A new simplified sensorless direct stator field-oriented control of induction motor drives

A field-orientation scheme is a typical control technique of induction motors to obtain sophisticated performance. The stator field-oriented control is less sensitive to parameter variations than the rotor field-oriented control. In addition, the estimation of the stator flux is more accurate than that of the rotor flux. Therefore, the stator flux system is considered a good choice for variable speed drives. However, the traditional configuration of the system includes four PI controllers which need effort in tuning. In this article, simple calculations are proposed such that the configuration and performance of the stator field-oriented control systems are improved by including only two PI controllers. In addition, with the aid of the machine phase axes, a simple procedure for the speed estimation target is suggested to effectively estimate the rotor speed of the machine with a direct estimation without any need for a PI controller or additional observers in the speed observer procedure. The obtained results confirm the effectiveness of the proposed control scheme.