High-Performance Continuous-Current Capacitive Battery Balancer With Flexibility in Battery Cells Connection and Independent of Cells Location

Active cell balancing systems often face significant challenges in balancing speed, operational continuity, configuration flexibility, and volumetric and gravimetric constraints, particularly with magnetic-based solutions. This paper introduces the CS2CAB circuit, which enables continuous charge redistribution based on the average SoC across battery cells, independent of neighboring cell conditions. This approach ensures that cells charge or discharge only as necessary, preventing unnecessary energy transfers, reducing losses, enhancing balancing speed, and improving overall battery health. A mathematical model demonstrates that the balancing currents are inherently proportional to voltage deviations from the pack average, allowing automatic charge redistribution without the need for complex control systems. The CS2CAB circuit supports versatile configurations, operating seamlessly with both series-connected and isolated cells, making it suitable for a wide range of applications. Steady-state analysis highlights that complementary operation optimizes energy transfer paths, minimizing current stress on individual cells while maintaining high balancing speeds. Optimal parameter selection and operational frequency are evaluated to ensure peak performance. Experimental results and simulations under various scenarios validate the design, revealing balancing speeds 2 to 4 times faster than other capacitor- or converter-based systems. Furthermore, the proposed system achieves an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathrm{I_{DC}}$</tex-math></inline-formula>-to-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mathrm{I_{RMS}}$</tex-math></inline-formula> ratio close to unity, outperforming other balancers, which typically exhibit ratios between 1.5 and 5. This efficiency translates to reduced power losses and minimized battery self-heating, underscoring the superior balancing capabilities of the CS2CAB circuit.