Power Converter Current Limiting for Open-Phase Fault Ride-Through
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Solution Overview
Problem
During an open-phase fault, power converters experience overcurrent, leading to operation shutdown for protection, and upon fault removal, they struggle to quickly return to normal operation.
Innovation Solution
A power conversion device with a control system that detects voltage or current unbalanced components, limiting the alternating current flowing between the power converter and the AC circuit based on these unbalanced components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the power converter outputs current as usual during open-phase fault, then the power converter can maintain normal power delivery, but overcurrent flows through the power converter causing it to stop operation for protection
Solution Approach 1:
The control device dynamically adjusts the alternating current magnitude based on the detected unbalanced component. During normal operation, full current is permitted for maximum power delivery. During open-phase fault, the control device limits the current magnitude to prevent overcurrent damage while still allowing continued operation. This dynamic adaptation resolves the contradiction between maintaining productivity and ensuring reliability.
2Reliability
If the power converter stops operation during open-phase fault for protection, then the power converter is protected from overcurrent damage, but it cannot quickly return to normal operation upon fault removal
Solution Approach 1:
The control device continuously monitors the unbalanced component of the alternating-current circuit and uses this feedback to adjust the current magnitude in real-time. When fault is detected, feedback triggers current limiting; when fault is removed, feedback automatically permits full current restoration. This closed-loop feedback mechanism eliminates the need for operation shutdown and enables immediate recovery, resolving the time loss contradiction.
3Reliability
If the control device limits alternating current magnitude based on unbalanced component, then the power converter can continue operation during fault, but the magnitude of alternating current is restricted
Solution Approach 1:
The control device changes the operating parameter (current magnitude) based on the detected unbalanced component. During open-phase fault, the parameter is changed from full current to limited current to ensure reliable continued operation. When fault is removed, the parameter is restored to full current for maximum productivity. This parameter adaptation resolves the contradiction between reliability and productivity.
Data Source
AI summary
A power conversion device includes a power converter connected between a multi-phase alternating-current circuit and a direct-current circuit, and a control device to control the power converter. The control device detects an unbalanced component indicating a voltage unbalanced component or a current unbalanced component of the alternating-current circuit and limits a magnitude of an alternating current flowing between the power converter and the alternating-current circuit based on the unbalanced component.