UPS Parallel Modules with Auxiliary Counter Voltage Standby
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Solution Overview
Problem
Conventional uninterruptible power supply devices have a slow response to changes in load current and failures, as they activate additional units only after load increases or unit failures occur, leading to delayed adjustments.
Innovation Solution
An uninterruptible power supply device with multiple units connected in parallel, equipped with a current detector and controller that dynamically selects units to share load current and an auxiliary unit to provide counter voltage, allowing for quick adjustments to load changes and failures by activating additional units swiftly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If additional uninterruptible power supply units are activated only after load current increases or unit failure occurs, then the system maintains simplicity in control logic, but the response speed to load changes and failures becomes slow
Solution Approach 1:
The patent applies preliminary action by pre-selecting and pre-charging a standby uninterruptible power supply unit before it is actually needed. The controller pre-selects one unit from the parallel-connected units to be in standby mode with its switch closed and capacitor charged, so that when load increases or a failure occurs, the standby unit can immediately begin sharing the load without activation delay. This resolves the contradiction by preparing the system in advance while maintaining relatively simple control logic.
Solution Approach 2:
The patent implements dynamics by creating a dynamic control system that can switch between different operational states. The controller dynamically adjusts the state of uninterruptible power supply units based on real-time conditions - normally operating units share load, while a pre-selected standby unit remains ready to activate. When load changes or failures occur, the system dynamically transitions by having the standby unit join the active group and selecting a new standby unit, providing fast response while maintaining manageable control complexity through systematic state management.
2Reliability
If multiple uninterruptible power supply units are kept in standby state with pre-charged capacitors, then the response speed to failures improves, but the energy consumption and system complexity increase
Solution Approach 1:
The patent applies local quality by creating different operational states for different units within the parallel-connected system. Instead of all units being in the same state, one unit is designated as standby with its switch closed and capacitor pre-charged, while other units remain in normal operation or off state. This localized preparation of only one standby unit provides fast failure response capability while limiting energy consumption to only what is needed for maintaining that single standby unit, rather than all units.
3Loss of time
If a standby uninterruptible power supply unit is pre-selected and pre-charged, then the response time to unit failure is reduced, but the risk of current flow between units during transition increases
Solution Approach 1:
The patent applies equipotentiality by ensuring that the standby unit's output voltage matches the common bus voltage before connecting it to share the load. The controller monitors the output voltage of the standby unit and only closes its switch when the voltages are equalized. This prevents harmful current flow between units during transition, as there is no voltage difference to drive such current. The standby unit is pre-charged to the same voltage level as the operating units, creating an equipotential condition that eliminates the risk of damaging current flow when the standby unit joins the active group.
Data Source
AI summary
An uninterruptible power supply device includes N UPS modules connected in parallel with one another between an AC power supply and a load, a current detector configured to detect a load current, and a controller configured to select n UPS modules, and an auxiliary UPS module, based on a result of detection by the current detector. Each of the n UPS modules is configured to supply, to the load, a shared current which is 1/n of the load current. The auxiliary UPS module is configured to output, to the load, a counter voltage having a value in accordance with output voltages of the n UPS modules, and thereby to stand by in a state where no current flows between the auxiliary UPS module and the n UPS modules and between the auxiliary UPS module and the load.