Five-Phase Winding Reconfiguration for Open-Circuit Fault Tolerance

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Solution Overview

Problem

Hybrid-electric and electric vehicles with three-phase motors often shut down when an open-circuit winding occurs, preventing the vehicle from completing a drive cycle due to changed torque characteristics and inability to flow current through the affected winding.

Innovation Solution

A five-phase electric machine system with dual inverters and a controller that switches between star and square configurations based on detected open-circuit conditions and vehicle speed, allowing the remaining windings to operate effectively and maintain torque output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the vehicle operates with a three-phase motor under normal conditions, then the system is simple and reliable, but the vehicle must shut down when an open-circuit winding occurs, preventing completion of the drive cycle

Engineering Contradiction:

Improvecontinuous operation capabilityVSAvoidconfiguration flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic reconfiguration of the motor windings from a standard three-phase connection to an open-phase configuration when an open-circuit fault is detected. The controller dynamically switches the connection topology to maintain torque production capability, allowing the vehicle to continue operation rather than shutting down. This dynamic adaptation resolves the contradiction by enabling continuous operation through real-time configuration changes.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the electrical connection parameters of the motor windings in response to detected faults. By altering the winding connection configuration (e.g., changing from star to delta connection, or reassigning phase connections), the system maintains operational capability despite open-circuit conditions. This parameter change enables the vehicle to adapt to faulty conditions and continue the drive cycle.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the motor shuts down when an open-circuit winding is detected, then the system maintains safety and prevents degraded operation, but the vehicle cannot finish the drive cycle

Engineering Contradiction:

Improvesafe operationVSAvoiddrive cycle completion

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent converts the harmful effect of an open-circuit winding (which would normally cause shutdown) into a manageable condition by implementing alternative winding configurations. The controller detects the open circuit and reconfigures the remaining healthy windings to continue producing torque. This transforms a failure condition into a degraded-but-acceptable operating mode, allowing drive cycle completion while maintaining safe operation through controlled degradation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If the windings are reconfigured to maintain operation after an open circuit, then the vehicle can complete the drive cycle, but the torque characteristics change and require complex control

Engineering Contradiction:

Improvedrive cycle completionVSAvoidcontrol system complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a control system that can operate the motor in multiple configurations - normal three-phase operation and degraded open-phase operation. The same controller and power electronics hardware perform both standard and fault-tolerant functions. This multi-functionality reduces overall system complexity compared to having separate systems for normal and fault conditions, while enabling drive cycle completion through adaptive reconfiguration.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Productivity

If the motor operates with degraded torque characteristics due to open circuit, then the vehicle can continue moving, but the torque output is reduced and performance is compromised

Engineering Contradiction:

Improvecontinuous operationVSAvoidtorque output

Core Design Contradiction:

ProductivityVSPower

Solution Approach 1:

The patent accepts partial torque output from the reconfigured windings as sufficient for continued operation. Rather than attempting to maintain full rated torque (excessive action), the system operates with reduced torque capability that is adequate for completing the drive cycle. This partial action approach balances power loss with the goal of continuous operation, resolving the contradiction between maintaining power output and enabling continuous operation under degraded conditions.

Inventive Principle:

Principle #16Partial or excessive action

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 the vehicle to continue operating by reconfiguring the windings, maintaining torque output and preventing shutdowns due to open-circuit conditions, with improved torque-speed performance by switching between star and square configurations based on speed thresholds.

Implementation Method 1

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS10523148B2Reconfigurable winding connection for five-phase permanent magnet electric machine

Publication Date: 2019.12.31 FORD GLOBAL TECH LLC

AI summary

A vehicle includes a five-phase electric machine with open windings driven at each side by phase legs of an inverter. A controller monitors for open-circuit windings. In response to detecting an open-circuit winding above a predetermined speed threshold, the controller operates the inverter to drive the windings that are not open-circuited in a square configuration.