Generalized PWM algorithm for Direct Torque Controlled Induction Motor Drives using the only Sampled Voltages

This paper presents a simple generalized pulse width modulation (GPWM) algorithm for direct torque controlled induction motor drives. Though the classical direct torque control (DTC) algorithm gives fast dynamic response, it gives large steady state ripples and variable switching frequency operation of the inverter. To overcome these problems, space vector pulse width modulation (SVPWM) algorithm is used for DTC drives. But, as the SVPWM algorithm requires angle and sector information the complexity involved is more. Also, it gives more switching losses of the inverter. To reduce the complexity involved the proposed algorithm uses the instantaneous phase voltages only. Moreover, the proposed approach gives the realization of various carrier based PWM algorithms that include both SVPWM and various discontinuous PWM (DPWM) algorithms by using a generalized control algorithm and is obtained via unequal sharing of zero states. In the proposed approach, by varying a constant   k value from zero to one, various DPWM algorithms can be generated along with the SVPWM algorithm. To validate the proposed GPWM algorithm based DTC drive, several numerical simulation studies have been carried out and the results have been presented. The simulation results show the effectiveness of the proposed algorithm.