Direct Torque Versus Predictive Control of the Induction Motor

The direct torque control (DTC) is the preferred control technique of the induction motor in electric traction applications. It has advantages, as it is a sensorless control technique, but also disadvantages. The main disadvantage is related to the switching frequency which is the same with the sampling frequency of the entire control loop. This determines high requirements for the control system which must be quite performant. The control is simulated and the results are compared with the ones obtained when the predictive concepts are used for obtaining the pulse width modulation strategy of a voltage fed inverter which supplies an induction motor, as the both determine, during each sampling period, the next stator voltage phasor, but considering different criteria. The reference values of the currents are obtained from a classical rotor flux vector control scheme. The described technique is similar with the preset currents (bang-bang) pulse width modulation technique, but it has the advantage of fixed switching frequency