Daisy Chain Power Converter Communication Error Detection
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Solution Overview
Problem
In cascade-connection type SVCs, the high potential difference between cells and the risk of communication errors due to optical fiber cable disconnections or short circuits lead to increased costs and longer control signal transmission times, particularly when incorporating error detection features.
Innovation Solution
A power conversion device with a daisy-chain communication configuration between the central control unit and cell control units, utilizing a specific pattern signal within the optical serial signal frame to distinguish it from the control signal frame, allowing for efficient error detection without lengthening the control signal frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a special optical fiber cable with high dielectric strength is used to withstand potential differences, then communication reliability is improved, but system cost increases
Solution Approach 1:
The communication path is segmented into multiple sections with local pattern signal generation at each cell control unit. This eliminates the need for a single long high-insulation cable by dividing the communication function across multiple shorter segments, each generating its own pattern signals locally.
Solution Approach 2:
Each cell control unit generates its own specific pattern signals locally and transmits them downstream, rather than requiring all pattern signals to be transmitted from the central control unit through the entire cable length. This self-service approach reduces the insulation requirements for the communication cable.
2Reliability
If error detection features are incorporated into the control signal frame, then communication error detection capability is improved, but control signal transmission time increases
Solution Approach 1:
Specific pattern signals are transmitted periodically at predetermined timings between control signal frames. This periodic transmission of pattern signals enables error detection without requiring continuous error detection data in every control signal frame, thus minimizing time overhead.
Solution Approach 2:
The error detection function is extracted from the control signal frame structure and implemented separately through dedicated specific pattern signals. This separation allows error detection to operate independently without adding bits to the control signal frames, avoiding increased transmission time.
3Extent of automation
If the control signal frame includes information for controlling all cells, then centralized control capability is improved, but transmission time increases notably
Solution Approach 1:
The control system is segmented such that each cell control unit generates and transmits its own specific pattern signals locally downstream, rather than all cells receiving pattern signals from the central control unit. This segmentation reduces the transmission distance and time for pattern signals while maintaining centralized control through the control signal frames.
Data Source
AI summary
A power conversion device includes: a plurality of cascade-connection type single-phase power converters; and a central control unit that controls the plurality of the single-phase power converters, wherein each of the plurality of single-phase power converters has a single-phase power converter control unit, and the central control unit and the plurality of the single-phase power converter control units are connected via a communication means having a daisy-chain configuration, wherein the single-phase power converter control unit transmits and receives a control signal via the communication means having the daisy-chain configuration, as well as a specific pattern signal, other than a control signal frame, which can be distinguished from the control signal frame, and determines a communication error due to not receiving the specific pattern signal at the single-phase power converter control unit, or an inconsistency between the received signal and the specific pattern signal.