Switched-Mode Power Converter Ripple Attenuation Circuit

Solution Overview

Problem

Switched-mode power converters experience undesirable ripples in output voltage due to switching, and existing methods to reduce these ripples, such as using additional filters, incur costs and size penalties and introduce conduction losses.

Innovation Solution

A switched-mode power converter system with a ripple attenuation circuit that adjusts a voltage source to generate a ripple attenuation signal, which is added to the output voltage, using a pair of switching devices and an inductor to cancel out alternating current and stabilize the output voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If an additional filter is used at the output to reduce ripples, then the ripple reduction is achieved, but the device size and cost increase due to large inductor and capacitor components

Engineering Contradiction:

Improveoutput voltage rippleVSAvoiddevice size

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The harmful ripple component is extracted from the output voltage using a ripple sensor that detects the ripple signal separately. This extracted ripple signal is then processed through a controller that generates a compensating signal, which is injected back to cancel the ripple. This approach removes the need for large passive filter components by actively extracting and canceling the harmful ripple component.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The ripple, which is normally a harmful effect, is converted into a useful signal for control. The ripple sensor detects the ripple and feeds it to the controller, which uses this information to generate a compensating signal. By utilizing the ripple signal itself as the basis for correction, the system transforms the harmful ripple into a beneficial control input that enables active ripple cancellation without requiring large passive components.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Object-affected harmful factors

If an additional filter is used at the output to reduce ripples, then the ripple reduction is achieved, but the device cost increases due to additional components

Engineering Contradiction:

Improveoutput voltage rippleVSAvoiddevice cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The harmful ripple component is extracted from the output voltage using a ripple sensor that detects the ripple signal separately. This extracted ripple signal is then processed through a controller that generates a compensating signal, which is injected back to cancel the ripple. This approach removes the need for large passive filter components by actively extracting and canceling the harmful ripple component.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The ripple, which is normally a harmful effect, is converted into a useful signal for control. The ripple sensor detects the ripple and feeds it to the controller, which uses this information to generate a compensating signal. By utilizing the ripple signal itself as the basis for correction, the system transforms the harmful ripple into a beneficial control input that enables active ripple cancellation without requiring large passive components.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If an additional filter is used at the output to reduce ripples, then the ripple reduction is achieved, but conduction losses and delay increase due to current flowing through the extra inductor

Engineering Contradiction:

Improveoutput voltage rippleVSAvoidconduction losses

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The harmful ripple component is extracted from the output voltage using a ripple sensor that detects the ripple signal separately. This extracted ripple signal is then processed through a controller that generates a compensating signal, which is injected back to cancel the ripple. This approach removes the need for large passive filter components by actively extracting and canceling the harmful ripple component.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The ripple, which is normally a harmful effect, is converted into a useful signal for control. The ripple sensor detects the ripple and feeds it to the controller, which uses this information to generate a compensating signal. By utilizing the ripple signal itself as the basis for correction, the system transforms the harmful ripple into a beneficial control input that enables active ripple cancellation without requiring large passive components.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Object-affected harmful factors

If traditional filtering methods are used, then ripple reduction is achieved, but the device complexity increases due to additional components

Engineering Contradiction:

Improveoutput voltage rippleVSAvoidcircuit complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The ripple cancellation function is merged with the existing power converter control system. The ripple sensor, controller, and signal injection mechanism are integrated into the existing converter architecture, allowing ripple cancellation to be achieved without adding completely separate filtering circuits. This merging approach reduces overall system complexity compared to traditional passive filtering methods.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system employs feedback control where the ripple sensor continuously monitors the output voltage ripple and feeds this information to the controller. The controller processes this feedback and adjusts the compensating signal accordingly, creating a closed-loop system that adaptively cancels ripple. This feedback mechanism provides intelligent ripple cancellation without requiring complex passive filter designs.

Inventive Principle:

Principle #23Feedback

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 solution effectively reduces or eliminates ripples in the output voltage, providing a more stable voltage level without the need for large additional components, thus improving efficiency and reducing size and cost.

Implementation Method 1

a ripple attenuation circuit coupled to the output node and a voltage source. The voltage source is adjusted to generate a ripple attenuation signal by the ripple attenuation circuit at the output node

Methodology Applied

Scientific EffectElectrical resonance: Resonance

Data Source

PatentUS11502594B2Switched-mode power converter with ripple attenuation

Publication Date: 2022.11.15 ANALOG DEVICES INT UNLTD CO

AI summary

A switched-mode power converter apparatus includes a switching converter to receive an input voltage, to convert the input voltage to an output voltage, and to transmit the output voltage to an output node. The apparatus also includes a ripple attenuation circuit coupled to the output node and a voltage source. The voltage source is adjusted to generate a ripple attenuation signal by the ripple attenuation circuit at the output node.