How does the Altivar 71 (ATV71) manage to give good torque at low speeds when running in Sensorless Vector Control, and what basic settings should I adjust to get the best performance in heavy-duty applications? Please give me some tips.
The ATV71 uses a real-time motor model to estimate rotor flux and torque without needing an encoder. It constantly measures motor current and voltage, then adjusts torque-producing and flux-producing current separately. This lets the drive hold torque even at very low speeds.
To get the best performance, make sure you:
- Enter exact motor nameplate data (voltage, current, speed, PF).
- Run auto-tuning — rotational auto-tune gives better low-speed torque.
- Adjust torque boost if the motor struggles to start under load.
- Fine-tune slip or IR compensation if speed drops during heavy load.
- Set switching frequency higher if you need smoother low-speed operation (watch drive temperature).
These basic adjustments typically bring the ATV71 to its best low-speed torque performance in most heavy-duty applications.
1 Like