Failure‐mode analysis of modular multilevel capacitor‐clamped converter for electric vehicle application

Abstract

The bi-directional buck/boost converter is being widely used as bi-directional DC/DC converter (BDC) in an electric vehicle (EV) traction system owing to its simple topological configuration. The major drawback of this configuration is in the event of failure of any of the power semiconductor devices and the power supply to the load will be interrupted. To overcome the above drawback, this work proposes a modular multilevel capacitor clamped converter (MMCCC) for EV application employing battery and ultracapacitor (UC) as energy storage sources. The battery-ultracapacitor (UC) combination provides better acceleration capability during high power demands and efficient energy recovery during regenerative braking. The design, control, and failure-mode analysis of MMCCC are discussed in detail to showcase the merits in terms of conversion gain, modularity, and reconfiguring capability under fault conditions. The high conversion gain owed to the modularity of the topology ascertains optimal stacking of UC thus reducing the weight and cost. Simulation is performed in MATLAB/SIMULINK environment, and hardware prototype is fabricated to validate the simulation results.