The direct torque method performs very well even without speed sensors. However, the flux estimation is usually based on the integration of the motor phase voltages. Due to the inevitable errors in the voltage measurement and stator resistance estimate the integrals tend to become erroneous at low speed.
The direct torque method can operate effectively without relying on speed sensors, but its flux estimation is reliant on the integration of motor phase voltages. This process becomes unreliable at low speeds due to errors in voltage measurement and stator resistance estimation.