An increased efficiency series hybrid electric bus using decoupled DC-link voltages

This paper proposes a new main circuit topology, the back-to-back current fed quasi-Z-source architecture, for the series hybrid electric bus (SHEB) using decoupled dc-link voltages, which will greatly improve system efficiency. This work is based on urban drive cycle operating conditions, the optimal operating region of the internal combustion engine, and the varying voltage requirement of traction motors. The paper presents how the efficiency of the SHEB can be significantly enhanced by decoupling the dc-link voltage at the generator end of the topology from that of the traction inverter end. The analyzed results verify the proposed circuit for SHEB applications.