Rotor Angular Position Estimation During Sensor Fault

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Solution Overview

Problem

Hybrid and electric vehicle power systems face challenges in accurately estimating rotor angular position and velocity when a position sensor fails, leading to potential motor control inaccuracies and the need for immediate shutdowns.

Innovation Solution

The system operates in a symmetrical three-phase short-circuit mode to generate back EMF voltages, allowing for the estimation of rotor angular position and velocity using measured stator currents, and employs a lookup table to verify the accuracy of position sensor outputs during recovery mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a position sensor is used to provide rotor angular position information for vector control, then motor control accuracy is improved, but the system becomes vulnerable to sensor faults that cause incorrect measurements and require immediate shutdown

Engineering Contradiction:

Improverotor angular position measurement accuracyVSAvoidsystem reliability during sensor fault

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces an intermediary estimation mechanism that uses measurable quantities (stator currents and voltages) as mediators to indirectly determine rotor angular position when the direct position sensor fails. This intermediary approach allows the system to bypass the faulty sensor while maintaining control accuracy through mathematical estimation based on the relationship between electrical quantities and rotor position.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary action by continuously monitoring position sensor outputs for validity before relying on them for control. The method pre-establishes estimation algorithms and validity detection mechanisms that are ready to activate immediately when sensor fault is detected, avoiding the need for shutdown and enabling seamless transition to sensorless operation.

Inventive Principle:

Principle #10Preliminary action

2Object-affected harmful factors

If the system shuts down immediately when position sensor fault is detected, then safety is improved, but productivity is reduced due to unnecessary shutdowns

Engineering Contradiction:

Improvecontrol safetyVSAvoidmotor operation continuity

Core Design Contradiction:

Object-affected harmful factorsVSProductivity

Solution Approach 1:

The system performs preliminary validation of position sensor outputs by comparing them against physically plausible ranges and consistency checks before accepting them for control. This preliminary action detects sensor faults that would produce harmful control commands, allowing the system to safely activate estimation modes rather than shutting down, thus maintaining productivity while ensuring safety.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms that continuously monitor the consistency between position sensor measurements and other measurable system quantities (currents, voltages, speed). When inconsistency indicating sensor fault is detected, the feedback loop triggers activation of estimation algorithms, providing continuous safe operation without shutdown and maintaining productivity.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If complex estimation algorithms are used to estimate rotor angular position during sensor fault, then estimation accuracy is improved, but computational power requirements increase

Engineering Contradiction:

Improveestimated rotor angular position accuracyVSAvoidcomputational power consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent segments the estimation problem into manageable components based on available measurements and physical relationships. Rather than using a single complex algorithm, the method divides the estimation task into sequential steps that process readily available electrical measurements (currents, voltages) through simplified mathematical relationships, reducing computational burden while maintaining accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The estimation algorithm uses the motor's own operating characteristics and readily measurable quantities (stator currents, voltages, and frequency) to self-determine rotor angular position without requiring external sensors or complex computation. This self-service approach leverages the inherent relationship between electrical inputs and rotor position in AC motors, providing accurate estimation with minimal computational power.

Inventive Principle:

Principle #25Self-service

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 accurate estimation of rotor angular position and velocity even during position sensor faults, ensuring valid motor control and preventing shutdowns due to inaccurate sensor data, with minimal computational power requirements.

Implementation Method 1

The system operates in a symmetrical three-phase short-circuit mode to generate back EMF voltages

Methodology Applied

Scientific EffectBack EMF: Electromagnetic Induction

Data Source

PatentUS8185342B2Estimating rotor angular position and velocity and verifying accuracy of position sensor outputs

Publication Date: 2012.05.22 GM GLOBAL TECHNOLOGY OPERATIONS LLC

AI summary

Methods, system and apparatus are provided for estimating rotor angular position and angular velocity during a position sensor fault, and for verifying the accuracy or inaccuracy of a position sensor's outputs based on the estimated rotor angular position and angular velocity of the rotor following a position sensor fault.