Comparative evaluation of direct torque control strategies for permanent magnet synchronous machines

This paper presents a detailed comparative evaluation of several direct torque control (DTC) strategies for permanent magnet synchronous machines (PMSMs), namely basic DTC, model predictive DTC (MPDTC) and DTC with duty ratio modulation (DTC-duty). Moreover, field orient control (FOC) is also included in this study. The aforementioned control strategies are reviewed and their performances are analyzed and compared. The comparison is carried out through simulation of a 60 kW PMSM fed by a two-level voltage source inverter (VSI). With the intent to fully reveal advantages and disadvantages of each control strategy, critical evaluation has been conducted on the basis of several criteria: torque and stator flux ripple, inverter switching frequency, machine parameter sensitivity, computational complexity and stator current total harmonic distortion (THD). The choice of control scheme can be determined based on specific requirements of particular application under consideration.