High controllability soft switching step-up DC-DC converter with CI, (QBC) structure and VM technique

In this article, an ultra-high step-up DC-DC converter inspired by the quadratic boost converters (QBC) consisting of coupled inductor (CI) and voltage multiplier (VM) technique with high controllability is introduced. The proposed converter is consisted of three boost stages managed to provide a reliable higher level of voltage into the output load. The primary windings side of the CI is incorporated with two switched-capacitor (SC) boost stages which lift up the input voltage and transfer the energy into the output load through the CI. The secondary winding side of the CI is integrated with a VM cell in order to provide the third boost stage to ultimate increase the output voltage gain. Some major drawbacks such as limited output voltage gain, high voltage stress on power switches, low efficiency due to high component count and controllability issues are observed in conventional converters. Compared with the existing QBC structures, the proposed converter can obtain a much higher output voltage under the same duty cycle while mitigating the voltage stresses on semiconductors. The significant advantages of the proposed converter include items such as high voltage gain, lower losses, continuous input current and robust performance which provide a reliable output power for various applications such as renewable energy systems and photovoltaic (PV) energy-based systems. Furthermore, using fewer components and lower voltage stress on switches and diodes, also lower current stress across switching devices due to ZCS performance are among the other advantages of the suggested structure. The presence of a common ground between source and load makes the converter suitable for a wide range of applications. The reliability of the suggested converter is investigated with the help of pole-placement control method to ensure a robust performance. Finally, to ascertain of flawless performance, a 150 W prototype of the proposed converter with 20 V input and 345 V output voltage operating under 50 kHz switching frequency with almost 93% of practical efficiency is built and tested in laboratory. By validating the theoretical analysis with practical results, in the comparison section, the characteristics of the suggested converter such as output voltage gain, voltage stress, efficiency and other major parameters are compared with similar structures to demonstrate the advantages and disadvantages of the proposed converter.