A Modularized Voltage Equalizer Based on Phase-Shift Modulation for Series-Connected Battery Strings

The modular design can effectively improve the circuit extensibility and control flexibility of equalizers for long series-connected battery strings. This article proposes a modular battery equalizer based on phase-shift modulation. The LC resonant converters with synchronous rectification are employed as the automatic cell-level equalizer to realize any-cells-to-any-cells (AC2AC) equalization and soft-switching operation, which enhances the balancing speed and efficiency. Different cell-level equalizers are connected with auxiliary windings. The fast equalization between modules is achieved by adjusting the phase shift of driving signals applying for the cell-level equalizers. A prototype with three modules, each consisting of three series cells, is built and tested. Experimental and comparative results confirm the validity and characteristics of the proposed modular equalizer.

Automated summary

This article proposes a modular battery equalizer based on phase-shift modulation, which can effectively improve the circuit extensibility and control flexibility of equalizers for long series-connected battery strings. The LC resonant converters with synchronous rectification are employed as the automatic cell-level equalizer, realizing any-cells-to-any-cells equalization and soft-switching operation. The fast equalization between modules is achieved by adjusting the phase shift of driving signals.