Motor Control Using Position Sensors for Commutation Error Compensation

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Solution Overview

Problem

Brushless motors face challenges in accurate commutation due to imprecise position sensor mounting, hysteresis, and manufacturing imperfections, leading to imbalanced phase conduction, torque ripples, and reduced power efficiency, especially when generating sinusoidal back-EMF requires higher resolution and adaptive control.

Innovation Solution

A method and circuit for monitoring position sensors to measure transition times, calculate commutation error fractions, and adjust commutation times based on back-EMF calibration, ensuring precise waveform alignment and dynamic speed control through a Look-Up Table and PWM modulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If position sensors are mounted in limited space, then device compactness is improved, but measurement precision deteriorates due to imprecise mounting

Engineering Contradiction:

Improvedevice compactnessVSAvoidcommutation timing accuracy

Core Design Contradiction:

Volume of moving objectVSMeasurement precision

Solution Approach 1:

The system performs preliminary calibration by measuring actual transition times of position sensors during a calibration revolution period, then calculates commutation error fractions to compensate for mounting inaccuracies before normal operation begins

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors position sensor output patterns, measures actual transition times, compares them with expected values, and uses the calculated commutation error fractions to adjust commutation timing in real-time, creating a closed-loop feedback system that compensates for mounting errors

Inventive Principle:

Principle #23Feedback

2Device complexity

If digital-output position sensors are used, then device complexity is reduced, but measurement precision deteriorates due to insufficient resolution for sinusoidal-weighted control

Engineering Contradiction:

Improvecontrol system complexityVSAvoidcommutation timing resolution

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system changes the parameter of commutation timing by calculating error fractions based on measured transition times and using these to adjust the timing of commutation events, transforming fixed digital outputs into dynamically adjusted control signals

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system introduces dynamic adjustment to the commutation timing by calculating and applying commutation error fractions that vary with operating conditions, enabling adaptive control that maintains precision across different speeds and loads

Inventive Principle:

Principle #15Dynamics

3Device complexity

If commutation timing is not accurately adjusted, then device complexity is reduced, but power efficiency deteriorates due to imbalanced phase conduction and torque ripples

Engineering Contradiction:

Improvecontrol algorithm complexityVSAvoidpower efficiency

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The system performs preliminary calibration to determine commutation error fractions before normal operation, establishing the foundation for accurate commutation timing without requiring complex real-time calculations during motor operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from measured transition times to continuously adjust commutation timing based on calculated error fractions, ensuring optimal phase conduction and minimizing torque ripples and energy losses

Inventive Principle:

Principle #23Feedback

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 improves motor control accuracy, reduces phase delays, and enhances power efficiency by aligning commutation times with Hall transition times, providing smoother operation and precise control, especially at low speeds.

Implementation Method 1

position sensors (e.g. magnetic Hall sensors)

Methodology Applied

Scientific EffectHall effect: Hall Effect

Implementation Method 2

brushless motors are configured to generate a sinusoidal back-Electromotive Force (EMF) during operation

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS9634591B2System and method for motor control using position sensors

Publication Date: 2017.04.25 INFINEON TECHNOLOGIES AG

AI summary

An embodiment method for motor control includes monitoring a plurality of position sensors coupled to a revolving motor. The monitoring includes measuring transition times of respective output patterns produced by the position sensors, the respective output patterns each including at least one transition time that repeats in accordance with each revolution of the motor. The method further includes determining a first revolution period in accordance with the measured transition times. The method also includes determining an elapsed fraction of the first revolution period that has elapsed since a start time of the first revolution period.