Motor Commutation Phase Adjustment via Back-EMF

Solution Overview

Problem

Existing motor commutation methods, such as those using Hall effect sensors, increase motor weight and cause torque ripple, while sensorless commutation methods are sensitive to circuit noise, leading to delayed or early commutations that reduce motor performance.

Innovation Solution

A method and apparatus that measure voltage at multiple motor windings to compute an overall back electromotive force, generating a result to adjust the commutation phase and period, thereby improving timing consistency and reducing noise and current surges without adding weight or using sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If Hall effect sensors or other devices are used to directly measure rotor position for commutation, then commutation accuracy is improved, but motor weight increases and torque ripple occurs

Engineering Contradiction:

Improverotor position measurement accuracyVSAvoidmotor weight

Core Design Contradiction:

Measurement precisionVSWeight of moving object

Solution Approach 1:

The patent extracts the commutation control function from sensor-based systems to sensorless systems by computing rotor position and commutation timing from back electromotive force (EMF) measurements taken from motor windings during normal operation, eliminating the need for Hall effect sensors or other position measurement devices

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The motor system uses its own operational characteristics (back EMF generated during normal motor operation) to determine commutation timing, making the system self-sufficient without requiring external sensors or additional measurement components

Inventive Principle:

Principle #25Self-service

2Measurement precision

If Hall effect sensors or other devices are used to directly measure rotor position for commutation, then commutation accuracy is improved, but torque ripple increases

Engineering Contradiction:

Improverotor position measurement accuracyVSAvoidtorque ripple

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the commutation control function from sensor-based systems to sensorless systems by computing rotor position and commutation timing from back electromotive force (EMF) measurements taken from motor windings during normal operation, eliminating the need for Hall effect sensors or other position measurement devices

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system continuously monitors back EMF signals from motor windings and uses this feedback to dynamically adjust commutation timing, ensuring optimal commutation points that minimize torque ripple while maintaining accurate rotor position control

Inventive Principle:

Principle #23Feedback

3Weight of moving object

If sensorless commutation is used by detecting back electromotive force, then motor weight is reduced, but commutation timing accuracy deteriorates due to sensitivity to circuit noise

Engineering Contradiction:

Improvemotor weightVSAvoidcommutation timing accuracy

Core Design Contradiction:

Weight of moving objectVSMeasurement precision

Solution Approach 1:

The system continuously monitors back EMF signals from motor windings and uses this feedback to dynamically adjust commutation timing, ensuring optimal commutation points that minimize torque ripple while maintaining accurate rotor position control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent adjusts commutation timing parameters (commutation advance angle and commutation period) based on computed back EMF characteristics, optimizing these parameters to achieve accurate commutation timing despite the presence of circuit noise

Inventive Principle:

Principle #35Parameter changes

4Weight of moving object

If sensorless commutation is used by detecting back electromotive force, then motor weight is reduced, but commutation timing consistency deteriorates leading to delayed or early commutations

Engineering Contradiction:

Improvemotor weightVSAvoidcommutation timing consistency

Core Design Contradiction:

Weight of moving objectVSStability of the object's composition

Solution Approach 1:

The system continuously monitors back EMF signals from motor windings and uses this feedback to dynamically adjust commutation timing, ensuring optimal commutation points that minimize torque ripple while maintaining accurate rotor position control

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent adjusts commutation timing parameters (commutation advance angle and commutation period) based on computed back EMF characteristics, optimizing these parameters to achieve accurate commutation timing despite the presence of circuit noise

Inventive Principle:

Principle #35Parameter changes

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 enhances motor performance by aligning current with back electromotive force, reducing surge currents, noise, and heat, while maintaining efficiency and output power, and is cost-effective.

Implementation Method 1

computes an overall back electromotive force for the motor using the voltage measured at each winding in the plurality of windings

Methodology Applied

Scientific EffectBack electromotive force: Electromagnetic Induction

Data Source

PatentUS10014805B2Method and apparatus for adjusting motor commutation phase and period

Publication Date: 2018.07.03 THE BOEING CO

AI summary

A method and apparatus for controlling commutation of a motor. A voltage is measured at each of a plurality of windings of a motor using an electric circuit. A controller computes an overall back electromotive force for the motor using the voltage measured at each winding in the plurality of windings. The controller generates a result having either a first value or a second value based on the overall back electromotive force. The controller adjusts the commutation phase and the commutation period of the motor using the result.