UPS Frequency Converter Ripple Voltage Filtering

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Converters in UPS, frequency converters, and line conditioners often experience inefficient operation due to unwanted distortion in input current, leading to harmonic distortion and subharmonic oscillations, which can result in costly repairs and productivity losses.

Innovation Solution

A system and method that filters ripple voltage from control signals to produce an average control signal with reduced distortion, driving the input current of the converter toward a reference current value, thereby reducing or eliminating harmonic distortion and subharmonic oscillations through the use of a control module with a filter and a lead-lag compensator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional converter control is used, then the converter can operate with simple control circuitry, but harmonic distortion and subharmonic oscillations occur in the input current

Engineering Contradiction:

Improveconverter operation stabilityVSAvoidharmonic distortion and subharmonic oscillations

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the harmful ripple voltage component from the control signal using a filter. The filter separates the desired average control signal from the unwanted ripple, eliminating the source of harmonic distortion and subharmonic oscillations in the converter input current

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary filter between the voltage regulator and the pulse width modulator. This filter acts as a mediator that processes the control signal to remove ripple components before they can cause harmonic distortion in the input current

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If ripple voltage is not filtered from the control signal, then the control circuit remains simple, but distortion passes through to the converter output

Engineering Contradiction:

Improvecontrol circuit simplicityVSAvoidoutput power quality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The filter extracts the ripple voltage component from the control signal, removing the distortion that would otherwise pass through to the converter output and affect the quality of the output power

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The filter serves as an intermediary component that cleans the control signal before it reaches the pulse width modulator, ensuring that only the average control signal passes through to control the converter switches

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the control signal includes ripple voltage distortion, then no additional filtering components are needed, but input current efficiency decreases

Engineering Contradiction:

Improvecontrol signal pathVSAvoidconverter operation efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The filter extracts and removes the ripple voltage from the control signal, preventing it from causing inefficient operation in the converter and reducing energy losses associated with distorted input current

Inventive Principle:

Principle #2Taking out (Extraction)

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

This approach improves converter efficiency by minimizing harmonic distortion and subharmonic oscillations, enhancing the reliability and longevity of connected electronic equipment while meeting industry standards for harmonic levels.

Implementation Method 1

The control signal can include distortion associated with the ripple voltage. The method produces an average control signal having less distortion than the control signal by filtering at least a portion of the ripple voltage from the control signal.

Methodology Applied

Scientific EffectFiltering: Filter (electronic)

Implementation Method 2

In various embodiments a lead-lag compensator shifts a phase of the average control signal.

Methodology Applied

Scientific EffectPhase shifting:

Data Source

PatentUS7881079B2UPS frequency converter and line conditioner

Publication Date: 2011.02.01 SCHNEIDER ELECTRIC IT CORP

AI summary

Systems and methods disclosed herein monitor and control input to a converter in one or more of a UPS, a frequency converter, or a line conditioner. Distortion due at least in part to ripple voltage can be removed from a control signal that controls input current to the converter. The systems and methods described herein afford a simple and effective way to reduce or eliminate one or more of subharmonic oscillation and total harmonic distortion from a converter input current during synchronous and asynchronous modes of operation. The converter may include one or more of a rectifier and an inverter.