UPS Bypass Device for Fast DC Fault Clearance
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Solution Overview
Problem
Existing uninterruptable power supply (UPS) systems face inefficiencies and safety concerns when providing DC power to loads, particularly due to unnecessary AC/DC and DC/AC conversion steps, which limit fault clearance capabilities and increase system and operator risks during abnormal operating conditions like short circuits.
Innovation Solution
A UPS system design that delivers two-wire DC power with a bypass mechanism using a power converter and a bypass device, where the bypass device receives AC power and supplies pulsed power directly to the load, overriding current limitations and enabling fast fault clearance through the AC source impedance, thus eliminating the need for additional protective devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bypass device with very high current source capability is implemented, then fault clear capability is improved, but device complexity and practical feasibility worsen
Solution Approach 1:
The patent introduces an intermediary bypass device that mediates between the AC source and DC load during fault conditions. This bypass device acts as a mediator that provides high current capability when needed without requiring the main power converter to have this capability, thus resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The bypass device is designed to be dynamically activated only during fault conditions rather than being permanently active. The switching unit dynamically connects or disconnects the bypass path based on system needs, providing high current capability on-demand without continuously adding complexity to the normal operating configuration.
2Loss of energy
If AC/DC and DC/AC conversion steps are eliminated, then energy efficiency is improved, but fault clear capability worsens
Solution Approach 1:
The patent segments the power conversion function from the fault clearance function. The main power converter handles efficient AC/DC conversion during normal operation, while a separate bypass device handles fault clearance. This segmentation allows each component to be optimized for its specific function, maintaining efficiency while restoring fault clear capability.
Solution Approach 2:
The bypass device serves as an intermediary mechanism that restores fault clear capability without interfering with the efficient AC/DC conversion path during normal operation. It provides a separate parallel path that activates only during faults, thus resolving the contradiction between efficiency and reliability.
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 solution enhances system and operator safety by ensuring immediate fault clearance and reducing energy losses, while maintaining system performance and reliability without requiring specialized protective devices for fault currents.
Implementation Method 1
a bypass device for passing power from its output side to the DC output line, whereby the bypass device and the power converter are connected in parallel to the DC output line, and the bypass device comprises at least one switching unit, which receives AC power at its input side, and a control unit, whereby the switching unit is controlled by the control unit to supply pulsed power from an AC power supply with essentially the same polarity as the DC output line
Data Source
AI summary
The present invention provides an uninterruptable power supply system and method with a first AC source providing three-phase AC power, a DC source providing DC power, and a power converter receiving AC power from the first AC source and/or DC power from the DC source and delivering two wire DC power to a load via a DC output line. One pole of the DC output line is connected to the neutral reference of the four-wire AC-power supply line. The system may include a bypass device for passing power from its output side to the DC output line with the bypass device and the power converter being connected in parallel to the DC output line. The bypass device may include at least one switching unit, which receives AC power at its input side, and a control unit to supply pulsed power from an AC power supply.