Buck-Boost Converter Control Circuit Reducing Switching Loss
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Solution Overview
Problem
Traditional buck-boost converters experience increased switching loss and reduced conversion efficiency due to frequent switching of all four power switches when the input voltage is close to the output voltage, leading to increased switch noise and reduced efficiency.
Innovation Solution
A control circuit for a buck-boost converter that generates specific switching signals to minimize the frequency of switching the four power switches by varying the timing of the switching signals based on the voltage difference between the input and output voltages, using a feedback compensator, determining element, mode selection element, and controllers to manage the switching of the first and third switches differently from the second and fourth switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the traditional switching regulator operates in buck-boost mode with four power switches turned on or off alternatively, then the converter can handle input voltage close to output voltage, but the frequent switching increases switching loss and reduces conversion efficiency
Solution Approach 1:
The patent divides the switching control into two independent groups: a first group containing the first and second switches, and a second group containing the third and fourth switches. Each group is controlled by separate controllers that generate switching signals independently. This segmentation allows different switching strategies to be applied to different switch groups, reducing overall switching frequency and loss while maintaining voltage conversion capability.
Solution Approach 2:
The patent implements dynamic control where the switching signals for different switch groups are generated with different timing and duration based on real-time voltage conditions. The first controller generates a first switching signal with a first duration, while the second controller generates a second switching signal with a second duration, allowing the system to adaptively optimize switching behavior for buck-boost operation.
2Adaptability or versatility
If the four power switches are turned on or off frequently to maintain voltage conversion when input voltage approximates output voltage, then the converter maintains adaptability, but the switch noise increases and efficiency decreases
Solution Approach 1:
By segmenting the switch control into independent groups with separate controllers, the patent reduces the frequency of simultaneous switching events across all four switches. This independent control allows for optimized switching patterns that minimize noise-generating events while preserving voltage conversion functionality.
Solution Approach 2:
The patent employs periodic switching action where the first and second switches are turned on simultaneously for a first duration, followed by the third and fourth switches being turned on simultaneously for a second duration. This structured periodic operation reduces random switching noise while maintaining continuous voltage conversion capability.
Data Source
AI summary
A buck-boost converter and a control circuit thereof are disclosed. When an input voltage is close to an output voltage (i.e., the buck-boost converter operates in a buck-boost mode), the control circuit of the buck-boost converter generates specific switching signals. Four switches of a switching regulator are switched by the switching signals, so that the four switches are not turned-on or turned-off frequently because of the input voltage closing to the output voltage. Accordingly, the buck-boost converter and the control circuit thereof of the disclosure can reduce switch noise of the four switches and switching loss of the whole circuit, to improve conversion efficiency of the buck-boost converter.