A new switching technique for Direct Torque Control of Induction Motor using Four-Switch Three-Phase Inverter with DC - link voltage imbalance

This paper presents a new switching technique for direct torque control of induction motor using four-switch three phase inverter (DTC-FSTPI-IM) for low power applications with DC - link voltage imbalance. The new control algorithm and modified switching table are based using a real-time compensation SVPWM technique when generating switching control signal in consideration of unbalanced DC-link voltages by direct calculation of switching times based on four basic space vectors in FSTPI. By using reasonable mathematical transform, direct torque control technique for FSTPI under DC-link voltage imbalance have been solved, which is based on the establishment of basic space vectors and modulation technique in similarity with six-switch three-phase inverters. This approach has a very important sense to solve hard problems for FSTPI under DC-link voltage imbalance. The validity of new proposed technique is verified by simulation and experimental results using Matlab/Simulink and DSpace 1104.