Minimum Inductor Current Tracking in DAB-Based Isolated DC/DC Converter for Q Control With Harmonic Analysis Approach Employing FOGI Filter for EV Applications

This article presents an improved control technique based on a triple-phase shift (TPS) modulation scheme to manage the reactive power flow into the dual active bridge (DAB)-based isolated converter over a wide electric vehicle’s (EVs) voltage range. The reactive power circulation in the high-frequency transformer (HFT) of the DAB converter during a light load condition is high with conventional control schemes like single-phase shift (SPS), DPS, and EPS due to the limited range of ZVS operation and high leakage inductor peak current. The proposed TPS modulation technique adjusts the inner and outer phase shift ratios as per operating loading condition and reduces the peak of the leakage inductor current, which in-turn reduces the reactive power flow. For the same, the mathematical analysis of the DAB-based isolated topology with TPS control by using the Fourier series (harmonic analysis) is developed to reduce the intricacy encountered with the linear piecewise time domain analysis. By employing fourth-order generalized integrator (FOGI)-based filter, the fundamental components of ac link parameters of H-bridge, such as current and voltage, are extracted. The extracted fundamental components are then passed through the inverse P&O algorithm to obtain the optimal inner phase ratio for reactive power flow control. Further, through proper analysis, ZVS range with proposed TPS technique is also developed and its subsequent impact on switching loss, and efficiency is also presented. The simulations of the proposed modulation technique have been validated using MATLAB/Simulink. Further, the experimental prototype has been developed with a 1 kW system to verify the effectiveness of the proposed control algorithm.