Modelling and Implementation of Space Vector Modulation Based Direct Torque Control in Stator Flux Reference Frame for Induction Motor Drive

The paper presents modelling of space vector modulation based direct torque control (SV -DTC) in stator flux reference frame for induction motor drive (IMD). In conventional DTC of IMD, usually hysteresis controllers are employed to select the appropriate voltage vector. Hence, this results in current, flux, torque and speed ripples. While, the SV-DTC in stator flux reference frame employs the space vector modulation (SVM) by which the current, flux, torque and speed ripples are minimized. The minimization of ripples can be attributed to selection of reference voltage vector by SV -DTC is appropriate during the operation of IMD. In addition, the paper also highlights the advantage of stator flux reference frame over stationary reference frame for IMD operation. The advantage of stator flux reference frame is the flux and torque of IMD are controlled individually as they can be decoupled. The decoupling of the flux and torque also helps in proper PI tuning of controllers and to get proper machine control. All the above, the controller computational complexity is less as they are independent of the rotor parameter. To analyze different operating conditions of IMD, MATLAB/Simulink simulation-based modelling of SV -DTC in stator flux reference frame is presented in the paper. The paper also gives a comparative study that gives flexibility to analyze the machines with conventional DTC and SV-DTC in stator flux and stationary reference frames.