| Lead-acid batteries have become an irreplaceable product of social development and human life due to its wide application.The formation of lead-acid batteries is the last and the most important process before delivery,which directly affects the quality and service life of the battery.And it is also a process with which chemical energy and electrical energy are fully converted after a series of charge and discharge crafts including constant voltage,constant current,pulse that can be provided by the formation equipment.At present,the formation equipment on the market mostly adopts a multi-channel integrated structure which can increase the production,and it also makes the formation equipment larger in size,complicated in structure,and inconvenient for production management and later maintenance upgrades.In this dissertation,a parallel-connected charger with flexible structure is designed and it can realize independent output of each channel and also realize multi-channel parallel output.Combined with a powerful computer software,process setting,data monitoring,automatic current sharing and intelligent control can be realized in the process of formation,improving the quality and efficiency of formation.The formation principle is firstly studied.The specific electrochemical reaction process in the formation is described in detail with the target and the main parameters of the formation combined with the existing formation algorithms of constant voltage,constant current and pulse.A multi-stage formation algorithm which combines constant current and pulse was developed.Then,the overall scheme of the formation system is designed.According to the formation target and functional requirements of the formation system,the whole system is divided into some units and the specific design scheme of each unit is given.The core part of the formation system which is the bidirectional DC/DC converter is mainly designed;Then the hardware circuit of the system is specifically designed,mainly including: the main control circuit unit,voltage and current signal acquisition unit,four bi-directional DC/DC converter parallel unit,IGBT driver unit,CAN communication unit,and system power supply unit,an overall hardware architecture is built;Finally,based on digital current sharing technology,the method which combined a master-slave current sharing and CAN bus was introduced and detailed description of the specific current sharing strategy and control process.The closed-loop control system is given by small-signal modeling analysis,and the good dynamic performance of the system is verified by simulation analysis.Finally,a four-channel DC/DC converter parallel experimental prototype was developed in this dissertation,and tested various functions and items.Then,a formation experiment was operated with a 6Ah lead-acid battery,compared with the traditional formation algorithm,the multi-stage formation algorithm was preliminarily proved to be effective in this dissertation.From the test results,it generally meets the actual use requirements.However,there are also problems such as insufficient control system,which will continue to be optimized in order to achieve the best performance indicators. |
