Buck-Boost Regulator Control for Ripple Reduction
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Solution Overview
Problem
Existing step-up/step-down switching regulators face issues such as frequency subharmonics, increased voltage and current ripple, mode hunting, reduced conversion efficiency, and increased component stress when the voltage ranges of the power source and load overlap, particularly in battery-powered portable equipment.
Innovation Solution
The proposed solution involves a switching regulator circuit with a control algorithm that operates in current mode compensation, using a four-switch arrangement with P-channel and N-channel devices, and employs specific phase control logic to manage the current through the inductor, allowing efficient step-up and step-down operations without mode changes, thereby reducing current ripple and component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional H-bridge circuit is used as buck-boost DC to DC converter, then step-up/step-down conversion is achieved, but large current ripple occurs and component stress increases
Solution Approach 1:
The patent implements dynamic mode switching between buck and boost operation based on real-time comparison of input and output voltages. The control system automatically transitions between operating modes without manual intervention, optimizing performance for each mode while maintaining adaptability across the full voltage range. This dynamic adaptation eliminates the need for fixed H-bridge configurations and reduces the harmful current ripple associated with conventional approaches.
2Adaptability or versatility
If conventional switching regulator operates when input voltage overlaps with output voltage range, then voltage conversion is possible, but mode hunting and frequency subharmonics occur
Solution Approach 1:
The patent employs a feedback control mechanism that continuously monitors the relationship between input voltage (VIN) and output voltage (VOUT). When VIN exceeds VOUT, the system transitions to buck mode; when VIN falls below VOUT, it switches to boost mode. This feedback-driven mode selection eliminates mode hunting and frequency subharmonics by providing clear, stable transition criteria based on real-time voltage comparisons, ensuring operational stability across the entire voltage range.
3Adaptability or versatility
If four switch arrangement is used for buck and boost regulation, then step-up/step-down operation is achieved, but device complexity increases
Solution Approach 1:
The patent utilizes a four-switch bridge circuit where each switch serves multiple functions depending on the operating mode. During buck operation, switches S1 and S2 function as primary switching elements while S3 and S4 provide synchronous rectification. During boost operation, the roles reverse or reconfigure. This universal design allows the same circuit topology to efficiently perform both buck and boost regulation, achieving versatility without proportionally increasing complexity, as the switches dynamically adapt their functions based on operating conditions.
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
This approach achieves improved conversion efficiency, reduced component stress, and low current ripple across the entire input-to-output voltage range, maintaining good transient response and efficient power delivery without mode changes.
Implementation Method 1
the current through the inductor, allowing efficient step-up and step-down operations
Implementation Method 2
The inductor, capacitors and power switches must be rated at a much larger current than the load current
Data Source
Figure 1~2
Figure 3a~4b
Figure 5a~5b
AI summary
A step-up/step-down switching regulator control method for a regulator having an inductor with first and second leads, a first switch for controllably coupling the first lead to a source of power, a first device between the first lead and a circuit ground, a second switch for controllably coupling the second lead to the circuit ground, and a second device between the second lead and a regulator, the method comprising operating the switches in a sequence of phases when the source of power has a voltage exceeding the regulator output and in the same sequence of phases when the source of power has a voltage less than the regulator output, the phases being phase 1 with the first and second switches closed, phase 2 with the first switch closed and the second switch open, and phase 3 with both switches open. The first and second devices may be switches or diodes. Various embodiments are disclosed.