Electric Motor Sensor Fault Detection via Current Variable Transformation
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Solution Overview
Problem
Existing methods for detecting sensor failures in electric machines with permanent magnet rotors are inadequate, particularly in controlling sinusoidal currents and torque regulation, as they are not suitable for machines operating in both static and dynamic regimes.
Innovation Solution
A method and system that utilize a change of variable to transform the control signals and currents into a cooperative system, allowing for the determination of minimum and maximum limits of direct and quadratic components, enabling the detection of sensor faults by comparing measured values with these limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing sensor failure detection methods are used, then detection capability is limited, but the system cannot operate securely in both static and dynamic regimes
Solution Approach 1:
The patent transforms the static sensor failure detection method into a dynamic one by introducing time-varying test signals and evaluating sensor responses across different operating conditions. The system adapts the detection approach based on whether the machine is in static or dynamic regime, using regime-appropriate test signals and evaluation criteria to ensure reliable detection across all operating conditions.
Solution Approach 2:
The patent changes the parameters of the test signals based on the operating regime. In static conditions, specific test currents are applied, while in dynamic conditions, different test signal characteristics are used. The evaluation parameters (such as voltage thresholds and response criteria) are also adjusted according to the operating regime to maintain detection accuracy across varying conditions.
2Reliability
If sensor failure detection is implemented, then system safety improves, but the complexity of the verification system increases
Solution Approach 1:
The patent implements self-service by using the machine's own operational characteristics and existing sensors to perform failure detection. The verification system utilizes the machine's back-EMF and electrical parameters during normal operation to detect sensor failures, eliminating the need for separate external testing equipment or complex additional sensing systems.
Solution Approach 2:
The patent employs feedback mechanisms where the sensor outputs are continuously monitored and compared against expected values derived from the machine model and actual operating conditions. When discrepancies exceed predefined thresholds, the system triggers failure detection and appropriate responses, creating a closed-loop verification system that adapts to changing operating conditions.
Data Source
Figure 1~2
AI summary
Method and corresponding system for verifying the operation of a motor propulsion plant fitted to an automotive vehicle with electric or hybrid traction, the motor propulsion plant comprising an electric motor furnished with a permanent-magnet rotor, said method comprising a regulation (E00) of the currents of the stator and a measurement of the direct and quadratic components of the currents (E01), the method comprising: - an application (E03), in a model of the electric motor linking the control signals to the direct and quadratic components of the currents, of a change of variable in which X=Iq3+Id3, Y=Iq-Id, - determination (E04) of minimum and maximum bounds for X and Y so as to deduce therefrom minimum and maximum bounds for Iq and Id, - a comparison (E05) between the measured direct and quadratic components of the currents and said minimum and maximum bounds for Iq and Id.