UPS Ring Bus Bypass Switch Fault Current Injection
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Solution Overview
Problem
Existing ring bus architectures for uninterruptible power supplies (UPS) have limitations in fault current capability, which can lead to increased choke size requirements, affecting cost, feasibility, and viability.
Innovation Solution
The implementation of a ring bus system with multiple UPSs, each equipped with a rectifier, inverter, and a bypass switch, where the bypass switch closes in response to detected faults to increase fault current capability, allowing for reduced choke size by injecting additional fault current through the choke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing ring bus architectures are used, then the system structure is simple, but the fault current capability is limited
Solution Approach 1:
The system divides the fault current provision function into multiple UPS units, where each UPS can independently contribute fault current to the ring bus. This segmentation allows the system to achieve higher overall fault current capability while maintaining a modular and manageable structure.
Solution Approach 2:
The bypass switch is pre-configured and ready to close rapidly upon fault detection. This preliminary preparation enables the system to quickly inject fault current from the bypass source without delay, enhancing the fault current capability when needed most.
2Reliability
If fault current capability is increased, then reliability improves, but choke size must increase
Solution Approach 1:
The patent combines the fault current contribution from multiple UPS units and the bypass source through the common choke. By merging these current sources, the system achieves higher fault current capability without requiring a proportionally larger choke, as the currents are summed at the bus level rather than requiring individual large chokes for each source.
Solution Approach 2:
The ring bus architecture acts as an intermediary that allows multiple UPS units to contribute fault current independently. Each UPS sees a limited current demand through its own choke, while the bypass switch provides additional current through the ring bus, effectively sharing the fault current provision burden and avoiding the need for oversized individual chokes.
3Ease of manufacture
If choke size is reduced, then cost decreases, but fault current capability is insufficient
Solution Approach 1:
The bypass switch and bypass source are designed to serve multiple functions: they provide fault current capability enhancement, system protection, and support for reduced choke sizing. This multi-functionality allows the same components to deliver cost savings through smaller chokes while simultaneously ensuring adequate fault current capability is maintained.
Solution Approach 2:
The system changes the operational parameters by introducing a bypass switch that can rapidly alter the circuit configuration during faults. This parameter change enables the system to achieve higher fault current capability dynamically without requiring permanently oversized passive components like chokes, thereby reducing overall system cost.
Data Source
AI summary
A system is provided. The system includes a ring bus, at least one voltage source, and a plurality of uninterruptible power supplies (UPSs) electrically coupled between the at least one voltage source and the ring bus, wherein at least one UPS of the plurality of UPSs includes an input, an output, a rectifier having a rectifier input and a rectifier output, an inverter having an inverter input and an inverter output, wherein the rectifier output is electrically coupled to the inverter input, and a bypass switch electrically coupled between the rectifier input and the inverter output, the bypass switch configured to close in response to detection of a fault on the ring bus.