Interleaved Split-Switched-Capacitor Boost Converter With Continuous Output Current for Electric Vehicle Standalone Photovoltaic Charging Systems

This article presents an interleaved high-gain boost converter for standalone photovoltaic-based electric vehicle charging. The proposed converter is an improvement on the conventional switched-capacitor boost converter, which is achieved by splitting the step-up network and introducing an additional input inductor and switch. The proposed converter features continuous input and output currents while significantly reducing the filter capacitance requirement. As a result, the need for an electrolytic capacitor is eliminated, leading to improved overall system reliability. In continuous conduction mode (CCM), when the driving signals of the two switches have a phase difference of 180 degrees and their duty cycles satisfy the constraint relationship of d(2) = 1/(2-d(1)), the proposed converter automatically achieves current sharing between the two input inductors throughout the entire duty cycle range. This feature eliminates the need for inductor current detection, reduces current stress, and lowers costs. Furthermore, the proposed converter offers twice the voltage gain of a conventional boost converter, with the voltage stresses of all power components equal to or close to half of the output voltage. The working principle, steady-state characteristics, small signal models, and control method of the proposed converter in CCM are thoroughly analyzed. The operation of the proposed converter is validated through a comprehensive 500-W/50-kHz prototype experiment, which demonstrates the correctness of the theoretical analysis. The measured efficiencies are 97.1% and 97.7% at an output voltage of 300 V under full load, with input voltages of 48 and 90 V, respectively.