Comparative Performance Assessment of Hysteresis and Constant Switching Frequency DTC over AC Machines

AC machines and drives are widely used in industrial applications. This prioritizes that AC drives operates with high efficiency and high performance in general. In this respect, one of the hottest topics in the literature is Direct Torque Control (DTC) since it is inherently mechanical sensorless, strong robust, driving method. Furthermore, it is a generic method applicable different type of machines such as permanent magnet and the new synchronous reluctance motors. DTC is classified as Hysteresis based DTC (HDTC), and Space Vector Pulse Width Modulation based DTC (SVPWM-DTC) which is also called as constant switching frequency DTC. In this study, Induction Motor (IM), Interior Permanent Magnet Synchronous Motor (IPMSM), Surface Mounted Permanent Magnet Synchronous Motor (SPMSM), and Synchronous Reluctance Motor (SynRM) are driven by HDTC and SVPWM-DTC, and results are compared to each other in terms of performance indexes. Consequently, it is concluded that the flux and torque ripples become lower with SVPWM-DTC. However, it is inferred that greatly increasing torque response and robustness against external disturbances are obtained by HDTC.