Trapezoidal Current Mode for Bidirectional High Step Ratio Modular Multilevel dc-dc Converter

Comparison of the Trapezoidal Current and Stepped 2-Level Modulation Techniques in Modular DC-DC Converter

“…MDCC topology with high step ratio conversion is made up of a stack of series connected N half-bridge sub-modules (SM) that support the high-voltage (HV) side, an active full-bridge converter represents the connection of the low-voltage (LV) side, as shown in figure 1 [19].…”

“…To do this, the same waveform used for the SMs modulation with a Ts phase shift to increase the resulting frequency v L1 while maintaining SM capacitor voltages balance [15]. The output voltage of the first SM v 1 represents the repeating signal with a period of (N.Ts) dictated by the transition timings as illustrated in figure 4 [19]. If the SM capacitor voltages are balanced and equal to VC with a phase shift equal to Ts, a three level time-controlled voltage with an amplitude of V C , center in (N-1).…”

“…Using the stack modulation previously presented, the duty cycles (D 1 , D 2 , D 3 and D 4 ) of the voltages v L1 , v L2 could be managed with two additional phase-shift parameters Φ 1 and Φ 2 to generate a trapezoidal current across the inductor (Figs. 5(a), (b)) [19].…”