Series-Interconnected Six-Phase Motor Control for Fault Resilience

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Solution Overview

Problem

Existing systems for controlling polyphase motors are not adequately robust to both open-circuit and short-circuit failures, particularly for six-phase motors, leading to inefficiencies and increased costs due to electrical losses.

Innovation Solution

A device comprising two six-phase motors interconnected in series with independent power sources and inverters, allowing for independent control of each motor through Id and Iq current components, with redundant power and inverter configurations to manage failures without additional neutral point creation or fault detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If series redundancy of inverter electronic switches is implemented to protect against short-circuit failures, then reliability is improved, but electrical losses and cost increase due to doubled switches

Engineering Contradiction:
Improverobustness to short-circuit failureVSAvoidelectrical losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The invention divides the six-phase motor into two independent three-phase motors, each controlled by its own inverter. This segmentation allows each inverter to operate independently with only three switches per inverter, avoiding the need for series redundancy (six switches) that would be required to protect a single six-phase inverter against short-circuit failures. The segmentation thus maintains reliability while reducing electrical losses.

Inventive Principle:
Principle #1Segmentation

2Reliability

If duplication of inverter with separate power sources is implemented to protect against short-circuit failure, then reliability is improved, but cost and complexity increase

Engineering Contradiction:
Improverobustness to short-circuit failureVSAvoidinverter configuration complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention segments the six-phase motor control into two independent three-phase motor controls, each with its own inverter and power source. This segmentation naturally provides redundancy against short-circuit failures while maintaining manageable complexity through standardized inverter designs.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses universal three-phase inverters and three-phase motor control techniques for both six-phase motors, leveraging existing proven technology rather than requiring specialized six-phase inverters. This universality reduces device complexity while maintaining reliability.

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

3Reliability

If additional phase is added to make inverter robust to open-circuit failure, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improverobustness to open-circuit failureVSAvoidmotor phase configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention segments the six-phase motor into two independent three-phase motors, each with its own inverter. This segmentation provides inherent robustness to open-circuit failures because each three-phase inverter-motor pair can operate independently. If one phase fails in one three-phase motor, the other three-phase motor remains fully operational, and the failed three-phase motor can still operate in reduced capacity.

Inventive Principle:
Principle #1Segmentation

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

Enables simultaneous independent control of two six-phase motors with reduced costs and minimized electrical losses, maintaining operational reliability in the event of open-circuit and short-circuit failures.

Implementation Method 1

The two six-phase motors are interconnected in series, with two-by-two connections of respective successive branches, said connections being alternately in phase and in phase opposition

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2903155B1Device for controlling two multiphase motors
Publication Date: 2017.07.05 THALES SA
  • EP2903155B1 patent drawingFigure 1~3
  • EP2903155B1 patent drawingFigure 2
  • EP2903155B1 patent drawingFigure 4

AI summary

The control device for two polyphase motors comprises a first and a second six-phase motors (MH1, MH2) with six branches corresponding to six spatially uniformly distributed phases, interconnected in series, and said series interconnection of the two six-phase motors (MH1, MH2) comprising pairwise connections of successive respective branches of the two six-phase motors (MH1, MH2), said connections being alternately in phase and in opposite phase.