DC-DC Converter Inductor Current Sampling for Measurement Accuracy

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Solution Overview

Problem

Existing DC-DC converters face challenges in accurately measuring inductor current due to the complexity of methods requiring peak and valley current measurements, leading to errors caused by variations in inductor values.

Innovation Solution

A DC-DC converter system that includes a controller to sense and sample inductor current at a predetermined time between peak and valley currents, allowing for accurate detection of average current and control of converter operations, including switching frequency adjustment and droop current management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If peak current and valley current measurement method is used, then inductor current can be obtained, but circuit complexity increases and measurement precision deteriorates due to inductor value variation errors

Engineering Contradiction:

Improveinductor current measurement accuracyVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts only the necessary portion of current waveform information by sampling at a specific moment (when inductor current equals average current) rather than measuring the entire waveform through peak and valley points. This extraction approach obtains the required average current information while eliminating the complexity of full waveform measurement circuits.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the measurement parameter from measuring peak and valley currents (which are sensitive to inductor value variations) to sampling the current waveform at a specific time point where the instantaneous current equals the average current. This parameter change makes the measurement less sensitive to inductor value variations, improving measurement precision.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If peak current and valley current measurement method is used, then inductor current information can be obtained, but measurement precision deteriorates due to inductor value variation

Engineering Contradiction:

Improveinductor current measurement accuracyVSAvoidmeasurement reliability under inductor value variation

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the measurement parameter from peak/valley currents to instantaneous current at a specific time point. By sampling when the inductor current naturally equals the average current, the measurement becomes independent of inductor value variations, simultaneously improving both precision and reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes the natural characteristic of the inductor current waveform itself - the moment when instantaneous current equals average current - to perform the measurement. This self-service approach leverages the waveform's own properties to enable accurate measurement without external compensation for inductor variations.

Inventive Principle:

Principle #25Self-service

3Device complexity

If simple current sensing is used, then device complexity is reduced, but measurement precision deteriorates without proper sampling timing

Engineering Contradiction:

Improvemeasurement circuit simplicityVSAvoidaverage current detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary action by determining the specific sampling time point (when inductor current equals average current) before actually sampling the current. This preliminary timing determination ensures that the simple sensing circuit samples at the correct moment, achieving both simplicity and precision.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses feedback by comparing the sensed inductor current with a reference and using this information to control the sampling timing. This feedback mechanism ensures that sampling occurs precisely when the inductor current equals the average current, maintaining measurement accuracy with simple circuitry.

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

This approach simplifies the measurement of inductor current, reduces errors, and enables precise control of converter operations, improving the accuracy and efficiency of DC-DC conversion.

Implementation Method 1

a controller configured to sense inductor current flowing in the inductor to generate a sensed signal

Methodology Applied

Scientific EffectElectrical sensing:

Implementation Method 2

to sample and hold the sensed signal for a predetermined sampling time to detect average current of the inductor

Methodology Applied

Scientific EffectSignal sampling and holding:

Data Source

PatentUS9548661B2DC-DC converter and electronic system including the same

Publication Date: 2017.01.17 SAMSUNG ELECTRONICS CO LTD

AI summary

A DC-DC converter is provided. The DC-DC converter includes at least one converter circuit configured to include an inductor and to supply a current to a load through the inductor; and a controller configured to sense the current to generate a sensed signal, to sample and hold the sensed signal at a predetermined sampling time to detect an average current of the inductor, and to control an operation of the at least one converter circuit according to the average current. The sampling time is set to a time in a period while the inductor current is less than a peak and greater than a valley.