FPGA implementation of the direct torque control with constant switching frequency of induction motor

Abstract

The aim of this paper is to present a digital implementation of the direct torque control (DTC) of an induction motor with a constant switching frequency using the field programmable gate array (FPGA) component. The FPGA is used in order to overcome the digital Signal Processing And Control Engineering (dSPACE) limitations such as the sequential processing which increase the sampling time. The Conventional Direct Torque Control (CDTC) presents some disadvantages, such as the torque and stator flux ripples, and stator current distortions due to the variable commutation frequency of the inverter. To overcome the conventional DTC limitations the switching frequency is imposed by using space vector modulation (SVM). The hardware implementation is proposed to take advantages of the FPGA in digital control field of electrical machines in real time, such as the reduction of the execution time by adopting a parallel processing, the possibility of implementing more complex and more efficient algorithms by exploiting the parallel computing. The performances of the direct torque control with space vector modulation are evaluated by digital simulation using the toolbox Xilinx System Generator (XSG) and implementation results on the FPGA. It has been found that the proposed control yields high performances in term of ripples and execution time.