Transformer primary side series connection LLC and output parallel connection BUCK two-stage converter

Abstract

The invention discloses a transformer primary side series connection LLC and output parallel connection BUCK two-stage converter which comprises two high-frequency isolation transformers, wherein primary sides of the two high-frequency isolation transformers are connected in series and then connected into an LLC resonant network; the other end of the LLC resonant network is connected into a bridge circuit; secondary sides of the two high-frequency isolation transformers are sequentially connected with rectifying circuits and BUCK circuits; and output ends of the two BUCK circuits are staggered and connected in parallel. The converter can achieve zero voltage switch-on of switching tubes on the primary sides of the high-frequency transformers, and zero current switch-off of rectifying tubes on the secondary sides of the high-frequency transformers, so that the efficiency and the power density of the LLC converter are improved; and equal primary side voltage of two primary side series connection high-frequency transformers of a preceding-stage converter can be achieved based on control of the same duty ratio of the two BUCK circuits which are staggered and connected in parallel, so that the two high-frequency transformers share equallyinput power, magnetism equilibrium distribution of the high-frequency transformers is achieved, the reliability of the converter is improved, and the cost is lowered.

Description

Technical field [0001] The present invention belongs to the technical field of power electronics, and relates to the related technology of wide input high voltage, output low / high current, high frequency, high power density module power supply, in particular to a transformer primary side series LLC plus output parallel BUCK (buck chopper) Circuit) Two-stage converter. Background technique [0002] With the continuous development of science and technology, higher requirements are put forward for the efficiency, power density and reliability of DC / DC converters. The soft switching of the switching tube can realize zero loss during the switching process of the switching tube, and at the same time effectively suppress the voltage spike in the switching process of the switching tube and reduce the EMI radiation of the circuit, which improves the efficiency and reliability of the converter. The series voltage equalization of the primary side of the high-frequency transformer can effec...

AI Technical Summary

Problems solved by technology

The droop method realizes the current sharing of the parallel modules by changing the output internal resistance of the parallel modules, thus reducing the output load characteristics of the modules; while the active current sharing method requires a dedicated current sharing control circuit, which needs to detect the input or output current of each module. And the current sharing bus is susceptible to interference, so the design of the control system is complicated, the reliability is reduced, and the system cost is high

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