DTC Principles in Multilevel and Multiphase Induction Motor Drives

Direct Torque Control (DTC) is considered particularly interesting for the absence of coordinate transformations, current regulators and PWM signal generators. In spite of its simplicity, DTC allows a good torque control in steady state and transient operating conditions to be obtained. However, the presence of hysteresis controllers for flux and torque leads to torque and current ripple. These drawbacks can be mitigated by using advanced control algorithms to select the voltage vectors of basic DTC schemes or increasing the number of available voltage vectors. DTC technique is well suited for exploiting the improved number of voltage vectors available with multilevel and multiphase converters. A discussion is carried out in order to emphasize the potentiality of DTC based induction motor drives fed by these new power converter topologies.