Motor Torque Control Logic for Direction-Aware Abnormality Detection
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Solution Overview
Problem
Existing control devices for rotating electrical machines in vehicles may inadvertently accelerate without driver intention due to abnormalities, leading to unnecessary fail-safe processes that lower drivability, as they struggle to accurately detect abnormalities and differentiate between intended and unintended torque changes.
Innovation Solution
A control device that calculates target values based on redundant and non-redundant signals, with a difference calculation unit determining abnormality only when the vehicle is traveling forward if the target value exceeds a first determination value or traveling backward if it's below a second determination value, thereby preventing unnecessary fail-safe processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control device continuously monitors the difference between target value and target monitoring value to detect abnormalities, then the reliability of abnormality detection is improved, but the drivability deteriorates due to unnecessary fail-safe processes being triggered
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the monitoring threshold based on vehicle traveling direction. When traveling forward, the threshold is set to detect when target value ≥ first determination value; when traveling rearward, the threshold is set to detect when target value ≤ second determination value. This directional parameter adjustment prevents false abnormality detections during normal reverse operation while maintaining reliable abnormality detection capability.
2Measurement precision
If the control device calculates the difference between target value and target monitoring value in all operating conditions, then the measurement precision of abnormality detection is improved, but the device complexity increases due to continuous monitoring requirements
Solution Approach 1:
The patent applies dynamics by making the monitoring process conditional rather than continuous. The difference calculation is dynamically enabled or disabled based on real-time operating conditions (traveling direction and target value magnitude). This dynamic approach maintains high measurement precision when abnormalities are likely while reducing system complexity by avoiding unnecessary continuous monitoring in normal operating conditions.
Data Source
AI summary
The control device includes a target-value calculation unit calculating a target-value of a controlled variable that is torque of a rotating electrical machine, drive force, or acceleration of a vehicle, based on redundant signal and non-redundant signals, an inverter operation unit operating the inverter to control the controlled variable to the target-value, and a monitoring-value calculation unit calculating a target-monitoring-value of the controlled variable based on the redundant signal. A difference calculation unit that, when the vehicle travels forward, calculates a difference between the target-value and the target-monitoring-value when the target-value is a first determination value or more, and does not calculate the difference when the target-value is less than the first determination value, and that, when the vehicle travels rearward, calculates the difference when the target-value is a second determination value or less, and does not calculate the difference when the target-value is more than the second determination value.