Field Validation of a Heat-Optimized Active Battery Balancing Architecture With Integrated Communication for Grid Energy Storage Systems

This article presents an active balancing architecture that unifies energy transfer and communication on a single AC bus, using pulse-frequency modulation for broadcast control and daisy-chained UART for feedback. By operating balancing on the mandatory communication line, the system leverages redundancy already required by functional-safety standards while reducing wiring complexity. The architecture was validated across three contexts: sodium-ion modules from the NAIMA project, an NMC pack in CurrentDirect, and a 180S4P industrial LFP ESS operated for over 9000 hours. Across all systems, the platform maintained stable operation and consistent voltage-spread control. A key advantage is the low thermal footprint of the Voltage Balancing Units (VBUs), which remained below 45${}^{\circ}$C under continuous operation. This behavior supports high-density packaging and positions the approach as a strong candidate for integrated, IC-ready BMS designs.