Parallel UPS Module Current Equalization Control
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Solution Overview
Problem
In uninterruptible power supply systems with multiple modules connected in parallel, when one module fails, the remaining modules are forced to increase their output, leading to increased power loss and voltage variations, reducing system efficiency and potentially causing cross-currents.
Innovation Solution
An uninterruptible power supply system with n uninterruptible power supplies connected in parallel, each comprising m modules with switches and an integrated controller that detects failures and adjusts output currents to equalize among remaining modules, ensuring efficient and stable power delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the remaining uninterruptible power supply modules increase their output current after a module failure, then the load can still be supplied with AC power, but power loss increases and operation efficiency decreases
Solution Approach 1:
The patent changes the control parameter from fixed current output to dynamically adjusted current output. When a module fails, the remaining modules adjust their output current based on real-time system state, ensuring they operate within optimal efficiency ranges while still meeting load requirements. This prevents excessive power loss by avoiding operation at inefficient high-current points.
Solution Approach 2:
The control device monitors the operating state of all power supply modules and implements feedback control. When a module failure is detected, the system receives feedback about the changed system state and automatically adjusts the output current of remaining modules accordingly. This closed-loop control ensures power loss is minimized while maintaining reliable power supply.
2Reliability
If the remaining uninterruptible power supplies increase their output currents to compensate for module failure, then the load remains powered, but voltage variations occur and cross-currents may flow
Solution Approach 1:
The patent dynamically adjusts the output current parameter of remaining power supply modules based on system state. Instead of increasing current to maximum capacity, the control device calculates optimal current values that maintain voltage stability. This parameter optimization prevents voltage variations and eliminates cross-currents between parallel power supplies while ensuring continuous load power supply.
Solution Approach 2:
The control device ensures that remaining power supply modules operate at equivalent potential by coordinating their output currents. When modules detect failures in other modules, they adjust their output to maintain equal voltage levels across all parallel connections, preventing cross-current flow. This equipotential operation maintains voltage stability while preserving system 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
The system minimizes power loss and voltage variations, allowing efficient and stable power supply to loads by isolating failed modules and redistributing the load among remaining modules, preventing cross-currents and maintaining system efficiency.
Implementation Method 1
The converter converts the first AC power supplied from the AC power source, into DC power
Implementation Method 2
The inverter converts the DC power into second AC power, and supplies the second AC power to the load
Data Source
AI summary
Each of n uninterruptible power supplies connected in parallel includes m uninterruptible power supply modules connected in parallel between an input terminal and an output terminal. In each uninterruptible power supply module, a controller controls an inverter so that the current value of AC power supplied from the inverter to a load matches a first instruction value. The n×m controllers are connected to one another to constitute an integrated controller. When a failure is detected in one of the m uninterruptible power supply modules in any one of the n uninterruptible power supplies, the integrated controller disconnects the failed uninterruptible power supply module and changes the first instruction value to a second instruction value so as to equalize the current values of AC power output from the inverters of the remaining normal uninterruptible power supply modules.