Converter Cell Bypass via Daisy-Chain Control
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Solution Overview
Problem
Existing electrical multi-phase converters often fail when a converter cell experiences a short circuit, leading to unreliable operation, as existing bypass solutions are complex and not efficiently integrated.
Innovation Solution
The implementation of a superordinate controller and additional control boards within each converter cell, connected via a daisy chain network, allows for efficient data communication and control of bypass switches to short-circuit failed cells, ensuring reliable operation by simplifying the bypass function and providing redundant data paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bypass switch is added to each converter cell to enable bypassing of failed cells, then the reliability of the electrical converter is improved, but the device complexity increases due to additional control boards and communication interfaces
Solution Approach 1:
The control system is segmented into a superordinate controller and distributed additional control boards, where each additional control board is responsible for controlling the bypass switch in its respective converter cell. This segmentation allows the bypass function to be implemented in a modular manner, improving reliability while managing complexity through functional distribution.
Solution Approach 2:
The additional control boards are interconnected via a daisy-chain communication interface, merging the communication paths into a single continuous network. This approach reduces the overall number of communication interfaces needed compared to having each control board independently connected to the superordinate controller, thereby managing device complexity while maintaining the bypass functionality.
2Reliability
If a master controller connected to each converter cell via fiber optic interface is used for bypass control, then the bypass function is achieved, but the device complexity and cost increase
Solution Approach 1:
Multiple communication paths (fiber optic interfaces) are merged into a single daisy-chain communication interface that connects adjacent converter cells sequentially. This reduces the total number of communication interfaces from N (where N is the number of converter cells) to N-1, simplifying the communication architecture while maintaining reliable bypass control.
Solution Approach 2:
The daisy-chain communication interface acts as an intermediary between the superordinate controller and individual converter cells. Instead of direct connections, the communication passes through intermediate converter cells, allowing bypass control to be achieved with reduced interface complexity while maintaining system reliability.
3Power
If converter cells are series-connected at their outputs for high voltage operation, then the power handling capability is improved, but the reliability decreases when one cell fails due to lack of bypass capability
Solution Approach 1:
A bypass switch is pre-configured in each converter cell, ready to be activated when a failure occurs. This preliminary preparation ensures that when a cell fails in a series-connected high-voltage configuration, the bypass can be quickly activated to maintain operation, preventing the entire system from failing due to a single cell failure.
Solution Approach 2:
The electrical configuration of each converter cell can change from series-connected to short-circuited (bypassed) state when a failure is detected. This parameter change allows the failed cell to be electrically removed from the series chain, maintaining the high-voltage operation of the remaining cells while isolating the failed component.
Data Source
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Figure 3~4
AI summary
An electrical converter (100) comprises: a plurality of converter cells (104) series-connected at their outputs, each of the converter cells (104) adapted for converting a supply voltage (110) into an output voltage (114); a superordinate controller (230) for controlling the output voltage (114) of each of the converter cells (104); wherein each of the converter cells (104) comprises a control board (218) for controlling power switches (S1, S2, S3, S4) of the converter cell (104), a bypass device (222) adapted for short-circuiting the converter cell (104) at its output and an additional control board (224) for controlling the bypass device (222); wherein each of the control boards (218) is at least connected to the superordinate controller (230) for data communication; wherein each of the additional control boards (224) is at least connected to another additional control board (224) for data communication.