A Novel Closed-Loop Control Method for Li-Ion Batteries Connected in Series Power Supply Based on the Time Sequences Recalculation Algorithm

The charging time of Li-ion batteries connected in series (LBCSs) power supply is the main concern in an electromagnetic propulsion system. However, the capacity loss of a Li-ion battery is inevitable due to the repetitive operation of LBCSs power supply, which leads to the decrease in the average current. Thus, the voltages of symmetrically distributed pulse capacitors of LBCSs power supply will not reach the setting value in the specified time. This paper proposes a novel closed-loop control method to solve the problem. By collecting the pulse capacitor voltage and the circuit current, the time sequences of Li-ion batteries are recalculated in real time in a closed-loop to increase the average current. The time-domain model of the circuit topology of the LBCSs power supply and an innovative closed-loop control method based on the time sequences recalculation algorithm are described first. Then, the circuit model is built in PSIM for simulation analyses. Finally, a series of experiments are conducted to confirm the effectiveness of the method on the megawatt LBCSs power supply platform. Both the simulation and experimental results validate that the proposed method not only shortens the charging time, but also increases the average current. In practical experiments, the charging time is shortened by 4.5% and the average current is increased by 4.8% using the proposed method at the capacity loss of 50 V.