Temperature control system

Abstract

The utility model provides a temperature control system which comprises a refrigerating system and a circulating system, and the refrigerating system comprises a compressor, a condenser, a liquid storage device, an electronic expansion valve set, a first side of an evaporator and a gas-liquid separator which are sequentially connected in series to form a refrigerating loop. The electronic expansion valve set comprises a first electronic expansion valve and a second electronic expansion valve which are arranged in parallel, the first electronic expansion valve is a pulse type electronic expansion valve, and the second electronic expansion valve is a stepping type electronic expansion valve. The flow of the refrigerant in the refrigerating system is controlled by adopting the parallel double electronic expansion valves, and the regulation and control characteristics of the pulse type electronic expansion valve and the stepping type electronic expansion valve are fused and utilized, so that the precise regulation of the refrigerating capacity can be realized, the response speed and the stability can be improved, and the load temperature control requirement can be better met.

Description

Technical Field

[0001] This application relates to the technical field of temperature control, and more particularly, to a temperature control system. Background Art

[0002] Semiconductor temperature control equipment is used to provide fast, accurate, and stable temperature output for semiconductor integrated circuit etching equipment to ensure the precise manufacturing of integrated circuits, and it is one of the important equipment in the upstream support link of the semiconductor industry. Currently, the refrigeration system of the temperature control equipment used to control the temperature of the process chamber of the etching equipment mainly adopts the method of combining an evaporator with an electric heater, and only a single electronic expansion valve is used for throttling and pressure reduction between the condenser and the evaporator. This electronic expansion valve is often connected to the temperature sensor on the circulation side, and the opening degree of the electronic expansion valve is adjusted through PID control to adjust and adapt to the refrigeration capacity of the load, realizing the adjustment of the refrigeration capacity, and thus realizing the control of the temperature. Electronic expansion valves usually come in two forms: stepper and pulse. If a stepper electronic expansion valve is used, the adjustment fluctuation is small but the adjustment speed is slow; if a pulse electronic expansion valve is used, the adjustment speed is fast but the adjustment fluctuation is large and it is easy to overshoot. Therefore, if only the opening degree of a single electronic expansion valve is controlled to achieve rapid and accurate temperature adjustment, there are problems of low stability and poor flexibility. Summary of the Invention

[0003] The purpose of this application is to provide a temperature control system that uses a parallel dual electronic expansion valve to control the flow rate of the refrigerant in the refrigeration system, improves the precise adjustment of the refrigeration capacity of the refrigeration system, and can improve the response speed and stability of the refrigeration system in the face of load changes, so as to better meet the temperature control requirements of the load.

[0004] To this end, this application proposes a temperature control system, including a refrigeration system and a circulation system. The refrigeration system includes a compressor, a condenser, a liquid receiver, an electronic expansion valve group, the first side of the evaporator, and a gas-liquid separator that are sequentially connected in series to form a refrigeration circuit. The electronic expansion valve group includes a first electronic expansion valve and a second electronic expansion valve that are arranged in parallel. Among them, the first electronic expansion valve is a pulse type electronic expansion valve, and the second electronic expansion valve is a stepper type electronic expansion valve; the circulation system includes the second side of the evaporator, a circulation water tank, a circulation water pump, and an electric heater that are sequentially connected in series to form a circulation circuit. Among them, the pipeline between the outlet of the electric heater and the second side of the evaporator is used to flow through the load component.

[0005] In the temperature control system of the present application, by adopting a parallel dual electronic expansion valve to jointly participate in the flow control of the refrigerant in the refrigeration system, combining the performance advantages of the step-type and pulse-type electronic expansion valves, not only can the cooling capacity be accurately adjusted, but also the response speed and stability of the refrigeration system can be improved in the face of load changes, so as to better meet the temperature control requirements of the load. In addition, by accurately adjusting the cooling capacity of the refrigeration system, the temperature of the coolant at the outlet of the circulation water tank in the circulation system is kept relatively stable, which is also beneficial to reducing the load of the electric heater and thus reducing the power consumption of the temperature control device. Brief Description of the Drawings

[0006] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0007] Figure 1 It is a schematic structural diagram of the temperature control system provided by the present application;

[0008] Figure 2 It is a schematic flow chart of the control method of the temperature control system provided according to an embodiment of the present application.

[0009] Reference Signs:

[0010] 1 - Compressor; 2 - First Temperature Sensor; 3 - First Pressure Sensor; 4 - Condenser; 5 - Liquid Receiver; 6 - First Electronic Expansion Valve; 7 - Second Electronic Expansion Valve; 8 - Evaporator; 9 - Gas-Liquid Separator; 10 - Second Pressure Sensor; 11 - Second Temperature Sensor; 12 - Circulation Water Tank; 13 - Third Temperature Sensor; 14 - Circulation Water Pump; 15 - Electric Heater; 16 - Fourth Temperature Sensor; 17 - Load Component. Detailed Description of the Embodiments

[0011] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Usually, the components of the embodiments of the present application described and illustrated in the drawings here can be arranged and designed in various different configurations.

[0012] Accordingly, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but merely represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the scope of protection of the present application.

[0013] In the description of the present application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present application. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0014] In addition, terms such as "horizontal" and "vertical" do not mean that the components are absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0015] In the description of the present application, it should also be noted that unless otherwise clearly specified and defined, the terms "set", "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0016] Next, in conjunction with Figure 1 a temperature control system according to an embodiment of the present application will be described.

[0017] Referring to Figure 1 , this embodiment provides a temperature control system, which includes two parts: a refrigeration system and a circulation system.

[0018] Specifically, the refrigeration system includes a compressor 1, a condenser 4, a liquid receiver 5, an electronic expansion valve group, the first side of an evaporator 8, and a gas-liquid separator 9 that are sequentially connected in series to form a refrigeration circuit. Among them, the electronic expansion valve group includes a first electronic expansion valve 6 and a second electronic expansion valve 7 that are arranged in parallel. The first electronic expansion valve 6 is a pulse-type electronic expansion valve, and the second electronic expansion valve 7 is a step-type electronic expansion valve.

[0019] The circulation system includes the second side of the evaporator 8, the circulation water tank 12, the circulation water pump 14, and the electric heater 15 that are connected in series in sequence to form a circulation loop. Among them, the pipeline between the outlet of the electric heater 15 and the second side of the evaporator 8 is used for flowing through the load component 17.

[0020] Specifically, in the refrigeration system, the outlet of the compressor 1 is connected to the inlet of the condenser 4, the outlet of the condenser 4 is connected to the inlet of the liquid storage tank 5, the outlet of the liquid storage tank 5 is divided into two paths, which are respectively connected to the inlet of the first electronic expansion valve 6 and the inlet of the second electronic expansion valve 7. After the outlets of the first electronic expansion valve 6 and the second electronic expansion valve 7 are combined, they are connected to the inlet of the first side of the evaporator 8. The outlet of the first side of the evaporator 8 is connected to the inlet of the gas-liquid separator 9, and the outlet of the gas-liquid separator 9 is connected to the inlet of the compressor 1.

[0021] In the circulation system, the outlet of the second side of the evaporator 8 is connected to the inlet of the circulation water tank 12, the outlet of the circulation water tank 12 is connected to the inlet of the circulation water pump 14, the outlet of the circulation water pump 14 is connected to the inlet of the electric heater 15, and the outlet of the electric heater 15 is connected to the inlet of the second side of the evaporator 8; the pipeline between the outlet of the electric heater 15 and the inlet of the second side of the evaporator 8 is used for flowing through the load component 17.

[0022] The temperature control system of this embodiment uses a parallel dual electronic expansion valve to jointly participate in the flow control of the refrigerant in the refrigeration system, integrating the advantages of the stepper electronic expansion valve with small regulation fluctuations and the pulse electronic expansion valve with fast regulation speed. It can not only achieve precise regulation of the refrigeration capacity, but also improve the refrigeration capacity change rate (i.e., response speed) and stability of the temperature control system in the face of load changes, so as to better meet the temperature control requirements of the load.

[0023] The refrigeration system is used to provide refrigeration capacity output, and transfers the refrigeration capacity to the coolant in the circulation loop of the circulation system through heat exchange in the evaporator 8 to achieve the primary regulation of the coolant temperature, so that the real-time outlet temperature at the outlet of the circulation water tank 12 tends to be consistent with the preset outlet temperature. The electric heater 15 in the circulation system is used to provide heat output to the coolant to achieve the secondary regulation of the coolant temperature, so that the real-time target temperature at the outlet of the electric heater 15 tends to be consistent with the preset target temperature. Through the coordinated control of the refrigeration system and the electric heater 15, precise and stable temperature output can be achieved.

[0024] In this way, during the temperature control process, by precisely regulating the refrigeration capacity of the refrigeration system with a parallel dual electronic expansion valve, when the temperature of the coolant at the outlet of the circulation water tank in the circulation system is stably maintained at the preset outlet temperature, it is beneficial to control the output power of the electric heater 15, thereby reducing the load of the electric heater 15, lowering the power consumption of the temperature control device, and at the same time increasing the refrigeration capacity change rate of the temperature control system to better adapt to the rapid changes of the external load.

[0025] Furthermore, the temperature control system is also provided with a plurality of pressure sensors and a plurality of temperature sensors to monitor the operating conditions of various parts of the system in real time. Based on the real-time monitoring data, the operating states of the actuators in the temperature control system can be adjusted. In addition, when the monitoring data exceeds the threshold range, an alarm signal can also be sent.

[0026] Reference Figure 1 , a first temperature sensor 2 and a first pressure sensor 3 are provided at the outlet of the compressor 1. For example, the first temperature sensor 2 and the first pressure sensor 3 are arranged between the outlet of the compressor 1 and the inlet of the condenser 4 to monitor the temperature and pressure at the outlet of the compressor 1 to ensure the operating safety of the system.

[0027] A second temperature sensor 11 and a second pressure sensor 10 are provided at the inlet of the compressor 1. For example, the second temperature sensor 11 and the second pressure sensor 10 are arranged between the outlet of the gas-liquid separator 9 and the inlet of the compressor 1.

[0028] A third temperature sensor 13 is provided at the outlet of the circulation water tank 12 to obtain the real-time outlet temperature at the outlet of the circulation water tank 12. For example, the third temperature sensor 13 is arranged between the outlet of the circulation water tank 12 and the inlet of the circulation water pump 14.

[0029] A fourth temperature sensor 16 is provided at the outlet of the electric heater 15 to obtain the real-time target temperature at the outlet of the electric heater 15. For example, the fourth temperature sensor 16 is arranged between the outlet of the electric heater 15 and the load component 17, and the real-time target temperature of the refrigerant at the outlet of the electric heater 15 is the temperature after heat exchange through the refrigeration system and the electric heater 15.

[0030] These temperature sensors and pressure sensors obtain the temperature values or pressure values at the corresponding positions according to the set sampling period. Their respective sampling periods can be set to be the same or different.

[0031] The refrigeration system is used to perform real-time regulation on the refrigeration capacity of the refrigeration system according to the first deviation between the real-time outlet temperature detected by the third temperature sensor 13 and the preset outlet temperature, so that the real-time outlet temperature is consistent with the preset outlet temperature, that is, the above first deviation is within the first preset deviation interval.

[0032] Specifically, for the refrigeration system, by controlling the opening states and degrees (i.e., opening degrees) of the two electronic expansion valves in the electronic expansion valve group, the flow rate of the refrigerant in the refrigeration system is adjusted, so as to ensure that an appropriate amount of refrigerant enters the first side of the evaporator 8 when the refrigeration system operates. This helps to maintain the stable operation of the temperature control system and the refrigeration effect. While controlling the refrigerant flow rate, the electronic expansion valve can also reduce the pressure of the refrigerant, enabling it to reach the required low temperature state when evaporating in the evaporator 8, thus achieving the refrigeration effect. Controlling the opening degrees of the two electronic expansion valves according to the working conditions of the temperature control system and the load demand can improve the working efficiency and energy consumption of the temperature control system.

[0033] Therefore, the real-time regulation of the refrigeration capacity of the refrigeration system includes dynamically adjusting the opening degrees of the two electronic expansion valves in the above-mentioned electronic expansion valve group according to the above first deviation. Since the first electronic expansion valve 6 and the second electronic expansion valve 7 are of different types. In this embodiment, the advantages of small regulation fluctuations of the stepper electronic expansion valve and fast regulation speed of the pulse electronic expansion valve will be integrated and utilized, and different control strategies will be adopted for the two respectively to improve the control accuracy, response speed and stability of the refrigerant flow rate control when facing load changes.

[0034] Since the pulse electronic expansion valve can only be in the fully open state or the fully closed state, therefore, the mass flow rate of the refrigerant in the refrigeration system can be changed by controlling the opening time within a unit cycle. Therefore, in this embodiment, the duty ratio of the first electronic expansion valve 6 is adjusted to change the mass flow rate of the refrigerant flowing through the branch where the first electronic expansion valve 6 is located in the refrigeration system. Wherein, in this embodiment, the duty ratio refers to the ratio of the opening time when the first electronic expansion valve 6 is in the fully open state to the entire cycle time within a unit cycle. The value range of the duty ratio is 0 - 100%.

[0035] The electric heater 15 is used to dynamically adjust the heating amount of the electric heater 15 in real time according to the second deviation between the real-time target temperature detected by the fourth temperature sensor 16 and the preset target temperature, so that the real-time target temperature is consistent with the preset target temperature, that is, the above second deviation is within the second preset deviation range.

[0036] Furthermore, the temperature control system of this embodiment further includes a controller (not shown). The controller can obtain the real-time data of the temperature control system, such as temperature, pressure, etc. through each sensor, and then perform calculations and analyses according to the preset control logic, and finally generate control signals and send them to the actuators in the temperature control system, and the temperature control system is controlled and adjusted through the actuators. Thus, the temperature control system can not only achieve precise adjustment of the refrigeration capacity, but also improve the response speed and stability of the refrigeration system when facing load changes, so as to better meet the temperature control requirements of the load.

[0037] Specifically, in an embodiment of the present application, the controller is electrically connected to the first temperature sensor 2, the first pressure sensor 3, the second temperature sensor 11, the second pressure sensor 10, the third temperature sensor 13, and the fourth temperature sensor 16 respectively. The controller is used to receive the temperature feedback signals detected by the first temperature controller 2, the second temperature sensor 11, the third temperature sensor 13, and the fourth temperature sensor 16 respectively. The controller is also used to receive the pressure feedback signals detected by the first pressure sensor 3 and the second pressure sensor 10 respectively.

[0038] At the same time, the first electronic expansion valve 6, the second electronic expansion valve 7, and the electric heater 15, as actuators in the temperature control system, can receive the control signals sent by the controller and complete the adjustment function corresponding to the control signals. In other words, the controller is also electrically connected to the first electronic expansion valve 6, the second electronic expansion valve 7, and the electric heater 15 respectively to send control instructions to the first electronic expansion valve 6, the second electronic expansion valve 7, and the electric heater 15 respectively.

[0039] Specifically, the controller generates a first control signal based on a preset control logic according to the temperature feedback signals of the second temperature sensor 11 and the third temperature sensor 13 and the pressure feedback signal of the second pressure sensor 10 received, and sends the first control signal to the first electronic expansion valve 6 to adjust the duty cycle of the first electronic expansion valve 6.

[0040] The controller also generates a second control signal based on a preset control logic according to the temperature feedback signal of the third temperature sensor 13 received, and sends the second control signal to the second electronic expansion valve 7 to adjust the opening percentage of the second electronic expansion valve 7.

[0041] In this way, by adjusting the duty cycle of the first electronic expansion valve 6 and the opening percentage of the second electronic expansion valve 7, the first electronic expansion valve 6 and the second electronic expansion valve 7 jointly participate in the adjustment of the refrigerating capacity of the refrigeration system, realizing the real-time regulation of the refrigerating capacity of the refrigeration system, and making the real-time outlet temperature detected by the third temperature sensor 13 tend to be consistent with the preset outlet temperature.

[0042] The controller is also electrically connected to the electric heater 15, and is used to generate a third control signal based on a preset control logic according to the temperature feedback signal of the fourth temperature sensor 16 received, and send the third control signal to the electric heater 15 to adjust the output power of the electric heater 15. In this way, the real-time regulation of the heating output of the electric heater 15 can be realized, making the real-time target temperature detected by the fourth temperature sensor 16 tend to be consistent with the preset target temperature, so as to meet the temperature control requirements of the load.

[0043] Next, elaborate in detail how the controller generates corresponding control signals based on a preset control logic to adjust the duty cycle of the first electronic expansion valve 6, the opening percentage of the second electronic expansion valve 7, and the output power of the electric heater 15, respectively.

[0044] The control logic of the temperature control system of this application is mainly as follows: The first part is to adjust the refrigeration system to make the temperature at the outlet of the coolant-side evaporator basically constant; the second part is to perform fine-tuning through the electric heater 15 to keep the output temperature of the temperature control system at the target temperature.

[0045] Reference Figure 2 , based on the above control logic, another embodiment of this application provides a control method for a temperature control system, and this control method for the temperature control system is applied to the temperature control system described in the above embodiment.

[0046] Specifically, the temperature control method applied to the temperature control system of the above embodiment includes:

[0047] Obtain the first deviation between the real-time outlet temperature at the outlet of the circulation water tank 12 in the circulation system and the preset outlet temperature; according to the first deviation, respectively adjust the opening degrees of the two electronic expansion valves in the electronic expansion valve group, so that both of them participate in the adjustment of the refrigeration capacity of the refrigeration system, thereby making the real-time outlet temperature tend to be consistent with the preset outlet temperature.

[0048] According to the second deviation between the real-time target temperature at the outlet of the electric heater 15 in the circulation system and the preset target temperature, perform real-time adjustment on the heating output of the electric heater 15, so that the real-time target temperature tends to be consistent with the preset target temperature.

[0049] Thus, the temperature control system makes the temperature of the coolant at the outlet of the circulation water tank 12 approach the preset outlet temperature through the regulation of the refrigeration system, realizing the coarse adjustment of the coolant temperature; then, through the regulation of the electric heater 15, the temperature of the coolant in the pipeline flowing through the load component 17 approaches the preset target temperature, realizing the fine adjustment of the coolant temperature. In this way, through the coordinated control of the refrigeration system and the electric heater 15 in the circulation system, accurate temperature control can be achieved.

[0050] To improve the measurement accuracy and reduce the influence of random errors, the real-time outlet temperature is the average value of the temperature measurement values continuously obtained by the third temperature sensor 13 multiple times.

[0051] Since the first electronic expansion valve 6 and the second electronic expansion valve 7 arranged in parallel in the electronic expansion valve group are two different types of electronic expansion valves, therefore, according to the above first deviation, different control strategies are applied to the first electronic expansion valve 6 and the second electronic expansion valve 7 respectively to adjust their opening degrees, which can quickly change the mass flow rate of the refrigerant in the refrigeration system, control the change of the refrigerating capacity, and achieve the constant temperature control of the outlet temperature of the evaporator on the secondary refrigerant side. The specific control strategies of the above two electronic expansion valves will be elaborated in detail below.

[0052] Since the pulse-type electronic expansion valve can only be in the fully open state or the fully closed state, therefore, the mass flow rate of the refrigerant in the refrigeration system can be changed by controlling the opening time within a unit cycle. Therefore, according to the above first deviation, the adjustment of the opening degree of the first electronic expansion valve 6 includes:

[0053] First step, use the above first deviation as the input of the first PID controller to obtain the output Uk1 of the first PID controller. That is, use the PID control logic to regulate the refrigerating capacity of the refrigeration system.

[0054] Second step, according to the output Uk1 of the first PID controller, adjust the duty cycle of the first electronic expansion valve 6. Wherein, in this embodiment, the duty cycle refers to the ratio of the opening time when the first electronic expansion valve 6 is in the fully open state within a unit cycle to the entire cycle time. The value range of the duty cycle is 0-100%.

[0055] Further, adjusting the duty cycle of the first electronic expansion valve 6 according to the output Uk1 of the first PID controller specifically includes:

[0056] Divide the threshold range of the output Uk1 of the first PID controller into multiple intervals, and at the same time configure multiple duty cycles for the first electronic expansion valve 6, and the multiple duty cycles are mapped one by one with multiple opening values;

[0057] When the output Uk1 of the first PID controller is in one of the above multiple intervals, adjust the opening time of the first electronic expansion valve 6 within a unit cycle with the duty cycle corresponding to this interval.

[0058] Taking the division into 5 intervals as an example, the threshold range [Umin, Umax] of the output Uk1 of the first PID controller can be respectively [Umin, Umin + a], (Umin + a, Umin + 2a], (Umin + 2a, Umin + 3a], (Umin + 3a, Umin + 4a] and (Umin + 4a, Umax], where a = (Umax - Umin) / 5. The 5 duty cycles corresponding to the above 5 intervals are D1, D2, D3, D4 and D5 respectively.

[0059] Exemplarily, assume that 1000 milliseconds is a unit cycle for the opening and closing control of the first electronic expansion valve. The threshold range of the output Uk1 of the first PID controller is 0 to 100. When the output Uk1 is in the interval [0, 20], the duty ratio of the first electronic expansion valve 6 is set to 10%. Then, within one unit cycle, the opening time of the first electronic expansion valve 6 in the fully open state is 100 milliseconds, and the closing time in the fully closed state is 900 milliseconds, and it cycles periodically like this; when the output Uk1 is in the interval (20, 40], the duty ratio of the first electronic expansion valve 6 is set to 30%. Then, within one unit cycle, the opening time of the first electronic expansion valve 6 in the fully open state is 300 milliseconds; when the output Uk1 is in the interval (40, 60], the opening degree of the first electronic expansion valve 6 is set to 50%. Then, within one unit cycle, the opening time of the first electronic expansion valve 6 in the fully open state is 500 milliseconds; when the output Uk1 is in the interval (60, 80], the opening degree of the first electronic expansion valve 6 is set to 70%. Then, within one unit cycle, the opening time of the first electronic expansion valve 6 in the fully open state is 700 milliseconds; when the output Uk1 is in the interval (80, 100], the opening degree of the first electronic expansion valve 6 is set to 90%. Then, within one unit cycle, the opening time of the first electronic expansion valve 6 in the fully open state is 900 milliseconds.

[0060] Furthermore, the opening degree adjustment of the first electronic expansion valve 6 further includes: when the interval where the output Uk1 of the first PID controller is located falls within a sub-threshold range, correcting the duty ratio of the first electronic expansion valve 6 on the basis of the duty ratio corresponding to the interval, where the sub-threshold range is located within the above-mentioned threshold range and can correspond to one or more of the above-mentioned multiple intervals.

[0061] Specifically, when the output Uk1 of the first PID controller is within the sub-threshold range, correcting the duty ratio of the first electronic expansion valve 6 on the basis of the duty ratio corresponding to the interval includes:

[0062] Obtaining the suction superheat SH at the inlet end of the compressor 1;

[0063] Judging whether the suction superheat SH is within a preset superheat range;

[0064] When the suction superheat SH exceeds the upper limit SH2 of the preset superheat range, increasing the duty ratio of the first electronic expansion valve 6 on the basis of the duty ratio corresponding to the current interval, thereby increasing the opening time of the first electronic expansion valve 6 in the fully open state within one unit cycle;

[0065] When the suction superheat SH is lower than the lower limit SH1 of the preset superheat range, the duty ratio of the first electronic expansion valve 6 is reduced based on the duty ratio corresponding to the current interval, so as to reduce the opening time of the first electronic expansion valve 6 in the fully open state within a unit period.

[0066] When the suction superheat SH is within the preset superheat range, the duty ratio of the first electronic expansion valve 6 is maintained at the duty ratio corresponding to the current interval without change.

[0067] Furthermore, in this embodiment, when the suction superheat SH exceeds the upper limit SH2 of the preset superheat range, the opening time of the corrected first electronic expansion valve (6) within a unit period is increased by K*(SH - SH2) milliseconds based on the opening time corresponding to the duty ratio before correction;

[0068] When the suction superheat SH is lower than the lower limit SH1 of the preset superheat range, the opening time of the corrected first electronic expansion valve (6) within a unit period is reduced by K*(SH1 - SH) milliseconds based on the opening time corresponding to the duty ratio before correction; where K is a constant, and K*(SH - SH2) and K*(SH1 - SH) do not exceed 10% of the unit period time.

[0069] Wherein, the suction superheat SH is the difference between the measured value PV1 of the second temperature sensor and the saturation temperature value PV2 corresponding to the measured value of the second pressure sensor.

[0070] Furthermore, according to the above first deviation, the opening degree of the second electronic expansion valve 7 is adjusted, specifically including:

[0071] In the first step, the above first deviation is used as the input of the second PID controller to obtain the output Uk2 of the second PID controller.

[0072] In the second step, according to the output Uk2 of the second PID controller, the opening degree percentage of the second electronic expansion valve 7 is controlled.

[0073] Furthermore, according to the output Uk2 of the second PID controller, controlling the opening degree percentage of the second electronic expansion valve 7 includes:

[0074] When the output Uk2 of the second PID controller is greater than or equal to the set threshold, the opening degree percentage of the second electronic expansion valve 7 gradually increases at a rate of N% per millisecond, that is, the opening degree percentage of the second electronic expansion valve 7 increases by N% per millisecond until it reaches 100%;

[0075] When the output Uk2 of the second PID controller is less than the set threshold, the opening percentage of the second electronic expansion valve 7 gradually decreases at a rate of M% per millisecond until the lowest preset opening percentage. The purpose of setting the lowest preset opening percentage is to ensure that the temperature control system is in a continuous operation state, and the refrigerant in the refrigeration system can circulate, so as to prevent the situation where both electronic expansion valves are in a fully closed state (i.e., the opening percentage is 0), the refrigerant in the refrigeration system does not circulate, but the compressor 1 is still in an operating state, thus avoiding potential hazards.

[0076] Preferably, the change rates of the opening increase and decrease of the second electronic expansion valve 7 are the same, i.e., M = N.

[0077] Exemplarily, assume that the threshold range of the output Uk2 of the second PID controller is 0 - 100. When the output Uk2 is greater than or equal to 50, the opening of the second electronic expansion valve 7 increases at a rate of N% per millisecond, and the maximum opening is 100%, i.e., fully open; when the output Uk2 is less than 50, the opening of the second electronic expansion valve 7 decreases at a rate of n% per millisecond, and the lowest preset opening percentage is 10%.

[0078] In summary, the specific idea for controlling the refrigerating capacity of the refrigeration system is as follows: Based on the first deviation between the real-time outlet temperature at the outlet of the circulation water tank 12 and the preset outlet temperature, use the PID algorithm to control the openings of the first and second electronic expansion valves 7, and cooperate with superheat control to jointly adjust the opening of the first electronic expansion valve 6.

[0079] Furthermore, for the real-time regulation of the heating output of the electric heater 15 according to the second deviation, the PID control logic is also used to regulate the heating output of the electric heater. Specifically, it includes:

[0080] Obtain the difference between the measured value PV4 of the fourth temperature sensor 16 and the set value SV4 of the fourth temperature sensor 16 in real time as the input of the third PID controller;

[0081] Control the output power of the electric heater 15 according to the output Uk3 of the third PID controller. There is a one-to-one mapping relationship between the output Uk3 of the third PID controller and the output power of the electric heater 15.

[0082] In summary, for the temperature control method of the present embodiment, according to the first deviation between the real-time outlet temperature at the outlet of the circulation water tank 12 in the circulation system and the preset outlet temperature, different control strategies are respectively applied to the two electronic expansion valves in the electronic expansion valve group to adjust their respective opening degrees, so as to control the refrigerant flow rate in the refrigeration system and quickly respond to load changes. At the same time, according to the second deviation between the real-time target temperature at the outlet of the electric heater 15 and the preset target temperature, the output power of the electric heater 15 is adjusted in real time to achieve precise temperature control and meet the cooling capacity requirements of the load. By using a parallel dual electronic expansion valve for temperature control and applying different opening degree adjustment strategies to the two electronic expansion valves respectively, combining the advantages of the step type and the pulse type, better control accuracy, response speed and stability can be achieved.

[0083] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A temperature control system, comprising a refrigeration system and a circulation system, characterized in that the refrigeration system includes a compressor (1), a condenser (4), a liquid receiver (5), an electronic expansion valve group, the first side of an evaporator (8), and a gas-liquid separator (9) that are connected in series in sequence to form a refrigeration circuit. The electronic expansion valve group includes a first electronic expansion valve (6) and a second electronic expansion valve (7) that are arranged in parallel. Among them, the first electronic expansion valve (6) is a pulse-type electronic expansion valve, and the second electronic expansion valve (7) is a stepper electronic expansion valve; the circulation system includes the second side of the evaporator (8), a circulation water tank (12), a circulation water pump (14), and an electric heater (15) that are connected in series in sequence to form a circulation circuit. Among them, the pipeline between the outlet of the electric heater (15) and the second side of the evaporator (8) is used for flowing through a load component (17).

2. The temperature control system according to claim 1, wherein A third temperature sensor (13) is provided between the outlet of the circulation water tank (12) and the inlet of the circulation water pump (14) for obtaining the real-time outlet temperature at the outlet of the circulation water tank (12).

3. The temperature control system according to claim 2, wherein A fourth temperature sensor (16) is provided between the outlet of the electric heater (15) and the load component (17) for obtaining the real-time target temperature at the outlet of the electric heater (15).

4. The temperature control system according to claim 3, characterized in that, A second temperature sensor (11) and a second pressure sensor (10) are provided between the outlet of the gas-liquid separator (9) and the inlet of the compressor (1).

5. The temperature control system according to claim 1, wherein A first temperature sensor (2) and a first pressure sensor (3) are provided between the outlet of the compressor (1) and the inlet of the condenser (4).

6. The temperature control system according to claim 4, wherein The temperature control system further includes a controller, and the controller is electrically connected to the second temperature sensor (11), the second pressure sensor (10), the third temperature sensor (13), and the fourth temperature sensor (16) respectively; the controller is used to receive the temperature feedback signals detected by the second temperature sensor (11), the third temperature sensor (13), and the fourth temperature sensor (16) respectively, and receive the pressure feedback signal detected by the second pressure sensor (10); the controller is also electrically connected to the first electronic expansion valve (6), the second electronic expansion valve (7), and the electric heater (15) respectively.

7. The temperature control system according to claim 6, characterized in that, The controller is used to send a first control signal to the first electronic expansion valve (6) according to the temperature feedback signals of the second temperature sensor (11) and the third temperature sensor (13) and the pressure feedback signal of the second pressure sensor (10) to adjust the duty cycle of the first electronic expansion valve (6).

8. The temperature control system according to claim 6, characterized in that, The controller is used to send a second control signal to the second electronic expansion valve (7) according to the temperature feedback signal of the third temperature sensor (13) to adjust the opening percentage of the second electronic expansion valve (7).

9. The temperature control system according to claim 6, wherein The controller is used to send a third control signal to the electric heater (15) according to the temperature feedback signal of the fourth temperature sensor (16) to adjust the output power of the electric heater (15).

Images