Refrigerating unit for refrigerated container

Abstract

The invention discloses a refrigerating unit for a refrigerated container, and the refrigerating unit comprises a power module which is provided with a first power supply channel and a second power supply channel which are independent; the first refrigerating system is provided with a first refrigerant circulation loop, so that a refrigerant circulates in a loop composed of a first compressor, a first condenser, a first electronic expansion valve and a first evaporator, and a first power supply channel provides single-phase power for the first refrigerating system; the second power supply channel provides single-phase power for the second refrigerating system; and the controller controls the first refrigerating system and the second refrigerating system through double independent signal channels respectively, so that the first refrigerating system and the second refrigerating system work in an alternate refrigerating mode, a collaborative refrigerating mode or a quick cooling mode. By arranging the double-refrigeration-system single-phase electric refrigeration unit, three modes of alternate refrigeration, collaborative refrigeration and quick refrigeration are supported, and different refrigeration requirements in various different scenes are met.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology for refrigerated containers, and more specifically to a refrigeration unit for refrigerated containers. Background Technology

[0002] Currently, traditional sea / land transport units for refrigerated containers mostly use three-phase 380 / 460V power supplies, which cannot be adapted to the single-phase 220-240V voltage standard for North American household use. This limits their application in scenarios such as static warehousing and restricts the development of the household market for specialized refrigerated containers. Existing single-phase electric refrigeration units have two core defects: one is a single system, which achieves a simple one-in-one-backup dual system. While it can meet the fault isolation requirements of physical separation, it lacks a collaborative operation design and cannot meet the requirements of extremely low temperatures / rapid cooling. The other is a dual system that is not physically separated, sharing core components such as the liquid receiver. Failures are easily interconnected, making it difficult to guarantee the reliability of system application. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a refrigeration unit for refrigerated containers. By setting up a dual-refrigeration system single-phase electric refrigeration unit, it supports three major modes: alternating refrigeration, coordinated refrigeration, and rapid cooling, adapting to different refrigeration needs in various scenarios.

[0004] To achieve the above-mentioned objectives, the present invention employs the following technical solution: This application relates to a refrigeration unit for refrigerated containers, comprising: The power module has an independent first power supply channel and a second power supply channel; The first refrigeration system has a first refrigerant circulation loop, which allows the refrigerant to circulate in a loop consisting of a first compressor, a first condenser, a first electronic expansion valve, and a first evaporator. The first power supply channel provides single-phase power to the first refrigeration system. The second refrigeration system has a second refrigerant circulation loop, which allows the refrigerant to circulate in a loop consisting of a second compressor, a second condenser, a second electronic expansion valve, and a second evaporator. The second power supply channel provides single-phase power to the second refrigeration system. The controller controls the first and second refrigeration systems respectively through two independent signal channels, enabling them to operate in a rotating refrigeration mode, a coordinated refrigeration mode, or a rapid cooling mode. In the rotating cooling mode, the first cooling system and the second cooling system are controlled to take turns cooling. By monitoring the difference between the temperature inside the box and the target temperature inside the box, the system controls whether to switch to the collaborative cooling mode or the rapid cooling mode. In the coordinated cooling mode, after the initial start of one cooling system, the other cooling system starts. While both cooling systems are running, the total current output by the power module is stabilized by adjusting the corresponding frequencies of the first and second compressors. When the absolute value of the difference between the first current on the first power supply channel and the second current on the second power supply channel reaches a preset current difference limit, the opening of the first and second electronic expansion valves is adjusted to balance the cooling output between the two cooling systems. The system controls whether to switch to the rotating cooling mode by monitoring the difference between the internal temperature and the target internal temperature. In the rapid cooling mode, after the first refrigeration system starts at full load for a second time, the other refrigeration system starts at full load. While both refrigeration systems are running, the total current output by the power module is stabilized by controlling the corresponding frequencies of the first and second compressors. The system controls whether to switch to the rotating cooling mode by monitoring the temperature inside the chamber or the running time.

[0005] In some embodiments of this application, the controller sets a first trigger condition for triggering the rotating cooling mode, a second trigger condition for triggering the coordinated cooling mode, and a third trigger condition for triggering the rapid cooling mode; When the first triggering condition is met, the controller controls the refrigeration unit to enter the rotating refrigeration mode; When the second triggering condition is met, the controller controls the refrigeration unit to enter the collaborative refrigeration mode; When the third triggering condition is met, the controller controls the refrigeration unit to enter the rapid cooling mode.

[0006] In some embodiments of this application, when entering the rotating cooling mode, the system first rotates according to the default rotation and monitors the difference in runtime and loss between the two cooling systems in real time. When the loss difference does not reach the first loss threshold and the runtime difference does not reach the first time threshold, the first refrigeration system and the second refrigeration system take turns refrigerating to maintain the default rotation value. Otherwise, the rotation value is adaptively adjusted according to the load. When the load is large, the rotation value is reduced based on the default rotation value, and when the load is small, the rotation value is increased based on the default rotation value.

[0007] In some embodiments of this application, a first fault monitoring process is performed during the rotating cooling mode; During the first fault monitoring process, if any refrigeration system has a minor fault that can be self-healed by reducing the load or adjusting the opening of the corresponding electronic expansion valve, the load of the refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted, and the remaining refrigeration system remains in its current operating state. If any refrigeration system has a major fault other than a minor fault, the refrigeration system is shut down and the other refrigeration system is started at the same time.

[0008] In some embodiments of this application, in the coordinated cooling mode, the total current output by the power module is stabilized by adjusting the corresponding frequencies of the first compressor and the second compressor, specifically as follows: Detect the first current output by the first power supply channel and the second current output by the second power supply channel; Calculate the sum of the first current and the second current as the total output current of the power module; Using a PID algorithm, the current difference between a preset current limiting threshold and the total current is used as the deviation to control the output compressor frequency adjustment amount, which is used to adjust the frequency of the first compressor and the frequency of the second compressor respectively.

[0009] In some embodiments of this application, a second fault monitoring process is performed during the collaborative cooling mode; During the second fault monitoring process, if any refrigeration system has a minor fault that can be self-healed by reducing the load or adjusting the opening of the corresponding electronic expansion valve, the load of the refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted, and the remaining refrigeration system remains in its current operating state. If any refrigeration system has a major fault other than a minor fault, the refrigeration system is shut down, and another refrigeration system is started at full load at the same time.

[0010] In some embodiments of this application, in the rapid cooling mode, the total current output by the power module is stabilized by controlling the corresponding frequencies of the first compressor and the second compressor, specifically as follows: Detect the first current output by the first power supply channel and the second current output by the second power supply channel; Calculate the sum of the first current and the second current as the total output current of the power module; Using a PID algorithm, the current difference between a preset current limiting threshold and the total current is used as the deviation to control the output compressor frequency adjustment amount, which is used to adjust the frequency of the first compressor and the frequency of the second compressor respectively.

[0011] In some embodiments of this application, a third fault monitoring process is performed during the rapid cooling mode; During the third fault monitoring process, if any refrigeration system has a minor fault that can be self-healed by reducing the load or adjusting the opening of the corresponding electronic expansion valve, the load of the refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted, and the remaining refrigeration system remains in its current operating state. If any refrigeration system has a major fault other than a minor fault, the refrigeration system is shut down, and another refrigeration system is started at full load at the same time.

[0012] In some embodiments of this application, after the fault of a refrigeration system with a severe fault is repaired, it is started and run at a low load for a certain period of time, and then the operation of the two refrigeration systems is controlled according to the current operating mode.

[0013] In some embodiments of this application, the refrigeration unit of the refrigerated container further includes: A fixed frame is connected to the body of a refrigerated container through mounting holes. The refrigeration unit is embedded and installed at one end port of the refrigerated container. A sealing part is provided on the part of the fixed frame that is directly opposite the circumferential edge of the port. The fixed frame has fixed plates and frame openings arranged vertically. The heat-insulating inner liner is installed at the frame opening and has a refrigeration system installation space. All components of the two refrigeration systems, except for the first evaporator, the second evaporator, and the evaporation fan, are installed in the refrigeration system installation space. The position above the heat-insulating inner liner corresponding to the fixed plate forms the evaporation system installation space. The first evaporator, the second evaporator, and the evaporation fan are all installed in the evaporation system installation space. The evaporation fan is used to blow the airflow flowing through the first evaporator and / or the second evaporator into the housing.

[0014] The refrigeration unit for refrigerated containers provided by this invention has the following advantages and beneficial effects: (1) The refrigeration unit can provide single-phase electricity to meet the needs of households in North America; (2) Provides dual refrigeration systems with three modes: alternating refrigeration, coordinated refrigeration and rapid cooling. The alternating refrigeration mode is used for medium and low temperature cold storage needs with small refrigeration requirements, the coordinated refrigeration mode is used for rapid cooling and ultra-low temperature freezing scenarios, and the rapid cooling mode is used for emergency rapid cooling needs, meeting different usage needs in multiple scenarios. (3) During the operation of the collaborative cooling mode and the rapid cooling mode, while meeting the needs of rapid cooling / ultra-low temperature freezing and emergency rapid cooling, the total current is controlled to avoid single-phase current exceeding the limit, and the reliability of the refrigeration unit and the adaptability of the scenario are taken into account. (4) In the collaborative cooling mode, while responding to the cooling demand, the total current is stabilized and the cooling output of the two cooling systems is balanced to ensure uniform cooling inside the box and achieve precise temperature control.

[0015] Other features and advantages of the present invention will become clearer after reading the detailed embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This invention illustrates the principle of switching between rotating refrigeration mode, coordinated refrigeration mode, and rapid cooling mode in the refrigeration unit for refrigerated containers. Figure 2 A flowchart illustrating the operation of the rotating refrigeration mode in the refrigeration unit for refrigerated containers proposed in this invention is shown. Figure 3 A flowchart illustrating the collaborative refrigeration mode operation in the refrigeration unit for refrigerated containers proposed in this invention is shown. Figure 4 The flowchart illustrates the operation of the refrigeration unit for refrigerated containers in medium-speed cooling mode as proposed in this invention. Figure 5 The structure of the refrigeration unit for refrigerated containers proposed in this invention is shown. Figure 1 ; Figure 6 This invention illustrates the structure of a refrigeration unit for refrigerated containers. Figure 1 The dual refrigeration system is not shown. Figure 7 The structure of the refrigeration unit for refrigerated containers proposed in this invention is shown. Figure 2 ; Figure label: 100. Fixed frame; 110. Frame opening; 120. Fixed plate; 200. Insulated inner liner; 210. Refrigeration system installation space; 300. Evaporation system installation space; 400. Sealing part; 500. Electrical control box. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "inner," and "outer," which indicate directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0020] In order to balance the refrigeration reliability, efficiency and adaptability to multiple scenarios of refrigerated containers, this application relates to a refrigeration unit for refrigerated containers, which includes a power module (not shown), a dual refrigeration system (not labeled) and a controller (not shown).

[0021] This refrigeration unit can achieve three modes: rotating refrigeration, coordinated refrigeration, and rapid cooling. The rotating refrigeration mode refers to the dual refrigeration systems being used alternately, which is suitable for medium and low temperature refrigeration needs with small refrigeration capacity. The coordinated refrigeration mode refers to the dual refrigeration systems operating in tandem, which is suitable for rapid cooling and extremely low temperature freezing needs. The rapid cooling mode refers to the dual refrigeration systems starting at full load, which is suitable for emergency rapid cooling needs.

[0022] The power module is used to provide power to the refrigeration unit. In some embodiments of this application, the power module has a built-in single-phase AC-DC conversion circuit, which is compatible with single-phase household electricity (220-240V, 60Hz) in North America, such as the United States, and is equipped with a US standard 30A four-hole plug.

[0023] The power module integrates two independent power supply channels: a first power supply channel and a second power supply channel. The first power supply channel and the second power supply channel provide single-phase power to a refrigeration system respectively. In the dual refrigeration system collaborative refrigeration mode and rapid cooling mode, the current of the first power supply channel and the second power supply channel are dynamically allocated to avoid the current superposition exceeding the limit when running at the same time.

[0024] The power module also features a soft-start buffer circuit, which gradually increases the single-system startup voltage from, for example, 30% to 100% in both coordinated cooling and rapid cooling modes, preventing tripping caused by inrush current and ensuring power supply reliability. Furthermore, the power module incorporates a wide-range adaptive voltage regulator circuit, employing PWM pulse width modulation to ensure stable single-phase power supply.

[0025] The dual refrigeration system includes an independent first refrigeration system and a second refrigeration system. The first refrigeration system has a first refrigerant circulation loop, which allows the refrigerant to circulate in a loop composed of a first compressor, a first condenser, a first electronic expansion valve, and a first evaporator. The second refrigeration system has a second refrigerant circulation loop, which allows the refrigerant to circulate in a loop composed of a second compressor, a second condenser, a second electronic expansion valve, and a second evaporator.

[0026] The first and second refrigeration systems are arranged independently to achieve physical isolation, so that they do not interfere with each other in the event of a fault, thereby improving the reliability of the refrigeration unit.

[0027] In some embodiments of this application, the first compressor and the second compressor are both scroll compressors adapted to single-phase electricity, with anti-frequent start-up function (start-stop interval ≥ 1 minute), supporting short-term full-load operation in synergistic cooling mode and quick cooling mode, and adaptively adjusting according to rated load, for example, 30%~80%, in rotation mode.

[0028] The first and second condensers are each independently configured with their own corresponding condensing fans. In the coordinated cooling mode and the rapid cooling mode, the condensing fans automatically switch to the highest speed to improve heat dissipation efficiency.

[0029] In addition, each refrigeration system is equipped with an independent receiver (not shown) to avoid cross-contamination of refrigerants, and only the single system is affected in the event of a failure; each refrigeration system is also equipped with an independent dryer filter to filter refrigerant impurities and ensure the cleanliness of the refrigerant circulation loop of the single system.

[0030] The dual refrigeration systems share a controller, which controls the first and second refrigeration systems respectively through two independent signal channels, enabling mode switching and operation in the corresponding mode.

[0031] In some embodiments of this application, an ambient temperature sensor (not shown) is required to detect the ambient temperature T. env The internal temperature sensor (not shown) detects the internal temperature T. in A pressure sensor (not shown) for detecting high and low pressure in the refrigerant circulation loop; and a sensor for detecting the first current I in the first power supply channel for the first refrigeration system. A The current sensor (not shown) and the second current I in the second power supply channel for the second refrigeration system B A current sensor (not shown) and a magnetic door switch (not shown) arranged on the container door.

[0032] In some embodiments of this application, the controller can be arranged in the electrical control box 500 and equipped with a human-machine interface (not shown). Through the human-machine interface, a rotating button (not shown) can be set to trigger the rotating cooling mode, a collaborative button (not shown) can be set to trigger the collaborative cooling mode, and a rapid cooling button (not shown) can be set to trigger the rapid cooling mode. By manually pressing the corresponding button, the corresponding cooling mode can be manually triggered, thereby realizing manual mode switching.

[0033] When operating in the corresponding cooling mode, the fault alarm of the first or second cooling system can be displayed on the human-machine interface, and the fault type, system number and fault time can be recorded simultaneously.

[0034] The following describes the mode switching between the refrigeration unit's rotating refrigeration mode, coordinated refrigeration mode, and rapid cooling mode, as well as the operation process under each mode.

[0035] In some embodiments of this application, in addition to setting the button to trigger the corresponding mode as described above, see also... Figure 1 It also sets a first trigger condition for entering the rotating cooling mode, a second trigger condition for entering the collaborative cooling mode, and a third trigger condition for entering the rapid cooling mode. When the current condition meets the corresponding trigger condition, the corresponding cooling mode can be automatically triggered to achieve automatic mode switching.

[0036] The first, second, and third trigger conditions can be flexibly set according to user needs.

[0037] In some embodiments of this application, the first triggering condition can be selected as the target temperature T inside the chamber. ref ≥-10℉, ambient temperature T env ≤80℉, and there is no need for rapid cooling or refrigeration.

[0038] When the current conditions meet the first trigger condition, the system enters the rotating cooling mode.

[0039] Figure 2 The process of the rotating cooling mode is illustrated below, which will be combined with... Figure 2 This describes the process of the rotating cooling mode.

[0040] A default rotation time (e.g., 30 minutes) can be set, that is, the first cooling system starts running for 30 minutes and then stops, the second cooling system starts running, the second cooling system starts running for 30 minutes and then stops, the first cooling system starts running again, and so on, to ensure that only one cooling system is active at any given time.

[0041] In some embodiments of this application, in order to ensure the cooling effect in the rotating cooling mode, the rotation value is not always kept at the default value, but is adaptively adjusted according to the current operating status of the cooling system. Specifically, during the operation of the rotating cooling mode, the runtime difference ΔTime and the loss difference ΔP between the first cooling system and the second cooling system are monitored in real time, and the default rotation value is determined based on the runtime difference ΔTime and the loss difference ΔP.

[0042] The loss difference of the refrigeration system can be measured in a variety of ways, such as by using the load rate (i.e., the ratio of the average current to the rated current).

[0043] In some embodiments of this application, in the rotating cooling mode, a runtime difference threshold (e.g., 20 hours) and a loss difference threshold (e.g., 15%) are set for comparison with the real-time monitored runtime difference ΔTime and loss difference ΔP.

[0044] If △Time does not reach the runtime difference threshold (e.g., △Time≤20h) and △P does not reach the loss difference threshold (e.g., △P≤15%), it indicates that both cooling systems are running relatively smoothly. This means that it is appropriate to use the current default rotation value for rotation. Therefore, the current operation is maintained, and the default rotation value is still used.

[0045] When ΔTime reaches the runtime difference threshold (e.g., ΔTime > 20h) or ΔP reaches the loss difference threshold (e.g., ΔP > 15%), it indicates that the current dual refrigeration system is operating unevenly. In order to avoid damage to a refrigeration system with high loss or long operating time, the rotation value is adaptively adjusted according to the load. The adjusted rotation value is used to switch between the first refrigeration system and the second refrigeration system.

[0046] The principle for adjusting the rotation schedule is as follows: the rotation schedule for refrigeration systems with high loads is reduced from the default rotation schedule, for example, from 30 minutes to 20 minutes; the rotation schedule for refrigeration systems with low loads is increased from the default rotation schedule, for example, from 30 minutes to 40 minutes. In this way, different situations of different refrigeration systems can be matched to ensure the reliable operation of the refrigeration unit.

[0047] In some embodiments of this application, in the rotating cooling mode, the internal temperature T is monitored. in and the target temperature T inside the chamber ref The temperature difference ΔT between the two controls whether to switch to collaborative cooling mode or rapid cooling mode.

[0048] In the rotating cooling mode, a first temperature difference threshold (e.g., 13℉) is set for the temperature difference ΔT, which is then compared with the real-time monitored ΔT.

[0049] When the temperature difference ΔT meets the first threshold condition, which can be the upper limit of the first temperature difference threshold (e.g., ΔT≥14℉), it indicates that the current temperature inside the chamber is high and there is a need for rapid cooling, and the chamber will automatically switch to the collaborative cooling mode.

[0050] Alternatively, the first temperature difference threshold can be set to 15℉. When the temperature difference ΔT≥15℉, the conditions for triggering the collaborative cooling mode are met, and the mode will automatically enter collaborative cooling mode.

[0051] In some embodiments of this application, since the rapid cooling mode meets the need for quick freezing (e.g., of room temperature food), its triggering conditions are not directly related to the temperature difference ΔT. Therefore, monitoring the temperature difference ΔT cannot directly trigger the switch to rapid cooling mode. In the rotating cooling mode, manual switching to rapid cooling mode can be initiated by pressing the rapid cooling button to meet the need for quick freezing.

[0052] In some embodiments of this application, the second triggering condition described above can be selected as the target temperature T inside the chamber. ref ≤-20℉ (indicating a need for extremely low temperatures), or a temperature difference △T≥15℉ (indicating a need for rapid cooling).

[0053] When the current conditions meet the second trigger condition, enter the collaborative cooling mode.

[0054] Figure 3 The process of the collaborative cooling mode is illustrated below, which will combine... Figure 3 This describes the process of a collaborative cooling mode.

[0055] In the coordinated cooling mode, in order to avoid the current superposition caused by the two cooling systems during the initial start-up and thus exceed the limit, the first and second cooling systems are started off at off-peak times.

[0056] In some embodiments of this application, the staggered start-up time can be flexibly set. In the collaborative cooling mode, the staggered start-up time can be set to 30 seconds to 60 seconds.

[0057] When entering the collaborative cooling mode, one cooling system is initially started, for example, after 1 minute, and then the other cooling system is started.

[0058] During the operation of both refrigeration systems, the total current output of the power module is stabilized by controlling the corresponding frequencies of the first and second compressors to ensure that the current does not exceed the limit during coordinated operation. Furthermore, the refrigeration output between the two refrigeration systems is balanced by adjusting the opening of the first and second electronic expansion valves.

[0059] In some embodiments of this application, a PID algorithm is used to control the frequency adjustment of the first compressor and the second compressor.

[0060] In the collaborative cooling mode, the first current I is obtained. A Second current I B And calculate the total current I. total .

[0061] The PID algorithm uses the current deviation as the control variable and the output variable as the compressor frequency adjustment variable, which simultaneously adjusts the frequency f of the first compressor. A The frequency f of the second compressor B This enables current control to prevent it from exceeding limits.

[0062] In some embodiments of this application, the current limit I limit Determined based on the current limiting value of the American standard plug, for example, I limit =30A.

[0063] The formula for the PID algorithm is as follows: .

[0064] Wherein, the deviation e(t) = I limit -I total The output u(t) is the compressor frequency adjustment Δf, and the PID parameters include the proportional coefficient K. p Integral coefficient K i and differential coefficient K d .

[0065] Adjust f synchronously using △f A and f B That is, f A =f A +△f,f B =f B +△f.

[0066] In the process of using PID control to control the total current, integral saturation can be prevented by limiting the integral amplitude, and output amplitude can also be limited to ensure that a single frequency adjustment does not exceed a preset value, such as 5Hz, thus avoiding system oscillation.

[0067] During the operation of the coordinated cooling mode, while avoiding current over-limit and balancing the cooling output of the two cooling systems, in some embodiments of this application, based on the first current I... A Second current I B Control and adjust the opening S of the corresponding first electronic expansion valve A The opening degree S of the second electronic expansion valve B .

[0068] in|I A -I B | Reaching the preset current difference limit △I limit When the upper limit is reached, it indicates that the current difference is large. At this time, it is necessary to add a cooling balance compensation amount to balance the cooling output between the two cooling systems.

[0069] In some embodiments of this application, the cooling output is compensated by adjusting the opening degree of the electronic expansion valve.

[0070] That is, △S A =K bal *(I B -I A ); △S B =Kbal *(I A -I B ).

[0071] Use △S A and △S B Adjust S respectively A and S B That is, S A =S A +△S A S B =S B +△S B .

[0072] Using the adjusted S A and S B Verify whether |S A -S B | Reaching the preset opening difference limit value △S limit (For example, 15%) is the upper limit.

[0073] In |S A -S B | Reaching the preset opening difference limit value △S limit The lower limit value, for example, |S A -S B When the opening is ≤15%, complete the cooling balance compensation and no longer adjust the opening degree; otherwise, maintain the opening degree adjustment.

[0074] In some embodiments of this application, in the collaborative cooling mode, the internal temperature T is monitored. in and the target temperature T inside the chamber ref The temperature difference ΔT between the two controls whether to switch to the rotating cooling mode.

[0075] In the collaborative cooling mode, a second temperature difference threshold (e.g., 3℉) is set for the temperature difference ΔT to be compared with the real-time monitored ΔT.

[0076] When the temperature difference ΔT meets the second threshold condition, which can be the lower limit of the second temperature difference threshold (e.g., ΔT≤3℉), it indicates that the current temperature inside the chamber is already low, and the chamber switches to the rotating cooling mode.

[0077] After switching from collaborative cooling mode to rotating cooling mode, the default rotating value is read first, and then rotating control is performed.

[0078] In some embodiments of this application, since the rapid cooling mode meets the need for quick freezing (e.g., of room temperature food), its triggering conditions are not directly related to the temperature difference ΔT. Therefore, monitoring the temperature difference ΔT cannot directly trigger the switch to rapid cooling mode. In the coordinated cooling mode, users can manually switch to rapid cooling mode by pressing the rapid cooling button to meet the need for quick freezing.

[0079] In some embodiments of this application, in order to balance cooling demand and current stability in the collaborative cooling mode, multiple different temperature difference thresholds can be set for the temperature difference ΔT. For different temperature difference thresholds, the PID parameters of the PID algorithm can be set within that stage.

[0080] When entering the collaborative cooling mode, if ΔT meets the third threshold condition (which can be the upper limit of the third temperature difference threshold, e.g., ΔT > 5℉), the PID parameters are set to the first set of parameters, e.g., K. p =2.5, K i =0.15, K d =0.5, quickly responding to cooling needs while ensuring current stability.

[0081] If ΔT≤5℉, the PID parameters are set to the second set of parameters, for example, K. p =1.2, K i =0.1, K d =0.3, prioritizes stabilizing the current and precisely controlling the temperature.

[0082] In some embodiments of this application, the third triggering condition as described above can be selected as the chamber temperature T. in ≥32℉ and target temperature T inside the chamber ref With a temperature of ≤10℉, the temperature inside the box differs greatly from the target temperature, making it suitable for the rapid freezing needs of room temperature food.

[0083] When the current conditions meet the third trigger condition, enter the rapid cooling mode.

[0084] Figure 4 The process of the collaborative cooling mode is illustrated below, which will combine... Figure 4 This describes the process of a collaborative cooling mode.

[0085] In rapid cooling mode, to avoid the current superposition caused by the dual refrigeration systems during initial startup and thus exceeding the limit, the first and second refrigeration systems are started off at off-peak times.

[0086] In some embodiments of this application, the off-peak start-up time can be flexibly set. In rapid cooling mode, the off-peak start-up time can be set to 30 seconds to 60 seconds.

[0087] To meet the rapid cooling requirement, when entering rapid cooling mode, one refrigeration system is first started at full load for 30 seconds, and then another refrigeration system is started at full load.

[0088] During the operation of both refrigeration systems, the total current output by the power module is stabilized by controlling the opening degree of the corresponding frequencies of the first and second compressors, ensuring that the current does not exceed the limit when the two refrigeration systems operate in the rapid cooling mode.

[0089] In some embodiments of this application, a PID algorithm is used to control the frequency adjustment of the first compressor and the second compressor.

[0090] In rapid cooling mode, the first current I is obtained. A Second current I B And calculate the total current I. total .

[0091] The PID algorithm uses the current deviation as the control variable and the output variable as the compressor frequency adjustment variable, which simultaneously adjusts the frequency f of the first compressor. A The frequency f of the second compressor B This enables current control to prevent it from exceeding limits.

[0092] In some embodiments of this application, the current limit I limit Determined based on the current limiting value of the American standard plug, for example, I limit =30A.

[0093] The formula for the PID algorithm is as follows: .

[0094] Wherein, the deviation e(t) = I limit -I total The output u(t) is the compressor frequency adjustment amount Δf.

[0095] Adjust f synchronously using △f A and f B That is, f A =f A +△f,f B =f B +△f.

[0096] In the process of using PID control to control the total current, integral saturation can be prevented by limiting the integral amplitude, and output amplitude can also be limited to ensure that a single frequency adjustment does not exceed a preset value, such as 5Hz, thus avoiding system oscillation.

[0097] In rapid cooling mode, it is necessary to maximize rapid cooling and strongly suppress current overshoot. Therefore, the proportional coefficient K in the PID parameters is crucial in rapid cooling mode. p The proportional coefficient K in the PID parameters is greater than that in the coordinated cooling mode.p .

[0098] In some embodiments of this application, in rate cooling mode, the internal temperature T is monitored. in The runtime can be used to control whether to switch to the rotating cooling mode.

[0099] In rapid cooling mode, the internal temperature T is monitored. in Has the target temperature T inside the chamber been reached? ref Control whether to switch to rotating cooling mode.

[0100] Temperature T inside the chamber in Reaching the target temperature T inside the chamber ref When the time is right, the control will exit the rapid cooling mode and switch to the rotating cooling mode.

[0101] In rapid cooling mode, the internal temperature T is monitored. in and the target temperature T inside the chamber ref The temperature difference ΔT between the two controls whether to switch to the rotating cooling mode.

[0102] In rapid cooling mode, a fourth temperature difference threshold (e.g., 5℉) is set for the temperature difference ΔT, which is then compared with the real-time monitored ΔT.

[0103] When the temperature difference ΔT meets the fourth threshold condition, which can be the lower limit of the fourth temperature difference threshold (e.g., ΔT≤5℉), it indicates that the current temperature inside the chamber is already low, and the chamber switches to the rotating cooling mode.

[0104] In rapid cooling mode, a runtime limit (e.g., 2h) is set for comparison with the runtime t monitored in real time.

[0105] When the running time t reaches 2 hours, it indicates that the current rapid cooling mode has been running for a long time and has met the requirement for rapid freezing. At this time, switch to the rotating cooling mode.

[0106] The quick-cooling mode can also be manually turned off by pressing the quick-cooling button again, at which point it will switch to the rotating cooling mode.

[0107] After switching from rapid cooling mode to rotating cooling mode, the default rotating value is read first, and then the rotating control is performed.

[0108] In some embodiments of this application, in order to achieve seamless fault switching and mild self-healing and improve the working efficiency of the refrigeration unit, system fault conditions are also detected during operation in rotating refrigeration mode, coordinated refrigeration mode, or rapid cooling mode.

[0109] Faults are classified into minor faults and major faults. Minor faults are those that can be self-healed by reducing the load or adjusting the opening of the electronic expansion valve (e.g., slight overload of a single system (e.g., slightly high current in a single system), slightly low pressure). Major faults are those that cannot be healed except for minor faults (e.g., high pressure protection, refrigerant leakage).

[0110] For the rotating cooling mode, see Figure 2 The first fault monitoring process is set up. During the first fault monitoring process, if any refrigeration system has a minor fault, the load on that refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted to allow it to self-heal, while the remaining refrigeration system maintains its current operating state without affecting the overall cooling of the refrigeration unit; if any refrigeration system has a major fault, that refrigeration system is shut down, and the other refrigeration system is started at the same time.

[0111] For the collaborative cooling mode, see Figure 3 A second fault monitoring process is set up. During the second fault monitoring process, if any refrigeration system has a minor fault, the load on that refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted to allow it to self-heal, while the remaining refrigeration system maintains its current operating state, without affecting the overall cooling of the refrigeration unit; if any refrigeration system has a major fault, that refrigeration system is shut down, and the other refrigeration system is started at full load at the same time.

[0112] For rapid cooling mode, see Figure 4 A third fault monitoring process is set up. During the third fault monitoring process, if any refrigeration system has a minor fault, the load on that refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted to allow it to self-heal, while the remaining refrigeration system maintains its current operating state without affecting the overall cooling of the refrigeration unit; if any refrigeration system has a major fault, that refrigeration system is shut down, and the other refrigeration system is started at full load at the same time.

[0113] During the fault monitoring process described above, when shutting down a refrigeration system with a severe fault, the system number, fault number, and alarm can be recorded simultaneously.

[0114] After the shut-down refrigeration system is repaired, it is started and run at a low load (e.g., 30%) for a certain period of time (e.g., 10 minutes). Then, the operation of the two refrigeration units is controlled according to the current operating mode. That is, when the current operating mode is the alternating refrigeration mode, the default rotation value is read first, and then the rotation control of the two refrigeration systems is performed. When the current operating mode is the collaborative refrigeration mode or the rapid cooling mode, the control method described above is followed.

[0115] The refrigeration unit involved in this application has two independent refrigeration systems that are physically separated to isolate faults. The two independent power supply channels can provide power to the two refrigeration systems respectively. It can match the rotating refrigeration mode, the collaborative refrigeration mode or the rapid cooling mode according to different usage needs, covering a wide temperature range. The rotating refrigeration mode is used for daily use, the collaborative refrigeration mode is used for extremely low temperatures, and the rapid cooling mode is used for emergency cooling / rapid freezing, accurately matching various household needs.

[0116] In the coordinated cooling mode and the rapid cooling mode, the dual cooling systems start up at off-peak times, stabilize the total current, solve the problem of current exceeding limits, and improve the reliability of operation.

[0117] Seamless fault switching and mild self-healing improve the operating efficiency of the refrigeration unit.

[0118] In some embodiments of this application, the refrigeration unit can be modularly arranged to fit a standard 20-foot container. To facilitate modular assembly, the refrigeration unit also includes a basic insulated structural frame for supporting the unit; see [link to relevant documentation]. Figures 5 to 7 The basic thermal insulation structure frame includes a fixed frame 100 and a thermal insulation inner liner 200.

[0119] The fixed frame has 100 circumferentially arranged mounting holes (not shown), which are connected to the container body (not shown) through the mounting holes (e.g., to the container's pre-embedded nuts). The refrigeration unit is embedded and installed at one end of the refrigerated container. The size of the entire basic insulation structure frame is the same as that of existing marine refrigeration units, improving versatility and interchangeability.

[0120] The heat-insulating inner liner 200 is installed on the fixed frame 100. Specifically, the fixed frame 100 has upper and lower fixed plates 120 and a frame opening 110. The heat-insulating inner liner 200 is installed at the frame opening 110, forming a refrigeration system installation space 210 (see...). Figure 6 The opening of the refrigeration system installation space 210 faces the outside of one port of the container, which facilitates the arrangement of some components of the refrigeration unit in the refrigeration system installation space and also facilitates later maintenance. During installation, the heat-insulating inner liner 200 extends into the container.

[0121] As described above, all components in the first and second refrigeration systems, except for the first evaporator, the second evaporator, and the evaporator fan, are arranged within the refrigeration system installation space 210. (See attached image.) Figure 5 and Figure 6 .

[0122] An evaporation system installation space 300 is formed above the insulated inner liner 200 and at the position corresponding to the fixing plate 120, see [reference]. Figure 7The first evaporator, the second evaporator, and the evaporation fan are all installed within the evaporation system installation space 300. During installation, this space needs to extend into the container so that when the dual refrigeration system is operating, the evaporation fan can vertically direct the cold airflow passing through the first and second evaporators into the container.

[0123] The insulated inner liner 200 isolates heat exchange between the inside and outside of the container. In addition, a sealing part 400 is provided on the portion of the fixed frame 100 directly opposite the circumferential edge of the container port where the mounting base insulation structure frame is installed. (See also...) Figure 7 The sealing part 400 is used to fill the gap between the two after being connected to the housing to prevent heat leakage.

[0124] In some embodiments of this application, the sealing part 400 may be composed of a single layer or multiple layers of sealing lips, and is sealed around the perimeter after installation.

[0125] The components located within the refrigeration system installation space 210 are equipped with housings, and these housings feature quick-release access panels. The panels utilize snap-fit ​​connections for easy routine maintenance and component replacement. Internal wiring harnesses employ plug-in interfaces to reduce installation complexity.

[0126] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions claimed by the present invention.

Claims

1. A refrigeration unit for refrigerated containers, characterized in that, include: The power module has an independent first power supply channel and a second power supply channel; The first refrigeration system has a first refrigerant circulation loop, which allows the refrigerant to circulate in a loop consisting of a first compressor, a first condenser, a first electronic expansion valve, and a first evaporator. The first power supply channel provides single-phase power to the first refrigeration system. The second refrigeration system has a second refrigerant circulation loop, which allows the refrigerant to circulate in a loop consisting of a second compressor, a second condenser, a second electronic expansion valve, and a second evaporator. The second power supply channel provides single-phase power to the second refrigeration system. The controller controls the first and second refrigeration systems respectively through two independent signal channels, enabling them to operate in a rotating refrigeration mode, a coordinated refrigeration mode, or a rapid cooling mode. In the rotating cooling mode, the first cooling system and the second cooling system are controlled to take turns cooling. By monitoring the difference between the temperature inside the box and the target temperature inside the box, the system controls whether to switch to the collaborative cooling mode or the rapid cooling mode. In the coordinated cooling mode, after the initial start of one cooling system, the other cooling system starts. While both cooling systems are running, the total current output by the power module is stabilized by adjusting the corresponding frequencies of the first and second compressors. When the absolute value of the difference between the first current on the first power supply channel and the second current on the second power supply channel reaches a preset current difference limit, the opening of the first and second electronic expansion valves is adjusted to balance the cooling output between the two cooling systems. The system controls whether to switch to the rotating cooling mode by monitoring the difference between the internal temperature and the target internal temperature. In the rapid cooling mode, after the first refrigeration system starts at full load for a second time, the other refrigeration system starts at full load. While both refrigeration systems are running, the total current output by the power module is stabilized by controlling the corresponding frequencies of the first and second compressors. The system controls whether to switch to the rotating cooling mode by monitoring the temperature inside the chamber or the running time.

2. The refrigeration unit for refrigerated containers according to claim 1, characterized in that, The controller sets a first trigger condition for triggering the rotating cooling mode, a second trigger condition for triggering the coordinated cooling mode, and a third trigger condition for triggering the rapid cooling mode; When the first triggering condition is met, the controller controls the refrigeration unit to enter the rotating refrigeration mode; When the second triggering condition is met, the controller controls the refrigeration unit to enter the collaborative refrigeration mode; When the third triggering condition is met, the controller controls the refrigeration unit to enter the rapid cooling mode.

3. The refrigeration unit for refrigerated containers according to claim 1, characterized in that, When entering the rotating cooling mode, the system first rotates according to the default rotation and monitors the difference in runtime and loss between the two cooling systems in real time. When the loss difference does not reach the first loss threshold and the runtime difference does not reach the first time threshold, the first refrigeration system and the second refrigeration system take turns refrigerating to maintain the default rotation value. Otherwise, the rotation value is adaptively adjusted according to the load. When the load is large, the rotation value is reduced based on the default rotation value, and when the load is small, the rotation value is increased based on the default rotation value.

4. The refrigeration unit for refrigerated containers according to claim 3, characterized in that, During the rotating cooling mode, a first fault monitoring process is executed; During the first fault monitoring process, if any refrigeration system has a minor fault that can be self-healed by reducing the load or adjusting the opening of the corresponding electronic expansion valve, the load of the refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted, and the remaining refrigeration system remains in its current operating state. If any refrigeration system has a major fault other than a minor fault, the refrigeration system is shut down and the other refrigeration system is started at the same time.

5. The refrigeration unit for refrigerated containers according to claim 1, characterized in that, In the coordinated cooling mode, the total current output by the power module is stabilized by adjusting the corresponding frequencies of the first and second compressors, specifically as follows: Detect the first current output by the first power supply channel and the second current output by the second power supply channel; Calculate the sum of the first current and the second current as the total output current of the power module; Using a PID algorithm, the current difference between a preset current limiting threshold and the total current is used as the deviation to control the output compressor frequency adjustment amount, which is used to adjust the frequency of the first compressor and the frequency of the second compressor respectively.

6. The refrigeration unit for refrigerated containers according to claim 5, characterized in that, During the collaborative cooling mode, a second fault monitoring process is executed; During the second fault monitoring process, if any refrigeration system has a minor fault that can be self-healed by reducing the load or adjusting the opening of the corresponding electronic expansion valve, the load of the refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted, and the remaining refrigeration system remains in its current operating state. If any refrigeration system has a major fault other than a minor fault, the refrigeration system is shut down, and another refrigeration system is started at full load at the same time.

7. The refrigeration unit for refrigerated containers according to claim 1, characterized in that, In the rapid cooling mode, the total current output by the power module is stabilized by controlling the corresponding frequencies of the first and second compressors, specifically as follows: Detect the first current output by the first power supply channel and the second current output by the second power supply channel; Calculate the sum of the first current and the second current as the total output current of the power module; Using a PID algorithm, the current difference between a preset current limiting threshold and the total current is used as the deviation to control the output compressor frequency adjustment amount, which is used to adjust the frequency of the first compressor and the frequency of the second compressor respectively.

8. The refrigeration unit for refrigerated containers according to claim 7, characterized in that, During the rapid cooling mode, a third fault monitoring process is executed; During the third fault monitoring process, if any refrigeration system has a minor fault that can be self-healed by reducing the load or adjusting the opening of the corresponding electronic expansion valve, the load of the refrigeration system is reduced or the opening of the corresponding electronic expansion valve is adjusted, and the remaining refrigeration system remains in its current operating state. If any refrigeration system has a major fault other than a minor fault, the refrigeration system is shut down, and another refrigeration system is started at full load at the same time.

9. The refrigeration unit for refrigerated containers according to any one of claims 4, 6, and 8, characterized in that, After the refrigeration system with a severe fault is repaired, it is started and run at a low load for a certain period of time, and then the operation of the two refrigeration systems is controlled according to the current operating mode.

10. The refrigeration unit for refrigerated containers according to claim 1, characterized in that, The refrigeration unit includes: A fixed frame is connected to the body of a refrigerated container through mounting holes. The refrigeration unit is embedded and installed at one end port of the refrigerated container. A sealing part is provided on the part of the fixed frame that is directly opposite the circumferential edge of the port. The fixed frame has fixed plates and frame openings arranged vertically. The heat-insulating inner liner is installed at the frame opening and has a refrigeration system installation space. All components of the two refrigeration systems, except for the first evaporator, the second evaporator, and the evaporation fan, are installed in the refrigeration system installation space. The position above the heat-insulating inner liner corresponding to the fixed plate forms the evaporation system installation space. The first evaporator, the second evaporator, and the evaporation fan are all installed in the evaporation system installation space. The evaporation fan is used to blow the airflow flowing through the first evaporator and / or the second evaporator into the housing.

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