A Modular Multi-Level Converter for Energy Management of Hybrid Storage System in Electric Vehicles

This paper presents a novel energy management system (EMS) that for hybrid energy storage devices in Electric Vehicles (EVs). The use of ultra-capacitors as the power pulsating storage device in EVs mitigates the inefficiencies associated with the slow power dynamics of battery cells. Thus, Li-ion batteries can only supply the EV average power due to their high energy density characteristics. Such a hybrid system leads to challenging tasks in managing the energy between the individual battery and UC cells. Additionally, accounting for the motor loading conditions and extending the maximum torque per ampere operation is desirable for an EV drive powertrain. Thus, a modular multi-converter is configured to manage the energy between the different storage cells for an EV application. Furthermore, the use of MMCs eliminates the need for a system-level drive inverter feeding the EV motor. The presented results verify the proposed configuration effectiveness.