Magnetic Coupling Reactor Ripple Current Suppression

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Solution Overview

Problem

Boost converter circuits using magnetic coupling reactors face an issue where ripple current components of different phases synchronize, leading to increased ripple current in the filtering capacitor, resulting in larger capacitor sizes and higher manufacturing costs.

Innovation Solution

A power conversion device is designed with a magnetic coupling reactor where the coupling factor is adjusted to suppress ripple current flowing into the capacitor, achieved by controlling the magnetic coupling reactor's coupling factor to a value equal to or less than a set value, thereby reducing the size of the capacitor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a magnetic coupling reactor with high coupling factor is used, then power conversion efficiency is improved, but ripple current in the capacitor increases leading to larger capacitor size

Engineering Contradiction:
Improvepower conversion efficiencyVSAvoidcapacitor size
Core Design Contradiction:
Loss of energyVSVolume of stationary object

Solution Approach 1:

The invention changes the coupling factor parameter of the magnetic coupling reactor from a high value to a specific range (0.3 to 0.8), which optimizes the balance between power conversion efficiency and ripple current suppression, thereby reducing capacitor size without sacrificing too much efficiency

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention introduces a feedback mechanism by measuring the ripple current in the capacitor and adjusting the coupling factor accordingly, using the relationship between coupling factor and ripple current to achieve optimal performance

Inventive Principle:
Principle #23Feedback

2Loss of energy

If a magnetic coupling reactor with high coupling factor is used, then power conversion efficiency is improved, but manufacturing cost increases due to larger capacitor requirements

Engineering Contradiction:
Improvepower conversion efficiencyVSAvoidmanufacturing cost
Core Design Contradiction:
Loss of energyVSEase of manufacture

Solution Approach 1:

The invention changes the coupling factor parameter to a specific range (0.3 to 0.8) that reduces the required capacitor size, thereby lowering manufacturing costs while maintaining acceptable power conversion efficiency

Inventive Principle:
Principle #35Parameter changes

3Volume of stationary object

If the coupling factor of the magnetic coupling reactor is reduced, then ripple current in the capacitor is suppressed, but the reactor design becomes more complex

Engineering Contradiction:
Improvecapacitor sizeVSAvoidreactor design complexity
Core Design Contradiction:
Volume of stationary objectVSDevice complexity

Solution Approach 1:

The invention simplifies the reactor design by specifying a concrete coupling factor range (0.3 to 0.8) rather than requiring complex adaptive mechanisms, achieving ripple current suppression through parameter optimization alone

Inventive Principle:
Principle #35Parameter changes

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 results in a compact, efficient power conversion device with reduced capacitor size and lower manufacturing costs by effectively managing the ripple current.

Implementation Method 1

a magnetic coupling reactor element (10) having a plurality of reactors (L1, L2) which are magnetically coupled to each other

Methodology Applied
Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentEP3425783B1Power conversion device
Publication Date: 2021.12.29 MITSUBISHI ELECTRIC CORP
  • EP3425783B1 patent drawingFigure 1
  • EP3425783B1 patent drawingFigure 2
  • EP3425783B1 patent drawingFigure 3

AI summary

Provided is a power conversion device using a magnetic coupling reactor and being capable of reducing the number of parts and reducing the size of not only the magnetic coupling reactor but also an input capacitor. The magnetic coupling reactor is connected between a semiconductor switch element group, which executes power conversion, and the input capacitor. The coupling factor of two reactors in the magnetic coupling reactor is kept to a value equal to or less than a set value, for example, 0.8. The set value takes into consideration an area in which a ripple current of the input capacitor increases rapidly in response to a rise in coupling factor. The ripple current flowing in the input capacitor is reduced by thus setting the coupling factor.