency reduction direction of the present invention. Detailed Implementation

[0033] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0034] The schematic diagram of the frequency control hardware structure of the variable frequency condensing unit of this invention is shown below. Figure 2 As shown, the variable frequency condensing unit of the present invention also includes other components such as a four-way valve assembly and an evaporator. Since these components are not the focus of this invention, they are not discussed further. Figure 2It is not disclosed in the text, but those skilled in the art will understand that components such as four-way valves are essential components for the operation of variable frequency condensing units, and their working methods and principles are well-known technologies, so they will not be described in detail here.

[0035] It is understood that variable frequency condensing units can be used in energy-saving air conditioners, energy-saving refrigerators, and other refrigeration equipment; this invention does not limit this application. The variable frequency condensing unit includes a variable frequency compressor, an operating parameter detection module, and a compressor controller. The operating parameter detection module is used to detect the operating parameters of the variable frequency condensing unit. These operating parameters include any one or more of the existing detection parameters used to adjust compressor frequency changes, such as power, discharge pressure, cooling / heating capacity, condensing temperature, evaporating temperature, target cooling temperature, and current cooling temperature. The compressor controller is used to compare the detected operating parameters with the user-set temperature, generate and execute corresponding frequency adjustment commands, thereby changing the compressor's operating frequency.

[0036] The core control logic of the compressor frequency conversion control method for the variable frequency condensing unit of the present invention is as follows: Based on the comparison between the target cooling temperature and the current cooling temperature, the direction of compressor frequency adjustment (increasing or decreasing frequency) is determined; then, based on the compressor's current frequency range (below the high-efficiency performance frequency range, within the high-efficiency performance frequency range, or above the high-efficiency performance frequency range) and the adjustment direction, the corresponding frequency adjustment speed is selected. It is understood that since the frequency of the variable frequency compressor is variable, when the frequency increases, its power is greater and the cooling capacity produced is greater; when the frequency decreases, its power is smaller and the cooling capacity produced is less. Therefore, the present invention adjusts the compressor frequency based on the target cooling temperature and the current cooling temperature to minimize compressor energy consumption while meeting the target cooling temperature.

[0037] like Figure 3 As shown, specifically, the control process of the compressor variable frequency control method of the variable frequency condensing unit of the present invention includes: The direction of compressor frequency adjustment is determined based on the comparison between the target cooling temperature and the current cooling temperature. The compressor frequency adjustment speed is set according to the compressor's current frequency and the direction of frequency adjustment, specifically including: When the compressor's current frequency is within the high-efficiency performance frequency range, regardless of whether the adjustment direction is to increase or decrease the frequency, the compressor's frequency is adjusted slowly at the set first adjustment speed in order to extend the compressor's operating time in the high-efficiency performance frequency range. When the compressor frequency is adjusted towards the high-efficiency performance frequency range, and the compressor's current frequency is not within the high-efficiency performance frequency range, the compressor frequency is quickly adjusted at a set second adjustment speed, wherein the second adjustment speed is greater than the first adjustment speed (for example, the first adjustment speed can be set to 1Hz / s, and the second adjustment speed can be set to 3Hz / s). By quickly adjusting the compressor frequency, the compressor can enter the high-efficiency performance frequency range in the shortest time, reducing the running time in the low-efficiency range.

[0038] This invention dynamically adjusts the frequency change rate based on the current compressor frequency range and adjustment direction, thereby achieving precise control over the compressor's operating frequency. When the compressor is in the high-efficiency performance frequency range, a slow adjustment is used to extend the compressor's operating time in the high-efficiency performance frequency range; when the compressor is in the low-efficiency range and the adjustment direction is close to the high-efficiency performance frequency range, a fast adjustment is used to shorten the compressor's operating time in the low-efficiency range, thereby maximizing the duration of the compressor in the high-efficiency operation phase and reducing the duration of the high-energy-consumption operation phase.

[0039] like Figure 3 As shown, in some preferred embodiments of the present invention, setting the compressor frequency adjustment speed according to the current compressor frequency and the compressor frequency adjustment direction further includes: When the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the compressor frequency adjustment direction is far away from the compressor's high-efficiency performance frequency range, the compressor frequency is kept unchanged for a set period of time, and then it is determined whether the current cooling temperature meets the requirements. If yes, the compressor frequency is kept unchanged; otherwise, the compressor frequency is slowly adjusted at a set third adjustment speed, wherein the third adjustment speed is less than the second adjustment speed.

[0040] When the compressor is in the low-efficiency zone and the adjustment direction is far from the high-efficiency performance frequency range, this invention first maintains the compressor frequency unchanged for a set period of time before judging whether the current cooling temperature meets the requirements. If the temperature requirements cannot be met, the frequency is slowly adjusted to keep the compressor operating frequency near the high-efficiency performance frequency range as much as possible, thus avoiding blind adjustment that leads to high energy consumption.

[0041] like Figure 4 As shown, in some other embodiments of the present invention, setting the compressor frequency adjustment speed according to the current compressor frequency and the compressor frequency adjustment direction further includes: When the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the compressor frequency adjustment direction is far from the compressor's high-efficiency performance frequency range, the compressor frequency is directly adjusted slowly at the set third adjustment speed, wherein the third adjustment speed is less than the second adjustment speed.

[0042] At this point, there is no need to maintain the current frequency. Instead, the compressor frequency can be adjusted slowly to speed up the frequency adjustment and meet the temperature control requirements more quickly.

[0043] It should be noted that the third adjustment speed is less than the second adjustment speed. The third adjustment speed can be greater than the first adjustment speed, equal to the first adjustment speed, or less than the first adjustment speed. The present invention does not impose any restrictions on this.

[0044] In some preferred embodiments of the present invention, the third adjustment speed is less than the first adjustment speed. Because the adjustment method of the present invention leads to increasingly lower compressor efficiency when the compressor is in the low-efficiency zone and the adjustment direction is far from the high-efficiency performance frequency range, a slower third adjustment speed is used to slowly adjust the frequency. This ensures that when the temperature control target is achieved, the distance between the compressor operating frequency and the high-efficiency performance frequency range is as close as possible, maintaining higher energy efficiency and avoiding unnecessary energy consumption due to excessive adjustment.

[0045] like Figure 3 As shown, in the variable frequency condensing unit compressor variable frequency control method of the present invention, before setting the compressor frequency adjustment speed according to the current compressor frequency and the compressor frequency adjustment direction, it further includes: The high-efficiency performance frequency range of the compressor is obtained based on the operating conditions of the variable frequency condensing unit.

[0046] This invention pre-tests the performance of the variable frequency condensing unit under various operating conditions to obtain the high-efficiency performance frequency range under various operating conditions, forming a mapping table between operating conditions and high-efficiency performance frequency ranges, which facilitates obtaining the optimal performance frequency range of the compressor based on the current operating conditions of the compressor.

[0047] Specifically, this invention, based on the measured calibration performance curve of the compressor, calibrates two fixed frequency points: the lower limit of the peak frequency for high-efficiency performance, f_opt_min, and the upper limit of the peak frequency for high-efficiency performance, f_opt_max, to form a continuous high-efficiency operating range. Figure 1 As shown, it perfectly matches the actual performance characteristics of the compressor, which increases and then decreases in high-efficiency performance, thus solving the problem of easy fluctuation in single-point frequency and deviation from the high-efficiency performance frequency range.

[0048] In this embodiment of the invention, the high-efficiency performance frequency range of the compressor is obtained based on the compressor's operating conditions. The specific values ​​of the high-efficiency performance frequency range vary depending on the compressor model and operating conditions. The high-efficiency performance frequency range can be determined experimentally or based on the compressor's performance curve. Specifically, the coefficient of performance (COP) of the compressor at different operating frequencies can be tested within the rated operating range, and the continuous frequency range corresponding to the peak COP level is determined as the high-efficiency performance frequency range.

[0049] Specifically, in some embodiments of the present invention, the operating conditions of the variable frequency condensing unit include the condensing temperature and the evaporating temperature of the variable frequency condensing unit.

[0050] Since the condensing and evaporating temperatures of the variable frequency condensing unit are usually constant when it is not individually set, and they affect the target cooling temperature together with the operating frequency of the compressor, in this embodiment of the invention, the operating conditions of the variable frequency condensing unit are set to the condensing and evaporating temperatures of the variable frequency condensing unit.

[0051] like Figure 5 As shown, the high-efficiency performance frequency range of the compressor is obtained based on the operating conditions of the variable frequency condensing unit, including: The system searches a pre-established mapping table based on the compressor's operating conditions to determine if a matching operating condition exists. If there is an operating condition that matches the current operating condition of the compressor, then the high-efficiency performance frequency range corresponding to it shall be used as the high-efficiency performance frequency range of the current compressor. If no matching operating condition exists, the two closest operating conditions above and below the current operating condition and their corresponding high-efficiency performance frequency ranges are obtained. The upper and lower limits of the two obtained high-efficiency performance frequency ranges are linearly interpolated to obtain the upper and lower limits of the high-efficiency performance frequency range of the current compressor.

[0052] Because it's impossible to exhaustively represent every operating condition when creating a mapping table between operating conditions and high-efficiency performance frequency ranges through sampling, and because the parameters corresponding to operating conditions may change with environmental variations during the operation of the variable frequency condensing chiller, the following method is used: If no matching operating condition exists during the search, the two closest operating conditions above and below the current operating condition and their corresponding high-efficiency performance frequency ranges are obtained. Linear interpolation is then used to calculate the high-efficiency performance frequency range of the current compressor, thus providing a relatively accurate estimate of its corresponding high-efficiency performance frequency range even when no matching operating condition exists.

[0053] The following example illustrates how linear interpolation can be used to calculate the high-efficiency frequency range of the current compressor: Laboratory calibration. In the laboratory, the evaporation temperature Te = 25℃ was kept constant.

[0054] Test condition A (Tc=30℃): The frequency range corresponding to the peak plateau of the COP curve was measured to be 40Hz~55Hz. Record: f_opt_min=40Hz, f_opt_max=55Hz.

[0055] Test condition B (Tc=35℃): The frequency range corresponding to the peak plateau of the COP curve was measured to be 45Hz~62Hz. Record: f_opt_min=45Hz, f_opt_max=62Hz.

[0056] Dynamic linear interpolation during operation: If, during actual operation, the sensor measures Te = 25℃, while the condensing temperature changes to Tc = 32℃ (between 30 and 35℃) due to fluctuations in external wind speed, the following interpolation calculation is performed: f_opt_min_now=40+[(32-30) / (35-30)]×(45-40)=42Hz; f_opt_max_now=55+[(32-30) / (35-30)]×(62-55)=57.8Hz≈58Hz.

[0057] Ultimately, the system successfully and dynamically obtained the high-efficiency performance frequency range for the current operating condition as [42Hz, 58Hz].

[0058] like Figure 6 As shown, determining the direction of compressor frequency adjustment based on the target cooling temperature and the current cooling temperature includes: If the current cooling temperature is higher than the target cooling temperature, then the direction of compressor frequency adjustment is determined to be the direction of frequency increase; If the current cooling temperature is lower than the target cooling temperature, then the direction of compressor frequency adjustment is determined to be the direction of frequency reduction; If the current cooling temperature is equal to the target cooling temperature, then the compressor frequency remains unchanged.

[0059] It is understandable that since the compressor's frequency determines its cooling capacity, if the current cooling temperature is higher than the target cooling temperature, the compressor frequency is adjusted to increase; if the current cooling temperature is lower than the target cooling temperature, the compressor frequency is adjusted to decrease. Different adjustment methods are used for the compressor frequency based on the different adjustment directions and the current frequency range it falls within.

[0060] The following is combined Figure 7 The control method for adjusting the compressor frequency in the direction of frequency increase is explained.

[0061] The frequency upshifting trigger condition is: the current refrigeration temperature T_now is higher than the target refrigeration temperature T_set, and the compressor has no fault and is in normal operation. The compressor controller first determines the interval where the current frequency f_now is located, then executes the frequency upshifting action at a corresponding rate. The frequency interval is taken as the core judgment basis throughout the whole process, and the current refrigeration temperature only serves as an auxiliary correction condition. It should be noted that frequency upshifting will inevitably lead to an increase in the power of the compressor and increase the energy consumption of the compressor. The purpose of the present invention is to reduce the energy consumption of the compressor as much as possible while meeting the target refrigeration temperature T_set set by the user, and the control logic is to enable the compressor to operate in the high-efficiency performance frequency interval for as long as possible.

[0062] When the current frequency is lower than the lower limit frequency of the high-efficiency performance frequency interval (f_now<f_opt_min), the compressor controller determines that the compressor is in a low-frequency and low-efficiency operation state, and the core control objective is to enter the COP high-efficiency performance frequency interval in the shortest time. At this time, the influence of the temperature difference on the rate is shielded, and frequency upshifting is directly performed at the fast frequency upshifting rate V_rise_fast. The compressor frequency is increased at a fixed rate in each control cycle, and no delay or attenuation processing is performed. The current frequency change is monitored in real time. When f_now reaches f_opt_min, the control logic is switched immediately to enter the high-efficiency performance frequency interval control, so as to minimize the operation time of the compressor in the low-efficiency frequency band.

[0063] When the current frequency is in the high-efficiency performance frequency interval (f_opt_min≤f_now≤f_opt_max), the compressor controller determines that the compressor enters the COP optimal operation state, and the core control objective is to stably operate in the optimal frequency band and avoid frequency overshoot. The frequency upshifting rate is switched to the slow frequency upshifting rate V_rise_slow, the frequency is increased by a small amplitude in each control cycle, and the frequency adjustment amplitude is reduced to avoid quickly exceeding the upper limit of the peak value. Meanwhile, the change of the current refrigeration temperature is monitored in real time: if the current refrigeration temperature gradually approaches the target value, the frequency upshifting is suspended immediately, and the operation is maintained at the current frequency; if the current refrigeration temperature is still higher than the target value, the frequency upshifting continues at the slow rate until f_now reaches f_opt_max, and then the control is switched to high-frequency frequency limiting control. In this stage, through slow adjustment, the operation duration of the compressor in the high-efficiency performance frequency interval is prolonged, which ensures optimal energy efficiency and improves the stability of temperature control.

[0064] When the current frequency is higher than the upper limit of the high-efficiency performance frequency range (f_now > f_opt_max), the compressor controller determines that the compressor has entered a high-frequency, high-energy-consumption operating state. Theoretically, the compressor's power is already high and the cooling capacity is sufficient, and it should be able to quickly meet the user's target cooling temperature. The core control objective is energy saving priority, with passive frequency compensation. Active frequency increase is immediately stopped, the current frequency is maintained, and a timer is started, t_count is reset to zero, and accumulation begins. Each control cycle synchronously monitors the current cooling temperature and the timer duration. If the timer has not reached t_limit and the current cooling temperature has reached the target, the frequency is maintained, and no frequency increase is performed. If the timer reaches t_limit and the current cooling temperature still has not reached the target, it indicates that the user-set target cooling temperature is likely too low, and the compressor cannot generate enough cooling capacity at the current frequency to achieve the target cooling temperature. Therefore, the frequency limit needs to be lifted, and the frequency is increased slightly at a slow rate. After the frequency increase, the frequency range is re-evaluated. If the current cooling temperature meets the target, frequency maintenance is immediately resumed. In this stage, the control logic avoids blindly increasing the frequency. The frequency is only passively increased when the temperature control requirements cannot be met. This minimizes the high-frequency and high-energy-consumption operating time and keeps the compressor's operating frequency as far away from the high-frequency and high-energy-consumption range as possible.

[0065] The following is combined Figure 8 The control method for adjusting the compressor frequency in the direction of frequency reduction is explained.

[0066] The frequency reduction trigger condition is: the current cooling temperature T_now is lower than or equal to the target cooling temperature T_set, and the cooling load is reduced. The frequency reduction phase employs control logic that is completely symmetrical to the frequency increase phase, maintaining consistency in energy efficiency optimization across the entire frequency band. The compressor controller first determines the range of the current frequency f_now, and then executes the corresponding rate of frequency increase. Throughout the process, the frequency range is the core determination criterion, with the current cooling temperature only serving as an auxiliary correction condition.

[0067] When the current frequency is higher than the upper limit of the high-efficiency performance frequency range (f_now > f_opt_max), the compressor controller determines that the compressor is in a high-frequency, high-energy-consumption state, and the core control objective is to quickly return to the high-efficiency performance frequency range. Frequency reduction is performed at a rapid frequency reduction rate V_drop_fast, significantly reducing the frequency each control cycle to quickly exit the high-energy-consumption range. Frequency changes are monitored in real time, and when f_now drops to f_opt_max, the controller switches to high-efficiency performance frequency range frequency reduction control.

[0068] When the current frequency is in the high-efficiency performance frequency range (f_opt_min≤f_now≤f_opt_max), the compressor controller determines that the compressor is in an optimal operating state, and the core control objective is to slowly reduce the frequency to prolong the high-efficiency operation. The compressor is switched to the slow frequency reduction rate V_drop_slow to reduce the frequency by a small margin, so as to avoid quickly exiting the high-efficiency performance frequency range. The current refrigeration temperature is monitored synchronously: if the current refrigeration temperature is stably up to the standard, the frequency reduction is continued at the slow rate; if the current refrigeration temperature shows a rising trend, the frequency reduction is suspended immediately, and the current frequency is maintained to prevent the current refrigeration temperature from rebounding caused by insufficient refrigeration capacity. When f_now drops to f_opt_min, the control is switched to low-frequency stop-of-decrease control.

[0069] When the current frequency is lower than the lower limit frequency of the high-efficiency performance frequency range (f_now<f_opt_min), the compressor controller determines that the compressor enters a low-frequency and low-efficiency state, and the core control objective is to prevent the current refrigeration temperature from rebounding caused by excessive frequency reduction. Active frequency reduction is stopped immediately, the current frequency is maintained for a period of time, and the change of the current refrigeration temperature is continuously monitored. If the current refrigeration temperature is continuously low, the frequency is reduced by a small margin at the slow rate, so as to prevent insufficient refrigeration capacity caused by excessive frequency reduction, avoid re-triggering high-frequency frequency increase and forming a frequency reduction-frequency increase control cycle that causes electric power waste.

[0070] In the variable frequency control method for a compressor of a variable frequency condensing unit of the present invention, the adjustment direction of the compressor frequency is determined through the target refrigeration temperature and the current refrigeration temperature, it is determined whether the compressor needs frequency increase or frequency reduction, and then the frequency is adjusted by adopting the set speed regulation logic, which realizes energy efficiency optimization in the whole frequency band without any control blind area, and effectively reduces the operating energy consumption of the condensing unit.

[0071] The present invention also provides a computer-readable storage medium, which stores a computer program, and when the computer program is executed by a processor, the above-mentioned variable frequency control method for a compressor of a variable frequency condensing unit is implemented.

[0072] Please refer to Figure 2 , the present invention also provides a variable frequency condensing unit, comprising: a variable frequency compressor; an operating parameter detection module, configured to detect operating parameters of the variable frequency unit; a compressor controller, configured to control the operating frequency of the compressor according to the operating parameters of the variable frequency unit and parameters set by a user, wherein when controlling the operating frequency of the compressor, the compressor controller executes the above-mentioned variable frequency control method for a compressor of a variable frequency condensing unit.

[0073] The present invention also provides a computer-readable storage medium, the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned variable frequency control method for a compressor of a variable frequency condensing unit is implemented.

[0074] In summary, the technical solution of the present invention has at least one of the following advantages: 1. By dividing the compressor frequency into three regions—the high-efficiency performance frequency range, the lower high-efficiency performance frequency range, and the higher high-efficiency performance frequency range—and dynamically adjusting the frequency change rate according to the current frequency region and adjustment direction, fine-grained control of the compressor's operating frequency is achieved.

[0075] 2. When the compressor is in the high-efficiency frequency range, slow adjustment is used to extend the compressor's operating time in the high-efficiency frequency range; when the compressor is in the low-efficiency range and the adjustment direction is close to the high-efficiency frequency range, fast adjustment is used to shorten the compressor's operating time in the low-efficiency range; when the compressor is in the low-efficiency range and the adjustment direction is far from the high-efficiency frequency range, blind adjustment is avoided by delay judgment and slow frequency adjustment; through the above frequency adjustment methods, the compressor's operating frequency is kept as close as possible to the high-efficiency frequency range, thereby reducing the compressor's energy consumption. The variable frequency condensing unit and its compressor variable frequency control method of the present invention can be applied to energy-saving air conditioners to improve the energy efficiency of air conditioners.

[0076] It should be noted that the terminology used above is for describing specific embodiments only and is not intended to limit the exemplary embodiments of the present invention. When the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof. The order of execution of actions, steps, etc., in the apparatus and methods shown in the specification and drawings may be implemented in any order unless a specific express order is specified, and as long as the output of a previous process is not used in a subsequent process. Similar sequential terms used for ease of description do not imply that such an order must be followed.

[0077] Techniques, methods, and apparatus known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as constraints. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A variable frequency control method for a compressor in a variable frequency condensing unit, characterized in that, include: The direction of compressor frequency adjustment is determined based on the target cooling temperature and the current cooling temperature; The compressor frequency adjustment speed is set according to the compressor's current frequency and the direction of frequency adjustment. If the compressor's current frequency is within the compressor's high-efficiency performance frequency range, then the compressor's frequency is adjusted at the set first adjustment speed; If the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the compressor frequency adjustment direction is closer to the compressor's high-efficiency performance frequency range, then the compressor frequency is adjusted at a set second adjustment speed, wherein the second adjustment speed is higher than the first adjustment speed.

2. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 1, characterized in that, The compressor frequency adjustment speed is set according to the compressor's current frequency and the direction of frequency adjustment, and also includes: If the compressor's current frequency is not within the compressor's high-efficiency performance frequency range and the compressor frequency adjustment direction is far from the compressor's high-efficiency performance frequency range, then the compressor frequency is kept unchanged for a set period of time before judging whether the current cooling temperature meets the requirements. If yes, the compressor frequency is kept unchanged; otherwise, the compressor frequency is adjusted at a set third adjustment speed, wherein the third adjustment speed is lower than the second adjustment speed.

3. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 1, characterized in that, The compressor frequency adjustment speed is set according to the compressor's current frequency and the direction of frequency adjustment, and also includes: If the current frequency of the compressor is not within the high-efficiency performance frequency range of the compressor and the adjustment direction of the compressor frequency is far away from the high-efficiency performance frequency range of the compressor, the frequency of the compressor is adjusted at a set third adjustment speed, wherein the third adjustment speed is lower than the second adjustment speed.

4. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 2 or 3, characterized in that, The third adjustment speed is lower than the first adjustment speed.

5. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 1, characterized in that, Also includes: The high-efficiency performance frequency range of the compressor is obtained based on the operating conditions of the variable frequency condensing unit.

6. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 5, characterized in that, The high-efficiency performance frequency range of the compressor is obtained based on the operating conditions of the variable frequency condensing unit, including: The system searches a pre-established mapping table based on the compressor's operating conditions to determine if a matching operating condition exists. If there is an operating condition that matches the current operating condition of the compressor, then the high-efficiency performance frequency range corresponding to it shall be used as the high-efficiency performance frequency range of the current compressor. If no matching operating condition exists, the two closest operating conditions above and below the current operating condition and their corresponding high-efficiency performance frequency ranges are obtained. The upper and lower limits of the two obtained high-efficiency performance frequency ranges are linearly interpolated to obtain the upper and lower limits of the high-efficiency performance frequency range of the current compressor.

7. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 5 or 6, characterized in that, The operating conditions of a variable frequency condensing unit include its condensing temperature and evaporation temperature.

8. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 2, characterized in that, The step of determining the direction of compressor frequency adjustment based on the target cooling temperature and the current cooling temperature includes: If the current cooling temperature is higher than the target cooling temperature, then the direction of compressor frequency adjustment is determined to be the direction of frequency increase; If the current cooling temperature is lower than the target cooling temperature, then the direction of compressor frequency adjustment is determined to be the direction of frequency reduction; If the current cooling temperature is equal to the target cooling temperature, then the compressor frequency remains unchanged.

9. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 8, characterized in that, If the compressor frequency is adjusted in the direction of increasing frequency, then: When the current frequency of the compressor is lower than the lower limit of the high-efficiency performance frequency range, the frequency of the compressor is increased at the second adjustment speed until the current frequency of the compressor reaches the lower limit of the high-efficiency performance frequency range. When the compressor's current frequency is within the high-efficiency performance frequency range, the compressor's frequency is adjusted by increasing the frequency at the first adjustment speed. When the compressor's current frequency is higher than the upper limit of the high-efficiency performance frequency range, the frequency increase is stopped and the compressor's frequency is kept constant for a set period of time. Then, the current cooling temperature is monitored to see if it meets the requirements. If it does, the compressor's frequency is kept constant; otherwise, the compressor's frequency is increased at the third adjustment speed.

10. The compressor frequency conversion control method for a frequency conversion condensing unit according to claim 8, characterized in that, If the compressor frequency is adjusted in the direction of frequency reduction, then: When the current frequency of the compressor is higher than the upper limit of the high-efficiency performance frequency range, the frequency of the compressor is adjusted to be reduced at the second adjustment speed until the current frequency of the compressor is reduced to the upper limit of the high-efficiency performance frequency range. When the compressor's current frequency is within the high-efficiency performance frequency range, the compressor's frequency is adjusted by reducing the frequency at the first adjustment speed; When the compressor's current frequency is lower than the lower limit of the high-efficiency performance frequency range, the frequency reduction is stopped and the compressor's frequency is kept constant for a set period of time. Then, the current cooling temperature is monitored to see if it meets the requirements. If it does, the compressor's frequency is kept constant; otherwise, the compressor's frequency is reduced at the third adjustment speed.

11. A computer-readable storage medium, characterized in that, The system contains a computer program that, when executed by a processor, implements the compressor frequency conversion control method for a frequency conversion condensing unit as described in any one of claims 1 to 10.

12. A variable frequency condensing chiller unit, characterized in that, include: Variable frequency compressor; The operating parameter detection module is used to detect the operating parameters of the variable frequency unit; A compressor controller is used to control the operating frequency of the compressor according to the operating parameters of the variable frequency unit and the parameters set by the user. When controlling the operating frequency of the compressor, the compressor controller executes the compressor variable frequency control method of the variable frequency condensing unit as described in any one of claims 1 to 10.

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