A new approach to DTC-ISVM for induction motor drive system fed by indirect matrix converter

In this paper a high performance Direct Torque Control (DTC) theme for the induction motor fed by indirect matrix converter is proposed and investigated. Since the indirect matrix converter has an intermediate dc link, the control process can be separated into rectifier stage modulation and inverter stage modulation. Indirect space vector modulation (ISVM) for input current is applied on the rectifier bridge, while the inverter and motor can be seen as constant current load in DC link and ISVM for output voltage is applied on the inverter bridge. The modulation processes of rectifier stage and inverter stage are considered simultaneously. This paper investigates the use of four-step commutation strategy in rectifier bridge of indirect matrix converters to reduce problem of snubber circuit in the rectifier stage. By suitably selecting switching pattern, the electromagnetic torque ripple of the motor is effectively reduced. The simulation results of DTC system based on IMC and the comparison of motor performance under the proposed control system with respect to those obtained under conventional DTC confirm its effectiveness and accuracy.