As a core component of electric motor control systems, resolver sensors play a critical role in position detection, speed feedback, and other essential functions. Their failure can directly lead to abnormal motor operation and even pose safety hazards. This article systematically outlines the typical symptoms of sensor damage and corresponding repair solutions, combining real-world cases with technical principles.
Five Core Symptoms of Sensor Damage
Intermittent Power Output
When sensor signal transmission is disrupted, the motor controller cannot accurately obtain rotor position information, resulting in intermittent power interruptions. Maintenance data from an electric vehicle (EV) brand shows that 67.3% of power-related anomalies are directly linked to sensor failures, manifesting as sluggish acceleration, speed fluctuations, or sudden power loss.
Steering System Failure
The sensor provides real-time rotor angle data for steering control systems. Sensor damage can lead to incorrect steering angle feedback, causing heavy steering, delayed response, or even complete steering lock. Transport authorities report that 23% of EV rollover accidents involve steering system failures, with 79% stemming from abnormal sensor signals.
Brake System False Activation
In EV braking systems, sensors form a closed-loop control with brake signals. Sensor failures may trigger abnormal brake pedal stiffness, constantly illuminated brake lights, and other erroneous operations—particularly hazardous during nighttime driving. Third-party testing reveals that 41% of brake-related accidents under sensor failure conditions occur at night.
Abnormal Range Decline
Incorrect sensor signals can cause controllers to misjudge motor load, leading to excessive energy consumption. Tests indicate that sensor failures can reduce driving range by 38%-52%, with intermittent faults often misdiagnosed as battery degradation.
Abnormal Noise and Overheating Warnings
Internal circuit contact issues or chip damage in sensors may produce clicking noises accompanied by a burning smell, indicating circuit overload. Fire departments report that 12% of EV spontaneous combustion cases originate from sensor-related circuit failures.
Root Causes of Sensor Damage
Environmental Factors
Prolonged exposure to high temperatures, humidity, or strong electromagnetic interference can degrade sensor component performance. For example, voltage fluctuations caused by poor-quality chargers account for 34% of failure cases.
Physical Damage
Aging wiring, loose connectors, or mechanical vibrations may disrupt sensor signals. In one maintenance case, a worn-through exhaust temperature sensor wire caused a urea pump failure, triggering engine torque limitation.
Manufacturing Defects
Poor sensor chip encapsulation or calibration errors can lead to signal drift. For instance, a shorted nitrogen oxide (NOx) sensor wire may cause emission non-compliance, prompting the system to restrict engine torque.
Professional Repair Solutions and Preventive Measures
Fault Diagnosis Process
Basic Inspection: Use a smartphone flashlight to check for cracks on the sensor surface and verify connector tightness.
Signal Testing: Monitor sensor output waveforms with an oscilloscope to detect open circuits or shorts.
Phase Adjustment Testing: Calibrate A/B/C phase sensors to ensure signal consistency.
Repair Technical Considerations
Component Replacement: Use sensors matching original equipment manufacturer (OEM) specifications to avoid compatibility issues.
Wiring Repair: Insulate abraded wires and re-bundle connectors.
Software Updates: Refresh ECU firmware to correct sensor signal compensation algorithms.
Preventive Maintenance
Regular Calibration: Quarterly sensor sensitivity checks using professional equipment.
Environmental Control: Avoid exposing motors to extreme temperatures or humidity.
Charging Protocols: Use OEM chargers to prevent voltage fluctuations from damaging sensors.
Industry Solution References
An EV brand’s “Three-Step Troubleshooting Method” offers practical guidance:
Power Testing: Gently press the accelerator to check for linear speed response.
Steering Testing: Make sharp turns at low speeds to detect steering jams.
Data Monitoring: Use an OBD diagnostic tool to compare real-time sensor values against standard ranges.
Additionally, temporary replacement with universal sensors can restore basic vehicle functionality while awaiting professional repairs.
Conclusion
Repairing damaged resolver sensors in electric motors requires integrating fault symptoms, technical principles, and industry experience. Systematic diagnosis and preventive maintenance can significantly reduce failure rates, ensuring long-term stability of motor systems. For complex faults, prioritizing authorized service centers is recommended to avoid secondary damage from improper handling.