A novel Hexagonal Flux control method to improve constant switching performance of multilevel 3-phase DTC

Abstract

This paper presents the advantage of implementing a novel Hexagonal Flux Control Method to improve constant switching performance of multilevel 3-phase DTC scheme. The Direct Torque Control (DTC) scheme is well known to provide rapid decoupled control of torque and flux in motor control drive via a simple control structure. The utilization of 3-level CHMI in this DTC can minimize the output torque ripple by providing larger number of voltage vectors. However, DTC Scheme is known to have two major shortcomings, which are the irregular switching frequency of power switches and high torque output ripple. The usage of torque hysteresis controller plays a major role in cause of this problem. The implementation of PI based constant switching controller to replace the hysteresis controller able to solve these problems while remaining the simple DTC control structure. Conversely, there are presents of minor oscillation in the torque regulation of constant switching method in which contributed by the flux regulation factor. This paper presents about the Hexagonal Flux method implementation in-order to mitigate the flux regulation problem. The detail explanation and calculation of optimal PI parameter tuning strategy with the combination of Hexagonal Flux method have been discussed. In order to validate the feasibility, the proposed method has been compared with convention DTC system via simulation and experiment results.