The current energy shortage has become an important factor restricting social and economic development. How to achieve efficient energy use is an important issue we face. As a new type of green light source, LED has the characteristics of energy saving, environmental protection, long life and small size, and it is more and more widely used in real life. Nowadays, solar panel charging technology has been greatly developed. Many of the street lamps on both sides of the road are charged by solar energy. The existing charging and lighting technologies work according to the preset settings, and cannot be automatically adjusted according to changes in the environment, so that the energy utilization rate can be further improved.
In the original charging technology, the angular position of the solar panel is fixed, so the angle of the sun's illumination in a day is also different. This makes solar charging impossible to achieve maximum efficiency. If the design system can adjust the angle according to the change of the sun position during the day, the charging panel is always facing the sun and obtain the maximum illumination, which can greatly improve the charging efficiency. When lighting at night, you can adjust the brightness of the LED according to the lighting of the environment, as well as save energy.
The MSP430F169 microcontroller used in this system is a 16-bit ultra-low power mixed-signal processor produced by Texas Instruments. It has the advantages of ultra-low power consumption, powerful processing capability, and rich on-chip peripheral modules. Used in some low power products.
1. Overall system design
The intelligent charging lighting control system is mainly composed of the following modules: optical signal detecting module, MSP430 single chip module, motor control and driving module, solar panel charging module, LED lighting module and the like. When the system is running during the daytime, the light signal detection module will detect the light intensity in different directions to find the maximum light intensity, that is, the sun light angle. The rotation of the motor is controlled by the single chip processing, so that the solar panel can face the light and charge with maximum efficiency. In the evening or at night, the photoresist is used to detect the brightness of the external environment, and the current flowing through the LED is controlled by the single-chip microcomputer, so that the illumination can be automatically adjusted according to the ambient brightness.
2. Analysis and explanation of each discrete module of the system
2.1 Optical signal detection module
The optical signal detection module mainly uses different phototransistors as sensors to detect the illumination intensity at different angles of the outside world, and converts the non-electricity of the illumination intensity into a current and sends it to the AD of the single-chip microcomputer for further processing. When exposed to light, a photocurrent is formed inside the phototransistor from the base into the emitter, resulting in an amplified signal current in the collector loop. Compared with photodiodes, it has a large photocurrent amplification effect and thus has high sensitivity.
2.2 MSP430 MCU module design
The system MCU module adopts the MSP430F169 minimum system board. When the charging mode is working, the AD sampling module is used to collect the output voltage value of the optical signal detection module. According to the analysis of the collected voltage changes, the control signal is generated to control the rotation of the stepping motor to realize the tracking of the sun illumination. And positioning. When the illumination mode is working, the MCU can use AD to collect the voltage value of the photoresistor, and generate data to process the control information to control the brightness of the illumination LED to realize the automatic brightness adjustment function.
2.3 Motor Control and Drive Module
The module mainly uses the control information generated by the single chip to work, so that the panel rotates at a certain angle to achieve the purpose of direct sunlight. The motor drive circuit is realized by the motor drive chip L298N. L298N is a constant voltage constant current bridge type 2A driver chip produced by SGS. It contains 4 channels of logic drive circuit. It can adjust the output voltage directly through the power supply. It can also directly use the IO port of the microcontroller to provide signals. The circuit is simple and easy to use.
2.4 LED lighting module
Since the LED is current driven, the module should be designed to include a current source module. The module can convert the ambient brightness value detected by the photoresistor into a voltage change during night illumination, and the data processing of the single chip module controls the current flowing through the LED to realize the function of automatically adjusting the brightness of the LED.
The input of this module is the output voltage of the microcontroller DA. After the input signal passes through the op amp and NPN, the C-pole current of the NPN is a constant current source. Therefore, LEDs can be driven to achieve LED illumination.
3. System software design and analysis
The system software design is mainly through the program design to enable the MCU to realize the data analysis and control circuit work. The MSP430F169 microcontroller has a 12-bit 8 external channel continuous approximation analog-to-digital converter (AD) module and a 12-bit digital-to-analog converter (DA) voltage output module. When the system works, the single-chip AD collects the detection voltage value of the phototransistor. After processing by the single-chip microcomputer, the DA converter converts the digital signal into an analog signal and adds it to the motor drive module, and drives the motor to rotate to face the sun illumination for maximum efficiency charging. . In addition, during illumination operation, the optical acquisition module converts the optical signal intensity change into a voltage change, and inputs this voltage to the AD module of the MSP430 microcontroller to achieve data acquisition. The data is processed by the microcontroller and the digital signal is converted to an analog signal by the DA module to the LED lighting module. This method can automatically change the brightness of the LED according to the change of external light intensity.
4. Design feasibility analysis
The system includes two parts: smart charging and LED lighting. When charging, the system can obtain the angle of sunlight according to the detection and analysis, and control the rotation of the motor, so that the solar panel can face the sunlight with the largest area, and can fully utilize the sunlight to charge. The intelligent LED lighting part uses the photoresistor to detect the brightness of the external environment, and then analyzes the brightness of the control current control LED through the single-chip analysis. The combination of these two parts can maximize the charging efficiency and automatically adjust the brightness of the lighting according to the ambient brightness. It can fully save energy and plays an important role in today's low carbon life and energy conservation. In addition, the system is simple in design, low in cost, easy to operate, and highly feasible.
The design of the system fully considers the current social theme of energy conservation, and combines existing technologies and principles to improve the charging lighting system. With the development of science and technology, the efficient use of energy technology will be more mature, and the society will further strengthen energy conservation.