Photovoltaic high-frequency isolation boost soft switch DC/DC converter and control method thereof

Abstract

The invention relates to a photovoltaic high-frequency isolation boost soft switch DC/DC converter and a control method thereof, which is used for solving the problems of difficult current conversion of leading leg in idle load or light load and low efficiency in full load, improving the efficiency of the converter and realizing full-power converter. The photovoltaic high-frequency isolation boost soft switch DC/DC converter comprises a high-frequency transformer, wherein the primary side of the high-frequency transformer is provided with a phase shift PWM (pulse-width modulation) control converter; the high-frequency transformer is provided with three secondary sides; two secondary sides are formed by connecting bridge type diode rectification circuits in series for outputting high voltages, the output ends of the secondary sides are connected with output voltage and current sampling circuits, and the output voltage and current sampling circuits are connected with a controller; the third secondary side is formed by connecting a voltage dropping winding with a current converting inductor and a switch in series; the primary side of the transformer is provided with a blocking capacitor Cb and a saturation inductor LS which are connected in series; output filtering capacitors Lfl and Lf2 are coupling capacitors and share one magnetic core; output ends Df1-R1-Cf1 and Df2-R2-Cf2 form a crossed clamping buffer circuit; and the asymmetrical phase shift PWM controller controls power switching devices VT1 to VT4 and a switch K0.

Description

technical field [0001] The invention relates to a photovoltaic high-frequency isolation boost soft switch DC / DC converter and a control method thereof. Background technique [0002] At present, photovoltaic grid-connected power generation has become the main development trend of photovoltaic utilization and the focus of related technology research (CarrascoJ M, Franquelo L G, Bialasiewicz J T, et al. Power-electronics systems for the grid integration of renewable energy sources: a survey[J] . IEEE Transactions on Industrial Electronics, 2006, 53(4): 1002-1016.). Since the maximum power output of a photovoltaic array is seriously affected by factors such as light intensity, panel temperature, and performance parameters of each series module (Trishan Esram, Patrick L Chapman. Comparison of photovoltaic array maximum power point tracking techniques[J]. IEEE Transactions on Energy Conversion , 2007, 22(2): 439-449.), usually try to reduce the number of panels connected in serie...

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Problems solved by technology

[0005] The purpose of this invention is to meet the high input voltage requirements of three-phase photovoltaic grid-connected inverters and overcome the serious shortage of power frequency step-up isolation transformer consumables, and propose a photovoltaic high-frequency isolation step-up soft switch DC / DC conversion Its high-frequency transformer has three secondary sides, of which two boost windings are used for series rectification to achieve high voltage output; It is difficult to commutate the super forearm under load and the efficiency is reduced under full load, which significantly improves the efficiency of the converter

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