Abstract
This article presents a novel control method for a multilevel dc–dc flying capacitor converter for applications in medium voltage range. Quasi-two-level modulation provides the possibility to obtain low flying capacitance even below 1 μF, whereas the triangular current mode controller part enables to achieve zero voltage switching at turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> for a wide operating range, lowering power losses, and providing the possibility to operate at higher frequencies. The proposed novel control converges the advantages of these both methods leading to very high efficiency with high power density. Performance of the flying capacitor converter with the proposed control method is illustrated with a model-based Saber simulation at first, and then, an experimental model operating at wide frequency range (40 ÷ 250 kHz) and in medium voltage range was designed and constructed. A series of laboratory tests at up to 1.5 kV dc and 10 kW confirmed the noteworthy characteristics of the converter. The voltage between the power devices is balanced and the efficiency achieved reached as high as 99.1%. Therefore, the proposed converter can be competitively employed against classical two-level, as well as three-level and series connection-based counterparts.
Highlights
In the recent years, the environmental requirements to limit the fossil fuel usage and its consequences demand worldwide employment of RES and further improvements in the department of electrical energy conversion, especially in terms of efficiency, power density and cost
It is confirmed that the proposed TCM-Q2L control method for a 3L FCC provides a possibility to construct highly efficient DC/DC converters with low passive component volume that is comparable or even surpasses conventional and state-of-the-art solutions in this power/voltage range in terms of performance
In order to initially validate the proposed TCM-Q2L control method for a FCC a simulation study in Synopsys Saber was conducted, so that the Power MOSFET modelling tool could be employed for semiconductor power transistors ensuing highly accurate results, as simulating the resonance between the output MOSFET capacitances and the inductor requires precise switching models
Summary
A novel TCM-Q2L control method for a well-known three-level FCC [32,33,34] is proposed It is based on the convergence of Q2L approach [19,20,21,22], and TCM [35,36,37,38] providing the possibility to achieve ZVS at turn-on for all power transistors without any auxiliary circuits. It is confirmed that the proposed TCM-Q2L control method for a 3L FCC provides a possibility to construct highly efficient DC/DC converters with low passive component volume that is comparable or even surpasses conventional and state-of-the-art solutions in this power/voltage range in terms of performance.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
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
