Numerical Control Constant Current Power Supply Based On Solar Energy

Power supply is the most important part of electrical equipment and it’s the power source of the work. Solar energy has the advantages of large reserves, renewable, no pollution, so it has been widely concerned, many industries will develop solar energy as new hot spot. For some remote areas and no power supply area, solar energy have an important role, whether it’s for scientific research, data monitoring, emergency communication, livelihood or production. With the development of science and technology, photovoltaic panels, batteries and components costs drop dramatically. It offers a variety of solutions for the efficient, low cost and widespread use of solar energy. At the same time, electronic equipment on the power of the increasingly high demand. Due to the external components, large volume, low conversion efficiency characteristics, analog power supply has been unable to meet the requirements, so the current power supply are mainly using the micro controller to control the digital switching power supply, which has fewer external components, small size, programmable, upgrading and flexible features.This paper designed a digital constant current power supply based on solar energy, which can be used for the application of solar street lights, traffic warning lights or in power supply area for data monitoring, scientific research and so on. The first chapter introduces the development and utilization of solar energy, advantages and disadvantages of the analog power supply and digital power supply; The current technology and application of parallel power supply; The second chapter mainly introduces the switching power supply technology and photovoltaic battery charging control technology; the third chapter introduces the system architecture and finished the hardware design; The fourth chapter completed the software design; The fifth chapter completes software testing, hardware testing and results analysis.The hardware design is divided into three parts: the first part is to design a solar charging controller, which used to convert the solar energy stored in the battery(charging), charge controller with maximum power point tracking(MPPT) and overvoltage, overcurrent and discharge(undervoltage) protection function, the charge control mainly by the microprocessor output a certain duty cycle PWM wave to control the switching state of FET, charging the battery; Overvoltage, overcurrent, over-discharge(undervoltage) and other protective measures mainly through the ADC, the current sensor, operational amplifiers and other components collected array of photovoltaic cells output voltage, output current and the battery terminal voltage, charge current to achieve, through the acquisition value compared with the set value, if the acquisition value exceeds the safe working set value, the associated protective measures taken by software. The second part is to design a constant current power supply, which can set the output current through the keyboard, it use the closed-loop operational amplifier control mode, DAC converted the preset current value to an analog voltage, the analog voltage is applied to the back-end circuit, achieve the constant current output; Current sensor, ADC and operational amplifier constitute the voltage acquisition circuit, collecting the actual current value of constant current power supply, and displayed on the LCD. The third part is to design a power supply parallel current controller to achieve two constant current power supply equally shared the load power, to achieve the purpose of expansion the current and meet the high-power load demand for electricity, and when the load or input voltage changes, can automatically adjustment, this part mainly using ADC module, operational amplifiers and current sensors to make up the current acquisition circuit, collecting the total load current, use the single-channel constant current real-time value compared to the half of the load current value, if less than,the constant current power supply output value will be gradually increased up to the half of the total load current; if greater than, permanent current source output value will gradually reduced to the half of the total load current, and so forth, the two constant current power supply shared equally the load power.Finally, we use EDA software Candence 16.6 for simulation and Tektronix DMM4050 Digital Multimeter for actual test. By analysis the result of simulation test and hardware test, the system achieved it’s desired function.