Bipolar DC-DC Converter Based on LCCT-Trans-Z-Source Topology

In this paper, we propose a bipolar LCCT-Trans-ZSC (Inductor-Capacitor-Capacitor-Trans-Z-source DC-DC Converter) that can mitigate voltage stress and capacitor voltage ripple and generate a bipolar output voltage according to the duty ratio. The proposed method has the characteristics and structure of both the quasi-ZSC and the conventional LCCT-ZSC but replaces the two-winding HF (High Frequency) transformer of the Z-network with a three-winding HF transformer. This method reduces voltage ripple and voltage stress compared to conventional methods, allowing CCM (Continuous Current Mode) operation with reduced input current ripple. For each method, a DSP-based experiment was performed to confirm the validity of the proposed method. The proposed method can generate bipolar output voltages of positive 90 V and negative 50 V with respect to an input voltage of DC 70 V. In addition, as a result of comparing the capacitor voltage ripple of the Z-network and output stage voltage stress under the same conditions for each method, it was confirmed that the proposed method has lower voltage stress (1.3%) and capacitor voltage ripple (10.3%) than the conventional method. In terms of the input current ripple, positive output was similar to each other, but negative output was slightly improved by about (1.14%) in the proposed method. Finally, the efficiency of each method according to the change in load and duty ratio was compared.