Power Electronic Converter for Linear Electric Machine Levitation

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Solution Overview

Problem

The complexity of magnetically levitated linear electric machines arises from the need to control both thrust and levitation forces, making it challenging to maintain desired thrust forces and limit tilting between the primary and secondary parts within acceptable limits.

Innovation Solution

A power electronic converter with force-generating windings for longitudinal thrust, tilt-control windings for angular deviation control, and a control system that adjusts currents based on position and tilting information to manage transversal magnetic forces and levitation, using mechanical connections between sections to cancel out forces and control tilting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetically levitated linear electric machines use separate magnetically operating means for thrust generation and levitation, then levitation function is achieved, but system complexity increases

Engineering Contradiction:
Improvelevitation functionVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The force-generating windings serve dual purposes: generating longitudinal thrust force and generating transversal magnetic force for levitation. This multi-functionality eliminates the need for separate magnetically operating means, reducing system complexity while maintaining reliable levitation function.

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

Solution Approach 2:

The patent combines the thrust generation function and levitation function into a single magnetically operating means (force-generating windings). By merging these functions, the system structure is simplified, reducing the number of components and control systems required.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If magnetically levitated linear electric machines control both thrust and levitation forces, then levitation is achieved, but difficulty in maintaining desired thrust forces increases

Engineering Contradiction:
Improvelevitation stabilityVSAvoidthrust force control
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The control system is segmented into dedicated control sections: a first controller section controls force-generating currents for longitudinal thrust, while a second controller section controls current differences for transversal levitation. This segmentation allows independent optimization of thrust and levitation control, making it easier to maintain desired thrust forces while achieving stable levitation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different control strategies are applied to different aspects of the magnetic forces: the first controller section applies control based on thrust force requirements, while the second controller section applies control based on levitation position information. This local quality approach optimizes control for each specific function.

Inventive Principle:
Principle #3Local quality

3Reliability

If magnetically levitated linear electric machines control both thrust and levitation, then levitation function is achieved, but difficulty in limiting tilting increases

Engineering Contradiction:
Improvelevitation functionVSAvoidtilting control
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The control system is divided into specialized sections, with the second controller section specifically dedicated to controlling current differences that generate transversal magnetic forces. This segmentation enables focused control of tilting and levitation, making it easier to limit angular deviation while maintaining levitation function.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The control system uses position information and tilting information as feedback to adjust the force-generating currents and tilt-control currents. This feedback mechanism enables the system to automatically correct tilting and maintain proper alignment between primary and secondary parts.

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 precise control of thrust forces and tilting, ensuring stable operation of linear electric machines by effectively managing magnetic forces and levitation, thereby simplifying the system and improving performance.

Implementation Method 1

each primary section comprises force-generating windings for generating a longitudinal magnetic thrust force tending to move the primary part longitudinally with respect to the secondary part

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a transversal magnetic force pulling the primary section towards a respective one of the secondary sections

Methodology Applied
Scientific EffectLorentz force: Lorentz Force

Implementation Method 3

one or more tilt-control windings for generating one or more transversal magnetic tilt-control forces so as to control an angular deviation

Methodology Applied
Scientific EffectElectromagnetic force: Electromagnet

Data Source

PatentEP3703231B1A power electronic converter for controlling a linear electric machine
Publication Date: 2021.09.22 DANFOSS EDITRON OY
  • EP3703231B1 patent drawingFigure 1a
  • EP3703231B1 patent drawingFigure 1b~1c
  • EP3703231B1 patent drawingFigure 1d~1e

AI summary

A power electronic converter (160) comprises means for controlling a linear electric machine that comprises a primary part (101) and a secondary part (102) linearly movable with respect to each other. The primary part comprises primary sections (103, 104) each having an airgap surface. The secondary part comprises secondary sections (105, 106) each having an airgap surface facing towards the air-gap surface of the respective primary section. Each primary section comprises force-generating windings (U1, V1, W1, U2, V2, W2) for generating a magnetic thrust force and a transversal magnetic force pulling the primary section towards the respective secondary section. The resultant of the transversal magnetic forces is controllable to levitate the primary part. The primary part further comprises one or more tilt-control windings (T1, T2) for enabling the power electronic converter to control tilting of the primary part with respect to the secondary part.