Research On Non-energy Consumption Balance Of Power Lithium Battery For Automatic Guided Vehicle

With the continuous upgrading of industrial upgrading,labor cost and production requirements,the demand for intelligent manufacturing has become more and more obvious,and many manufacturing industries have started the road of transformation.In the new development situation,the AGV plays an important role.In actual production,multiple lithium batteries in series and parallel are needed to form high-voltage and high-capacity lithium battery pack to provide power source for AGV.Due to the limitations of production process and separation technology,it is difficult for monomers in the same production batch to be completely consistent,which will be more serious in the use process and affect the service life.Therefore,it is very important to adopt balanced control to improve the imbalance of lithium battery.This article has studied the balanced structure of lithium battery packs,and has studied the working characteristics and design difficulty of the energy consuming balanced structures and Non-energy consuming balanced structures such as switched capacitor type,switched inductor type,transformer type,and hybrid type.Method,equalization rate,and efficiency,summarize the advantages and disadvantages of various balance structures.This paper proposes a new switched capacitor non-energy-consumption equalization structure,and designs and builds an equalization system suitable for 24 V lithium battery packs.This structure has high balance efficiency and good balance rate,simple structure and strong expandability.The main circuit of the system balance uses a bidirectional Buck/Boost converter.By analyzing the working mode of the SCM in the Buck and Boost modes of the main circuit,The conditions under which both bridge arms work in ZVS are demonstrated through analysis.Parameter calculation and device selection are performed according to system requirements.The circuit is simulated using PSIM software to verify the feasibility of the circuit.Balanced system selects STM32F103 as control core,and the system was designed from the aspects of hardware and software.The hardware part includes the structure of a single voltage monitoring module built with LTC6811,opto-isolated drive module,converter sampling module,and a switch matrix,expounds the design and working principle of each module.The software part introduces the main functions of the controller and the selection of the balanced strategy,and describes the program design framework in the form of a flowchart,including the main program,the subroutine for monitoring the single data,and the subprogram for the equalization control.Finally,set up an experimental prototype of a balance system,and perform an balance experiment on a 24 V lithium battery pack composed of 6 strings of cells.The experimental observation shows that the consistency of the cell is improved,the system realizes constant current charging and discharging of the cell,and Converter works at soft switch mode,which reduces the system loss.