Motor Drive Device Abnormality Detection for Single-Phase Sensor Failures
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Solution Overview
Problem
In three-phase brushless motors, when only one of the sensor signals becomes abnormal, the existing techniques fail to prevent overcurrent in switching elements, leading to potential damage due to continued operation with two phases, as they do not accurately determine rotor lockage.
Innovation Solution
A motor drive device with an abnormality detection unit that counts the number of level changes in sensor signals and stops drive current supply when the count reaches a threshold, preventing overcurrent and potential damage to switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor operates with two phases when one sensor signal becomes abnormal, then the rotor continues to rotate, but overcurrent flows in switching elements causing damage
Solution Approach 1:
The abnormality detection unit performs preliminary detection of sensor signal abnormalities before they cause overcurrent damage. By counting level changes and detecting abnormal patterns in advance, the system stops the motor proactively, preventing the harmful overcurrent effect from occurring
Solution Approach 2:
The system implements feedback by continuously monitoring sensor signals and using the abnormality detection unit to detect abnormal patterns. When an abnormality is detected, the feedback loop triggers the motor stop, creating a closed-loop protection mechanism that prevents overcurrent damage
2Device complexity
If existing techniques determine rotor lockage based on rotational speed, then the control is simple, but single-phase failures are not detected accurately leading to false negatives
Solution Approach 1:
The abnormality detection unit segments the sensor signal analysis into distinct phases: normal operation monitoring, abnormality detection through level change counting, and threshold-based determination. This segmentation enables precise detection of single-phase failures without overly complicating the overall control structure
Solution Approach 2:
The abnormality detection unit acts as an intermediary between the sensor signals and the motor control system. It processes sensor signals to detect abnormal patterns and provides abnormality determination results to the motor control, enabling accurate single-phase failure detection while maintaining control system simplicity
Data Source
Figure 1A~1D
Figure 2
Figure 3~4
AI summary
A motor drive device (20) determines whether or not a combination of logic levels of sensor signals S1 to S3 is normal, whenever the logic levels of the sensor signals S1 to S3 are changed. Each of the sensor signals S1 to S3 indicates a rotation position of a rotor (1). When the combination is not normal, the number of the level changes in each of the sensor signals S1 to S3 is counted. When the count value of any one of the sensor signals reaches a threshold value Cth, supply of power to a motor is stopped.