Electric Motor Winding Temperature Sensing Without Thermistors

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Solution Overview

Problem

Existing methods for measuring electric motor winding temperature require additional components, leading to increased cost, bulkiness, and reduced reliability, and existing cooling systems face challenges in compact vehicles due to space constraints.

Innovation Solution

An electric machine that uses inbuilt sensors to measure winding resistance and temperature without additional components, employing a microcontroller to generate high-frequency sinusoidal signals, detect phase currents, and control motor operation based on temperature, using MOSFET switching units for commutation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If additional temperature sensing components are added to measure winding temperature, then temperature measurement capability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvewinding temperature measurementVSAvoidnumber of components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The existing current sensing circuitry is made to perform dual functionality by injecting a high-frequency signal and measuring the resulting voltage to determine winding resistance and temperature, eliminating the need for separate temperature sensors

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The controller's existing sensors and circuitry are designed to perform multiple functions: normal motor control, phase current detection, and winding temperature measurement through resistance detection using high-frequency signal injection

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If additional temperature sensing components are added to measure winding temperature, then temperature measurement capability is improved, but manufacturing cost increases

Engineering Contradiction:

Improvewinding temperature measurementVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The temperature measurement function is achieved by copying the measurement capability from the existing current sensing system through signal injection and resistance measurement, rather than adding a completely new sensing system

Inventive Principle:

Principle #26Copying

3Measurement precision

If additional temperature sensing components are added to measure winding temperature, then temperature measurement capability is improved, but system reliability decreases

Engineering Contradiction:

Improvewinding temperature measurementVSAvoidsystem reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The temperature measurement function is merged with the existing current sensing and control functions, using the same hardware resources and reducing the number of independent components that could fail

Inventive Principle:

Principle #5Merging (Combining)

4Object-affected harmful factors

If cooling systems are added to prevent thermal runaway, then thermal safety is improved, but space requirements increase

Engineering Contradiction:

Improvethermal runaway preventionVSAvoidcooling system space

Core Design Contradiction:

Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The system performs preliminary temperature monitoring through resistance measurement to detect heating trends before thermal runaway occurs, enabling early intervention through control adjustments rather than requiring extensive cooling infrastructure

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller continuously monitors winding resistance to detect temperature changes and provides feedback to adjust motor operation, preventing thermal runaway through control actions rather than relying solely on passive cooling systems

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

Provides a compact, cost-effective, and reliable solution for temperature measurement and control, enhancing vehicle safety by preventing thermal runaway and reducing dependency on external sensors.

Implementation Method 1

generating a high frequency sinusoidal signal and transferring the generated sinusoidal signal to one or more phase lines of the electric motor

Methodology Applied

Scientific EffectHigh-frequency sinusoidal signal generation:

Implementation Method 2

determining a winding resistance of the electric motor by processing a root mean square value of each phase current

Methodology Applied

Scientific EffectElectrical resistance measurement: Electrical Resistance

Implementation Method 3

The sinusoidal current of high frequency is adjusted in close proximity to a rated frequency of the electric machine to get a suitable sinusoidal current

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3917001B1An electric machine und method for controlling an electric machine

Publication Date: 2025.07.02 TVS MOTOR CO LTD

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AI summary

The present subject matter generally relates to an electric machine (100). The present subject matter specifically but not exclusively relates to an electric motor (100) which can be controlled depending on the temperature of the winding by eliminating the requirement of any additional components such as thermistors to determine the temperature and controlling the starting operation based on the detected temperature.