Buck-Boost Control Circuit With Adaptive Offset for Glitch-Free Transitions
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Solution Overview
Problem
Buck-boost power converters experience glitches in output voltage during mode transitions due to discontinuities in the error signal, which are not efficiently addressed by existing technologies.
Innovation Solution
An adaptive offset is applied to the error signal based on the operating mode, using a compensation unit to generate a pedestal signal that adjusts the delta signal, ensuring a linear error signal and eliminating output voltage glitches during mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a buck-boost power converter is used to handle wide input voltage variations, then the power converter can operate across buck mode, buck-boost mode, and boost mode, but voltage glitches occur during mode transitions due to error signal discontinuities
Solution Approach 1:
An adaptive offset compensation unit is introduced as an intermediary component between the error amplifier and the PWM modulator. This unit receives the error voltage signal and adds a mode-dependent offset to compensate for discontinuities during mode transitions. The offset is adaptively adjusted based on the current operation mode (buck, buck-boost, or boost), ensuring continuous and glitch-free control signals to the power switches, thereby maintaining output voltage stability across all operation modes.
2Device complexity
If the error voltage signal is determined without mode-dependent offset compensation, then the control circuit is simple, but the error signal exhibits discontinuities at mode transitions causing output voltage glitches
Solution Approach 1:
The offset compensation value is made dynamic and adaptive rather than fixed. The compensation unit continuously monitors the operation mode and adjusts the offset value accordingly. During mode transitions, the offset dynamically changes to match the specific requirements of each mode (buck, buck-boost, or boost), ensuring the error signal remains continuous and glitch-free. This dynamic adaptation maintains precise output voltage regulation without requiring overly complex circuitry.
Data Source
AI summary
The present document describes a control circuit for controlling a buck-boost power converter, which is configured to provide at an output node of the power converter an output current at an output voltage based on electrical power at an input voltage which is provided at an input node of the power converter. The control circuit is configured to determine an operation mode that the power converter is operated in; to determine an error voltage signal based on the output voltage, based on a reference voltage for the output voltage and based on the determined operation mode of the power converter; and to determine a control signal for controlling one or more power switches of the power converter in dependence of the error voltage signal.