Robust Direct Torque Control with Super-Twisting Sliding Mode Control for an Induction Motor Drive

A field-programmable gate array- (FPGA-) based nonlinear Direct Torque Control (DTC) associated with Space Vector Modulation (SVM), Input-Output Feedback Linearization (IOFL), and second-order super-twisting speed controller is proposed to control an induction motor drive. First, the nonlinear IOFL is proposed to achieve a decoupled flux and torque control and the SVM technique is used to control the inverter switching frequency which reduces the torque ripples and noise. Next, to enhance the speed regulation, a super-twisting speed controller is added to an SVM-DTC-IOFL scheme. The nonlinear SVM-DTC-IOFL ensures a high dynamic response, good robustness under the external load disturbances. The Lyapunov theory is used to analyze the system stability. Then, this paper presents the interest of implementing the suggested SVM-DTC-IOFL using a Field-Programmable Gate Array (FPGA) circuit. The main interest of the FPGA-implementation is the reduction of the control loop delay, which is evaluated to a few microseconds, thanks to the parallel processing offered by the FPGA. The performances of the proposed control algorithm are investigated by digital simulation using the Xilinx system generator tool and an experimental implementation utilizing an FPGA-Virtex-5-ML507.