Motor Fault Detection via Coupling Injection

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Solution Overview

Problem

Existing motor fault detection methods, particularly those using high-frequency signal injection through inverters, suffer from limited detection accuracy due to switching frequency limitations and nonlinear characteristics, leading to potential misjudgments and requiring offline maintenance, which is time-consuming and disrupts motor operation.

Innovation Solution

A motor fault detection system that injects high-frequency signals directly into the motor winding using a coupling circuit, independent of the inverter, allowing for real-time fault detection by analyzing the negative sequence component of the high-frequency current response, enabling accurate assessment of fault severity without interrupting motor operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If high-frequency detection signal is injected through inverter, then on-site fault detection is enabled, but detection accuracy is limited by inverter switching frequency and nonlinear characteristics

Engineering Contradiction:

Improvefault detection accuracyVSAvoidinverter dependency

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the high-frequency signal injection function from the inverter system by introducing an independent signal injection circuit. This separate circuit directly injects high-frequency signals into the motor windings without relying on inverter switching, thereby eliminating the limitations of inverter switching frequency and nonlinear characteristics on detection accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary signal injection circuit that acts as a mediator between the detection system and motor windings. This intermediary circuit generates and injects high-frequency detection signals independently, serving as a bridge that avoids direct interaction with the inverter system and its associated limitations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If off-line fault detection is performed, then motor maintenance is ensured, but detection period is long and real-time performance is poor

Engineering Contradiction:

Improvemotor maintenance reliabilityVSAvoiddetection period

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent enables continuous on-site fault detection during motor operation by injecting high-frequency signals into running motors. This continuous detection capability eliminates the need to stop the motor for maintenance checks, ensuring uninterrupted operation while maintaining reliable fault detection and early warning capabilities.

Inventive Principle:

Principle #20Continuity of useful action

3Ease of manufacture

If inverter switching frequency is used for signal injection, then signal generation is simplified, but detection accuracy is limited by nonlinear characteristics

Engineering Contradiction:

Improvesignal generation simplicityVSAvoidfault detection accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent extracts the signal generation function from the inverter by creating a dedicated high-frequency signal injection circuit. This separate circuit uses simple oscillating circuits or function generators to produce high-frequency sine waves, eliminating the complex inverter switching mechanism while maintaining signal generation simplicity and improving detection accuracy.

Inventive Principle:

Principle #2Taking out (Extraction)

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 system provides real-time, accurate motor fault detection without relying on inverter parameters, allowing for on-site monitoring and early warning of faults, applicable to various motor power levels, and reduces the need for offline maintenance, ensuring continuous operation.

Implementation Method 1

the input end of the motor is connected with the high-frequency detection signal source circuit through the coupling circuit to inject high-frequency detection signal into the motor winding

Methodology Applied

Scientific EffectElectrical coupling: Conduction (electrical)

Implementation Method 2

the high-frequency signal generates corresponding high-frequency current or voltage response in the motor winding

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11474152B2Motor fault detection system based on coupling injection of high frequency signals

Publication Date: 2022.10.18 TIANJIN POLYTECHNIC UNIV

AI summary

A motor fault detection system is based on coupling injection of high-frequency signal. An input end of the motor is connected with the high-frequency detection signal source circuit through the coupling circuit to inject a high-frequency detection signal into the motor winding; an input end of the high-frequency detection signal source circuit is connected with an output end of the controller to control the output of the high-frequency detection signal; an output end of the response signal processing circuit is connected with an input end of the controller to send the received voltage or current response signal to the controller; and the controller judges whether the motor has a fault and the degree of the fault by analyzing the response signal after applying an excitation.