Brushless Motor Pole Detection Using Current Direction and Rotor Rotation

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Solution Overview

Problem

Existing motor control devices for brushless motors with salient polarity require a significant amount of time to distinguish magnetic poles, which can be inefficient and power-consuming.

Innovation Solution

A motor control device that includes a rotation control unit, a rotation direction determining unit, and a magnetic pole distinguishing unit, which rotates the rotor and determines the rotation direction based on the orientation of the current flowing through the coil, allowing for the distinction of magnetic poles without the need for passing current in both directions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If voltage is applied in positive orientation then negative orientation through the coil to distinguish magnetic poles, then measurement precision is improved, but time required for distinguishing increases

Engineering Contradiction:

Improvemagnetic pole distinction accuracyVSAvoidtime required for distinguishing magnetic poles

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the necessary information (current orientation and rotation direction) needed to distinguish magnetic poles, eliminating the need to apply voltage in both positive and negative orientations. By taking out only the essential measurement components and using the natural current flow direction combined with rotation direction detection, the system achieves magnetic pole distinction with reduced time consumption while maintaining measurement accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If current is passed in both directions through the coil to estimate inductance, then measurement precision is improved, but use of energy increases

Engineering Contradiction:

Improveinductance estimation accuracyVSAvoidpower consumption during magnetic pole distinction

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent extracts only the necessary energy-consuming operation (applying voltage in one orientation) while deriving sufficient information from the combination of current orientation and rotation direction. By eliminating the redundant voltage application in negative orientation, the system reduces energy consumption during magnetic pole distinction while maintaining the ability to accurately estimate inductance and distinguish magnetic poles.

Inventive Principle:

Principle #2Taking out (Extraction)

3Measurement precision

If voltage is applied in both positive and negative orientations to determine inductance magnitude, then measurement precision is improved, but productivity decreases

Engineering Contradiction:

Improveinductance measurement accuracyVSAvoidspeed of magnetic pole distinction process

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent extracts only the essential measurement step (applying voltage in one orientation and detecting current orientation) while using rotation direction determination to compensate for the eliminated negative orientation voltage application. This extraction approach maintains sufficient inductance measurement accuracy for magnetic pole distinction while significantly improving the speed of the overall process by removing redundant operations.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary determination of rotation direction before completing the magnetic pole distinction process. By having the rotation direction information available in advance, the system can use a single voltage application direction to sufficiently distinguish magnetic poles, eliminating the need for subsequent negative orientation voltage application and thereby improving productivity.

Inventive Principle:

Principle #10Preliminary 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

This solution significantly reduces the time required to distinguish magnetic poles, improves efficiency, and lowers power consumption compared to traditional methods.

Implementation Method 1

a brushless motor 100 having a salient polarity... a rotation control unit configured to rotate a rotor 105 of a brushless motor 100 by supplying power

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

an orientation of a current flowing through a coil 101 to 103 of the brushless motor 100

Methodology Applied

Scientific EffectElectromagnetism: Electromagnet

Data Source

PatentUS12301141B2Motor control device

Publication Date: 2025.05.13 ADVICS CO LTD

AI summary

A motor control device includes: a rotation control unit that rotates a rotor of a brushless motor by supplying a power thereto; a rotation direction determining unit that determines a rotation direction of the rotor accompanying the power supplied to the brushless motor by the rotation control unit; and a magnetic pole distinguishing unit that distinguishes magnetic poles of the rotor based on an orientation of a current flowing through each of coils due to the power supplied to the brushless motor by the rotation control unit and the rotation direction of the rotor determined by the rotation direction determining unit.