Research On The Energy Balance Strategy Of The Cascade Fed Under The Condition Of Multi-path

With the advantages of high energy density and good energy storage effect,battery is widely used.In order to meet the requirements of voltage and capacity,the single battery needs to be used in series.However,the parameters of each battery can not be completely consistent in the production and manufacturing process,which leads to the overcharge or overdischarge of individual cells in the process of charging and discharging of the series battery pack,which will affect the service life and capacity of the whole battery pack.Therefore,it is of great significance to study the safe,reliable,fast and efficient equalization technology to ensure the safety of energy storage system,improve the effective capacity of single unit and prolong the cycle life.According to the series energy storage multi-path equalization circuit,based on the two-stage equalization mode,in order to give full play to the characteristics of the topology,a three-stage equalization mode with inductor continuous energy storage and continuous energy release is proposed,which realizes the group composed of any single body,any two or three adjacent single bodies and any two non adjacent single bodies can participate as energy release or storage units The function of equilibrium greatly expands the equilibrium path and can be applied to more complex imbalances.A simplified model of multi-path equalization circuit is established.The working mode of the equalization circuit and the energy ratio relationship of the single or group participating in the continuous energy storage or release are analyzed in detail after the introduction of the continuous energy storage or release link of inductance.The influence of duty cycle on the equalization performance such as equalization power and conversion efficiency is studied,and the determination method of duty cycle under the critical continuous mode is given.After inductor continuous energy storage and continuous energy release,there are many equalization paths.In the software processing,the framework of combining the bottom level equalization action and the top level equalization strategy is proposed.In order to cover all the abundant equalization paths,the underlying equalization is performed by four kinds of two-stage and 16 kinds of three-stage equalization subfunctions.In order to select the feasible equalization path and solve the order problem,the highest and lowest energy inter cell equalization strategy which is suitable for the condition that the pressure difference of the battery is too large and there is about to overcharge or overdischarge cell is proposed,and the predictive equalization strategy which can effectively shorten the equalization time is applied to the top part.Six lithium-ion series batteries are selected as the research object.The hardware and software of the multi-path equalization circuit are designed,and the multi-path equalization system is built.The simulation and experimental verification of the multi-path equalization system are carried out.The results verify the effectiveness of the three-stage equalization mode of the multi-path equalization circuit and the rationality of the equalization strategy.