Independent Fault Detection Pathways for Electric Motor Protection

Solution Overview

Problem

Existing electric motor systems rely on either hardware-based or software-based fault protection schemes, which can fail if hardware malfunctions, leading to continued operation under abnormal current conditions.

Innovation Solution

Implementing both hardware-based and software-based pathways for detecting and responding to fault conditions, such as over-current, independently operable to ensure redundant protection and swift shutdown of the motor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If hardware-based protection scheme is used, then response speed is improved, but reliability deteriorates due to potential hardware failure

Engineering Contradiction:

Improveresponse speedVSAvoidprotection reliability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The protection system is segmented into two independent pathways: a hardware-based pathway for fast response and a software-based pathway for reliable detection. Each pathway operates independently to detect fault conditions and initiate motor shutdown, ensuring that failure in one pathway does not compromise overall system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system implements redundant protection mechanisms in advance by providing both hardware and software pathways that can independently detect and respond to faults. This preliminary cushioning ensures that if one pathway fails, the other is already in place to provide protection.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If software-based protection scheme is used, then redundancy is improved, but response speed deteriorates

Engineering Contradiction:

Improveprotection redundancyVSAvoidresponse speed

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The protection system is segmented into two independent pathways: a hardware-based pathway for fast response and a software-based pathway for reliable detection. Each pathway operates independently to detect fault conditions and initiate motor shutdown, ensuring that failure in one pathway does not compromise overall system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system merges the advantages of both hardware-based and software-based protection schemes into a unified dual-pathway system. The hardware pathway provides fast response capability while the software pathway provides redundant verification, and both pathways work together to achieve both speed and reliability.

Inventive Principle:

Principle #5Merging (Combining)

3Device complexity

If single protection pathway is used, then device complexity is reduced, but reliability deteriorates due to lack of redundancy

Engineering Contradiction:

Improveprotection system complexityVSAvoidprotection redundancy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The protection system is segmented into two independent pathways: a hardware-based pathway for fast response and a software-based pathway for reliable detection. Each pathway operates independently to detect fault conditions and initiate motor shutdown, ensuring that failure in one pathway does not compromise overall system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Both pathways use the same fundamental detection logic (comparing voltage signals to predetermined maximum values to detect over-current conditions) and the same shutdown mechanism, ensuring homogeneous protection functionality while achieving redundancy through independent implementation.

Inventive Principle:

Principle #33Homogeneity

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

Combines the speed and reliability of hardware-based protection with the redundancy of software-based protection, effectively preventing motor operation under fault conditions and detecting various types of faults like over/under current and temperature.

Implementation Method 1

a first resistor block electrically connected between the power inverter and the power module, and operable to generate a first voltage signal that is representative of an electric current flowing to the motor

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a second resistor block electrically connected between the power inverter and the microprocessor, and operable to generate a second voltage signal that is representative of the electric current flowing to the motor

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 3

comparing the voltage signal to a predetermined maximum voltage signal, and based thereon, determining whether an over-current condition exists (by Ohm's law, the voltage is representative of the current)

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Data Source

PatentUS9735726B2Independent pathways for detecting fault condition in electric motor

Publication Date: 2017.08.15 NIDEC MOTOR CORP

AI summary

An electric motor system having substantially independent hardware-based and software-based pathways for detecting and initiating responses to fault conditions, such as over-current conditions, in an electric motor which is powered by a power inverter which is controlled by a power module and a microprocessor. Each pathway involves comparing a voltage, which is representative of an electric current flowing to the motor, to a predetermined maximum voltage, and if the former exceeds the latter using hardware or software to initiate shutting off the motor, such as by shutting off the power inverter. When one pathway detects a fault condition it may notify the other pathway, and the notified pathway may also initiate shutting off the motor.