Parallel UPS DC Bus Fuse Segmentation
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Solution Overview
Problem
Conventional uninterruptible power supply systems face issues with varying output voltages and cross currents between power converters, leading to potential failures when one converter fails, causing others to malfunction due to overcurrent flow.
Innovation Solution
The system incorporates fuses connected between the DC buses of power converters to ensure uniform input voltages and isolate failed converters, preventing cross currents and limiting failure range by blowing fuses when overcurrent occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If DC buses of multiple power converters are connected directly to make input voltages uniform, then cross current is suppressed, but when one converter fails, overcurrent flows to other converters causing them to fail
Solution Approach 1:
The patent divides the common DC bus system into segmented sections by inserting fuses between adjacent power converters. Each converter is isolated by fuse connections, creating separable segments. When one converter fails, the fuse blows to isolate that segment, preventing failure propagation while maintaining uniform voltage to other converters through the fused connections.
2Reliability
If fuses are installed between DC buses to isolate failed converters, then failure range is limited, but device complexity and cost increase
Solution Approach 1:
The fuse acts as an intermediary protective element inserted between the DC buses of adjacent power converters. This intermediary component provides automatic failure isolation without requiring complex control systems or additional active devices. The fuse simply blows when overcurrent occurs, creating a passive yet effective isolation mechanism that balances reliability improvement with minimal added complexity.
Data Source
AI summary
An uninterruptible power supply system includes a plurality of uninterruptible power supply devices, and each uninterruptible power supply device includes a conversion circuit, an inversion circuit, a DC positive bus, a DC negative bus, and a capacitor. The uninterruptible power supply system includes a first fuse connected between DC positive buses of two uninterruptible power supply devices, and a second fuse connected between DC negative buses of the two uninterruptible power supply devices. DC voltages between the plurality of DC positive buses and between the plurality of DC negative buses can be made uniform and a cross current can be suppressed. Even when one uninterruptible power supply device fails and an overcurrent flows between the two DC positive buses and between the two DC negative buses, the failure range can be narrowly limited by the first and second fuses.