Parallel Power Converter Droop Correction

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Solution Overview

Problem

Existing DC power-supply apparatuses with parallel-connected power converters face challenges in precisely correcting variations in droop characteristics, leading to uneven load distribution and potential overcurrent states, which complicates the design and sizing of the power-supply apparatus.

Innovation Solution

A switching power-supply apparatus with separate droop characteristic generators and correction units for each power converter, allowing for the detection and correction of output voltage and current variations, enabling precise droop characteristic correction and reducing the need for design considerations based on these variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the same correction value is used for all power converters, then the device complexity is reduced, but the manufacturing precision of droop characteristic correction deteriorates

Engineering Contradiction:
Improvecorrection value managementVSAvoiddroop characteristic correction precision
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent divides the correction value management into separate segments for each power converter. Each power converter has its own correction value stored in individual memory units, allowing independent correction of droop characteristics for each converter. This segmentation enables precise correction of variations in detection results of output currents for respective power converters while maintaining manageable device complexity through modular architecture.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If separate correction values are stored for each power converter, then the manufacturing precision of droop characteristic correction is improved, but the device complexity increases

Engineering Contradiction:
Improvedroop characteristic correction precisionVSAvoidcorrection value management
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a universal correction value management system where multiple power converters share the same structural framework for correction. Each converter follows the same pattern of having a correction value stored in its memory unit and applied by its correction unit, creating a multi-functional system that handles individual correction needs through a standardized approach. This universality reduces device complexity by avoiding custom designs for each converter while maintaining precise correction capabilities.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Device complexity

If droop characteristics are not corrected, then the device complexity is reduced, but the reliability of load distribution deteriorates

Engineering Contradiction:
Improvecorrection systemVSAvoidload distribution evenness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where detection units monitor the output currents of power converters, and correction units use this feedback information to adjust droop characteristics. The correction values stored in memory units are applied based on detected variations in droop characteristics, creating a closed-loop system that continuously ensures even load distribution. This feedback approach maintains high reliability of load distribution while managing device complexity through automated correction processes.

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 solution allows for the elimination of droop characteristic variations, preventing overcurrent states and enabling a reduced size and optimized design of the switching power-supply apparatus by allowing for precise correction of each power converter's droop characteristics.

Implementation Method 1

a first droop characteristic generator configured to generate a droop characteristic that reduces an output voltage of the first power converter as an output current of the first power converter increases, a second droop characteristic generator configured to generate a droop characteristic that reduces an output voltage of the second power converter as an output current of the second power converter increases

Methodology Applied
Scientific EffectDroop control:

Implementation Method 2

a first controller configured to perform PWM control on the first power converter so as to equalize a magnitude of an output voltage detected by the first output voltage detector and a target voltage value, a second controller configured to perform PWM control on the second power converter so as to equalize a magnitude of an output voltage detected by the second output voltage detector and the target voltage value

Methodology Applied
Scientific EffectPWM control:

Data Source

PatentEP3370330B1Switching power source device comprising two power converters having a droop characteristic correction
Publication Date: 2022.01.05 MURATA MFG CO LTD
  • EP3370330B1 patent drawingFigure 1
  • EP3370330B1 patent drawingFigure 2
  • EP3370330B1 patent drawingFigure 3

AI summary

In a switching power-supply apparatus (1) that controls magnitudes of output voltages of respective converters (11A, 11B) connected in parallel to be equal to a target voltage value, only selected one of the converters (11A, 11B) is made to operate. In this state, correction values generated by the respective converters (11A, 11B) are received and stored in memory (164). Droop characteristics generated for the respective converters (11A, 11B) are corrected using the correction values. Accordingly, a switching power-supply apparatus and a droop characteristic correction method capable of correcting variations in droop characteristics generated for respective power converters are provided.