The Design Of The Battery Management System In Solar System

With the rapid development of our society, the Energy crisis is becoming more and more prominent. Solar is deemed as a green, non-polluting and inexhaustible energy. In the past several years, the research and usage of solar have got an unprecedented development. But, Due to the influence of the environment and climate, the energy produced by solar is unstable. Usually, this energy is stored in a series of battery whose output is stable. All the time, the lead-acid battery is used as the storage of the energy, but the lead-acid battery has disadvantages of large volume, low energy density and so on. And the Lithium-ion battery is thought an excellent alternative of the lead-acid battery, because of its advantages.Compared with the lead-acid battery, the Lithium-ion battery has advantages of higher voltage, smaller volume, lighter weight, higher energy density and longer life, and recently, it has been used in many aspects, such as handset, laptop, electric bicycle, and electric vehicle and so on. But there is hidden danger when using Lithium-ion battery connected in series. As a result, the battery management system is needed to protect the Lithium-ion battery series working well. At the same time, a good management system can prolong the battery’s cycle life.In this paper, A fully function Li-on battery management system, which can be used in street lighting using solar energy as its power, electric bicycle and so on, is designed in the light of the characteristic of solar and lithium-ion battery. The Li-on battery series are charged by the power supplied by solar. The system will control the process of charging and discharging, and protect the battery series during it is working. The hardware’s design and software’s design of the battery management system is mainly introduced in this paper According to the module design ideas, by contrast and detailed analysis, the charging circuit, the voltage and current sampling circuit, balance circuit, protection circuit, and temperature measuring circuit are designed in this paper. And the disturbance observing method is used to realize MPPT (Maximum power point tracking) of the solar in software designing. LPC2138whose kernel is ARM7, is chose as the main controller unit, and the operation system, UC/OS-Ⅱ, is embedded in the controller unit.With the Experimental verification, the Li-on battery management system designed in this article has advantages of safety working, cheap in price, well performance in anti-interference, precise in calculating SOC (State of charge), and the value of voltage of the battery and the charging current are also very close to the real value. And the MPPT function is also achieved.