China Education Equipment Procurement Network News: With the increasing popularity of portable electronic products, the demand for rechargeable batteries is growing rapidly. Although the output of domestic batteries has increased year by year, compared with imported products, there is still a certain gap in the quality and performance of domestic batteries, especially the service life of domestic batteries has been difficult to meet the ideal requirements. Colleetor (current collector), which is a key component that affects quality and performance, must be processed in a constant temperature and low humidity environment for 24 hours to enhance the positive and negative effects of the battery, extend the service life of the battery, and improve the pass rate of the product. Therefore, the control accuracy of the constant temperature dehumidification room has become one of the important factors for battery production quality and performance assurance.

1 Overview

1.1 System indicators

In order to improve the quality and performance of the battery, the establishment of a stable constant temperature dehumidification room is an indispensable and important guarantee link in its production process. At present, the constant temperature control technology is relatively mature, but to ensure the dehumidification effect under constant temperature conditions, the realization of its control is relatively complicated. Using the latest Synco series general controllers from Siemens, we can better control the sealed constant temperature dehumidification workshop with an area of ​​18 square meters.

(1) Main control indicators:

a) The temperature is adjustable from 30 ℃ to 35 ℃, the fluctuation range is ± 1 ℃;

b) The humidity is adjustable from 10% to 15%, and the fluctuation range is 4%;

c) The temperature and humidity of the supply air and return air are monitored, and the online trend status is displayed. The on-site controller and the host computer can modify the setting parameters;

d) Other controlled equipment is only monitored;

e) Both on-site controller and host computer can start and stop control equipment.

(2) Main controlled equipment:

Refrigerator (switch control), electric heater (switch control), dehumidifier (including: dehumidification wheel, regenerative fan, regenerative electric heating), main fan (switch control).

(3) Other monitoring points:

Send back air temperature and humidity, fan failure status, filter clogging, etc.

1.2 Controller selection and point table

Controller selection According to user requirements and on-site control equipment, choose the latest Synco series general controller from Siemens (as shown below).

(1) The universal controller is mainly used for the control of integrated ventilation, air conditioning and cooling water equipment, and handles control variables such as temperature, relative / absolute humidity, pressure / differential pressure, airflow, and indoor air quality. Has the following characteristics:

· The controller can be freely configured to adapt to the relevant model of equipment to the greatest extent.

· Modular expansion.

· The menu-driven operation is performed by operating machines (plug-in type or separate type) respectively.

· Konnex bus connection for operation and program information.

(2) The general controller input is mainly used for:

Passive or active analog input signal, the input signal parameters related to: ℃,%, grams / kg, KJ / kg, watts / m2, bar, mbar, m / s, Pa and ppm

· Digital input signal (no potential contact).

(3) Basic functions of several controller models:

Model parameters Universal input positioning output switch output control ring number default language

RMU710-26221 German, English, French, New Latin

RMU720-28342 German, English, French, New Latin

RMU730-28463 German, English, French, New Latin

(4) Selection of automatic control equipment: According to the requirements of use, the system selects one RMU73O-2 controller. The system has three control loops, temperature, humidity, humidity differential control regenerative fan, etc. The specific control point table is as follows:

Model AIAODIDO circuit

RMU73O-24O353

Other equipment options: 1 embedded operation panel (RMZ790), 1 set of software and operation tools (OCI700.1), 2 air duct temperature and humidity sensors (QFM3160), 2 differential pressure switches (QBM81-5), air valves One actuator (GDB331.1E).

(5) Main functions of RMU730-2 controller:

The sequence controller has 3 heating sequences (reverse action) and 2 cooling sequences (positive action), can be used as a controller, providing P-, PI or PID mode, or used as a differential controller;

· Each sequence can be assigned as modulation control;

2 kinds of sequences can form the same analog control (such as priority cooling / dehumidification);

General limit function (each sequence controller forms a maximum / minimum function in PI mode), can be used as an absolute limit (such as for supply air temperature or supply air humidity), and can also be used as a relative temperature limit (such as indoor / send Wind and temperature difference). Restrictions apply to all orders.

1.3 Application Notes

The door of the battery constant temperature dehumidification room is opened once every twelve hours to pick and place the components. The rest of the time has been sealed to ensure that the components are fully dehumidified in the dehumidification room to meet the technical requirements of battery dehumidification.

(1) Application of dehumidifier in control

· The dehumidifier includes three parts: dehumidifier wheel, regenerative fan, exhaust fan, and electric heating.

· The opening of the dehumidifying wheel is based on the comparison between the actual value of the return air humidity and the set value of the controller, and is controlled by the output signal of the controller. There is an electric heater in the dehumidifier, which heats and evaporates the water on the dehumidification wheel and is discharged by the exhaust fan.

· The dehumidification effect is ideal or not, according to the difference of return air humidity, the closer the return air humidity value is, the worse the dehumidification effect is. At this time, the regeneration fan needs to be turned on. The regeneration fan directly blows the dehumidification wheel to accelerate the Water evaporates.

1.4 Main technical difficulties

According to site conditions and control requirements, there are several issues to consider:

(1) The controlled devices are all controlled by switches, the temperature should be kept at ± 1 ℃, the proportional integral time should be carefully adjusted on the controller, and the VARSTEP module and PUMP module should be selected according to the working conditions of the device.

(2) When the dehumidifier's dehumidification effect is not good, the regenerative fan and regenerative electric heating will be turned on. At this time, the energy of the dehumidifier and electric heating may affect the temperature and humidity, and will it cause disturbing fluctuations. When necessary, a temperature control switch should be added to the regenerative electric heating to prevent high temperature from affecting the temperature of the dehumidification room.

(3) If the dehumidifying wheel is particularly effective in absorbing moisture in the air, will it overshoot (the actual humidity value is lower than the set value), etc.

2 control scheme

2.1 Control scheme

The control system installs QFM3160 temperature and humidity sensors near the air outlet of the dehumidification room and the return air duct to monitor the temperature and humidity of the air supply and return air. In the actual system, the temperature and humidity of the fully mixed return air inlet should be closest to the greenhouse degree of the dehumidification room, so it is used as the temperature and humidity control target, that is, the temperature and humidity sensor is controlled. The effect and accuracy of the control system depends not only on the electrical characteristics of the control system, but also to a large extent on the design of the control scheme, the selection of the actuator and the determination of the control mode and parameters.

(1) Temperature control: control the refrigerator and electric heating according to the return air temperature. The actual temperature is higher than the set value of the controller, the refrigerator is turned on; the actual temperature is lower than the set value of the controller, the cold machine, and electric heating are turned on.

(2) Humidity control: control the dehumidifier based on the return air humidity. The actual humidity is higher than the set value of the controller, the dehumidification wheel is on, and the actual humidity is lower than the set value, the dehumidification wheel is off.

(3) Control of regenerative fan and regenerative electric heating: determine the dehumidifying effect of the dehumidifier based on the difference between the supply air humidity and the return air humidity. If the difference in humidity is very small, it is judged that the dehumidification effect is good, and the regenerative fan and regenerative electric heating can be started; when the difference is greater than the set value, the regenerative electric heating is turned off, and at the same time, the regenerative fan is turned off for a period of time to take away the residual heat.

(4) Filter detection: install differential pressure switches on the primary and intermediate efficiency filters to monitor the dust suction effect of the filter, determine whether the filter is clogged according to the differential pressure, and alarm on the controller to prompt to take measures.

(5) Fan status detection: monitor the fan operating status (such as on / off, normal / fault, etc.), and provide corresponding protection measures according to the operating status. When the fan stops or the fault stops, the controller alarms, prompts the fan to fail, and immediately stops all controlled equipment to protect the air conditioning unit.

(6) The linkage between the air valve and the fan: the air fan operates and the air valve opens; the air fan stops and the air valve closes.

2.2 System configuration

The entire control system consists of software and hardware.

Software part: ACS7 software, support online trend graph and online control.

Hardware part: The on-site controller adopts Siemens Synco series universal controller RMU730-2 and controller operation panel RMz791, etc., and the actuators and sensors are selected from supporting imported products. The controller is connected with the host computer, so that the system can achieve remote control and monitoring functions. The temperature and humidity sensor QFM3160 senses the temperature and humidity of the supply air, and controls the temperature and humidity of the dehumidification room through the controller and the actuator. The differential pressure switch QBM81-5 monitors the primary and intermediate efficiency filters, detects the obstruction of the air duct and alarms. The system control execution mechanism includes: chiller, electric heating, dehumidifying runner, regenerative fan, regenerative electric heating, main fan, etc.

2.3 Human-machine interface

The man-machine interface of the system is simple and clear, easy to control, and has the indoor temperature and humidity trend graph display function. The control interface adopts on-site process mode and modular structure.

3 Software design and system debugging

3.1 Control flow

According to system functions and control objectives, combined with system structure, performance of actuators and sensors.

3.2 RMU730-2 controller configuration

Siemens RMU7xx series controllers have 5 pre-programmed applications for each model. Some of these applications require expansion module support.

When commissioning a device, the relevant device model must be entered first. Then, activate all relevant functions, terminal assignments, settings, and displays, and at the same time, invalidate unnecessary parameters. In addition, each universal controller is loaded with 3 empty applications:

· 1 for base type A (ventilation controller)

· 1 for base type C (refrigeration controller)

· 1 for basic U (universal controller)

Using the operating machine RMZ790 or RMZ791, the controller can:

Activate pre-programmed applications.

· Modify pre-programmed applications.

· Freely configure the application.

· Optimize controller settings.

The "basic U (universal controller)" is selected on the RUM730-2 controller used in this system, that is, the "U mode" is selected in the controller mode. According to the control requirements, draw the connection diagram on the RMU730-2TYPEU module diagram, and adjust it gradually during the debugging process.

3.3 Description of main functional modules

1) Control main fan module application

This function module is more used in water pumps and mediation valves. The pump can be operated only when the mediation valve is opened. The valve opening can be set to a few percent when the pump starts to run, saving energy and avoiding holding back the pump. Because the percentage can be set, it is based on the output y of the controller. If you set 30%, y outputs 3.0V. At this time, q outputs the switch signal. In the dehumidification room control, ON is set to 0% and OFF is set to 0%, q always has an on signal, and the off signal is output only when the power is off or protected.

2) Humidity difference control loop application

Humidity difference control uses controller3 control loop. Comparing the return air humidity and the supply air humidity, the regeneration fan is turned on when the humidity difference is less than 4%. In the dehumidification room, the supply air humidity is always greater than the return air humidity. For the differential control of the return air humidity, the input NX1 must be connected to the Main of the controller3 module. The supply air humidity input NX4 must be connected to the Differential of the controller3 module, so that the controller3 module The difference between the supply air humidity and the return air humidity will be calculated at any time. If NX1 and NX4 are connected in reverse, a negative value will appear, and it will always be considered that the dehumidification effect is not good.

The difference setting method is to set the values ​​of ¤uppercomfsetp and ¤Lowcomfsetp of the controller3 module to the same number, and perform the difference calculation.

4) Alarm module application

The FAULS alarm module can accept four different alarm messages. During the alarm, the red light flashes, and the alarm message is displayed on the panel. In the RMU7xx series controller, the alarm message is written according to the actual situation on site (English only). This system mainly has an initial effect filter and an intermediate effect filter alarm, and a fan failure alarm.

3.4 Problems encountered in debugging and solutions

1) Set the module connection on the controller according to the preliminary connection diagram of the dehumidification room module. Observe for a period of time and find that the main fan cannot afford

Because the main fan is controlled, when the main fan is not available, the controller has considered that it is the protection mode, and the controller button turns red. The module is connected only according to the control connection diagram, without PID and program parameter settings. Under normal circumstances, the main fan affects the fan according to the start and stop of the controller. In the controller, the fan occupies the positive proportional contact of the humidity difference circuit and is connected to the step module. When the proportional output is 0%, the fan starts. That is to say, when the controller is running normally, the fan is always started. Only in the protected state, the fan stops.

2) Further debugging found that the temperature and humidity fluctuation range is large

The temperature and humidity fluctuation range is relatively large, mainly because the PID and other parameters of the controller are not coordinated with the entire control system. It is necessary to analyze the heat capacity of the system and then explore and set it, and wait for a system stability time through the experiment to gradually debug.

3) The indoor humidity meets the requirements, but the regeneration fan does not turn off

According to the system settings, the humidity should meet the set value and the dehumidifier should be turned off. The humidity difference is greater than 4%, the regeneration fan is not turned on, and the humidity difference is less than 4%. The dehumidification effect is considered to be poor. Moisture is dried and taken away to improve dehumidification efficiency. But the humidity is within the setting range of the controller. If the humidity difference is greater than the setting value, the regenerative fan and regenerative electric heating are also started according to the system settings, which is not allowed and will damage the dehumidification wheel.

4) Fan linkage control

When the system requires the controller to run normally, the fan will run. When the system is designed, the controller will be given a digital signal in the normal running state. In the TYPEA mode, this control can be completed by the air supply module. In the TYPEU mode, the Varstepswitch module can be used to adjust the signal input value to give the switching value, so that the set value is 0%, when the controller is running normally, the fan has control signal.

4 Conclusion

In the battery dehumidification room temperature and humidity control project, some technical requirements are different from other constant temperature and humidity projects. The humidity value is very low. It is far from being achieved by refrigeration and dehumidification, so special equipment-dehumidifier is used.

The requirements of the dehumidification room are constant temperature and humidity, and the humidity requirement is 10% to 15%. This humidity value requirement is very different from the air conditioners in other purification workshops, purification workshops, and pharmaceutical factories. However, after applying professional dehumidification equipment, only one switch point is controlled, and the production requirements of the battery can be fully achieved by adjusting PID and regenerative fan chain control. The interlocking control of the regenerative fan and dehumidifier requires the requirements of professional air-conditioning technicians. When formulating the control plan, if the contradiction between the humidity difference and the regenerative fan is not taken into account, the humidity will be lower than the set value, which may damage the dehumidification wheel. Due to the interlocking of regenerative fan and regenerative electric heating, if the runner does not rotate, the electric heating only heats the local area, which has serious consequences. Through the controller output external wiring connection input to the regeneration fan a priority stop signal, so that the regeneration fan and the dehumidification wheel are interlocked, coordinate work, and complete humidity control.

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