Seamless controlled parallel bi-directional DC-DC converter for energy storage system

A scalable parallel bidirectional DC-DC converter system, which enables efficient seamless control using an H-bridge topology, was developed and evaluated. Although the unified control structure is simple, four drive-mode, both charge and discharge with buck/boost, can be handled. The proposed system was extended for use in simple parallel converter management. This scheme achieves high efficiency over a wide load range, especially for light loads. The only hardware required is a power line and communication cable connection. All other functions are provided by software and operate autonomously. A 5-kW prototype converter was constructed and evaluated, and a four-unit parallel converter system was tested and confirmed to work well, changing load between 20-kW discharge and 20-kW charge.