Buck-Boost Converter Ramp Control for Stable Low-Loss Mode Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional buck-boost switching converters face issues such as instability when the voltage V2 is not smaller than voltage V3, higher switching loss and power consumption due to all four power switches operating in buck-boost mode, and slower response to load variations due to constant frequency operation.
Innovation Solution
A constant time buck-boost switching converter is designed with a power switch circuit comprising a buck switch unit and a boost switch unit, along with a modulation control circuit that generates buck and boost ramp signals to control the power switches, allowing operation in pure buck or boost modes without a buck-boost mode, thereby reducing switching loss and improving response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional buck-boost switching converter operates in buck-boost mode with all four power switches, then voltage conversion flexibility is improved, but switching loss and power consumption increase
Solution Approach 1:
The patent implements dynamic mode switching between buck mode and boost mode based on real-time comparison of input and output voltages. The control circuit dynamically selects which power switches to operate, avoiding the static operation of all four switches in conventional buck-boost mode, thereby reducing switching loss while maintaining voltage conversion flexibility
Solution Approach 2:
The patent applies different operational characteristics to different parts of the system by operating only the necessary power switches (either buck switches or boost switches) based on the specific voltage conversion requirement, rather than uniformly operating all four switches, thus reducing overall switching loss
2Device complexity
If conventional buck-boost switching converter uses constant frequency operation, then circuit control simplicity is improved, but response speed to load variations deteriorates
Solution Approach 1:
The patent transitions from constant frequency operation to variable frequency operation where the switching frequency dynamically adjusts in response to load variations and voltage conditions. This allows the system to respond faster to changing conditions while the control circuit automatically manages the frequency adjustments based on feedback signals
3Adaptability or versatility
If buck-boost conversion region is included (V2 < V3), then voltage conversion range is improved, but system stability deteriorates
Solution Approach 1:
The patent segments the voltage conversion operation into distinct buck mode and boost mode regions, eliminating the unstable buck-boost conversion region. By dividing the operation into separate modes with dedicated power switches and control logic, the system achieves both wide voltage conversion range and enhanced stability in each operational region
4Adaptability or versatility
If all four power switches operate simultaneously, then conversion mode flexibility is improved, but device complexity increases
Solution Approach 1:
The patent implements dynamic control where the system automatically selects and activates only the necessary power switches based on real-time voltage comparisons. This dynamic approach maintains conversion flexibility while simplifying the active circuit configuration at any given moment, reducing overall control complexity compared to managing all four switches simultaneously
Data Source
AI summary
A constant time buck-boost switching converter includes: a power switch circuit for switching a first terminal of an inductor between an input voltage and a ground, and for switching a second terminal of the inductor between an output voltage and the ground; and a modulation control circuit for generating a buck ramp signal and a boost ramp signal and for controlling the inductor according to comparisons of these two ramp signals with an error amplification signal, so as to convert the input voltage to the output voltage. The average levels of the buck ramp signal and the boost ramp signal are both equal to a product of the output voltage multiplied by a predetermined ratio. The upper limit of the buck ramp signal and the lower limit of the boost ramp signal are both equal to a product of the input voltage multiplied by the predetermined ratio.