Parallel Shorting Devices for Current Balancing in Power Converters
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Solution Overview
Problem
High power levels in DFIG systems require larger, more expensive shorting contactors, and existing systems face challenges with current imbalances in parallel contactors, leading to increased costs and unavailability of suitable components.
Innovation Solution
The implementation of parallel shorting devices coupled between bridge circuits and rotor inductors in a power converter, effectively using the impedance of the inductors to balance current and reduce the need for large, expensive contactors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If larger shorting contactors are used to handle high power levels, then the power handling capability is improved, but the cost and device size increase significantly
Solution Approach 1:
The invention divides the single large shorting contactor into multiple smaller parallel contactors (typically three). Each smaller contactor handles a portion of the total current, allowing the system to achieve high power handling capability while using smaller, more affordable individual contactor units. This segmentation resolves the contradiction by maintaining power handling through parallel configuration rather than requiring a single large device.
2Device complexity
If parallel contactors are used to reduce size and cost, then device complexity is reduced, but current imbalances occur between the parallel contactors
Solution Approach 1:
The rotor inductors serve as intermediary impedance elements that are naturally coupled between each parallel contactor and the rotor. These inductors provide current balancing by introducing impedance that equalizes the current distribution among parallel contactors, eliminating the need for additional balancing components while maintaining reliability.
3Productivity
If parallel bridge circuits are implemented to increase power output, then productivity is improved, but the need for larger shorting devices increases costs
Solution Approach 1:
The invention applies segmentation to the shorting devices by using multiple parallel contactors instead of a single large device. This allows the system to support higher power output from parallel bridge circuits while keeping individual contactor sizes manageable and costs controlled through the parallel configuration.
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 configuration allows for reliable operation of power converters with improved current balancing, enabling them to handle increased power levels without the need for large shorting devices, enhancing reliability and output capability.
Implementation Method 1
Each bridge circuit includes a bridge line coupled to a rotor inductor. The shorting devices are coupled between the bridge circuits and the rotor inductors such that an impedance of the inductors is effectively coupled between the shorting devices and the generator.
Data Source
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AI summary
A power generation system 200 may include a generator 220 and a power converter 262 coupled to the generator 220. The power converter 262 may include a plurality of bridge circuits 210 coupled in parallel. Each bridge circuit 210 may be coupled to an inductor 240. In addition, the power converter 262 may include a plurality of parallel shorting devices 244. The shorting devices 244 may be coupled to the bridge circuits 210 such that an impedance of the inductors 240 is effectively coupled between the shorting devices 244 and the generator 220.