An Optimal Design and Control of Dynamically Re-Configurable DC-DC Converter for Off-Board Charger Applications

This paper proposes an optimal design and control of a dynamically re-configurable DC-DC converter with a minimal ripple current content at its output for electric vehicle (EV) off-board charger application. Off-board chargers must support a wide output voltage range i.e. 200–1000 V DC, to meet the charging requirements of various EVs available globally. By exploiting the requirement of a wide output voltage range, this paper proposes an intelligent control algorithm that reduces the filter inductance value to 50% of the one used in a conventional interleaved converter. It maintains the minimum ripple at the output by thoughtfully varying the input voltage by adjusting the converter duty cycle with proper coordination with the current ripple cancellation factor. Reduction in the filter inductance size offers the dual advantage of higher converter power density and reduces the cost of the off-board chargers. In addition, high power efficiency is achieved throughout the range of load variations by properly selecting the optimal number of interleaved phases and dynamically allocating the appropriate interleaved angle between the phases that dynamically manage to cancel the ripple current effectively. The proposed algorithms in this paper are first simulated in MATLAB/Simulink and experimentally verified using the TMS320F28335 DSP-based control hardware on OPAL-RT based Hardware-in-the-Loop (HIL) system.