Active Equalization Circuit Of Series Lithium Battery Based On Energy Bus

With the rapid development of the new energy industry,more and more products use lithium batteries to replace traditional power devices.The safety of lithium batteries has also attracted more and more attention from users.In the use of lithium batteries,the state of charge of lithium batteries is an important prerequisite for their safe use,so the battery equalization circuit was born.Two sets of balanced topologies are proposed in this article,one of which is a simple,low-cost,and light-weight new topology of a series-connected battery active equalizing circuit,which is suitable for the scene of low-power electrical appliances.The topology is based on the “Energy BUS”,which allows serially connected batteries to exchange energy at the same time.The energy exchange is very intelligent and can be carried out automatically according to the voltage of each battery.The higher the battery voltage,the more energy it outputs;the lower the battery voltage,the more energy it absorbs,without the need for a single-chip microcomputer or embedded controller.In this topology,the MOS tube is used to convert the DC battery voltage into an AC voltage,and the amplitude of the AC voltage is proportional to the battery voltage;then the capacitor is used to transmit the AC voltage to the Energy Bus to realize energy self-balancing according to its voltage amplitude.Furthermore,there is not need of heavy components in this circuit,such as transformer or power inductor.So that the weight of the equalization circuit is very low,which is very suitable for the application of aerospace.Another active equalization circuit topology uses a DC-DC converter as the core component,and uses the energy of the entire battery pack to charge the lowest voltage battery.This topology is suitable for high-power battery packs.In the control strategy,starting and stopping the equalization is well controlled by setting the appropriate thresholds of voltage difference between each cell.The effectiveness of the first topology is verified by simulation results and experimental results.And 5 series of battery experiments system is built.And because the motor drive chip is used instead of MOS during the physical production,the circuit cost is also lower.When the voltage difference between cells is 1V,the equalization current can reach 180 m A.Aiming at the second set of equalization circuit topology,experiment board which can sample and equalize 16 batteries is manufactured.The experimental results verify the effectiveness of the proposed equalization system.The actual test results show that when the battery voltage is between 2.8-3.9V,the balance current can be maintained above 2A,and the maximum equalization current can reach 2.5A.