A Family of High Step–Up DC–DC Converters With Nc Step-Up Cells and M–Source Clamped Circuits

In this paper, in order to study the relationship among different converters, a novel concept-modular high step-up converter-is proposed, which is composed of one basic converter, one N_c step-up cell (N_c-SUC), and one M-source passive lossless clamped circuit (PLCC). N_c means the number of capacitors in step-up cell and M-source represents the number of capacitors in PLCC. N_c-SUCs composed of many voltage lift cells (VLCs) and many constant voltage lift cells (CVLCs) are proposed and their general voltage gain formula is deduced. Each type of N_c-SUCs has N_c+1 different structures and the same voltage gain formula. Different N_c-SUCs can converse each other by adding or removing VLC and CVLC. Then, the general voltage gain formula of the proposed converters with N_c-SUCs is deduced, which is an additive combination of the voltage gain of N_c-SUCs and basic converter. Besides, a novel clamp circuit called M-source PLCC which is consisted of M+1 capacitors and one diode is presented. M capacitors of the M-source PLCC come from the N_c-SUC of converter, so only one capacitor and one diode are added. In comparison with classical PLCC, it makes the converters with N_c-SUCs not only possible to recycle the energy stored in the leakage inductor, but also further reduce the voltage stresses of the switch and the output capacitor, further improve the voltage gain, and even realize a three-level converter. Compared with the classical PLCC, the cost in M-source PLCC is unchanged. As M increases, the number and the variety of M-source PLCCs will also increase. Therefore, different M-source PLCCs can be chosen for the same converter to recycle the energy stored in the leakage inductor. If adopting converse thinking, based on the general voltage gain formula, removing basic converter and M-source PLCC, then, the number and the combination way of VLC and CVLC of different N_c-SUCs will expose the relationship among different high step-up converter to researcher. Finally, an improved converter based on 3-SUC as a representative of the deduced converters is proposed and analyzed in detail in the laboratory to verify performances.