Dynamic DC Link Voltage Control in UPS Systems
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Solution Overview
Problem
Existing uninterruptible power supplies (UPS) systems face efficiency degradation when the output voltage is changed, often requiring costly and space-consuming solutions to maintain efficiency, such as over-sizing magnetic components or switching semiconductor devices.
Innovation Solution
A UPS system with a controller that dynamically adjusts the DC bus voltage based on user-selected output voltage levels, maintaining an amplitude modulation ratio to ensure efficiency remains constant across different voltage settings without increasing cost or space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the output voltage of the UPS system is changed, then the adaptability to different voltage requirements is improved, but the efficiency of the system deteriorates
Solution Approach 1:
The patent implements dynamic DC bus voltage adjustment by modifying the reference DC bus voltage signal based on the selected output voltage level. The controller dynamically changes the DC bus voltage from a first level for a first output voltage to a second level for a second output voltage, allowing the system to adapt efficiently to different operating conditions rather than maintaining a fixed voltage level
Solution Approach 2:
The patent changes the operating parameters of the UPS system by adjusting the DC bus voltage level according to the selected output voltage. The controller modifies the reference DC bus voltage signal parameter to correspond to the selected output voltage level, which in turn adjusts the switching characteristics of the semiconductor devices and maintains optimal efficiency across different voltage settings
2Loss of energy
If the DC bus voltage is adjusted dynamically, then the system efficiency is maintained across different voltage settings, but the device complexity increases
Solution Approach 1:
The patent employs feedback control by using a reference DC bus voltage signal that is dynamically adjusted based on the selected output voltage level. The controller continuously monitors the operating conditions and adjusts the DC bus voltage reference to maintain optimal efficiency, creating a closed-loop control system that automatically adapts to different voltage settings
Solution Approach 2:
The controller is designed to perform multiple functions: it manages the conversion of AC input power to DC bus power, controls the inverter conversion of DC bus power to AC output power, adjusts the DC bus voltage reference based on output voltage selection, and maintains system efficiency across different operating conditions. This multi-functional approach consolidates control complexity into a single controller rather than requiring separate control circuits
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 maintains efficiency by dynamically adjusting the DC bus voltage in response to user-selected output voltage levels, preventing efficiency loss when voltage is lowered, thus improving the UPS system's performance without additional costs or space needs.
Implementation Method 1
a converter coupled to the input and configured to convert the input AC power into DC power
Implementation Method 2
an inverter coupled to the DC bus and configured to convert the DC power from the DC bus into output AC power
Data Source
AI summary
According to one aspect, embodiments of the invention provide a UPS system comprising an input configured to receive input AC power, an output configured to provide output AC power to a load, a converter coupled to the input and configured to convert the input AC power into DC power, a DC bus configured to receive the DC power, an inverter configured to convert the DC power from the DC bus into output AC power and provide the output AC Power to the output, and a controller configured to receive an output AC output voltage level selection from a user, operate the inverter to generate the output AC power having an AC voltage level based on the output AC output voltage level selection, and operate the converter to generate the DC power having a DC voltage level based on the output AC output voltage level selection.