Continuous DTC of the Induction Motor

In the case of the classical direct torque control (DTC) of the induction motor, the minimum switching period of the inverter is equal with the sampling period of the control system. Due to this intrinsic characteristic, competitive real time control can be achieved only by using high performance control systems. If moderate performances system is used, the behavior of the drive is unsatisfactory, even inacceptable. The paper proposes continuous variants of the DTC, obtained by replacing the discrete controllers specific to the classical DTC with two or three continuous controllers, one of them being the speed controller. Thus, the sampling period of the control system is decoupled by the switching period of the inverter and a moderate performance real time control system can be used.