Buck-Boost Converter Flying Capacitor Cell for Lower Switch Stress
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multilevel buck-boost power converters face challenges in reducing voltage stress across inductors and switches, leading to increased power loss, size, and complexity.
Innovation Solution
The proposed buck-boost converter incorporates a multilevel switching cell with a flying capacitor network, which reduces voltage stress across inductors and switches by allowing for lower voltage switching and increased switching frequency, thereby minimizing inductor current ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional switching devices are used in power converters, then voltage control is achieved, but voltage stress on switches and inductors increases leading to higher power loss and larger component size
Solution Approach 1:
The power converter is divided into multiple switching stages (first converter stage and second converter stage), each handling a portion of the voltage conversion. This segmentation reduces the voltage stress on individual switches and inductors in each stage, thereby reducing power loss and component size while maintaining the overall voltage conversion function
Solution Approach 2:
Flying capacitors are introduced as intermediary energy storage elements between the input and output stages. These flying capacitors facilitate voltage transfer and enable the switching devices to operate at lower voltage levels, reducing voltage stress and power loss without requiring complex high-voltage switching arrangements
2Loss of energy
If voltage stress on switches and inductors is reduced, then power loss and component size decrease, but the converter structure becomes more complex
Solution Approach 1:
The converter is segmented into modular stages with standardized switching networks. Each stage uses similar switching device arrangements, which reduces complexity through repetition and standardization. The segmentation allows voltage stress to be distributed across multiple stages rather than concentrated in a single high-voltage switch
Solution Approach 2:
The switching networks in different converter stages use similar or identical switching device configurations that can handle multiple functions (voltage stepping, energy transfer, voltage stress reduction). This universality reduces design complexity while achieving the goal of reduced voltage stress and power loss
Data Source
AI summary
A buck-boost converter for converting an input voltage at an input node into an output voltage at an output node, the converter comprising: first and second inductor nodes for connection of an inductor therebetween; a first converter stage coupled between the input node and the first inductor node; and a second converter stage coupled between the second inductor node and the output node, wherein one or more of the first converter stage and the second converter stage comprises a switching network, comprising: a first switch for selectively connecting a first flying capacitor node to a stage input node; a second switch for selectively connecting the first flying capacitor node to a stage output node; a third switch for selectively connecting a second flying capacitor node to the stage output node; and a fourth switch for selectively connecting the second flying capacitor node to a reference voltage, the first and second flying capacitor nodes for connection of a flying capacitor therebetween.