Direct Torque Control Based On The The Dodecagon Flux Track The Study

As an effective AC regulating speed technology,Direct Torque Control(DTC)has many advantages,such as fast torque response,high stability and strong robustness.However,the torque ripple and current ripple of DTC based on hexagon flux linkage is too large at the status of operation. When the speed of the motors is low,especially close to zero,the detection of flux linkage and torque is seriously affected by the parameters of motors.All these defects affect the performance of DTC.In order to improve the current ripple and torque ripple,the controlling method based on dodecagon flux linkage is studied in this thesis.To sum up,the main content of this thesis is as follows:1.The base theory related by the controlling method based on dodecagon flux linkage is discussed.2.The controlling method based on dodecagon flux linkage is studied.The method to form dodecagon flux linkage locus,the self control of flux linkage,the computation of the amplitude flux linkage,the correct selection of voltage space vector and some other question are discussed.Meanwhile, the controlling method based on dodecagon flux linkage is compared with hexagon flux linkage.3.The digital design of the DTC system based on dodecagon flux locus is analyzed.4.The system is simulated with the SIMPOWER toolset of SIMULINK and the result of simulation is compared with that of hexagon flux linkage.The result of simulation demonstrates that the controlling method based on dodecagon flux linkage can improve the controlling precision of flux and torque,it can also reduce the torque ripple and current ripple.