Converter with Three Magnetically Coupled Windings

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Solution Overview

Problem

Conventional switching current sources for electric actuators with RL loads face challenges such as high dependence on load inductance, difficulty in limiting short-circuit currents, and electromagnetic compatibility issues, particularly in aeronautical applications, leading to restricted high-power applications with low switching frequencies.

Innovation Solution

A switching converter with three magnetically coupled windings on a single core, utilizing two diodes and switches to manage voltage and current, allowing configuration as either a voltage source or current source, and incorporating a smoothing capacitor to reduce size and cost while enhancing operational flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If conventional switching current sources use load inductance as energy storage element, then circuit dimensions are reduced, but short-circuit current limitation becomes very difficult and requires additional components

Engineering Contradiction:
Improvecircuit dimensionsVSAvoidshort-circuit current limitation
Core Design Contradiction:
Volume of stationary objectVSReliability

Solution Approach 1:

The patent introduces an intermediary inductance element (Lc) connected in series with the load that serves as the energy storage element for chopping operations. This mediator allows the circuit to achieve both compact dimensions and reliable short-circuit current limitation, as the inductance naturally limits current during fault conditions without requiring additional protection components.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If switching frequency is increased above 10 kHz, then converter efficiency improves, but electromagnetic compatibility with aeronautical standards becomes difficult to achieve

Engineering Contradiction:
Improveswitching frequencyVSAvoidelectromagnetic compatibility
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the energy storage function from the load inductance and places it in a dedicated inductance element (Lc) at the converter output. This separation allows the converter to operate at high switching frequencies for improved efficiency while the extracted inductance element can be properly designed and positioned to filter electromagnetic emissions, enabling compliance with aeronautical standards.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If output inductance is added to limit short-circuit current, then current limitation is achieved, but converter size and complexity increase

Engineering Contradiction:
Improveshort-circuit current limitationVSAvoidconverter structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent designs the output inductance element (Lc) to serve multiple functions simultaneously: it acts as the energy storage element for chopping operations, limits short-circuit currents, and can be integrated with the output filter structure. This multi-functionality achieves reliable current limitation without proportionally increasing converter complexity, as the inductance performs several protective and operational roles in one component.

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

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 reduces the size and cost of the converter, improves short-circuit current management, and enhances electromagnetic compatibility, enabling higher switching frequencies and broader application across different power levels, including aeronautical equipment.

Implementation Method 1

three magnetically coupled windings on a single core

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP1959550B1Converter with unipolar or bipolar cutting with three magnetically coupled windings
Publication Date: 2010.07.14 SAFRAN ELECTRONICS & DEFENSE SAS
  • EP1959550B1 patent drawingFigure 1A~1B
  • EP1959550B1 patent drawingFigure 2
  • EP1959550B1 patent drawingFigure 3A~3C

AI summary

The converter has three windings (Ls1, Ls2, Lp) rolled around a magnetic core, where ends of the winding (Ls1, Ls2) are connected to a positive potential (V-p) and a negative potential (V-m) by diodes (D1, D2), respectively. An end of the winding (Lp) is connected at a mid point of a branch connecting two potentials, where the part of branch has a switch forming unit (Q1) and diode (D3). Another end of the winding (Lp) is connected to an output terminal (SP). A number of turns in the winding (Lp) is greater than the number of turns in the windings (Ls1, Ls2). An independent claim is also included for a method for operating the chopper converter.