UPS Inverter Arc Energy Limiting via Bypass Inhibition
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Solution Overview
Problem
Existing solutions for fault arcs in electrical appliances are complex and expensive, and cannot reduce the delay time between arc occurrence and switching off to zero, leading to hazardous explosions and equipment damage.
Innovation Solution
An online, double-conversion uninterruptible power supply (UPS) with a bypass switch and fault arc detection, where the UPS inhibits bypass mode during fault arcs, limiting arc current with the inverter to reduce energy and prevent switching to bypass mode, thereby controlling the fault arc with the inverter's current limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If switching devices are used to cut off high currents in very short time, then arc energy is reduced, but device complexity and cost increase significantly
Solution Approach 1:
The patent introduces a current-limiting impedance as an intermediary element between the fault arc and the power source. This passive component limits the arc current without requiring complex active switching devices, thereby reducing arc energy while avoiding increased device complexity and cost.
Solution Approach 2:
The patent employs simple, inexpensive passive components (impedance elements) rather than expensive, complex switching devices. These passive elements provide the necessary current limiting function at low cost and with minimal complexity, sacrificing the need for sophisticated control hardware.
2Reliability
If circuit breakers are used to trip on fault arc detection, then safety is improved, but response time cannot be reduced to zero leading to equipment damage
Solution Approach 1:
The patent pre-positions current-limiting impedance elements in the circuit path before a fault occurs. When a fault arc develops, the impedance immediately limits the current without requiring any detection or switching action, providing instantaneous protection that eliminates response time delays.
Solution Approach 2:
The patent converts the inherently slow response of circuit breakers into an acceptable solution by adding impedance that passively limits arc current. The impedance element works continuously to constrain fault currents, transforming the limitation of slow mechanical switching into a non-issue by reducing the energy available to drive the arc during the breaker's operation time.
3Reliability
If bypass mode is activated for excessive power demand, then power supply reliability is improved, but arc current increases during fault arcs
Solution Approach 1:
The patent applies different characteristics to different parts of the power supply system. The bypass path is designed with current-limiting impedance specifically for fault protection, while the normal conversion path maintains high reliability. This local differentiation allows the bypass to provide reliability without exacerbating arc currents during faults.
Solution Approach 2:
The patent introduces impedance as an intermediary element in the bypass path that mediates between the need for power supply reliability and the need to limit arc current. This passive component allows the bypass to function for reliability while simultaneously constraining fault arc currents through its current-limiting property.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces the risk of personnel injury and equipment damage by limiting arc energy, minimizing downtime, and allowing the system to return to normal operation quickly.
Implementation Method 1
limiting arc current with the inverter to reduce energy
Implementation Method 2
a rectifier, whose input is connected to the UPS input; an inverter, whose input is connected to an output of the rectifier
Data Source
AI summary
An online, double-conversion uninterruptible power supply includes: a UPS input; a rectifier, whose input is connected to the UPS input; an inverter, whose input is connected to an output of the rectifier; a UPS output connected to an output of the inverter; a bypass switch connected between the UPS input and the UPS output; a control unit for closing the bypass switch in case of excessive output current and/or excessive voltage drop and/or excessive power demand at the UPS output; and an override input, which, when activated, inhibits closing the bypass switch.