BLDC Motor Current Monitoring for Jam and Control Error Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

BLDC motors face issues with detecting abnormal states such as foreign object jamming or damage, leading to potential damage to the motor driving IC due to abnormal current or voltage, and distinguishing normal from abnormal changes in phase current is challenging.

Innovation Solution

A motor driving device and control method that includes detecting zero-phase and maximum level changes in phase current, comparing cumulative average values with instantaneous variations, and determining if these exceed error levels to identify control errors, triggering protective measures like stopping or restarting the motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the BLDC motor controller drives the motor without protective operations, then the motor can operate continuously, but damage to the motor driving IC may occur due to abnormal current or voltage

Engineering Contradiction:

Improvemotor continuous operationVSAvoidmotor driving IC safety

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent implements preliminary protective actions by continuously monitoring phase current levels and detecting abnormal states before they cause damage. The controller proactively identifies foreign objects or motor damage through current level detection and executes protective operations to prevent IC damage, rather than waiting for failure to occur.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the instantaneous change amount of phase current level is used to determine abnormal state, then abnormal states can be detected, but normal changes according to command cannot be distinguished from abnormal changes

Engineering Contradiction:

Improveabnormal state detectionVSAvoiddistinction between normal and abnormal changes

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the monitoring parameter from instantaneous current level to cumulative current level. By integrating current over time, the system captures both normal operational variations and abnormal states, then uses the rate of change of cumulative current to distinguish between normal commanded changes and abnormal conditions such as foreign objects or motor damage.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback by continuously monitoring the cumulative current level and its rate of change, comparing these values against threshold criteria to determine abnormal states. This closed-loop feedback mechanism allows the controller to adaptively respond to changing motor conditions and accurately distinguish normal from abnormal operations.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP4625810A1Motor driving device, control method thereof, and electronic equipment driven by motor

Publication Date: 2025.10.01 LX SEMICON CO LTD

Figure 1~2
Figure 3
Figure 4~5

AI summary

The present invention is applicable to a motor driving device, for example, a device driving a direct current motor (DC motor), a control method thereof, and a device (electronic equipment) driven by a motor. The present invention may include, in a method of controlling a motor, a step of driving the motor according to a duty command; a step of obtaining a first value by detecting a zero-phase change amount of a first phase current driving the motor; a step of obtaining a second value by detecting a change amount of a maximum level of the first phase current; and a step of determining to be in a control error state if at least one of the detected first value and second value is greater than an error level.