Single-Inductor Buck-Boost Converter With Auxiliary Capacitor Buffering
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Solution Overview
Problem
Portable devices powered by current-limited batteries face reduced battery life due to high current pulses, which can cause brownouts and system shutdowns, preventing full capacity utilization.
Innovation Solution
A buck-boost converter design utilizing a single inductor and auxiliary capacitor, which allows for improved battery life by providing the necessary energy difference and enhancing load transient response, reducing the size and cost of the converter while operating with high capacity batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a conventional DC-DC converter is used with current-limited batteries, then the converter can deliver power to the load, but high current pulses cause brownouts and system shutdowns, reducing battery life and preventing full capacity utilization
Solution Approach 1:
The auxiliary capacitor is pre-charged during low-current periods when the battery can safely charge it, storing energy in advance. During high-current demand periods, this pre-stored energy is quickly discharged to supplement battery output, preventing brownouts and system shutdowns while extending usable battery capacity.
2Device complexity
If the converter uses a single inductor design, then the circuit size and cost are reduced, but achieving both buck and boost functionality with improved transient response becomes more challenging
Solution Approach 1:
The single inductor operates in a dynamic dual-mode configuration where its role switches between buck converter inductor and boost converter inductor based on operating conditions. The control circuit dynamically adjusts the switching patterns and inductor current profiles to optimize performance for either buck or boost operation, maintaining high efficiency and fast transient response despite the simplified hardware architecture.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The buck-boost converter design extends battery life, reduces circuit size and cost, and enables operation with current-limited batteries by using an auxiliary capacitor to manage energy and reduce the risk of undervoltage events, allowing for efficient power delivery and reduced transient response time.
Implementation Method 1
an auxiliary capacitor coupled to a second terminal of the third switch
Implementation Method 2
an inductor coupled between a second terminal of the first switch and a second terminal of the second switch
Data Source
AI summary
A buck-boost converter includes a voltage input terminal, a voltage output terminal, a first switch, a second switch, an inductor, a third switch, and an auxiliary capacitor. The first switch includes a first terminal coupled to the voltage input terminal, and a second terminal. The second switch includes a first terminal coupled to the voltage output terminal, and a second terminal. The inductor is coupled between the second terminal of the first switch and the second terminal of the second switch. The third switch includes a first terminal coupled to the second terminal of the second switch, and a second terminal. The auxiliary capacitor is coupled to the second terminal of the third switch.