Comparator Circuit for Electrical Machine State Detection

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Solution Overview

Problem

Existing methods for checking the operating state of electrical machines have high failure rates, particularly in critical applications like automotive and aviation, where reliability is paramount, due to the limitations of software-based consistency checks.

Innovation Solution

A hardware-based method using a comparator to compare demodulated pulse width modulation signals with reference signals representing rotational speed or current intensity, generating error or confirmation signals to determine the correct operating state of electrical machines, thereby achieving a significantly lower failure rate of 10^-9 failures per hour.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If software-based consistency checks are used to determine the operating state of electrical machines, then the checking mechanism is easier to implement and more adaptable, but the failure rate increases to approximately 10^-5 failures per hour

Engineering Contradiction:

Improveadaptability of checking mechanismVSAvoidfailure rate of checking mechanism

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces the software-based checking mechanism with a hardware-based electronic circuit that uses comparators to directly compare demodulated PWM signals with reference signals. This substitution of hardware for software eliminates the high failure rate associated with microprocessor-based software checks while maintaining the ability to perform consistency checks on electrical machine operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates hardware copies of the signal processing functions that were previously performed in software. By implementing comparators that directly compare signal waveforms in hardware, the system replicates the consistency checking functionality with significantly improved reliability, achieving a failure rate of 10^-9 failures per hour.

Inventive Principle:

Principle #26Copying

2Reliability

If hardware-based consistency checks are implemented using comparators, then the failure rate decreases to 10^-9 failures per hour, but the device complexity increases

Engineering Contradiction:

Improvefailure rate of checking mechanismVSAvoidcomplexity of checking circuit

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the essential comparison function from complex software algorithms and implements it using simple hardware comparators. By taking out only the core functionality of signal comparison and implementing it in hardware, the system achieves high reliability without requiring complex circuitry, thus managing device complexity effectively.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the operational parameters of the checking system by operating comparators in specific modes and configuring them with particular reference signals and threshold values. This parameter optimization allows the hardware circuit to achieve 10^-9 failure rates while maintaining manageable complexity through proper design choices.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If demodulated PWM signals are compared with reference signals representing rotational speed or current intensity, then the measurement precision of operating state detection is improved, but the difficulty of detecting and measuring increases

Engineering Contradiction:

Improveprecision of operating state detectionVSAvoidcomplexity of signal comparison

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces reference signals as intermediaries that represent expected values for rotational speed or current intensity. These reference signals mediate between the complex demodulated PWM signals and the comparison operation, enabling precise measurement of operating state by providing a standardized basis for comparison that simplifies the detection process.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11594997B2Method and circuit arrangement for determining an incorrect operating state of an electrical machine

Publication Date: 2023.02.28 ROLLS ROYCE DEUT LTD & CO KG

AI summary

The disclosure relates to a method for determining an incorrect operating state of an electrical machine with the aid of an electronic circuit having at least one comparator. The electrical machine is controlled with a pulse width modulation signal. The pulse width modulation signal is demodulated. A first signal, which represents the demodulated pulse width modulation signal, is compared with a second signal. The second signal represents a rotational speed or a rotational angle of the electrical machine and/or a current intensity of the electrical machine. This comparison is carried out with the aid of the at least one comparator. An error signal is generated based on the comparison in order to determine the incorrect operating state of the electrical machine.