When a frequency converter drives a motor, vibration issues typically stem from three core categories: parameter mismatch, wiring/hardware problems, and load/mechanical issues. It is a common operational abnormality in variable frequency speed regulation systems.
1. Mismatched Parameter Settings (Most Common Cause)
- Incorrect input of motor parameters (e.g., rated voltage, frequency, pole count, stator resistance) that do not match the actual motor specifications, leading to deviations in the frequency converter’s control algorithm.
- In vector control mode, inadequate or incomplete motor self-learning fails to accurately identify the motor’s inherent characteristics, resulting in imprecise magnetic field orientation.
- An excessively low carrier frequency (typically recommended to be 2–10 kHz) causes high harmonic interference during low-frequency operation, triggering motor vibration.
2. Wiring and Hardware Issues
- Loose connections or poor contact on the frequency converter’s output side, or cables that are overly long or undersized, leading to three-phase voltage imbalance.
- Damaged IGBT modules, aging filter capacitors in the frequency converter, or inter-turn short circuits in the motor windings/bearing wear, which cause abnormal vibration during operation.
- Poor grounding allows harmonic interference to destabilize the motor’s magnetic field—an issue particularly noticeable during high-frequency speed regulation.
3. Load and Mechanical Transmission Issues
- Excessive misalignment between the motor and its load (e.g., pumps, fans, reducers) or loose/damaged couplings, resulting in mechanical impact-induced vibration.
- Load jamming, stalling, or frequent load fluctuations that the frequency converter cannot respond to in a timely manner, causing speed instability and vibration.
- Insufficiently secured motor bases, where the resonance frequency coincides with the operating frequency, amplifying vibration amplitude.
4. Operating Mode and Frequency Range Issues
- Motor operation in the low-frequency range (typically below 5 Hz) leads to insufficient torque and high harmonic content, easily causing “crawling vibration.”
- Failure to enable torque compensation or slip compensation functions results in unstable output torque during low-frequency operation, leading to vibration.