Comparative Study of Direct Torque Control in Four Switch and Six Switch Three Phase Inverter

The present paper investigates the performance of four switch three phase inverter (FSTPI) and six switch three phase inverter (SSTPI) fed induction motor drive. Direct torque control of induction motor drives are done mainly using six switch three phase inverter. In low power applications, six switch three phase inverter can be replaced by four switch three phase inverter. FSTPI helps reduction in switching losses, gate drive requirements, circuit cost and computational time. Four unbalanced voltage vector produced by this four switch inverter is used for synthesis of six balanced voltage vectors having same magnitude as that of six switch three phase inverter by using a suitable lookup table. A comparative simulation study is done between four switch three phase inverter and six switch three phase inverter fed induction motor drives and verified using MATLAB/SIMULINK.