SEPIC circuit in parallel structure

Abstract

The invention discloses an SEPIC circuit in a parallel structure, and the circuit comprises a first inductor, a switching tube, a main central circuit, and an output capacitor. The main central circuit comprises a first isolation capacitor, a first diode, and a second inductor. The circuit also comprises one or more groups of auxiliary central circuits. Each group of auxiliary central circuits comprise a second isolation capacitor, a second diode, and a third inductor. Each group of auxiliary central circuits has a parallel structure with the main central circuit. The circuit can be used for a switching circuit system which is larger in output current, and can maintain the current equalization of the diodes.

Description

technical field [0001] The present invention relates to a SEPIC conversion circuit. Background technique [0002] For the power switching circuit of the traditional car 12V battery, if there is a step-down function requirement, the flyback circuit is often used as the preferred topology due to its low cost advantage. With the application of coupled inductors, more and more SEPIC circuits using coupled inductors are used to replace the flyback circuit topology. Compared with the flyback circuit topology, the SEPIC circuit using coupled inductors has a smaller input current ripple on the basis of maintaining cost. figure 1 shows an existing SEPIC circuit using coupled inductors. [0003] In applications with large output currents, a single output rectifier diode in the buck-boost topology cannot meet the application requirements. Not only is the system inefficient due to the increased power consumption of the rectifier diode, but it is even damaged due to the increased loss...

AI Technical Summary

Problems solved by technology

[0004] Although the use of synchronous rectification MOSFETs can effectively solve the problem of outputting large currents, a corresponding drive circuit is required, which makes the control complicated and increases the cost

In addition, the use of synchronous rectification MOSFET will bring additional EMC problems, which is due to the poor reverse recovery characteristics of the parasitic anti-parallel diode of synchronous rectification MOSFET (the Schottky diode used has no reverse recovery problem)

[0005] Directly using diodes in parallel can solve the problem to a certain extent, but due to the deviation of component parameters will lead to uneven current, and the diode conduction voltage drop has negative temperature characteristics (the higher the temperature, the smaller the conduction voltage drop), more Will exacerbate the uneven flow of current

Therefore, if the diodes are directly connected in parallel, there are high requirements for component parameter deviation and actual layout, and it is still difficult to ensure good current sharing

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