Direct Torque Compound Control of Induction Motors to Increase the Battery Operating Life in Electric Vehicles

The widespread utilization of induction motors as a driving force of electric vehicles has recognized the necessity for upgrading control system of these motors even more than ever before, in order to improve efficiency and reduce the torque ripple. This matter can lead to increase in the distance traveled by the electric vehicle at each charge and ultimately Increase the battery life. To this end, a predictive direct torque control method, as well as an optimal direct torque control method, was proposed. In the predictive direct torque control method, the reference voltage vector based on the predictive control is determined so that both the torque value and the charge value are equal to the reference values as quickly as possible. The optimal direct torque control method is also based on calculating the optimal stator reference flux according to the load torque. For comparison and evaluating the performance of controllers optimal direct torque control method and predictive direct torque control method along with the conventional direct torque control method, are simulated on an induction motor. Simulation results demonstrate that optimal direct torque control method in no-load mode and predictive direct torque control method when applying load have the highest efficiency, lowest current amplitude and torque ripple. Therefore in this paper, direct torque compound control method is presented. This method it uses optimal direct torque control in no-load and predictive direct torque control when applying load. This method has the best performance to increase battery life in electric vehicles.