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In this paper a new Space Vector Pulse Width Modulation (SVPWM) algorithm is proposed for multilevel voltage source inverters. The proposed algorithm directly identifies the two-level subhexagon in which the reference voltage vector lies. The switching sequence corresponding to a two-level inverter is determined. The proposed method can be extended to any m-level inverter and a generalized algorithm is proposed. Based on the mathematical model presented, a "five-level inverter, induction motor" system is investigated in steady state and transient responses. The induction motor is controlled using Field Oriented Control (F.O.C.). The improvement of the control scheme is achieved using Mamdani's fuzzy logic controller for both rotor speed and inverter current. The electric drive system is simulated in case of a five-level inverter and the presented results verify the good performance of the proposed SVPWM algorithm. [ABSTRACT FROM AUTHOR]

In this article, the control technique of an AC variable-speed drive is presented using a modified direct torque control method. The AC motor of the drive is an induction motor, and the modified scheme of the direct torque control uses the space vector modulation technique to create the switching pattern of the inverter. The steady state of operation is investigated in depth as well as the dynamic performance of the system. The results of this modified control scheme are compared to the corresponding results of the classical direct torque control method, leading to the conclusion that the modified scheme is more robust and smoother in comparison to the classical one. [ABSTRACT FROM AUTHOR]