Flying Capacitor Converter Fault Detection via Current Gradients
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Solution Overview
Problem
High-voltage flying capacitor converters require expensive switches and lack effective short circuit detection methods, making real-world operation challenging.
Innovation Solution
A method for detecting faults in flying capacitor converters by measuring currents and current gradients using multiple sensors, allowing for the division of the converter into cells with lower voltage switches, reducing the energy stored in capacitors and the need for extensive current sensing, and implementing a fault detection apparatus that can quickly identify and respond to short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If high-voltage converter switches are used in flying capacitor converters, then the converter can operate at high voltages, but the cost becomes quite expensive
Solution Approach 1:
The patent divides the high-voltage converter into multiple cells, each handling a portion of the total voltage. By segmenting the voltage handling across multiple lower-voltage switches arranged in series, the system achieves high-voltage operation using affordable low-voltage components rather than expensive high-voltage switches.
2Measurement precision
If multiple current sensors are used for fault detection in each cell, then fault detection precision improves, but device complexity increases
Solution Approach 1:
The patent implements a universal fault detection method that monitors current gradients across all cells using a minimal set of current sensors. The same detection algorithm and sensor type are applied universally to detect faults in any cell, eliminating the need for specialized sensors in each cell while maintaining comprehensive fault detection capability.
Solution Approach 2:
The patent uses current gradient measurement as a copied indicator of fault conditions. Instead of directly sensing each cell's internal state, the system copies the fault signature through current gradient measurements at accessible points, allowing indirect but effective fault detection without invasive sensing in each cell.
3Reliability
If fault detection is implemented quickly to minimize damage, then reliability improves, but response time requirements increase system complexity
Solution Approach 1:
The patent continuously monitors current gradients in real-time during normal operation, maintaining readiness to detect faults immediately when they occur. This preliminary monitoring action ensures that when a fault happens, the system can rapidly respond by disconnecting affected cells, minimizing damage without requiring complex post-fault analysis systems.
Solution Approach 2:
The patent implements a feedback mechanism where current gradient measurements continuously inform the control system about the health status of converter cells. When the gradient exceeds thresholds indicating a fault, the feedback triggers immediate protective action to isolate the faulty cell, creating a closed-loop system that automatically responds to faults.
Data Source
AI summary
A flying capacitor converter comprises a converter input comprising a positive pole and a negative pole, an output terminal, and a plurality of cells, each cell comprising two switches and a flying capacitor arranged between each cell. A method for detecting a plurality of faults in the converter includes measuring, by a second current sensor arranged at the positive pole, a second current; measuring by a third current sensor arranged at the negative pole, a third current; and detecting a first fault in the flying capacitor converter when the second current or the third current exceeds a first current threshold, and/or when a gradient of the second current or a gradient of the third current exceeds a first gradient threshold.