Modeling and Hardware Implementation on the FPGA of a Variable Structure Control Associated with a DTC-SVM of an Induction Motor

Abstract

The conventional Direct Torque Control (DTC) is considered as a powerful approach which is widely used to control induction motors. However, this control approach suffers from several problems like undesirable torque and flux ripples and stator resistance variations, especially at low speed. To overcome these problems, a Variable Structure Control associated with a DTC based on Space Vector Modulation (VSC-DTC-SVM) is proposed in this paper to reduce ripples and enhance the system robustness. Due to the complex scheme of the suggested VSC-DTC-SVM approach, its implementation on software solutions such as microcontrollers and digital signal processors requires a high sampling period. In fact, this period creates delay in applying the inverter switching states which results undesirable ripples and distortions in the torque and the stator current, respectively. This delay is inevitable, and thus the VSC-DTC-SVM performances are affected and the sampling frequency is limited. These limitations in digital control are mainly caused by the calculation speed which depends on the complexity of the algorithm and the serial processing of the software solutions. To cope with this problem, a programmable digital circuit such as the FPGA is chosen to preserve the performances of the VSC-DTC-SVM in spite of its complexity, thanks to its parallel processing. To illustrate this, a hardware implementation of the VSC-DTC-SVM of an induction motor on the FPGA is presented and analyzed. The VSC-DTC-SVM performances in terms of ripples, under stator resistance variation, are presented by a theoretical study, a digital simulation and a hardware co-simulation using an FPGA Virtex 5.

Keywords::

• direct torque control
• space vector modulation
• variable structure control
• Xilinx system generator
• FPGA

Additional information

Notes on contributors

Saber Krim

Saber Krim received his degree in electrical engineering from National School of Engineering of Monastir, Tunisia, in 2011. In 2013, he received his M.S degree in electrical engineering from Monastir University, Tunisia. He is currently pursuing his Ph.D. degree with the University of Monastir, Tunisia. His current research interests include rapid prototyping and reconfigurable architecture for real-time control applications of electrical system.

Soufien Gdaim

Soufien Gdaim received his degree in electrical engineering from National School of Engineering of Sfax, Tunisia, in 1998. In 2007, he received his M.S degree in electronic and real-time informatics from Sousse University and received his PhD degree in electrical engineering in 2013 from ENIM, Tunisia. His current research interests include rapid prototyping and reconfigurable architecture for real-time control applications of electrical system.

Abdellatif Mtibaa

Abdellatif Mtibaa is currently a professor in Micro-Electronics and Hardware Design with Electrical Department at the National School of Engineering of Monastir and Head of Circuits Systems Reconfigurable ENIM-Group at Electronic and Microelectronic Laboratory. He holds a diploma in electrical engineering in 1985 and received his PhD degree in electrical engineering in 2000. He has authored/coauthored over 150 papers in international journals and conferences. He served on the technical program committees for several international conferences. He also served as a co-organizer of several international conferences. His current research interests include system on programmable chip, high level synthesis, rapid prototyping and reconfigurable architecture for real-time multimedia applications.

Mohamed Faouzi Mimouni

Mohamed Faouzi Mimouni received his Mastery of Science and DEA from ENSET, Tunisia, in 1984 and 1986, respectively. In 1997, he obtained his doctorate degree in electrical engineering from ENSET, Tunisia. He is currently a full professor of electrical engineering with Electrical Department at the National School of Engineering of Monastir. He has authored/coauthored over 100 papers in international journals and conferences. He served on the technical program committees for several international conferences. His specific research interests include the area of power electronics, motor drives, solar and wind power generation.