Multistage parallel DC-DC converter

Abstract

A multistage parallel DC-DC converter comprises an input power supply, a first conversion unit, a second conversion unit and a third conversion unit, wherein the first conversion unit and the second conversion unit are connected in series, and the third conversion unit is connected with the first conversion unit and the second conversion unit in parallel. The first conversion unit comprises a PWMcircuit, and the voltage change rate of the first conversion unit is determined according to the switch duty ratio in the PWM circuit; the second conversion unit comprises a first half-bridge LLC resonance circuit, and the first half-bridge LLC resonance circuit comprises a first transformer; the voltage conversion rate of the second conversion unit is determined according to the first transformer; the third conversion unit comprises a second half-bridge LLC resonance circuit, and the second half-bridge LLC resonance circuit comprises a second transformer; the voltage conversion rate of the third conversion unit is determined according to the second transformer. According to the invention, the technical problem of low efficiency of a multi-stage DC-DC converter in the prior art is solved,and the technical effects of high conversion efficiency, controllable voltage amplitude and controllable single-phase or multi-phase combined output voltage are achieved.

Description

technical field [0001] The invention relates to the field of transformers, in particular to a multi-stage parallel DC-DC converter. Background technique [0002] Conventional DC-DC two-stage converters, such as figure 1 As shown, usually adopted. A buck or boost converter is used as the first stage converter to make the input voltage V in stabilizes to a constant value V 1 , as the input voltage of the next stage converter. The second-stage converter provides step-up or step-down of the high voltage ratio of the isolated core. The second stage converter is designed for high efficiency but cannot regulate voltage. In boost applications, an interleaved structure is often used to share high current inputs such as figure 2 shown. Converters 2 and 3 share the high current input Iin. The functions of converter 3 and converter 2 are the same. In step-down applications, the method of paralleling the secondary side is widely used, such as image 3 shown. [0003] In the a...

AI Technical Summary

Problems solved by technology

The second stage converter is designed for high efficiency but cannot regulate the voltage

[0003] In the above-mentioned DC-DC two-stage converter, the first-stage converter bears a large input current, resulting in large power loss and low efficiency, and the first-stage converter handles all the input power P in , the total efficiency of the whole system is η=η 1 ×η 2 , where, η is the total work efficiency, η 1 is the first-level work efficiency, η 2 for the second level of productivity

Generally speaking, the conversion efficiency of conventional two-stage or multi-stage converters is low, and the loss in the first-stage converter is large

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