Analysis of the Battery Capacity and Imbalanced Charging Ability for a Cascade H Bridge in Shinkansen Regeneration Energy Storage Application

The Shinkansen, as a highly popular mode of transportation in Japan, consumes and regenerates substantial amounts of electricity energy. Because of the AC power supply of Shinkansen, the energy generated by regeneration braking of the Shinkansen is wasted and sent back to the commercial power grid if there is no other Shinkansen in same power feeding section. To effectively utilize this surplus energy, the ground-based energy storage systems is necessary. Cascade H bridge (CHB) system has advantages such as ease of modularization and low voltage stress on switching devices, making it widely used in high-voltage and high-power applications. The CHB is also used in ground-based energy storage systems of Shinkansen. However, CHB has issues like unbalanced voltage and power between different modules. In this study, the relationship between battery capacity of each module and the maximum unbalanced charging power that the CHB can withstand is studied to ensure that there is sufficient battery capacity during the design phase to guarantee the system has enough unbalanced charging capability.