Dual-Current-Path Buck-Boost Control Circuit for Lower Conduction Loss
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Solution Overview
Problem
Traditional single-mode step-down/step-up converters face inefficiencies due to high inductor current and high voltage withstand switches, leading to increased conduction loss and higher chip costs.
Innovation Solution
A control circuit and method for a single-mode dual-current-path step-down/step-up converter that optimizes the structural relationship between flying capacitors and switches, reducing the number of high-voltage switches and inductor current, using a smaller inductor with larger DCR, and incorporating a return circuit to power MOS tubes without separate step-up circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional single mode step-down/step-up converter cascades a traditional step up converter and a step down converter, then the converter can achieve both step-up and step-down functions, but the inductor current will always be higher than the load current, resulting in significant conduction loss
Solution Approach 1:
The patent divides the single inductor into two separate inductors (L1 and L2), each dedicated to either step-up or step-down operation. This segmentation allows each inductor to operate independently with optimized current paths, eliminating the need for high inductor current to achieve both functions simultaneously.
Solution Approach 2:
The patent introduces a dual-current-path architecture that operates in different dimensional spaces - one path for step-up conversion and another for step-down conversion. By switching between these different operational dimensions, the system achieves both functions without requiring the inductor current to always exceed the load current.
2Loss of energy
If the inductor with smaller Direct Current Resistance (DCR) is selected to reduce conduction loss, then the conduction loss decreases, but the inductor size increases, which not only further increases a size of a chip but also increases a cost
Solution Approach 1:
By segmenting the single inductor into two smaller inductors (L1 and L2), each inductor can be designed with smaller size and higher DCR while maintaining low conduction loss through optimized current distribution. The total conduction loss is reduced because each inductor carries only a portion of the total current.
Solution Approach 2:
The patent changes the electrical parameters of the inductors by using two separate inductors with different current ratings instead of one large inductor. This allows selection of inductors with smaller sizes and higher DCR values that are more cost-effective while achieving lower overall conduction loss through the dual-path architecture.
3Loss of energy
If the new topology structure uses high voltage withstand switches to reduce inductor current, then the inductor current decreases, but the overall efficiency of the chip decreases due to increased conduction loss at the switch
Solution Approach 1:
The patent changes the operational parameters by using two separate inductors with optimized current distribution, allowing the use of standard switches instead of high voltage withstand switches. This parameter change optimizes the overall efficiency by reducing switch conduction loss while maintaining low inductor conduction loss through the dual-path 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
This approach reduces conduction losses, lowers chip costs, and improves overall efficiency by balancing inductor current and switch voltage withstand, while maintaining flexibility for both step-up and step-down conversions.
Implementation Method 1
during a charging period of the inductor, controlling the first switch, the fourth switch, and the fifth switch to close... during a discharging period of the inductor, controlling the first switch, the fourth switch, and the fifth switch to open
Implementation Method 2
the first capacitor and the second capacitor are flying capacitors... discharge the first capacitor and the second capacitor, and increase a current of the inductor
Data Source
AI summary
The present application discloses a control circuit and method of a single-mode dual-current-path step-down/step-up converter, including: during a charging period of an inductor, controlling a first switch, a fourth switch and a fifth switch to close, and controlling a second switch, a third switch and a sixth switch to open, so as to discharge a first capacitor and a second capacitor, and increase a current of the inductor; during a discharging period of the inductor, controlling the first, the fourth and the fifth switches to open, and controlling the second, the third switch and the sixth switches to close, so as to charge the first and second capacitor, and reduce the current of the inductor.