Abstract
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 Nc step-up cell (Nc-SUC), and one M-source passive lossless clamped circuit (PLCC). Nc means the number of capacitors in step-up cell and M-source represents the number of capacitors in PLCC. Nc-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 Nc-SUCs has Nc+1 different structures and the same voltage gain formula. Different Nc-SUCs can converse each other by adding or removing VLC and CVLC. Then, the general voltage gain formula of the proposed converters with Nc-SUCs is deduced, which is an additive combination of the voltage gain of Nc-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 Nc-SUC of converter, so only one capacitor and one diode are added. In comparison with classical PLCC, it makes the converters with Nc-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 Nc-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.
Highlights
Owing to the shortage of fossil fuels and seriously environment pollution, the renewable energy sources, such as photovoltaic systems and fuel cell, have become increasingly popular [1]
A named M-source passive lossless clamped circuit (PLCC) which is consisted of M + 1 capacitors and a diode is presented in order to recycle the energy stored in leakage inductor
2) As M increases, the number of the converters and the connection ways of M-source PLCCs are increased, so that the converters have more different structures to employ PLCC to recycle the energy stored in leakage inductor
Summary
Owing to the shortage of fossil fuels and seriously environment pollution, the renewable energy sources, such as photovoltaic systems and fuel cell, have become increasingly popular [1]. Various step-up cells are combined with coupled inductor together to improve the voltage conversion ratio of converter. As the number of series capacitors increases, the proposed converters will have more PLCCs. Besides, PLCC can further improve the voltage conversion ratio of the proposed converter and reduce the voltage stress of main switch. In the VL cell (VLC) as shown in Fig. (a), its capacitor connected in series with inductor L2 directly improves the voltage gain of converter, and the voltage of this cell is not a constant (0 or VLo2n + VLo2ff ). Compared with VLC, the voltage across this cell is a constant (VLo2ff ), and its capacitor indirectly increases the voltage gain of converter They are the same step-up cell, but try to improve the voltage gain in different ways. The number of the capacitors of Nc-SUC is equal to Nc
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
