SRM Brake Commutation Switching for Fast Stop and Position Setting

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Solution Overview

Problem

There is a need for a technology that can quickly and efficiently stop a switched reluctance motor (SRM) in emergency situations or for rapid control in a brake mode, and also for accurately setting the reference position of the SRM for stable shifting.

Innovation Solution

A motor control method and device that perform a motor brake mode through three-phase switching commutation, and initialize the motor position using a gate signal and motor current. The method involves three-phase, two-phase, and one-phase commutation based on calculated sustaining speed ratios, and includes emergency brake modes and self-diagnosis for position setting accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If three-phase commutation is used for motor braking, then braking speed and efficiency are improved, but current consumption and device stress increase

Engineering Contradiction:

Improvebraking speedVSAvoidcurrent consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The patent dynamically switches between three-phase, two-phase, and one-phase commutation modes based on the motor's rotation speed. At high speeds, three-phase commutation provides strong braking force. As speed decreases, the system transitions to two-phase and then one-phase commutation to maintain effective braking while reducing current consumption and device stress.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the commutation parameter (number of active phases) based on the motor rotation speed threshold. By monitoring the rotation speed and adjusting the commutation mode accordingly, the system optimizes the balance between braking performance and current consumption, preventing excessive device stress during the braking process.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If reference position is not set accurately, then shifting stability deteriorates, but position setting complexity increases

Engineering Contradiction:

Improveshifting stabilityVSAvoidposition setting complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent implements self-service position initialization by utilizing the motor's own back-EMF characteristics during startup. The system automatically detects the reference position by monitoring the back-EMF voltage generated when the motor starts rotating, eliminating the need for external position sensors or complex manual positioning procedures.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces mechanical position sensing methods with electrical detection using back-EMF signals. Instead of using mechanical encoders or position sensors, the system uses the electrical characteristics (back-EMF voltage) generated during motor startup to determine the reference position, simplifying the overall system while maintaining accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12244257B2Motor control device and method therefor

Publication Date: 2025.03.04 LG INNOTEK CO LTD

AI summary

A motor control method according to an embodiment of a present invention comprises the steps of: performing three-phase commutation in a first range section of a motor rotational speed in a brake mode of a motor; performing two-phase commutation in a second range section of the motor rotational speed performing one-phase commutation in a first range section of the motor rotational speed; and turning off commutation when the motor rotational speed is less than or equal to the first range section.