Parallel UPS Inverter Load Sharing Control

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Solution Overview

Problem

In parallel UPS systems, unequal power characteristics between connected UPS units can lead to reduced efficiency and performance, as load sharing may result in one unit being overwhelmed or underutilized, especially when powered by different sources with varying capacities or capabilities, potentially causing abrupt load drops or battery drainage.

Innovation Solution

A method and system for dynamically adjusting the load sharing between UPS units based on their power ratings and input power source capabilities, using a controllable gain stage and control circuitry to adjust the gain factor, ensuring optimal runtime and preventing overloads by optimizing the ratio of power provided by each unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If load sharing is performed equally between parallel UPS units, then simplicity of control is maintained, but unequal power characteristics cause one unit to be overwhelmed or underutilized

Engineering Contradiction:
Improvecontrol simplicityVSAvoidload sharing performance
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent adjusts the gain factor parameter of each UPS unit based on its power characteristics (power rating, input power source capability). By dynamically changing this control parameter, the system optimizes load distribution to match each unit's capabilities, resolving the contradiction between simple control and reliable load sharing.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If gain factor is adjusted based on power ratings and input power source capabilities, then load distribution is optimized, but control system complexity increases

Engineering Contradiction:
Improveload distribution optimizationVSAvoidcontrol system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control system continuously monitors power characteristics of each UPS unit and adjusts the gain factor accordingly. This feedback mechanism enables automatic optimization of load distribution without requiring complex manual configuration, balancing reliability improvement with acceptable control complexity.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

Each UPS unit autonomously adjusts its own gain factor based on its power characteristics and the operational status of other units in the parallel system. This self-service approach reduces the need for complex centralized control while achieving optimal load distribution.

Inventive Principle:
Principle #25Self-service

3Stability of the object's composition

If fixed gain factor is used, then system stability is maintained, but adaptability to changing power source capabilities is reduced

Engineering Contradiction:
Improvesystem stabilityVSAvoidadaptability to power source changes
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The gain factor is transformed from a fixed parameter to a dynamic one that automatically adjusts in response to changes in input power source capabilities. This dynamic adjustment maintains system stability through controlled adaptation, resolving the contradiction between stability and adaptability.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2769449B1Adaptive load sharing of parallel inverters system
Publication Date: 2020.05.13 SCHNEIDER ELECTRIC IT CORP
  • EP2769449B1 patent drawingFigure 1~1A
  • EP2769449B1 patent drawingFigure 1B
  • EP2769449B1 patent drawingFigure 1C

AI summary

According to one aspect, embodiments of the invention provide a method of operating a UPS system having a first UPS and a second UPS, the method comprising powering on the first UPS, receiving power from a first input power source coupled to an input of the first UPS, providing power to a load coupled to an output of the first UPS, adjusting the power provided to the load by the first UPS in response to power characteristics of the first UPS and power characteristics of the second UPS.