Resonant isolating transformer with ultra-wide voltage regulating range

Abstract

The invention provides a resonant isolating transformer with an ultra-wide voltage regulating range. The resonant isolating transformer is characterized by comprising a first half-bridge LLC resonantnetwork with a first transformer and a second half-bridge LLC resonant network with a second transformer, wherein the sub edge of the first transformer is the output end of the first half-bridge LLC resonant network; the sub edge of the second transformer is the output end of the second half-bridge LLC resonant network; the input voltage is simultaneously input into the first half-bridge LLC resonant network and the second half-bridge LLC resonant network; the output end of the first half-bridge LLC resonant network and the output end of the second half-bridge LLC resonant network are connected in series, are then sequentially connected with a rectifying circuit and a filter circuit and are then connected with a load. The voltage reduction capability of an LLC resonant circuit is greatly improved; the voltage can be reduced to 0 under any load condition; the zero voltage conduction characteristic of a raw edge switch is greatly improved.

Description

technical field [0001] The invention relates to a resonant isolation converter. Background technique [0002] Among many isolated DC / DC converters, the LLC isolated resonant converter is easy to realize the zero-voltage turn-on (ZVS) of the primary side switch and the zero-current turn-off (ZCS) of the secondary side diode due to its simple structure, high efficiency, and electromagnetic It has been widely used due to the advantages of low interference. [0003] But the LLC resonant converter has two major problems: [0004] 1) The pressure regulation performance is limited, especially the pressure reduction ability under light load conditions. The LLC resonant converter is a frequency modulated topology. like figure 1 As shown, the abscissa is the normalized switching frequency (switching frequency / resonant frequency), and the ordinate is the normalized gain (removing the influence of the transformation ratio of the transformer), and different curves correspond to diffe...

AI Technical Summary

Problems solved by technology

[0005] 2) When the normalized switching frequency is much greater than 1 and the load is light, the primary side switch will lose the zero-voltage conduction characteristic

[0006] On the one hand, the above two problems make the LLC resonant circuit unable to meet the wide voltage regulation requirements of many applications

On the other hand, the loss of zero-voltage conduction characteristics increases switching losses, easily causes current spikes, and increases electromagnetic interference problems

Images