Electric Motor Control Device Abnormality Detection

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Solution Overview

Problem

When an abnormality occurs in some induction motors, controlling them as if all motors are functioning properly can lead to further damage, as seen in cases like bearing seizing or coil short-circuits, potentially causing damage to other parts.

Innovation Solution

An electric motor control device that detects abnormalities based on voltage compensation signals and shuts down power supply to affected motors, preventing further damage by suspending their operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the same control as when all induction motors work properly is performed even though an abnormality is occurring in some of the induction motors, then the control system maintains simplicity and continuous operation, but damage spreads in the abnormally performing induction motors

Engineering Contradiction:
Improvecontinuous operationVSAvoiddamage spreading prevention
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The control device performs preliminary detection of abnormalities in induction motors before they cause severe damage. By monitoring voltage compensation signals and detecting deviations from normal ranges, the system identifies potential failures early and shuts down affected motors proactively, preventing further damage spread while maintaining overall system reliability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The control device uses feedback from voltage compensation signals to continuously monitor the operational status of each induction motor. When the voltage compensation signal deviates from the normal range, indicating an abnormality, the system responds by shutting down the affected motor, thus preventing damage spread while maintaining continuous operation of healthy motors

Inventive Principle:
Principle #23Feedback

2Productivity

If power supply is continuously maintained to all induction motors, then productivity is maximized, but damage spreads in abnormally performing motors causing greater losses

Engineering Contradiction:
Improvepower outputVSAvoiddamage spreading
Core Design Contradiction:
ProductivityVSObject-affected harmful factors

Solution Approach 1:

The control device segments the power supply control for each induction motor independently. By detecting abnormalities in individual motors through voltage compensation signals, the system can selectively shut down only the affected motor while maintaining power supply and operation of healthy motors, thus preventing damage spread while preserving overall productivity

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2899873B1Electric motor control device
Publication Date: 2021.01.06 MITSUBISHI ELECTRIC CORP
  • EP2899873B1 patent drawingFigure 1
  • EP2899873B1 patent drawingFigure 2
  • EP2899873B1 patent drawingFigure 3

AI summary

A current command generator (117) generates a current command that indicates a value of current supplied from an inverter circuit to electric motors connected in parallel with the inverter circuit. A voltage command calculator (120) generates a voltage compensation signal for compensating a difference between a value of actual current supplied to each of the electric motors and a value of current indicated by the current command. A determiner (135) determines, based on a value obtained from the voltage compensation signal, whether or not an abnormality is occurring in at least one of the electric motors. A shutdown controller (136) shuts down, upon the determiner (135) determining that an abnormality is occurring, the power supply from the inverter circuit to the each of the electric motors.