A New Predictive Direct Torque Control Method for Improving Both Steady-State and Transient-State Operations of the PMSM

In this paper, a new predictive direct torque control (DTC) method is proposed, improving the dynamic response of the classical DTC and reducing the torque- and flux-ripples through a voltage vector with an optimal phase. In the transient state, the voltage vector phase is selected in a manner where the fastest dynamic response is achieved, while in the steady state, this phase is selected in a manner where the stator flux amplitude reaches its commanding value at the end of the control cycle. In the steady state, the selected vector is applied to the motor with an optimal time duration calculated to achieve the minimum torque ripple. The five-segment space-vector modulation is used to synthesize the voltage vector, where a fixed switching frequency is obtained. To investigate the effectiveness of the proposed method, steady-state and transient-state performances are tested in the MATLAB software and in practice. Both the simulation and experimental results confirm that the proposed method reduces the torque and flux ripples effectively while improving the dynamic response of the classical DTC method. The comparative investigation of the proposed method with the recent DTC methods indicates that the proposed method has lower ripples in the steady state and a faster dynamic response in the transient state.