Motor Temperature Sensor Fault Detection Using Phase Current Integration
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Solution Overview
Problem
Conventional techniques for determining faults in temperature sensors in motor systems, such as those in hybrid and electric vehicles, are ineffective when the torque command is zero, preventing accurate temperature detection and protection of motor systems during conditions like high-speed engine-only operation or uphill driving without motor assistance.
Innovation Solution
A control device and method that determine the temperature detection condition by calculating integrated phase current values based on phase current thresholds, allowing for fault detection even when the torque command is zero, by integrating the amount by which the phase current exceeds or is below specific thresholds and monitoring variations in temperature detection values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fault determination is implemented using torque command values, then temperature sensor fault detection can be performed during motor operation, but fault determination cannot be implemented when torque command is zero (such as during high-speed engine-only operation or uphill driving without motor assistance)
Solution Approach 1:
The patent changes the parameter used for fault determination from torque command values to phase current values. By integrating the absolute values of phase currents and comparing them against integrated torque commands, the system can perform fault detection regardless of whether the torque command is zero, as phase currents may still be present during engine-only high-speed operation due to motor acting as a generator.
2Device complexity
If the fault determination system requires non-zero torque command, then the determination logic can be simplified, but the system fails to detect faults during engine-only high-speed operation where torque command is zero
Solution Approach 1:
The patent introduces an intermediary approach by using phase current values as a mediating parameter between the torque command and temperature sensor fault detection. Instead of directly using torque command (which can be zero), the system uses phase current as an intermediary that reflects actual motor operating conditions, thereby maintaining reliable fault detection without significantly increasing system complexity.
Data Source
AI summary
A temperature detection condition of a temperature detection unit used in a motor system is determined by: obtaining a phase current value flowing through a motor device and obtaining a temperature detection value; calculating, as an integrated phase current value, at least one of a first integrated phase current value, which is obtained by integrating an amount by which the phase current value exceeds a first phase current threshold, and a second integrated phase current value, which is obtained by integrating an amount by which the phase current value is smaller than a second phase current threshold that is equal to or smaller than the first phase current threshold; and determining an amount of variation in the temperature detection value detected by the temperature detection unit following the start of determination of the temperature detection condition and an amount of variation in the calculated integrated phase current value.