Application Research On Battery Management System Of Mine Lithium Iron Phosphate Battery

With the improvement of automation level of mining equipment and the progress of battery manufacturing technology,lithium batteries have been widely used in coal mine monitoring and communication system,emergency evasion facilities and power supply system for reserving emergency rescue equipment.The safe,reliable and stable operation of lithium batteries directly affects the performance of equipment and the safety of life and property of underground workers.In this paper,the state of charge estimation,balanced control management and fault self-diagnosis function of lithium iron phosphate batteries management system for mining are mainly studied in order to realize the state analysis,energy control and safety protection of batteries,improve the inconsistency between single batteries and the safety problems existing in the operation of power system.The research work of this paper is mainly carried out in the following aspects:First,the working principle and characteristics of lithium batteries and the special problems that should be paid attention to in the application of lithium batteries in coal mines are analyzed and studied.The main functions of the mine battery management system and the problems that should be paid attention to in the application of the system in the special working conditions of the coal mine are discussed.Secondly,The state of charge(SOC)of batteries is estimated by the combination of open circuit voltage(OCV)method and ampere-time integration method.The factors affecting the actual capacity of the battery,such as temperature,charge-discharge ratio and aging degree,were analyzed,and the correction coefficients of various factors were determined.At the same time,in order to reduce the influence of cumulative errors on the estimation results,in the critical period of charging and discharging,the battery terminal voltage is used to replace the open-circuit voltage,and the SOC estimation is corrected by the SOC-OCV curve.Third,In view of the inconsistency between individual batteries in series batteries and the specific operating conditions of energy storage batteries in mines,a passive resistance equalization control scheme is adopted to equalize the individual batteries in the charging process.By controlling the turn-on time of each equalization control switch,each cell can achieve equalization at the same time.In view of the limitation that passive equalization is not suitable for discharge state and static state,appropriate control measures are taken to improve the inconsistency between batteries.Fourth,Battery management system is an important guarantee for the safe and reliable operation of batteries.It contains many components,complex structure and high probability of failure.Moreover,the harm caused by its failure is greater than that caused by simple battery failure.For the common fault types in battery management system,the system,module and parts are stratified.The basic theory and characteristics of fault tree are analyzed,and the fault tree model of battery management system is constructed.The relationship between fault performance and fault causes of battery management system is established.Because the faults of battery management system are mostly complex and uncertain events,fault tree has limitations in the analysis of uncertainties.Therefore,a multi-layer Bayesian diagnostic network is constructed,which is more suitable for solving uncertainties.In order to reduce the difficulty of building Bayesian network model,the fault tree model is transformed into Bayesian diagnostic network model by using the intrinsic relationship between fault tree and Bayesian network.