Three-Phase Buck-Boost Regulator Ripple Control
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Solution Overview
Problem
Typical buck-boost DC converters suffer from limited line transient performance due to high current ripple in the input capacitors, necessitating a more flexible and robust solution for maintaining consistent voltage in portable electronic devices.
Innovation Solution
A three-phase buck-boost regulator system that operates in boost, buck, or buck-boost modes, utilizing controllable switches and an inductor for energy storage, with mode selection based on voltage comparisons to manage inductor current paths and minimize ripple voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical buck-boost DC converter is used, then the circuit topology is simple, but the line transient performance is limited due to high current ripple in the input capacitors
Solution Approach 1:
The patent divides the single-phase buck-boost converter into three separate switching phases with individual switches (S1, S2, S3) and inductors (L1, L2, L3). Each phase operates independently with its own current path, segmenting the total current ripple across multiple parallel paths. This segmentation reduces the ripple current through each input capacitor by approximately one-third compared to a single-phase design, thereby improving line transient performance without requiring complex additional filtering components.
2Reliability
If a single-phase buck-boost converter is used, then the device complexity is low, but the ripple voltage control is poor when input and output voltages are close
Solution Approach 1:
The converter is segmented into three independent phases, each capable of operating in buck, boost, or buck-boost mode. When input and output voltages are close, all three phases can simultaneously contribute to voltage regulation, distributing the control burden and improving ripple voltage control. The segmentation allows each phase to operate with smaller duty cycles, reducing individual phase ripple and improving overall voltage stability.
Solution Approach 2:
The controller dynamically selects the operating mode (buck, boost, or buck-boost) for each phase based on real-time comparison of input and output voltages. When Vin < Vout, phases operate in boost mode; when Vin > Vout, phases operate in buck mode; when Vin ≈ Vout, phases operate in buck-boost mode. This dynamic adaptation optimizes ripple voltage control for different operating conditions while maintaining manageable device complexity through standardized phase modules.
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 three-phase system maintains constant output voltage across mode changes and effectively controls ripple voltage, enhancing line transient performance and reducing current ripple, especially when input and output voltages are close.
Implementation Method 1
A three phase buck-boost regulator is disclosed. The regulator may work in a boost mode, a buck mode or in a buck-boost mode... The regulator comprises a plurality of controllable switches and an inductor as energy storage means
Data Source
AI summary
Systems, devices and methods using three separate switching phases for a buck-boost regulator are disclosed. The regulator may operate in a boost mode, a buck mode or in a buck-boost mode. The output voltage remains constant through mode changes and the ripple voltage is well-controlled. If the input voltage is lower than the output voltage by a first threshold, the regulator operates in boost (step-up) mode. If the input voltage is higher than the output voltage by a second threshold, it operates in buck (step-down) mode. The regulator operates in the buck-boost mode when the difference between the input and output voltages is within a certain range.