Switched-Mode Power Supply Ripple Prediction and Control

Solution Overview

Problem

Switched-mode power supplies experience output voltage ripple due to switching, which causes issues during high bandwidth operation, and existing filters like notch filters suffer from phase loss and complexity, increasing the cost and surface area of integrated circuits.

Innovation Solution

A system comprising a sinc filter module to determine the DC voltage component of the error between the measured output voltage and a reference voltage, and a cyclic integrator module that applies a learning gain to the difference between the signal with ripple and the predicted ripple, integrating and reconstructing segments to generate a predicted ripple for either ripple cancellation or parameter estimation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If notch filters are used to remove output voltage ripple, then the ripple attenuation is improved, but the device complexity and phase loss increase

Engineering Contradiction:

Improveoutput voltage rippleVSAvoidfilter complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent extracts only the harmful ripple component from the output voltage signal using a ripple sensor, while leaving the useful DC component intact. This selective extraction approach avoids the need for complex notch filters that would attenuate both ripple and useful signal, thereby reducing device complexity while effectively removing only the harmful ripple factor

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a ripple sensor as an intermediary component that specifically detects ripple voltage without affecting the main power signal. This intermediary device enables ripple measurement and cancellation without requiring complex filter circuits, thus reducing overall device complexity while maintaining effective ripple attenuation

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If notch filters are used to remove output voltage ripple, then the ripple attenuation is improved, but the integrated circuit surface area and cost increase

Engineering Contradiction:

Improveoutput voltage rippleVSAvoidintegrated circuit surface area

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

The patent extracts only the harmful ripple component from the output voltage signal using a ripple sensor, while leaving the useful DC component intact. This selective extraction approach avoids the need for complex notch filters that would attenuate both ripple and useful signal, thereby reducing device complexity while effectively removing only the harmful ripple factor

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a ripple sensor as an intermediary component that specifically detects ripple voltage without affecting the main power signal. This intermediary device enables ripple measurement and cancellation without requiring complex filter circuits, thus reducing overall device complexity while maintaining effective ripple attenuation

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If switched-mode power supply operates at high bandwidth, then the power conversion efficiency is improved, but the output voltage ripple increases

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidoutput voltage ripple

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where a ripple sensor continuously monitors the output voltage ripple and feeds this information to a controller. The controller adjusts the switching duty cycle in real-time to counteract ripple variations, enabling high bandwidth operation with controlled ripple levels, thus maintaining both high efficiency and low ripple

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically changes the switching duty cycle parameter based on real-time ripple measurements. By adjusting this parameter in response to ripple conditions, the system can operate at high bandwidth for improved efficiency while actively compensating to maintain acceptable ripple levels, effectively decoupling the trade-off between efficiency and ripple

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8698469B1System and method for predicting output voltage ripple and controlling a switched-mode power supply

Publication Date: 2014.04.15 MAXIM INTEGRATED PROD INC

AI summary

A system includes a sinc filter module and a cyclic integrator module. The sinc filter module (i) determines a direct current (DC) voltage component of an error between a measured output voltage of a switched-mode power supply and a reference voltage and (ii) determines a signal with ripple by subtracting the determined DC voltage component from the error. The cyclic integrator module (i) applies a learning gain to a difference between the determined signal with ripple and a predicted ripple, (ii) performs integration of each of N segments of the gain-applied difference, and (iii) generates the predicted ripple by reconstructing the N integrated segments, wherein N is an integer greater than one.