Three-Phase Motor Testing Without Mechanical Locking

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Solution Overview

Problem

Existing methods for testing three-phase motors are inefficient, costly, and require mechanical locking mechanisms, which complicate the testing process.

Innovation Solution

A method for testing a three-phase motor using single-phase voltage supply to two terminals, regulating current to a setpoint without generating a rotating magnetic field, allowing for quick and easy testing without mechanical blocking.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a three-phase voltage is applied to test the motor, then the test accuracy is improved, but a mechanical locking mechanism is required which increases device complexity and testing effort

Engineering Contradiction:
Improvetest accuracyVSAvoidmechanical locking mechanism
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts the essential testing function from the complex three-phase testing system by applying single-phase voltage to only two terminals, eliminating the need for mechanical locking mechanisms while retaining the ability to detect motor defects through current and voltage monitoring

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical locking mechanism with an electrical control approach, using a controllable voltage source to regulate single-phase voltage and current, thereby substituting mechanical constraints with electrical regulation to achieve the same testing objective

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a mechanical locking mechanism is used to prevent rotation, then the test reliability is improved, but the testing process becomes more complex and labor-intensive

Engineering Contradiction:
Improvetest reliabilityVSAvoidtesting effort
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent enables the motor to self-regulate during testing by monitoring the relationship between applied voltage and resulting current, allowing the system to automatically detect deviations without external mechanical intervention or complex control mechanisms

Inventive Principle:
Principle #25Self-service

3Ease of operation

If single-phase voltage is applied to two terminals, then the ease of operation is improved, but the test accuracy may be compromised

Engineering Contradiction:
Improvetesting effortVSAvoidtest accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent implements feedback control by continuously monitoring the current drawn by the motor under single-phase voltage and comparing it against expected values, using this feedback to detect motor defects and ensure testing accuracy despite the simplified single-phase approach

Inventive Principle:
Principle #23Feedback

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

Enables efficient, cost-effective, and labor-saving testing of three-phase motors by eliminating the need for mechanical locking, ensuring accurate results with minimal effort.

Implementation Method 1

the actual value of the current supplied to the motor with the single-phase voltage is regulated to a current setpoint

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

the actual value of the current supplied to the motor with the single-phase voltage is regulated to a current setpoint

Methodology Applied
Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentEP4337970B1Method for testing a three-phase motor and test arrangement for a three-phase motor
Publication Date: 2026.03.04 SEW EURODRIVE GMBH & CO KG
  • EP4337970B1 patent drawingFigure 1

AI summary

The invention relates to a method for testing a three-phase motor and to a test arrangement for a three-phase motor, wherein, in a first method step, a current setpoint value associated with a single-phase feed of the motor is determined, wherein a voltage absolute value of a single-phase voltage associated with the current setpoint value and provided for a single-phase feed of the motor is determined, in a second method step, a single-phase voltage is applied to two of the terminals (U, V) and the third terminal (W) is not supplied, wherein the actual value of the current fed to the motor is detected, wherein the actual value of the voltage is detected, wherein the voltage is set in such a way that the control deviation, that is to say the difference between the actual value of the current and the current setpoint value, is set to zero, wherein, when the absolute value of the control deviation falls below a threshold value, the result of the test of the motor depends on whether or not the actual value of the voltage exhibits an impermissibly high degree of deviation from the voltage absolute value.