Due to differences in installation capacity and retirement time

the capacity of retired lithium batteries (RLB) for electric vehicles is difficult to maintain consistently. However

the existing energy balancing schemes based on modular multilevel converters (MMC) cannot balance the energy of non-equal capacity RLB. Therefore

an energy balancing scheme for non-equal capacity RLB of electric vehicles based on high-level high-power MMC is proposed

and the state of charge (SOC) parameter of RLB is used to characterize the energy state of RLB. The impact of capacity differences on SOC balance is analyzed. The active power redistribution modules for the MMC upper and lower bridge arms

phase to phase

and sub module (SM) RLB are designed

which achieves output active power of RLB proportional to its capacity

and eliminates the impact of capacity differences on SOC balancing. An improved three-level SOC balancing control strategy is proposed to achieve SOC balancing of RLB in the MMC upper and lower bridge arms

interphase

and intra SM. The simulation results of Matlab/Simulink and the experimental results of the low-power experimental platform show that the proposed scheme can achieve SOC balance of equal/non-equal capacitance RLB in MMC upper and lower bridge arms

phase to phase

and SM.