Peak-Buck Peak-Boost Control for Buck-Boost Regulators
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Solution Overview
Problem
Current switched step-up step-down regulators face issues with varying switching frequency, high output voltage ripples, noise mode transitions, reverse current problems, and low power efficiency in current mode control schemes, particularly in applications requiring continuous conduction and reverse current handling.
Innovation Solution
A peak-buck peak-boost current mode control scheme is introduced, utilizing a single inductor sensing resistor to detect current, enabling reverse current handling while achieving low inductor and output voltage ripples, and high power efficiency across continuous and discontinuous conduction modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If voltage mode control scheme is used, then fixed switching frequency and low output voltage ripples are achieved, but reverse current handling capability is lost and mode transitions generate large output transient ripples
Solution Approach 1:
The patent implements dynamic mode selection that automatically switches between voltage mode control and pulse-skip/discontinuous conduction mode based on operating conditions. The controller detects when reverse current occurs and dynamically adjusts the control strategy, allowing the system to maintain stable output voltage during normal operation while gaining reverse current handling capability when needed.
2Adaptability or versatility
If pulse-skip or burst discontinuous conduction mode operation is used to handle reverse current, then reverse current is managed, but large output transient ripples are generated during mode transitions
Solution Approach 1:
The patent prepares for mode transitions by implementing preliminary detection of reverse current conditions and pre-configuring the control strategy before actual mode switching occurs. This preliminary action allows the controller to smoothly transition between voltage mode and discontinuous conduction mode, minimizing output voltage transient ripples during the switching process.
3Ease of operation
If conventional peak current mode control is used, then easy compensation and parallel outputs are achieved, but high inductor current ripples and low power efficiency occur
Solution Approach 1:
The patent changes the control parameter from conventional peak current mode to a modified current mode that incorporates reverse current detection and handling capabilities. By adjusting the control parameters and switching strategy based on operating conditions, the system achieves both easy compensation and improved power efficiency while maintaining the ability to handle reverse currents.
4Loss of energy
If valley-buck peak-boost control scheme is used, then low inductor current ripples and high power efficiency are achieved, but reverse current detection capability is lost during boost operations
Solution Approach 1:
The patent creates a universal control scheme that integrates multiple control strategies (voltage mode, valley-buck peak-boost, and pulse-skip modes) into a single system. This multi-functional controller can detect and handle reverse currents during both buck and boost operations while maintaining the efficiency benefits of valley-buck peak-boost control, making the system adaptable to all operating conditions.
Data Source
AI summary
A peak-buck peak-boost current mode control structure and scheme for a synchronous four-switch and non-synchronous two-switch buck-boost regulators sense input and output voltages to smoothly transition between buck mode, buck-boost mode, and boost mode for high power efficiency and low output ripples. With the inductor current sensing, the control scheme achieves the best performance in continuous conduction and discontinuous condition mode operations.