3. Conclusion

Depending on the type of application, drive power, speed range, etc., the most appropriate control mode for the asynchronous machine will not be the same. Even a brief presentation of these controls shows the advantages and disadvantages of each, and how they complement each other. Many studies have focused on :

• the robustness of these commands as a function of parametric variations;

• performance without a speed sensor, even in the very low-speed, high-torque range;

• the various deterministic and stochastic, linear and extended observers that can be used to estimate flow, velocity and possibly load torque.

Today's drives are very efficient, but there are still a number of problems that have not been satisfactorily resolved: