A low-power voltage compensation combined dc/dc converter circuit and its working method

Abstract

The invention discloses a small-power voltage compensation combined-type DC / DC converter circuit and a working method thereof. The circuit comprises an auxiliary power conversion circuit and a main power conversion circuit, wherein the auxiliary power conversion circuit adopts a single-ended forward conversion structure with a fixed duty ratio, and the main power conversion circuit is of a BUCK structure. Through the power compensation via the auxiliary power conversion circuit, the main power conversion circuit performs the boost output when an input voltage is less than a set threshold value, and the auxiliary power conversion circuit is cut off when the input voltage is greater than the set threshold value for the main power conversion circuit to autonomously complete the buck output ofthe main power conversion circuit. The circuit provided by the invention adopts a simple and easy-to-control line structure to realize boost conversion at the input low voltage while ensuring high efficiency and step-down, and solves the compatibility of the existing buck-boost converter in conversion efficiency and line complexity.

Description

technical field [0001] The invention belongs to the technical field of voltage compensation, and in particular relates to a low-power voltage compensation combined DC / DC converter circuit and a working method thereof, which are suitable for application occasions of switching power supplies requiring buck-boost and high-efficiency. Background technique [0002] Buck-boost DC / DC converter power topology can be divided into isolated or non-isolated, isolated is divided into: flyback, forward or push-pull topology, etc.; non-isolated mainly BUCK-BOOST level Link structure or BOOST-BUCK structure. [0003] (1) The isolated topology can realize the output buck-boost function due to the existence of the voltage transformer, but at the same time, the energy transmission through the transformer will bring inherent core loss and affect the conversion efficiency. In addition, the isolated transmission lines of the front and rear stage signals are more complicated. The loss is also rel...

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Problems solved by technology

However, the circuit has the following problems: ①The cascade connection of the power topology affects the conversion efficiency; ②The number of MOS transistors is large, and the control circuit is complicated; ③The design of the inductance parameters needs to be compatible with the boost and step-down operating modes, and the required inductor size and capacity are relatively large. Big

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