Distributed Control for Cascade Power Converters
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Solution Overview
Problem
Cascade power electronic converters rely on centralized control, which fails if the central controller malfunctions, leading to low reliability and inability to continue operation.
Innovation Solution
A fully distributed control system is implemented, where each power converter has a corresponding controller with a common-mode voltage loop and current loop, generating control signals to modulate the first side voltage without a centralized controller, allowing operation even if some controllers fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If centralized control is adopted, then control coordination is achieved, but system reliability deteriorates due to single point of failure
Solution Approach 1:
The patent divides the centralized control function into N distributed controllers, each managing one power converter unit. This segmentation eliminates the single point of failure in centralized control while maintaining coordination through inter-controller communication, directly resolving the contradiction between reliability and complexity
Solution Approach 2:
The patent introduces communication mechanisms as intermediaries between distributed controllers to coordinate control actions. This allows multiple independent controllers to work together as a unified system without requiring a central coordinator, improving reliability while managing complexity through standardized communication protocols
2Reliability
If centralized controller is used, then overall system control is achieved, but operational continuity worsens when controller fails
Solution Approach 1:
By segmenting the control function across N independent controllers, the patent ensures that failure of one controller does not halt the entire system. Each controller manages its local power converter autonomously, maintaining operational continuity while simplifying control management through distributed decision-making
Solution Approach 2:
The patent changes the control architecture parameter from centralized to distributed, fundamentally altering how control decisions are made. This parameter change enables the system to maintain operation during controller failures while adapting control management to a more resilient distributed model
3Reliability
If fully distributed control is implemented, then reliability improves, but control coordination difficulty increases
Solution Approach 1:
The patent implements feedback mechanisms where controllers exchange information about system state and control actions. This feedback enables automatic coordination without centralized management, maintaining reliability while reducing the subjective difficulty of coordination through algorithmic decision-making based on real-time information
Solution Approach 2:
Communication protocols serve as intermediaries that automatically coordinate between distributed controllers. This intermediary layer handles the complexity of coordination transparently, allowing controllers to operate independently while maintaining system-wide coherence without increasing operational difficulty
Data Source
AI summary
The present application provides a conversion system and a control method, including N power converters and N controllers, where each power converter includes a first side and a second side, the first sides of the N power converters are electrically coupled in series, and currents flowing through the first sides of the N power converters are the same, the N controllers correspond to the N power converters one to one. Each controller contains a common-mode voltage loop and a current loop. The common-mode voltage loop is configured to receive a voltage reference signal and a voltage feedback signal, and output a given signal. The current loop is configured to receive the given signal, a current reference signal, and a first side current of a corresponding power converter, and output a common-mode control signal to modulate a first side voltage of the corresponding power converter.