H-Bridge Buck-Boost Converter Ripple Current Reduction
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Solution Overview
Problem
Existing buck-boost converters face challenges in implementing an efficient and simple control scheme for dividing operations between pure buck, pure boost, and mixed buck-boost modes, leading to inefficiencies and increased component costs due to high inductor ripple current and complex feedback loops.
Innovation Solution
The implementation of a combined pulse-width-modulation control portion that generates separate switching signals for each switch in the H-bridge buck-boost converter, allowing for operation in all three modes while reducing inductor ripple current and using a first-order low-pass filter to improve feedback loop bandwidth, along with an intermediate-voltage-controlled buck control portion that regulates the input side of the inductor, enabling efficient voltage conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional buck-boost converter is used to handle both buck and boost operations, then it can convert voltage in both directions, but it results in high inductor ripple current and complex control schemes
Solution Approach 1:
The patent divides the single buck-boost converter into two separate converters: a buck converter for voltage reduction and a boost converter for voltage increase. Each converter operates independently with its own inductor, switching elements, and control circuitry. This segmentation eliminates the high ripple current problem associated with unified buck-boost operation while maintaining full bidirectional voltage conversion capability.
2Adaptability or versatility
If a unified buck-boost converter is implemented, then it can operate in all three modes (buck, boost, and mixed), but it requires complex feedback loops and control schemes
Solution Approach 1:
The control system is segmented into two independent control circuits: one for the buck converter and one for the boost converter. Each control circuit manages its respective converter independently, eliminating the need for complex unified feedback loops. The system maintains operational flexibility by selectively activating either the buck converter, the boost converter, or both simultaneously based on voltage requirements.
Solution Approach 2:
The patent introduces a voltage selection circuit that acts as an intermediary between the two converters and the load. This circuit selectively connects the output of either the buck converter, the boost converter, or both to the load based on the desired operating mode. This intermediary simplifies the overall control architecture by decoupling the control logic of each converter while maintaining coordinated operation.
3Object-generated harmful factors
If separate buck and boost converters are used, then inductor ripple current is reduced and control is simplified, but component count and circuit complexity increase
Solution Approach 1:
The patent merges the buck converter and boost converter into a single integrated circuit module with shared components where possible. The voltage selection circuit combines the outputs of both converters in a unified structure, and the control system integrates both control loops into a coordinated architecture. This merging reduces the overall footprint and component count compared to completely separate implementations while maintaining the benefits of reduced ripple current and simplified control.
Data Source
AI summary
An H-bridge buck-boost converter includes a first half-bridge portion having at least one first transistor, an inductor portion connected to the first half-bridge portion at a first connection, a second half-bride portion connected to the inductor portion at a second connection, the second half-bridge portion having at least one second transistor, and a control portion configured to provide a first switching signal to a gate of the first transistor of the first half-bridge portion as a function of a voltage at the first connection.