Multi-Level DC-DC Converter With Zone Switching and Capacitor Balancing
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Solution Overview
Problem
Existing DC-to-DC converter circuits face limitations in achieving a smaller minimum inductor size while allowing a full range of output voltages and preventing voltage overstress on switch transistors, particularly in low voltage CMOS technologies.
Innovation Solution
The invention introduces multi-level DC-to-DC converter circuits that alternate between adjacent zones to generate output voltages near boundaries, utilize a parallel 'shadow' capacitor voltage balancing circuit, and allow out-of-order state transitions to prevent voltage overstress, using a combination of lossless and lossy voltage balancing methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-level inverting buck-boost converter is used, then the circuit structure is simple, but the minimum inductor size is large and voltage overstress occurs on switch transistors
Solution Approach 1:
The patent divides the converter into multiple levels (3-level, 4-level, or 5-level configurations) by adding series-connected switches and capacitors. This segmentation reduces the voltage stress on individual switches while enabling a full range of output voltages without requiring a large minimum inductor size.
Solution Approach 2:
The patent introduces multiple operational zones (Zone 1, Zone 2, Zone 3, etc.) that expand the voltage conversion capability beyond the traditional two-level operation. This dimensional expansion allows the converter to operate in different modes (buck, boost, inverting) and achieve a full range of output voltages while maintaining smaller inductor sizes.
2Loss of energy
If the inductor size is reduced, then the converter efficiency improves, but the minimum inductor size constraint prevents achieving a full range of output voltages
Solution Approach 1:
The patent implements dynamic zone transition control that allows the converter to switch between different operational zones based on the desired output voltage. This dynamic operation enables the use of smaller inductors while maintaining the ability to generate a full range of output voltages through coordinated switching of multiple switches and capacitors.
Solution Approach 2:
The patent changes the voltage levels across the inductor by operating in multiple zones with different voltage combinations. In Zone 1, the inductor experiences voltage V1; in Zone 2, it experiences voltage V1/2; and in Zone 3, it experiences voltage -V2. This parameter change allows smaller inductor sizes while achieving full output voltage range.
3Adaptability or versatility
If multi-level DC-to-DC converter circuits are used, then a full range of output voltages is achieved with reduced inductor size, but voltage overstress may occur on switch transistors during transitions
Solution Approach 1:
The patent implements capacitor voltage balancing circuits that pre-charge or discharge capacitors before zone transitions occur. This preliminary action ensures that capacitor voltages are properly balanced and prevents voltage overstress on switch transistors during transitions between operational zones.
Solution Approach 2:
The patent uses voltage balancing control circuits that continuously monitor capacitor voltages and adjust switching patterns to maintain proper voltage levels. This feedback mechanism prevents voltage overstress by detecting and correcting imbalances before they cause harmful effects on the switch transistors.
4Adaptability or versatility
If boundary zone transitions are implemented, then output voltages near boundaries are generated, but transition state toggling may cause instability
Solution Approach 1:
The patent implements periodic alternation between adjacent zones (e.g., alternating between Zone 1 and Zone 2) when operating in boundary zones. This periodic action smooths out transition state toggling and generates stable output voltages near zone boundaries by averaging the effects of alternating transitions over time.
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 enables a full range of output voltages with reduced inductor size and prevents voltage overstress on switch transistors, enhancing efficiency and reliability in generating multiple voltage levels for electronic devices.
Implementation Method 1
couples two or more capacitors together to transfer charge from a higher voltage capacitor to a lower voltage capacitor
Implementation Method 2
Inductor L1 is coupled in a shunt configuration between switches on and φ12
Data Source
AI summary
Multi-level DC-to-DC converter circuits and methods that permit a full range of output voltages, including near and at zone boundaries. Embodiments alternate among adjacent or near-by zones, operating in a first zone for a selected time and then in a second zone for a selected time. Embodiments may include a parallel capacitor voltage balancing circuit that connects a capacitor to a source voltage to charge that capacitor, or couples two or more capacitors together to transfer charge, all under the control of real-time capacitor voltage measurements. Embodiments may include a lossless voltage balancing solution where out-of-order state transitions are allowed, thus increasing or decreasing the voltage across specific capacitors to prevent voltage overstress on the converter main switches. Restrictions may be placed on the overall sequence of state transitions to reduce or avoid transition state toggling, allowing each capacitor an opportunity to have its voltage steered as necessary for balancing.