Cascaded H-Bridge Converter Fault Isolation via Neutral Point Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power converter systems face challenges in efficiently detecting and isolating faults, particularly in cascaded H-bridge multilevel converters, leading to reduced reliability and increased costs due to the need for redundant systems or degraded power quality.
Innovation Solution
A novel power electronic circuit and method that utilizes a selectively isolated node and switches to rapidly detect and isolate faults, maintaining system operation with minimal disruption and cost, applicable to various modular multilevel converter topologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fault detection and isolation methods are used in cascaded H-bridge multilevel converters, then fault detection capability is provided, but system reliability decreases and implementation cost increases due to degraded power quality and need for redundant systems
Solution Approach 1:
The converter bridge is segmented into multiple independent H-bridge cells, each with its own fault detection and isolation capability. This segmentation allows localized fault management without affecting the entire system, thereby maintaining reliability while controlling complexity through modular design
Solution Approach 2:
A current sensor is positioned to detect current flowing through the neutral point of the converter bridge. This intermediary sensing mechanism provides fault detection capability without requiring complex monitoring systems in each H-bridge cell, reducing overall implementation complexity while maintaining system reliability
2Reliability
If redundant systems are implemented to maintain operation during faults, then system availability is improved, but cost increases
Solution Approach 1:
The system uses the existing neutral point current to detect faults and automatically isolates faulty H-bridge cells without requiring external redundant components. The healthy cells continue to operate and support the system, eliminating the need for additional redundant hardware while maintaining availability
Solution Approach 2:
When a fault is detected in an H-bridge cell, that cell is automatically disconnected from the system. The remaining healthy cells continue to operate, effectively discarding only the faulty portion while recovering and maintaining system functionality without requiring redundant components
3Reliability
If fault isolation is implemented to maintain operation, then power quality is maintained, but device complexity increases
Solution Approach 1:
The fault detection and isolation function is extracted as a separate control mechanism that monitors neutral point current and selectively disconnects faulty H-bridge cells. This extraction allows power quality to be maintained by isolating faults without requiring complex modifications to the power circuitry itself
Solution Approach 2:
The neutral point current sensor serves multiple functions: it monitors system operation, detects faults in any H-bridge cell, and provides information for isolation control. This multi-functionality maintains power quality through fault isolation while minimizing circuit complexity by using a single sensing mechanism
Data Source
AI summary
A faulted switch isolated replacement path for a power converter is provided using replacement switches connected to an isolated node. The replacement switches can be controlled by normal operating signals. The replacement path is isolated by isolation switches during normal operation. During a fault condition, the isolating switches are activated such that the isolated node is selectively connected to the appropriate power output.