Study Of Digital Asynchronous Machine Contirol System With A Direct Torque Control Using TMS320F240

Direct torque control (DTC) is an novel control method technique which is quite different from field-oriented control , which allows the precise and quick control of the flux linkage and torque without calling for complex control algorithms. In principle, moreover, DTC requires only the knowledge of the stator resistance. The paper starts by reviewing the basic math model of an asynchronous machine and of a PWM inverter using the space vector theory. Then the concept of DTC is illustrated and The DTC-based strategies, The Switching -Table strategy is dealt with in depth, illustrating by means of the flux linkage and torque responses generated with different choices of the switching table . Furthermore, an improved stator flux linkage regulator and torque regulator is presented which allows to keep the system under control even at low speed.A simulation system is developed using MATLAB/SINMULINKsoftware package for the purpose of validating asynchronous machine control system with a direct torque control(DTC). In the paper, parts of the simulation system are introduced, including the simulation modeling of sector seclecting, switching table, torque regulator and flux linkage regulator etc. Last, the results were simulated indicated a better performance at low speed,small torque ripple and flux ripples and quick dynamic performance etc. .Those demonstrate the effectiveness of the developed simulation system.The digital signal processor(DSP) makes possible implementation of DTC. The high processing speed of DSP allows sophisticated control techniques to be used to build a high-precision control system.This paper presents an implementation of digital asynchronous machine control system with a DTC using 16 bit fixed point digital signal processor(DSP) TMS320F240. During implementating the control system, perform primarily following works: (l)studying deeply the PWM generative mechanism, give an a new generative method; (2)Performing floating-point operation on the fixed-point DSP; (3)a complete set of control algorithm introduce PU(per unit), and enhance accuracy of operation; (4)carrying out the integrals and PI regulator by discretization operation. The Experiment results are shown at low-speed range using2.2KW general purposed asynchronous machine: the DTC system has great loading capacity and antijamming capability, torque and speed have high dynamic response ,and currents have less harmonic waves and so on. Those verity the feasibility of the improved stator flux linkage regulator and torque regulator,which is worth in engineering application.