With the improvement of people’s living standards and the increasing awareness of energy conservation, people are demanding more and more energy-saving and environmental-friendly products. Accordingly, people have more and more strict requirements on the performance of solar water heater products in their daily life. At present, there is still some backwardness in the control system of solar water heater in our country, which affects people’s use. Developing an efficient, convenient and convenient intelligent controller for solar water heater has become an urgent problem to be solved. Based on this, this paper takes single chip computer as the core, adds key setting, display function, alarm function to the solar controller, realizes the automation of heating, water supply and other functions, and realizes the functional control of solar water heater. Solar energy, referring to solar thermal radiation energy, is a renewable energy. At present, the wide application of solar energy has become an important part of human energy applications. Solar energy intensity varies with weather and season. Therefore, thermostatic element solar water heaters need to add auxiliary heating devices to ensure that people use hot water throughout the year. At present, most of the products on the market use switch control or PID control. However, due to the complexity of solar energy itself, it is difficult to accurately use digital model to express the heat collection and auxiliary heating process of solar water heater. Traditional control methods have been difficult to achieve customer satisfaction. For this, intelligent control Manufacturer has become an inevitable trend in the development of solar controller. This design mainly takes 89C51 single chip computer as the core of the intelligent controller. After the temperature signal in the temperature sensor and the water level signal in the detection sensor are processed by the single chip computer, the signal will be transmitted directly to the liquid crystal display screen to display the water temperature and water quantity of the current solar water heater. Moreover, when the solar heat is applied, the signal will be transmitted directly to the liquid crystal display screen. If the temperature of the water heater is insufficient and the water level is insufficient, or the water supply is needed, the controller drives the auxiliary heating device on the water heater into working state, and automatically realizes temperature control and water loading. At the same time, the intelligent controller also needs to have the functions of low temperature, high temperature alarm, water level bottom line and high limit alarm. According to the above design tasks and several functions of the intelligent control system, the author considers various functions, intellectualization of the controller and cost issues comprehensively, and realizes the hardware structure of the controller, as shown in Figure 1. In this design study, the author chooses STC89C51 as the central control system of intelligent controller, DS18B20 temperature sensor as the main device to detect water temperature, and 1602 LCD as the instrument to display temperature and water level. When the intelligent controller is in working state, the water temperature and water level signals of solar water heater will be processed and displayed on the display screen by single chip computer. In this design study, the author selected the DS18B20 temperature sensor, which was developed by Dallas Company, USA, and displayed the collected temperature in nine digits. This type of temperature sensor mainly transmits and receives data through bus interface, and the sensor can directly obtain the required voltage through the data line without external power supply, which improves its security. When the DS18B20 temperature sensor is running, it is mostly directly connected with the I/O port of the single chip computer. In this design, the water storage tank is divided into three parts. There are common electrodes on the bottom of the water. The corresponding devices can judge the water depth of the water storage tank through the difference of water level and the potential difference of the electrodes. The specific principle is as follows: first, the single-chip computer transports high level to the electrodes of different water levels in turn; secondly, the common electrodes realize the potential conversion of different water levels, if the water level reaches the corresponding electrode, output low level, if not reached, then input high level; finally, the corresponding device circulates to detect the voltage value, each time it will get four serial data, related equipment. The water level is determined by analyzing the data, and the specific data is displayed on the display screen, so the water level detection process is completed. In the design of the system, the relay device chosen by the author is the electromagnetic relay. It can be seen from the above that when the water temperature of solar water heater is too low, the intelligent controller will issue a heating command and the heating device will automatically open. When the water level of water heater storage tank is too low, in order to realize water supply automation, it is necessary to use water level and signal control switch, that is, to use relay control switch to automatically open water supply mode. The working principle of relay control is as follows: when the relay coil is on, because the relay has electromagnetic induction, the iron core produces magnetism, which produces adsorption force on the switch shrapnel, the switch opens automatically, and the external circuit is turned on. The main principle of the control circuit of electromagnetic relay is as follows: when the switch needs to be closed, the single chip computer will output a level signal, the light-emitting diode will be turned on, then the triode will be turned on, the relay coil will be turned on, the relay will be driven to run, the relay will be closed, and the circuit will be smooth. This system mainly uses LCD1602 LCD display screen. The LCD display of this type can display 16 *2 characters at the same time. The module mainly stores Arabic numerals 0-9, the capitalization of 26 English letters and so on. When the module is in working state, we can see the correlation coefficients of temperature and water level in the display screen only by displaying the dot matrix graphics of the corresponding address of the displayed characters. In addition, because the 1602 display screen identifies the ASCII code in the computer system, ASCII code can be directly assigned when the display module works. The internal drive module of 1602 LCD usually provides eight-bit or thought data bus connection mode. The module has some power interface and control signal interface outside. In the intelligent software design of the system, the initialization settings will be automatically completed when the system is powered on, so that the sensors and control circuits connected by the intelligent controller can complete the preparatory work. At the end of initialization, the program starts to measure the current water temperature and water level of the water heater, and displays the test structure on the LCD screen for users to view and use.
When the water temperature on the display is below the lower limit, the controller will automatically close the switch and the heating relay will work formally to raise the water temperature. When the water temperature rises to the specified value, the heating device will automatically close the switch and cut off the power supply. At the same time, in the design of this system, the author designed three water levels for it. The water level detection device will judge the current water level according to the height of the water level, and inform the user of the current water level in the form of indicator lamp. When the water level is below the minimum value, the controller will control the water relay to close the switch, and the corresponding device will automatically supply water. When the water level reaches the highest level of the water storage device, the relay will be cut off. In the design and research of this system, the automatic adjustment of water temperature and water level has been realized, the intellectualization of water heater has been improved, and the daily application of people has been facilitated. DS18B20 temperature acquisition process is mainly based on its communication protocol. When the core controller of SCM controls DS18B20, firstly, SCM should initialize it and complete the initial settings of registers; secondly, start the temperature conversion function and wait for the corresponding settings to get the temperature; after obtaining the specific temperature values, the relevant settings will read the data register to get the high byte data DH, and so on. Low byte data DL. Finally, the corresponding module connected by the intelligent controller carries out binary calculation and gets the real temperature value, which is displayed by the display screen. In this system, the specific situation that three water level lines of water storage device are submerged by water is the main basis of water level detection process. In water level detection, the controller uses three indicator lights to represent three water level lines, and informs users about the number of water heaters through the change of indicator lights. Through the above-mentioned research on the design of software and hardware of the system, the intelligent controller of solar water heater has been basically completed. In order to ensure the effectiveness of the intelligent controller, the author tested it in practice. First, the test of water temperature display.
The water temperature of this system is mainly measured by temperature sensor, and displayed on the display screen. The range of temperature measurement is between 0 ~90 C.
In the actual test, the author tested the water temperature of the water heater several times. The test results show that the water temperature detection device responds quickly and accurately in this system, and the temperature can be accurately displayed on the display screen.
Secondly, the test of water level display. In the actual measurement of water level, the author measured the water level display through several times of water conveyance and discharge. The results showed that when the water level was higher than the low level, the red light was on; when the water level was lower than the high level and higher than the middle level, the yellow light was on; and when the water level was above the high level, the green light was on.
After measurement, the design and research of the intelligent controller has good effect and can be directly used in solar water heater. In this design, the author has two systems for solar water heater: sunny weather, using solar energy to heat; rainy weather and night using electric energy to heat. Solar water heater mainly consists of exhaust pipe, heat preservation box, overflow pipe, water pipe, vacuum collector pipe, support frame, heat preservation pipe, shower and intelligent controller. This paper mainly introduces the design of intelligent controller. In fact, intelligent controller is an electronic and electrical product. It is mainly used for power supply when solar shower is short of solar energy and automatic supply when water is short. It not only facilitates people’s application, but also promotes the further development and application of solar water heater. After the design of each module of hardware and software system is completed, each electronic system or module is really constructed into voltage collector, temperature detection sensor, charge and discharge controller, water level detection instrument, display screen and so on. Finally, a complete intelligent controller is constructed from the above equipment. The test proves that the intelligent controller is well reflected. This hardware The design of module and circuit, the design of software system and the final installation test show that the final product has a good effect. This paper mainly describes the design and research process of the intelligent controller of solar water heater, in order to change the shortcomings of the traditional controller which can not achieve intelligent control, and to facilitate the user’s view and application. This paper introduces the system hardware of intelligent controller. In this design, the intelligent control system realizes the functions of automatic water feeding and heating, which facilitates people’s application.