阅读说明：本技术 基于级联型闭环pid调节的流体温度控制系统及控制方法 (Fluid temperature control system and control method based on cascade closed-loop PID regulation ) 是由 王志民 时阳 王家凯 邱明召 于 2019-12-11 设计创作，主要内容包括：本发明公开了一种基于级联型闭环PID调节的流体温度控制系统及控制方法,包括基于ARM架构CPU的控制器,制冷压缩机、冷凝器、干燥过滤器、前级节流电动调节阀、旁通电动调节阀、换热器和输送泵；控制器实时采集第一温度传感器、第二温度传感器、压力传感器输出的检测数据；当第二温度传感器检测的载冷剂温度值高于设定的温度阈值0.05℃时,控制器输出调节控制信号控制前级节流电动调节阀开度增大2%；当第二温度传感器检测的载冷剂温度值低于设定的温度阈值0.05℃时,控制器输出调节控制信号控制前级节流电动调节阀开度减小2%。本发明采用前级节流电动调节阀作为前级执行器,旁通电动调节阀作为后级执行器,实现对载冷剂温度的精密控制。(The invention discloses a fluid temperature control system and a control method based on cascade closed-loop PID regulation, which comprises a controller based on an ARM framework CPU, a refrigeration compressor, a condenser, a drying filter, a preceding stage throttling electric regulating valve, a bypass electric regulating valve, a heat exchanger and a delivery pump; the controller collects detection data output by the first temperature sensor, the second temperature sensor and the pressure sensor in real time; when the temperature value of the secondary refrigerant detected by the second temperature sensor is higher than the set temperature threshold value of 0.05 ℃, the controller outputs an adjusting control signal to control the opening of the front-stage throttling electric regulating valve to increase by 2%; when the temperature value of the secondary refrigerant detected by the second temperature sensor is lower than the set temperature threshold value of 0.05 ℃, the controller outputs an adjusting control signal to control the opening of the front-stage throttling electric adjusting valve to be reduced by 2%. The invention adopts the front-stage throttling electric regulating valve as a front-stage actuator and the bypass electric regulating valve as a rear-stage actuator, thereby realizing the precise control of the temperature of the secondary refrigerant.)

1. A fluid temperature control system based on cascade type closed loop PID regulation is characterized in that: the system comprises a controller based on an ARM framework CPU, a refrigeration compressor, a condenser, a drying filter, a preceding stage throttling electric regulating valve, a bypass electric regulating valve, a heat exchanger and a delivery pump; one path of the exhaust port of the refrigeration compressor is communicated with the inlet of the front-stage throttling electric regulating valve through the condenser and the drying filter through a three-way pipe, and the other path of the exhaust port of the refrigeration compressor is communicated with the inlet of the bypass electric regulating valve; an outlet of the pre-stage throttling electric regulating valve and an outlet of the bypass electric regulating valve are communicated with an inlet of a refrigerant channel of the heat exchanger, and an outlet of the refrigerant channel of the heat exchanger is communicated with an air suction port of the refrigeration compressor; a secondary refrigerant channel outlet of the heat exchanger is communicated with the inlet of the conveying pump, the outlet of the conveying pump is communicated with the inlet of the load heat exchange channel, and the outlet of the load heat exchange channel is communicated with the secondary refrigerant channel inlet of the heat exchanger; a pressure sensor and a first temperature sensor for detecting suction pressure and suction temperature are arranged at a suction port of the refrigeration compressor, and a second temperature sensor for detecting the temperature of secondary refrigerant is arranged at an outlet of the conveying pump; the detection signal output ends of the pressure sensor, the first temperature sensor and the second temperature sensor are respectively connected with the detection signal input end of the controller; the control signal input ends of the executing mechanisms of the pre-stage throttling electric regulating valve, the bypass electric regulating valve and the delivery pump are respectively connected with the control signal output end of the controller.

2. A control method of a fluid temperature control system according to claim 1, characterized in that: the method comprises the following steps:

step 1, the controller collects detection data output by the first temperature sensor, the second temperature sensor and the pressure sensor in real time;

step 2, when the temperature value of the secondary refrigerant detected by the second temperature sensor is higher than a set temperature threshold value by 0.05 ℃, and the difference value between the suction temperature and the suction pressure of the refrigeration compressor detected by the first temperature sensor and the pressure sensor and the temperature value corresponding to the refrigerant physical property table is increased by 0.1 ℃, the controller compares, judges and amplifies the temperature signal of the secondary refrigerant sent by the second temperature sensor, controls the opening of the front-stage throttling electric regulating valve to be increased by 2% according to a PID output regulation control signal, and reduces the temperature value of the secondary refrigerant to be within the set temperature threshold value by increasing the flow rate of the refrigerant flowing through the refrigerant channel of the heat exchanger;

step 3, when the opening of the front-stage throttling electric regulating valve is controlled to be increased in the step 2, the temperature value of the secondary refrigerant detected by the second temperature sensor is still higher than the set temperature threshold value by 0.05 ℃ and continuously rises to be higher than the set temperature threshold value by 0.1 ℃, the controller outputs a control signal to control the opening of the bypass electric regulating valve to be reduced, and the temperature value of the secondary refrigerant is reduced to be within the set temperature threshold value by reducing the flow rate of the refrigerant steam flowing through the refrigerant channel of the heat exchanger;

step 4, when the temperature value of the secondary refrigerant detected by the second temperature sensor is lower than the set temperature threshold value by 0.05 ℃, and the difference value between the suction temperature and the suction pressure of the refrigeration compressor detected by the first temperature sensor and the pressure sensor and the temperature value corresponding to the refrigerant physical property table is reduced by 0.1 ℃, the controller compares, judges and amplifies the temperature signal of the secondary refrigerant sent by the second temperature sensor, controls the opening of the front-stage throttling electric regulating valve to be reduced by 2% according to the PID output regulation control signal, and improves the temperature value of the secondary refrigerant to the set temperature threshold value by reducing the flow rate of the refrigerant flowing through the refrigerant channel of the heat exchanger;

and 5, after the opening of the front-stage throttling electric regulating valve is controlled to be reduced in the step 4, when the temperature value of the secondary refrigerant detected by the second temperature sensor is still lower than the set temperature threshold value by 0.05 ℃ and is continuously reduced to be lower than the set temperature threshold value by 0.1 ℃, the controller outputs a control signal to control the opening of the bypass electric regulating valve to be increased, and the temperature value of the secondary refrigerant is increased to be within the set temperature threshold value by increasing the flow of the refrigerant steam flowing through the refrigerant channel of the heat exchanger.

Technical Field

The invention relates to a fluid temperature control system, in particular to a fluid temperature control system and a control method based on cascade type closed-loop PID regulation.

Background

Semiconductor manufacturing equipment, battery manufacturing equipment, PCB manufacturing equipment, etc. all require temperature control systems that require higher cooling capacity and temperature control accuracy. At present, the temperature control system for the manufacturing equipment mostly adopts an automatic pressure proportional control valve to control the opening degree, and a bypass electromagnetic valve controls the temperature according to the set temperature and a method of controlling the average opening degree according to a time proportional control mode. The defects of the method are as follows: the controlled temperature fluctuation range is large; the bypass electromagnetic valve is controlled in a time proportion adjusting mode, so that the switching frequency impacts a system, and the service life of the bypass electromagnetic valve is shortened and the suction noise is large due to frequent switching of the bypass electromagnetic valve.

Disclosure of Invention

The invention aims to provide a fluid temperature control system based on cascade closed-loop PID regulation, and the invention also aims to provide a control method of the fluid temperature control system.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention discloses a fluid temperature control system based on cascade closed-loop PID regulation, which comprises a controller based on an ARM framework CPU, a refrigeration compressor, a condenser, a drying filter, a preceding stage throttling electric regulating valve, a bypass electric regulating valve, a heat exchanger and a delivery pump, wherein the controller is connected with the controller; one path of the exhaust port of the refrigeration compressor is communicated with the inlet of the front-stage throttling electric regulating valve through the condenser and the drying filter through a three-way pipe, and the other path of the exhaust port of the refrigeration compressor is communicated with the inlet of the bypass electric regulating valve; an outlet of the pre-stage throttling electric regulating valve and an outlet of the bypass electric regulating valve are communicated with an inlet of a refrigerant channel of the heat exchanger, and an outlet of the refrigerant channel of the heat exchanger is communicated with an air suction port of the refrigeration compressor; a secondary refrigerant channel outlet of the heat exchanger is communicated with the inlet of the conveying pump, the outlet of the conveying pump is communicated with the inlet of the load heat exchange channel, and the outlet of the load heat exchange channel is communicated with the secondary refrigerant channel inlet of the heat exchanger; a pressure sensor and a first temperature sensor for detecting suction pressure and suction temperature are arranged at a suction port of the refrigeration compressor, and a second temperature sensor for detecting the temperature of secondary refrigerant is arranged at an outlet of the conveying pump; the detection signal output ends of the pressure sensor, the first temperature sensor and the second temperature sensor are respectively connected with the detection signal input end of the controller; the control signal input ends of the executing mechanisms of the pre-stage throttling electric regulating valve, the bypass electric regulating valve and the delivery pump are respectively connected with the control signal output end of the controller.

The invention discloses a control method of a fluid temperature control system based on cascade closed-loop PID regulation, which comprises the following steps:

step 1, the controller collects detection data output by the first temperature sensor, the second temperature sensor and the pressure sensor in real time;

step 2, when the temperature value of the secondary refrigerant detected by the second temperature sensor is higher than the set temperature threshold value of 0.05 ℃, the temperature in the heat exchanger rises, the evaporation speed of the refrigerant in the heat exchanger is accelerated, the temperature of the refrigerant reaching the outlet of a refrigerant channel of the heat exchanger rises, the suction superheat degree of the refrigeration compressor is increased, and the suction temperature rises; when the difference value between the suction temperature and the suction pressure of the refrigeration compressor detected by the first temperature sensor and the pressure sensor and the temperature value corresponding to the refrigerant physical property table is increased by 0.1 ℃, the controller compares, judges and amplifies the secondary refrigerant temperature signal sent by the second temperature sensor, controls the opening of the front-stage throttling electric regulating valve to be increased by 2% according to the PID output regulation control signal, and reduces the secondary refrigerant temperature value to be within the set temperature threshold value by improving the refrigerant flow passing through the refrigerant channel of the heat exchanger;

step 3, when the opening of the front-stage throttling electric regulating valve is controlled to be increased in the step 2, the temperature value of the secondary refrigerant detected by the second temperature sensor is still higher than the set temperature threshold value by 0.05 ℃ and continuously rises to be higher than the set temperature threshold value by 0.1 ℃, the controller outputs a control signal to control the opening of the bypass electric regulating valve to be reduced, and the temperature value of the secondary refrigerant is reduced to be within the set temperature threshold value by reducing the flow rate of the refrigerant steam flowing through the refrigerant channel of the heat exchanger;

step 4, when the temperature value of the secondary refrigerant detected by the second temperature sensor is lower than the set temperature threshold value of 0.05 ℃, the temperature in the heat exchanger is reduced, the evaporation speed of the refrigerant in the heat exchanger is reduced, the temperature of the refrigerant reaching the outlet of a refrigerant channel of the heat exchanger is reduced, the suction superheat degree of the refrigeration compressor is reduced, and the suction temperature is reduced; when the difference value between the suction temperature and the suction pressure of the refrigeration compressor detected by the first temperature sensor and the pressure sensor and the temperature value corresponding to the refrigerant physical property table is reduced by 0.1 ℃, the controller compares, judges and amplifies the secondary refrigerant temperature signal sent by the second temperature sensor, controls the opening of the front-stage throttling electric regulating valve to be reduced by 2% according to the PID output regulation control signal, and improves the secondary refrigerant temperature value to be within the set temperature threshold value by reducing the refrigerant flow flowing through the refrigerant channel of the heat exchanger;

and 5, after the opening of the front-stage throttling electric regulating valve is controlled to be reduced in the step 4, when the temperature value of the secondary refrigerant detected by the second temperature sensor is still lower than the set temperature threshold value by 0.05 ℃ and is continuously reduced to be lower than the set temperature threshold value by 0.1 ℃, the controller outputs a control signal to control the opening of the bypass electric regulating valve to be increased, and the temperature value of the secondary refrigerant is increased to be within the set temperature threshold value by increasing the flow of the refrigerant steam flowing through the refrigerant channel of the heat exchanger.

The invention adopts a preceding stage throttling electric regulating valve as a preceding stage actuator and a bypass electric regulating valve as a subsequent stage actuator. The front-stage actuator adjusts the flow of the normal-temperature high-pressure refrigerant liquid entering the heat exchanger, and the rear-stage actuator adjusts the flow of the high-temperature high-pressure refrigerant steam entering the heat exchanger. The controller adopts an ARM framework CPU, and realizes the precise control of the temperature of the secondary refrigerant by the reciprocal regulation of the opening degrees of the preceding stage throttling electric regulating valve and the bypass electric regulating valve. According to the invention, the two electric regulating valves control the valve needle to move to control the opening of the valve body by utilizing the deflection angle of the executing motor of the electric regulating valves according to a preset program proportion control mode, so that the temperature fluctuation degree of the secondary refrigerant is greatly reduced, the system does not generate an impact phenomenon, simultaneously, the noise is greatly reduced, and the service life of the system is prolonged.

Drawings

Fig. 1 is a schematic diagram of the fluid temperature control system of the present invention.

FIG. 2 is a block diagram of the working principle of the cascaded closed loop PID regulation of the present invention.

Detailed Description

The following describes embodiments of the present invention in detail with reference to the drawings, which are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are provided, but the scope of the present invention is not limited to the following embodiments.

As shown in fig. 1, the fluid temperature control system based on the cascade closed-loop PID regulation of the present invention comprises a controller 1 based on an ARM architecture CPU, a refrigeration compressor 2, a condenser 3, a drying filter 4, a pre-stage throttling electric regulating valve 5, a bypass electric regulating valve 6, a heat exchanger 7 and a delivery pump 8; one path of an exhaust port of the refrigeration compressor 2 is communicated with an inlet of a preceding stage throttling electric regulating valve 5 through a condenser 3 and a drying filter 4 through a three-way pipe, and the other path of the exhaust port is communicated with an inlet of a bypass electric regulating valve 6; an outlet of the front-stage throttling electric regulating valve 5 and an outlet of the bypass electric regulating valve 6 are communicated with a refrigerant channel inlet 7.1 of the heat exchanger 7, and a refrigerant channel outlet 7.2 of the heat exchanger 7 is communicated with a suction port of the refrigeration compressor 2; a secondary refrigerant channel outlet 7.3 of the heat exchanger 7 is communicated with an inlet of a delivery pump 8, an outlet of the delivery pump 8 is communicated with a load heat exchange channel inlet 9.1, and a load heat exchange channel outlet 9.2 is communicated with a secondary refrigerant channel inlet 7.4 of the heat exchanger 7; a pressure sensor 2.1 and a first temperature sensor 2.2 for detecting suction pressure and suction temperature are arranged at a suction port of the refrigeration compressor 2, and a second temperature sensor 8.1 for detecting the temperature of secondary refrigerant is arranged at an outlet of the delivery pump 8; the detection signal output ends of the pressure sensor 2.1, the first temperature sensor 2.2 and the second temperature sensor 8.1 are respectively connected with the detection signal input end of the controller 1; the control signal input ends of the executing mechanisms of the pre-stage throttling electric regulating valve 5, the bypass electric regulating valve 6 and the delivery pump 8 are respectively connected with the control signal output end of the controller 1.

The invention discloses a control method of a fluid temperature control system based on cascade closed-loop PID regulation, which comprises the following steps:

step 1, a controller 1 collects detection data output by a first temperature sensor 2.2, a second temperature sensor 8.1 and a pressure sensor 2.1 in real time;

step 2, when the temperature value of the secondary refrigerant detected by the second temperature sensor 8.1 is higher than the set temperature threshold value by 0.05 ℃, and the difference between the suction temperature and the suction pressure of the refrigeration compressor 2 detected by the first temperature sensor 2.2 and the pressure sensor 2.1 and the temperature value corresponding to the physical property table of the refrigerant is increased by 0.1 ℃ (the temperature difference range is 2-52 ℃, and the opening range of the corresponding front-stage throttling electric regulating valve 5 is 0-100%), the controller 1 compares, judges and amplifies the temperature signal of the secondary refrigerant sent by the second temperature sensor 8.1, controls the opening of the front-stage throttling electric regulating valve 5 to be increased by 2% according to the output regulation control signal of PID, and reduces the temperature value of the secondary refrigerant to the set temperature threshold value by increasing the flow rate of the refrigerant flowing through the refrigerant channel of the heat exchanger 7;

step 3, when the opening of the preceding stage throttling electric regulating valve 5 is controlled to be increased in the step 2, the secondary refrigerant temperature value detected by the second temperature sensor 8.1 is still higher than the set temperature threshold value by 0.05 ℃ and continuously rises to be higher than the set temperature threshold value by 0.1 ℃, the controller 1 outputs a control signal to control the opening of the bypass electric regulating valve 6 to be reduced, and the secondary refrigerant temperature value is reduced to be within the set temperature threshold value by reducing the flow of the refrigerant steam flowing through the refrigerant channel of the heat exchanger 7;

step 4, when the temperature value of the secondary refrigerant detected by the second temperature sensor 8.1 is lower than the set temperature threshold value by 0.05 ℃, and the difference between the suction temperature and the suction pressure of the refrigeration compressor 2 detected by the first temperature sensor 2.2 and the pressure sensor 2.1 and the temperature value corresponding to the physical property table of the refrigerant is reduced by 0.1 ℃ (the temperature difference range is 2-52 ℃, and the opening range of the corresponding front-stage throttling electric regulating valve 5 is 0-100%), the controller 1 compares, judges and amplifies the temperature signal of the secondary refrigerant sent by the second temperature sensor 8.1, controls the opening of the front-stage throttling electric regulating valve 5 to be reduced by 2% according to the output regulation control signal of PID, and improves the temperature value of the secondary refrigerant to the set temperature threshold value by reducing the flow rate of the refrigerant flowing through the refrigerant channel of the heat exchanger 7;

and 5, after the opening of the front-stage throttling electric regulating valve 5 is controlled to be reduced in the step 4, when the temperature value of the secondary refrigerant detected by the second temperature sensor 8.1 is still lower than the set temperature threshold value by 0.05 ℃ and is continuously reduced to be lower than the set temperature threshold value by 0.1 ℃, the controller 1 outputs a control signal to control the opening of the bypass electric regulating valve 6 to be increased, and the temperature value of the secondary refrigerant is increased to be within the set temperature threshold value by increasing the flow rate of the refrigerant steam flowing through the refrigerant channel of the heat exchanger 7.

The refrigeration compressor 2 of the invention adopts R410A refrigerant, and Table 1 is a physical property table of the refrigerant R410A provided by the invention; the physical property tables for other refrigerants can be found in the refrigerant handbook.

The working principle of the cascade closed-loop PID regulation of the invention is shown in figure 2, and a refrigerating capacity/heating capacity PID control subsystem is taken as a front stage, and a compensation heating/refrigerating PID control subsystem is taken as a rear stage.

When the invention works, a smaller temperature threshold range is preset according to design requirements, when the temperature of a control target fluctuates, a disturbance quantity is generated, and if the variation of the disturbance quantity is smaller than the temperature threshold range, the preceding stage actuator carries out adjustment; if the target temperature fluctuation exceeds the temperature threshold range, the rear-stage actuator adjusts in a larger range; the preceding stage actuator plays roles in disturbance quantity amplification and frequency reduction.