Uninterruptible Power Supply Bus Bar Current Detection
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Solution Overview
Problem
Existing uninterruptible power supply systems face delays in switching between standby and operating states due to long sampling times, leading to delayed detection of rapid changes in load current and inefficient power distribution.
Innovation Solution
An uninterruptible power supply system with parallel-connected power converters, each equipped with a current detector, shared current command generator, and controller, allowing for quick detection and control of shared current supply based on average current values without sampling from other units, enabling rapid switching between supply states and reducing excessive current distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the controller samples detection results from current detectors in other uninterruptible power supplies and sums them to determine appropriate number of units, then the system can determine the appropriate number of UPS units required, but the sampling time becomes long and rapid changes in load current cannot be detected timely
Solution Approach 1:
The invention extracts the current detection function from individual UPS units and places it on the shared bus bar. The current detector detects the total current flowing through the bus bar, which represents the sum of currents from all parallel-connected power converters. This eliminates the need for each unit to sample and communicate with others, achieving rapid detection without communication delays.
Solution Approach 2:
The bus bar serves as an intermediary element that naturally carries the aggregate current from all parallel-connected power converters. By placing the current detector on the bus bar, the system obtains the total load current information without requiring direct communication between UPS units, thus reducing sampling time while maintaining detection accuracy.
2Productivity
If the controller determines appropriate number of UPS units by summing detection results from all units, then the system can optimize power distribution, but the switching between standby and operating states is delayed when load current changes rapidly
Solution Approach 1:
The current detector continuously monitors the total current on the bus bar in advance, maintaining real-time awareness of the load condition. When the load current exceeds the threshold, the system can immediately activate additional UPS units without waiting for sampling and communication cycles, thus achieving rapid switching while optimizing power distribution.
Solution Approach 2:
The current detector on the bus bar provides continuous monitoring of the total current, ensuring that the system always has up-to-date information about the load condition. This continuous feedback enables the controller to make immediate switching decisions, maintaining both high productivity through optimized power distribution and high speed in responding to load changes.
3Loss of information
If each uninterruptible power supply has its own current detector that samples and communicates current values to other units, then the system can calculate total load current, but the communication and processing time increases causing delayed response
Solution Approach 1:
The invention merges the current detection function into a single location on the bus bar rather than having separate detectors in each UPS unit. The single current detector captures the combined current from all parallel-connected power converters, eliminating the need for multiple sampling operations and inter-unit communication, thus reducing both information loss and time loss.
Data Source
AI summary
A plurality of uninterruptible power supplies of an uninterruptible power supply system controls start or stop of shared current supply from power converters to a load based on shared current commands, which indicate command values for determining a value of shared current to be supplied from the power converters of the plurality of uninterruptible power supplies to the load.