New aspects of a direct torque controlled induction motor drive

The Direct Torque Control (DTC) Is a competitive alternative of the Field Oriented Control nowadays in practical applications. By DTC the flux and the torque of the induction machine can be controlled directly. This paper presents a simulation working under the DTC concept, but for practical implementation some new aspects should be investigated: 1. The current is controlled indirectly, requiring the implementation of the current limitation mainly during starting operation; 2. The low speed operation is a special case of this drive. The possible unstable operating should be avoided; 3. The dynamic limits of the power switches must be considered. It contains the switching frequency, the minimal pulse width and the dead-time of the switches in the same inverter lag. The simulation and experimental results are given.