Direct Torque Control with Variable Level Discretization for Automotive Drives

Abstract:
This paper presents a direct torque control (DTC) scheme for induction machines fed by a modular multilevel converter (MMC). Section-wise defined functions are used to implement a variable spacevector selection depending on the number of used modules. In contrast to existing methods which are typically designed for a predefined number of levels with specific amplitudes, the proposed method offers a scalable control scheme which adapts to the number of available and/or active modules during operation. Thus the advantages of DTC, such as fast step response, are combined with the advantages of MMCs, such as small voltage steps and variable level discretization.