Power Converter H-Bridge Segmentation for Megawatt Aircraft
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Solution Overview
Problem
Traditional active rectifiers and inverters struggle to handle higher currents and voltages required by advanced 'more electric' aircraft architectures, necessitating improved power converters capable of efficiently managing megawatt electrical power.
Innovation Solution
A power converter design featuring series-connected transistors forming H-bridges with an AC link, a three-wire DC bus, and high-voltage MOSFET devices, enabling efficient conversion and reduced filtering needs through a 5-level phase voltage waveform, allowing for higher DC bus voltages up to 1600V or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional active rectifiers and inverters are used, then the design is simple and reliable, but they cannot handle higher currents and voltages required by modern aircraft architectures
Solution Approach 1:
The patent divides the power converter into modular H-bridge units, where each H-bridge contains four transistors arranged in specific configurations. This segmentation allows the system to handle higher power levels by combining multiple modules while maintaining manageable complexity at each module level. The AC link connects these segmented H-bridges, enabling scalable power handling capability.
Solution Approach 2:
The patent introduces a multi-level voltage structure by connecting transistors in series within H-bridges and using an AC link between them. This creates a dimensional expansion from single-level to multi-level voltage handling, enabling the converter to manage higher voltages and currents through hierarchical arrangement of transistor stages rather than simply increasing component ratings.
2Power
If higher DC bus voltages are used to increase power density, then power handling improves, but switching losses increase and reliability decreases
Solution Approach 1:
The power conversion process is segmented into multiple H-bridge stages connected via AC link. Each stage operates at lower voltage levels individually, distributing the total voltage stress across multiple components rather than requiring a single high-voltage switch. This segmentation reduces switching losses at each stage while achieving high overall power density through cascaded configuration.
Solution Approach 2:
The AC link serves as an intermediary between H-bridge stages, allowing power transfer without requiring direct high-voltage switching between stages. This intermediary approach enables each H-bridge to operate independently at optimized voltage levels, reducing overall switching losses while maintaining high power density through the cascaded multi-stage architecture.
3Power
If higher power levels are handled, then system capability improves, but filter weight and size increase
Solution Approach 1:
The converter is divided into multiple H-bridge modules that can be independently optimized. This segmentation allows filtering requirements to be distributed across stages rather than requiring a single large filter for the entire power level. Each module can use smaller, lighter filters appropriate to its specific power level, reducing total filter weight while maintaining high overall power handling capability.
Solution Approach 2:
The patent employs multi-level voltage switching that creates more refined voltage steps, reducing the amplitude of voltage ripple and current harmonics. This dimensional change in voltage structure reduces the filtering burden, allowing lighter filters to achieve the same level of power quality at higher power levels compared to conventional single-stage converters.
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 enables power converters to efficiently handle high voltages and currents with reduced switching losses, increased power density, and lower filter weight, suitable for megawatt power levels in aerospace applications.
Implementation Method 1
A power converter includes a first set of transistors electrically connected in series, a second set of transistors electrically connected in series, and an AC link. The second set of transistors is electrically connected in parallel with the first set of transistors to form an H-bridge.
Implementation Method 2
The power converter can include a three-wire DC bus electrically connected in parallel to the H-bridge. A first DC source of one-half the total DC voltage can be electrically connected between a first and a second DC wire. A second DC source of one-half the total DC voltage can be electrically connected between a second and a third DC wire.
Data Source
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AI summary
A power converter (100) includes a first set (102) of transistors electrically connected in series, a second set (104) of transistors electrically connected in series, and an AC link (108). The second set of transistors is electrically connected in parallel with the first set of transistors to form an H-bridge (110). The AC link is electrically connected between the first and second sets of transistors. A plurality of H-bridges are connected in parallel and a three-wire DC bus is electrically connected to the H-bridges.