dEv Speed Deviation fault in delta drive

dEv Speed Deviation fault in delta drive troubleshooting

Description

dEv is a closed-loop fault. When using an encoder (PG Card), the drive compares the "Commanded Speed" (what it asked the motor to do) vs. the "Actual Speed" (what the encoder says happened). If the difference between these two exceeds the deviation threshold parameter for a set time, dEv triggers.

Causes

1. Coupling Slip: The motor is turning, but the coupling connecting the encoder to the shaft is loose, so the encoder reports 0 RPM.
2. Torque Limit: The drive is hitting its torque limit (current limit) and cannot spin the motor fast enough to satisfy the speed command.
3. P-Gain Too Low: The PID speed loop gain is too weak, causing the motor to lag behind the command during acceleration.
4. Brake Drag: The mechanical brake did not release, physically holding the motor back.

Solution

Tune the loop:
1. Check Mechanics: Verify the encoder coupling is tight and the mechanical brake is releasing fully.
2. Increase Torque: If the load is heavy, increase the Torque Limit settings.
3. Tune ASR: Adjust the ASR (Automatic Speed Regulation) P and I gains. Increasing the P-gain (Proportional) helps the motor track the command more aggressively.
4. Widen Tolerance: If the application allows, increase the "Speed Deviation Detection Level" (Parameter 10-xx) to prevent nuisance tripping.