Duplex Control Device for Modular Power Converter
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Solution Overview
Problem
Existing power conversion devices face challenges in seamlessly switching between active and standby systems without disrupting sub-modules, particularly when an abnormality occurs in the control device, affecting AC and DC systems connected to them.
Innovation Solution
A power conversion device is designed with a duplex configuration of control and relay devices that can automatically switch between active and standby systems by selecting the operational system based on abnormality determination information, allowing sub-modules to continue operation without interruption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multiplex configuration is used for control devices to improve reliability, then system reliability is improved, but system complexity increases
Solution Approach 1:
The control system is segmented into multiple independent control devices (active and standby), each capable of independently controlling the sub modules. This segmentation allows the system to maintain reliability through redundancy while keeping each individual control device relatively simple in structure.
Solution Approach 2:
The system uses parameter changes in the form of control mode switching - transitioning between active system control and standby system control based on abnormality detection. This allows the system to adapt its operational parameters (which control device is active) without changing the fundamental structure, thereby maintaining reliability while managing complexity.
2Reliability
If system switchover is implemented quickly to maintain reliability, then system reliability is improved, but control precision deteriorates due to potential abnormality determination errors
Solution Approach 1:
The system performs preliminary abnormality determination using multiple determination methods before initiating system switchover. This preliminary action ensures that the switchover is based on accurate abnormality detection, preventing premature or incorrect switching while maintaining system availability.
Solution Approach 2:
The system implements feedback mechanisms where the result of abnormality determination is continuously monitored and used to adjust control decisions. The feedback loop ensures that switchover decisions are based on accurate and up-to-date information about system status, balancing reliability with detection precision.
3Reliability
If the active system is switched to standby system upon abnormality detection, then system reliability is improved, but loss of time occurs during the switchover process
Solution Approach 1:
The standby control device and relay device are pre-configured and ready to take over control immediately upon abnormality detection. This preliminary preparation eliminates the need for configuration or initialization during switchover, thereby minimizing switchover time while maintaining continuous operation capability.
Solution Approach 2:
The relay devices act as intermediaries that can rapidly switch control commands between active and standby control devices. This intermediary mechanism enables fast switchover by providing a dedicated control path that bypasses complex routing decisions during the transition, reducing switchover time.
4Measurement precision
If abnormality determination is performed before switchover to ensure accuracy, then measurement precision is improved, but loss of time increases due to extended determination period
Solution Approach 1:
The system performs partial abnormality determination continuously in the background using multiple determination methods, rather than waiting for complete analysis before initiating switchover. This partial action approach provides sufficiently accurate determination quickly, balancing precision with time efficiency.
Solution Approach 2:
When abnormality is detected with sufficient confidence through the determination process, the system rushes through the remaining determination steps and proceeds with switchover without delaying for complete analysis. This skipping approach maintains adequate detection accuracy while minimizing determination time.
Data Source
AI summary
A power conversion device includes: first and second control devices that generate first and second control commands respectively; and first and second relay devices that transmit, to each sub module, the first and second control commands respectively. The first and second control devices receive instruction information indicating a system that is to control operation of each sub module. The first and second control commands each include a drive command, abnormality determination information about the control device, and instruction information. Even when the instruction information indicates a first system, each sub module selects a second system as a system to control operation of each sub module in response to detection of occurrence of abnormality to the first control device, and performs PWM control for a switching element in accordance with the drive command included in the second control command for the second system.