Electric Motor Position Estimator for Resolver Offset Compensation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Position measurement errors in electric motor systems, such as those caused by misalignment between resolver and motor rotors, lead to inefficiencies, energy consumption instability, and adverse effects like reduced driving range and increased noise in vehicle propulsion systems.

Innovation Solution

A position estimator is used to estimate the rotor position by injecting a probing voltage signal into the motor system, allowing for the detection and compensation of angular offset errors between the actual and measured rotor positions, thereby aligning the estimated and actual rotor reference frames.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a resolver is used to measure rotor position, then position measurement is achieved, but position measurement errors occur due to manufacture variations and tolerances

Engineering Contradiction:

Improverotor position measurementVSAvoidrelative position between resolver and motor rotor

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The system performs preliminary action by injecting a probing voltage signal before normal operation to detect and estimate the angular offset between the resolver rotor and motor rotor. This preliminary detection allows the system to identify position measurement errors before they affect motor control performance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring the current response to the probing voltage signal and using this information to estimate the angular offset. The estimated offset is then used to compensate for position measurement errors, creating a closed-loop system that improves measurement precision despite manufacturing variations.

Inventive Principle:

Principle #23Feedback

2Productivity

If position measurement errors are present, then motor control operation continues, but control efficiency and energy consumption are reduced

Engineering Contradiction:

Improvemotor control operationVSAvoidenergy consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The system uses feedback from the current response to the probing voltage signal to detect position measurement errors. By continuously monitoring the q-axis current component and comparing it to expected values, the system can identify when position errors are affecting control efficiency and energy consumption.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system replaces direct mechanical alignment verification with an electrical detection method. Instead of relying solely on precise mechanical alignment between the resolver and motor rotor, the system uses electrical signals (probing voltage and current measurement) to detect and compensate for misalignment, improving control efficiency without additional mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Duration of action of moving object

If position measurement errors occur, then motor operation continues, but stability and performance deteriorate

Engineering Contradiction:

Improvemotor operationVSAvoidmotor operation stability

Core Design Contradiction:

Duration of action of moving objectVSStability of the object's composition

Solution Approach 1:

The system performs preliminary detection of position measurement errors using a probing voltage signal before normal motor operation is affected. By detecting the angular offset in advance through current response analysis, the system can compensate for errors that would otherwise cause instability and performance deterioration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system introduces an intermediary detection mechanism (probing voltage signal injection and current response measurement) that acts as a mediator between the resolver position measurement and the motor control system. This intermediary step allows the system to identify and compensate for position measurement errors, maintaining operational stability despite manufacturing variations.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach effectively reduces position measurement errors, improving motor control accuracy and efficiency, and enhancing the stability and performance of electric motor systems, particularly in vehicle propulsion applications.

Implementation Method 1

a position estimator is used to estimate the rotor position by injecting a probing voltage signal into the motor system, allowing for the detection and compensation of angular offset errors

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS10084399B2Detecting position measurement errors in an electric motor system

Publication Date: 2018.09.25 FARADAY&FUTURE INC

AI summary

A system for controlling an electric motor is disclosed. The system includes a position sensor configured to measure a physical position of a rotor of the electric motor; and a position estimator. The position estimator is configured to: inject a voltage signal having a predetermined frequency into the electric motor, generate an estimated position of a rotor flux based on a feedback current signal in response to the injected voltage signal, and compensate for an offset between the physical position measured by the position sensor and an actual position of the rotor flux based on the estimated position.