Speed sensorless DTC control of the induction motor using FPGA implementation

摘要

Purpose - The purpose of this paper is to present a fixed-point implementation of a complete directrntorque control (DTC) algorithm connected with a rotor speed estimation algorithm for the inductionrnmotor drive, using field-programmable gate array (FPGA).rnDesign/methodology/approach - The parallel processing approach is described, which requires arndecomposition of the control and estimation algorithms for the converter-fed induction motor tornseveral tasks, realised in parallel. The advanced data processing techniques are described, likernPIPELINE technique for data streams design, coordinate rotation digital computer algorithm forrntransformation of stator flux vector components from Cartesian to polar coordinates. Moreover, thernmethod for the qualitative analysis of the full-order state observer's sensitivity to the variations of therninduction motor equivalent circuit parameters is presented.rnFindings - It is shown that the developed FPGA-based DTC structure enables designing an efficientrnapplication for the induction motor control. Owing to the high-processing frequency, the digitalrnFPGA-based DTC application is similar in its features to the analogue realisation based on therncomparators. Yet all the advantages of the digital structure, i.e. high flexibility, parameterizationrncapability, etc. remain unchanged. Furthermore, FPGA is hardware realisation of a digital datarnprocessing algorithm; hence the reliability of the control system is improved.rnResearch limitations/implications - The investigations are performed in the developingrnprototype setup, based on PXI-1042 Industrial PC equipped with Xilinx Virtex-II FPGA matrix,rnprogrammed with Lab VIEW.rnPractical implications - The experimental tests of the FPGA-based implementation of the wholerncontrol structure of the sensorless DTC drive system are demonstrated. It is also shown, that thernfull-order state observer with the speed adaptation loop is significantly sensitive to motor parameterrnvariations in the low-speed region, which must be taken into account while designing the adaptationrnalgorithm for speed estimation in real application.rnOriginality/value - The paper's value lies in the overall, FPGA-based design of the speed sensorlessrnDTC structure for the induction motor including motor speed, torque and stator flux control loops, statorrnflux and rotor speed estimation.