Dual Bridge DFIG Rotor Converter Segmentation
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Solution Overview
Problem
Existing doubly fed induction generators (DFIG) face limitations in power generation capacity, reliability, and component size due to the need for large and high-rated converters, which are costly and prone to system-wide failures when individual components fail, especially when operating at utility scales beyond 3 megawatts.
Innovation Solution
The implementation of a system with a rotor side converter featuring a combination of controlled and uncontrolled current conducting bridges, including IGBT transistors and diodes, respectively, to optimize power converter design, reducing component count and stress, and improving reliability by leveraging diodes for high-power regeneration modes and IGBTs for reduced power conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple power bridges are connected in parallel to increase power generation capacity, then the power rating increases, but the system reliability decreases due to current sharing balance issues and increased complexity
Solution Approach 1:
The power conversion system is segmented into two independent single-bridge converters instead of using one large multi-bridge parallel system. Each bridge operates independently with its own control, eliminating current sharing balance issues while maintaining the required power generation capacity through coordinated operation of both bridges.
Solution Approach 2:
The system transitions from a single-dimensional parallel bridge configuration to a two-dimensional architecture where two separate single-bridge converters operate in parallel, each handling different power ranges. This dimensional change allows independent control of each bridge, improving reliability while achieving the desired power capacity.
2Power
If IGBT bridges are connected in parallel to achieve high power rating, then the power capacity increases, but the device complexity increases due to current balancing requirements
Solution Approach 1:
The complex parallel IGBT bridge system is segmented into two independent single-bridge converters. Each converter has its own IGBT bridge operating independently, eliminating the need for complex current sharing control circuits and algorithms while achieving the required power rating through coordinated operation.
Solution Approach 2:
Each single-bridge converter is designed to operate autonomously with self-contained control, eliminating the need for complex inter-bridge current balancing control. The converters self-regulate their operation based on their respective operating conditions, reducing overall system complexity.
3Power
If a single large converter is used to handle high power, then the component count is reduced, but the cost increases due to high-rated converter requirements
Solution Approach 1:
The high-power conversion system is segmented into two medium-power single-bridge converters instead of one large high-rated converter. This segmentation allows use of lower-rated, lower-cost components in each bridge while achieving the same total power handling capacity through coordinated operation of both converters.
Solution Approach 2:
The system changes the power rating parameters from one high-rated converter to two medium-rated converters. This parameter change allows selection of more economical components with lower voltage and current ratings that are cheaper to manufacture and purchase, while maintaining the required total power capacity.
4Power
If parallel IGBT modules are used to balance current sharing, then the power capacity is increased, but the loss of time increases due to control complexity
Solution Approach 1:
The control system is segmented into two independent control units, one for each single-bridge converter. This eliminates the need for complex real-time current sharing control algorithms and communication protocols between parallel bridges, reducing control computation time and improving dynamic response.
Solution Approach 2:
Each converter control unit operates independently and autonomously, making local control decisions without requiring time-consuming communication and coordination with other bridges. This self-service control approach reduces control latency and improves system response time.
Data Source
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AI summary
The present subject matter is directed to systems and methods for improving reliability of dual bridge 202 doubly fed induction generators (DFIGs) by reducing the number of required components in the converters associated with such DFIGs. A converter 186 is constructed using a pair of current conducting bridges 202, 204 wherein one of the current conducting bridges 202 is controlled and the second 204 is not controlled. The uncontrolled bridge 204 may correspond to a pair of diodes while the controlled bridge 202 may correspond to a pair of transistors, in particular, a pair of IGBT transistors.