Transformerless Cycloconverter with Distributed Energy Storage
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Solution Overview
Problem
Existing transformerless cycloconverters require complex and costly arrangements of bridge modules to connect three-line networks with different nominal voltages or frequencies, leading to high hardware complexity and limited flexibility in voltage adjustment.
Innovation Solution
A simplified topology using six bridge modules or series circuits, allowing for flexible voltage adjustment and redundancy, with the option to use bridge modules with different DC voltages and integrating batteries for uninterruptible power supply, reduces hardware complexity and enhances reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transformerless cycloconverter uses bridge modules to connect two three-line networks with different nominal voltages or frequencies, then electrical energy transfer between networks is enabled, but hardware complexity and cost increase significantly
Solution Approach 1:
The cycloconverter is divided into multiple identical bridge module units, each capable of independent operation. The patent uses six bridge modules arranged in a specific topology where each module handles a portion of the power conversion task, allowing the system to achieve high voltage and frequency adaptability while keeping each individual module simple and standardized.
Solution Approach 2:
Each bridge module is designed as a universal unit that can handle multiple functions: voltage transformation, frequency conversion, and power flow control in both directions. The modules can be configured in series to handle high voltage applications or parallel for high current applications, making the same basic module design adaptable to different network conditions without requiring specialized components for each scenario.
2Adaptability or versatility
If bridge modules are connected in series to increase output voltage flexibility, then voltage adjustment range is improved, but reliability decreases due to more potential failure points
Solution Approach 1:
The patent implements local redundancy within each bridge module by incorporating two capacitors per module that can be connected in series or parallel. This allows the system to maintain reliability at the local module level while achieving high voltage output through series connection of modules. If one capacitor fails, the other can compensate, and the module can continue operating in a degraded mode.
Solution Approach 2:
The control system continuously monitors the status of each bridge module and capacitor, and has pre-programmed switching strategies to redistribute power flow and reconfigure connections before a failure propagates through the system. The topology is designed with built-in bypass paths that can be activated immediately upon detecting a module failure, preventing cascading failures and maintaining system reliability.
3Device complexity
If six bridge modules are used instead of nine or more, then hardware complexity is reduced, but the ability to handle high voltage may be limited
Solution Approach 1:
The patent resolves the voltage limitation by transitioning from a planar arrangement of bridge modules to a three-dimensional switching topology. The six modules are connected with multiple switching paths that allow capacitors within and across modules to be reconfigured in series-parallel combinations. This dimensional switching capability enables the system to achieve high voltage output (equivalent to nine or more modules in traditional topologies) while using only six physical modules, thus reducing hardware complexity while maintaining power handling capability.
Data Source
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AI summary
The invention relates to a transformerless cycloconverter for connecting a first three-conductor grid (50), in particular a three-phase grid, to a second three-conductor grid (51), in particular a three-phase grid, by means of bridge modules comprising electronic semiconductor circuits (5, 6, 7, 8), having the following characteristics: a) a first bridge module (1) or a first series circuit (52) of bridge modules (1) is connected to a first conductor (500) of the first power supply grid (50) and to a first conductor (510) of the second power supply grid (51), b) a on one side and to a first conductor (510) of the second power supply grid (51) on the other side, b) a second bridge module (1) or a second series circuit (53) of bridge modules (1) is connected to a second conductor (501) of the first power supply grid (50) and to the on one side and to the first conductor (510) of the second power supply grid (50), c) a conductor (510) of the second power supply grid (51) on the other side, c) a third bridge module (1) or a third series circuit (54) of bridge modules (1) is connected to the second conductor (501) of the first power supply grid (50) and to a on one side and to a second conductor (511) of the second power supply grid (51), d) a conductor (511) of the second power supply grid (51) on the other side, d) a fourth bridge module (1) or a fourth series circuit (55) of bridge modules (1) is connected to a third conductor (502) of the first power supply grid (50) and to the on one side and to the second conductor (511) of the second power supply grid (51),conductor (511) of the second power supply grid (51) on the other side, e) a fiftha fifth bridge module (1) or a fifth series circuit (56) of bridge modules (1) is connected to the third conductor (502) of the first power supply grid (50)and to a on one side and to a third conductor (512) of the second power supply grid (51),conductor (512) of the second power supply grid (51) on the other side, and a sixth bridge module (1) or a sixth series circuit (57) of bridge modules (1) is connected to the first conductor (500) of the first power supply grid (50) and to the third conductor (512) of the second power supply grid (51). on one side and to the thirdaconductor (512) of the second power supply grid (51) on the other side.