Simultaneous Series-Parallel High-Speed and Accurate Active Cell Balancing for Improved Battery Life

Active Cell Balancing based on DC-DC converter has become prominent due to its improved balancing accuracy, high energy conversion efficiency, and modularized approaches to balancing the charge in cells. It is widely employed in emerging applications such as electric vehicles, UAVs, and renewable grid storage to enhance battery life. The state-of-the-art active cell balancing techniques employ separate cell balancing for series and parallel connected cells. However, during separate balancing of cells in series and parallel configuration, the cell balancing system suffers from high system latency, low balancing speed, and higher power consumption due to a large number of balancing components. This article introduces a simultaneous series-parallel Flyback converter-based PWM duty cycle controlled Active Cell Balancing methodology with Constant Current-Constant Voltage (CC-CV) charging/discharging. The battery pack model was simulated with capacity and State-of-Charge (SOC) imbalances. The results show an improvement of 32.5% in balancing time and 81.47% reduction in power consumption without compromising the balancing accuracy when compared to balancing series and parallel cells separately in state-of-the-art active cell balancing methodologies. This helps to prolong battery lifetime and improve safety.