Single-Inductor Buck-Boost Converter for Dual-Polarity Regulation
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Solution Overview
Problem
Existing power converters that regulate positive and negative voltages using switching regulators often require multiple internal switches and external inductors, increasing their cost and complexity.
Innovation Solution
A single-inductor power converter design utilizing four switches (or two switches plus two diodes) with a summing module, error amplifier modules, and a state machine module to generate switching signals, allowing operation in both two-phase and three-phase modes to efficiently supply positive and negative voltages to loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple internal switches and external inductors are used to regulate positive and negative voltages, then voltage regulation capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple inductor functions into a single shared inductor that serves both positive and negative voltage regulation circuits. This merging approach reduces the total number of external inductors from two or more to one, while maintaining the ability to regulate both positive and negative voltages through coordinated switching of the four internal switches (SW1-SW4). The single inductor is strategically positioned and controlled to fulfill multiple regulatory functions that traditionally required separate inductors.
Solution Approach 2:
The single inductor in the patent performs multiple functions: it serves as the energy storage element for both the positive voltage regulator and negative voltage regulator, and can operate in different modes (buck mode for positive output, boost mode for negative output) depending on the switching state. This multi-functionality eliminates the need for dedicated inductors for each regulation circuit, reducing component count while maintaining full voltage regulation capability for both polarities.
2Ease of manufacture
If the number of switches and external inductors is reduced, then cost is reduced, but voltage regulation performance may deteriorate
Solution Approach 1:
The patent employs dynamic switching control where the four switches (SW1-SW4) are actively managed through a state machine that transitions between different operational modes based on load conditions and voltage requirements. This dynamic control allows the single inductor to adaptively serve both positive and negative regulation circuits, ensuring stable voltage output performance despite the reduced component count. The coordinated switching ensures that at any given time, the inductor is properly charged or discharged to maintain both positive and negative voltage rails.
Solution Approach 2:
The patent incorporates feedback mechanisms through error amplifiers that monitor the positive and negative output voltages and adjust the switching signals accordingly. This feedback control ensures that even with a single shared inductor, the voltage regulation performance remains stable and meets design specifications. The feedback loops compensate for the increased complexity in control logic by actively adjusting switch timing and duration to maintain precise voltage regulation under varying load 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
The solution reduces the number of switches and external inductors, lowering costs while effectively regulating voltages for both positive and negative loads, even when load currents are unbalanced, by optimizing the charging and feeding phases.
Implementation Method 1
a TON phase during which the inductor is charged and one TOFF phase during which one of a first load and a second load is fed
Data Source
AI summary
A power converter includes an inductor, a first switch and a second switch. A summing module generates a voltage sum based on a ramp voltage and a first voltage based on a sensed inductor current. Error amplifier modules generate error voltages. A comparing and control signal generating module generates first and second switching signals and skip signals. A state machine module switches the first and second switches based on the first switching signal, the second switching signal and the skip signals. The state machine module, during a single clock period, operates in one of a two phase mode with a TON phase during which the inductor is charged and one TOFF phase during which one of a first load and a second load is fed and a three phase mode with the TON phase and two TOFF phases during which both the first load and the second load are sequentially fed.