Research And Implementation Of Key Technology For Fast Charge Of Electric Plant Protection UAV

With the rise of intelligent agriculture,UAV are more and more widely used in the field of agricultural plant protection.Compared with oil-driven plant protection UAV,electric UAV occupy the mainstream position in today’s plant protection market because of their simple structure and convenient maintenance.However,due to the limited battery capacity,electric UAV can only maintain more than 20 minutes in a single operation.How to shorten the charging time is the key to improve plant protection efficiency and UAV economy.On the basis of studying the structure,working principle and charging strategy of lithium-ion batteries,this paper designs a fast balanced charging device for two to six series lithium-ion batteries.It has high charging efficiency,adjustable charging current and voltage,and equipped with balanced charging protection circuit,which can prolong the cycle life of batteries.The whole system is mainly divided into two modules.The first module is the design of charging circuit.With Atmega32 microcontroller as the core,three-stage constant current and constant voltage charging strategy is adopted to realize the fast charging function of lithium-ion battery pack.The second module is the design of balanced charging protection circuit,which avoids the emergence of single battery when charging several series lithiumion batteries.Charging and undercharging,while avoiding the pressure difference between batteries and affecting the cycle life of batteries,based on the analysis of the necessity of balanced charging,a balanced protection circuit is designed by using the balanced strategy of resistance shunt.After prototype test,for 5300 mAh batteries,the charging time of charging device can be increased to 70 minutes at high current and fast charging,and the voltage difference between single batteries is very small,which proves that the three-stage fast charging strategy and the dividing equalization strategy adopted in this paper are effective.By fast charging,the first is to save the charging time of UAV and improve the operation efficiency;the second is to carry less spare batteries when working outside the field,which reduces the economic cost of plant protection operation.