Flying Capacitor Converter Driver Power from Switch Voltage
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Solution Overview
Problem
The use of isolated power supplies and cascaded bootstrap circuits for driver power supplies in flying capacitor multilevel converters leads to increased cost and space requirements, especially with a high number of levels, and results in reduced control voltage due to voltage drops.
Innovation Solution
Harvest energy for driver power supplies directly from voltage differences across controllable semiconductor switches in the flying capacitor multilevel converter topology, eliminating the need for isolated power supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If isolated power supplies are used for each driver, then each driver receives sufficient power, but the cost and space requirements increase significantly
Solution Approach 1:
Multiple driver power supplies are merged into a single common power supply system. The patent connects multiple driver circuits to a shared power supply through diodes, allowing one power supply to serve multiple drivers instead of requiring separate isolated power supplies for each driver.
Solution Approach 2:
The single common power supply performs multiple functions by serving as the power source for multiple different driver circuits. This universal power supply replaces what would traditionally require multiple specialized isolated power supplies, reducing overall system complexity.
2Device complexity
If cascaded bootstrap circuit is used to supply multiple drivers from single power source, then space requirements are reduced, but voltage drops occur reducing control voltage
Solution Approach 1:
Diodes are introduced as intermediary components between the common power supply and multiple driver circuits. These diodes provide isolated current paths that prevent voltage drops from affecting the control voltage, acting as mediators that maintain electrical isolation while sharing a common power source.
3Adaptability or versatility
If high number of levels are used in converter, then power range is extended, but number of isolated power supplies and space requirements increase
Solution Approach 1:
The patent merges multiple driver power supplies into a single common power supply that serves all drivers across different voltage levels. This consolidation dramatically reduces the space required for power supplies while maintaining the ability to support high-number level converters.
Data Source
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AI summary
A flying capacitor multilevel converter comprising at least one phase leg circuit (100) comprising a first group of series connected controllable semiconductor switches (S11, S12, S13, S14) and a second group of series connected controllable semiconductor switches (S21, S22, S23, S24), each controllable semiconductor switch being provided with a driver (20) configured to drive the controllable semiconductor switch, at least one capacitor (Cfc), each of the at least one capacitor being individually connected between a node connecting two adjacent controllable semiconductor switches of the first group and a node connecting respective two adjacent controllable semiconductor switches of the second group, and a power supply arrangement comprising at least two power supplies (10), wherein each power supply (10) is configured to supply power to at least one driver (20) and wherein each power supply is configured to be supplied by a voltage over at least one controllable semiconductor switch.