Stator Winding Fault Detection via Voltage Command Analysis
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Solution Overview
Problem
Current diagnostic systems for electric motors in vehicles struggle to isolate stator winding diagnostics from sensor faults, leading to potential operational limitations when faults are detected, and they do not effectively diagnose degradation before a fault occurs, which can limit vehicle operability.
Innovation Solution
A diagnostic system that includes a current command module, voltage command module, switching control module, and fault module to generate and apply commands to the electric motor's stator windings, with a fault module capable of indicating degradation and disabling sensor-related diagnostics, and a state of health module to assess the stator windings' health based on voltage commands, allowing for timely maintenance and minimizing operational limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diagnostic systems detect faults in stator windings or sensors, then system reliability is improved through fault detection, but vehicle operability deteriorates due to operational limitations imposed by fault protection mechanisms
Solution Approach 1:
The diagnostic system segments fault detection into distinct categories: sensor faults and stator winding faults. By analyzing specific voltage commands (vd) separately from current commands, the system can identify the type of fault and apply targeted responses rather than blanket operational limitations, thereby maintaining vehicle operability while ensuring reliability.
Solution Approach 2:
The system changes diagnostic parameters by monitoring the relationship between voltage commands and current commands in the d-axis and q-axis. By detecting deviations in vd compared to expected values based on iq and id commands, the system can identify stator winding faults without requiring complete system shutdown, thus maintaining operational capability while ensuring safety.
2Reliability
If the system limits motor torque request to prevent fault propagation, then stator winding damage is prevented, but vehicle productivity deteriorates due to reduced power output
Solution Approach 1:
The system performs preliminary diagnosis by continuously monitoring voltage commands against current commands before faults propagate. By detecting early signs of stator winding degradation through vd analysis, the system can take preventive action (torque limiting) only when necessary, rather than continuously restricting power output, thus protecting components while maintaining productivity during normal operation.
3Measurement precision
If the system monitors d-axis voltage command to detect stator winding faults, then diagnostic precision is improved, but device complexity increases due to additional monitoring requirements
Solution Approach 1:
The diagnostic system leverages existing motor control components (voltage command module, current command module, switching control module) that are already present in the motor control system. By utilizing the d-axis voltage command (vd) that is already being generated for motor control purposes, the system achieves precise stator winding diagnostics without adding separate dedicated monitoring hardware, thus improving measurement precision while minimizing increased device complexity.
Data Source
AI summary
A diagnostic system includes: a current command module configured to, based on a motor torque request, a motor speed, a direct current (DC) bus voltage, generate a d-axis current command for an electric motor and a q-axis current command for the electric motor; a voltage command module configured to, based on the d-axis current command and the q-axis current command, generate a d-axis voltage command and a q-axis voltage command; a switching control module configured to control switching of an inverter module based on the d-axis voltage command and the q-axis voltage command, where the inverter module is configured to apply power to stator windings of the electric motor from the DC bus; and a fault module configured to selectively indicate that the stator windings of the electric motor are degraded when the d-axis voltage command is less than a predetermined nominal d-axis voltage of the electric motor.