| In the field of AC machines control, a strategy called variable frequency control is mostly used. The direct torque control theory is a kind of new control method after vector control theory in AC control field. It calculates and controls the torque and the flux of AC electromotor in stator coordinate using the voltage space vector. Adopting the stator magnetism field direction method, it recurs to discrete Pang-pang control producing Pulse Width Modulation signal and controls the switch state of the transductor when better quality steady-state performance is produced. Because complicated vector transformation and asynchronous motor model simplified is ellipsised, the merits of DTC lie in the rapid dynamic response, simplicity of the control structure, easy implementation.In this paper, considered the developing actuality that more theoretical research but less systematic realization lies in the field of direct torque control system, we put the emphasis on the basic realization, and design a set of integrate system including software and hardware, which can realize direct control theory.Starting at the asynchronous motor model, according to the traditional theory of DTC and the principle of variable frequency control, we analyze the approximate round flux theory of DTC in the experiment. Using method of voltage vector selection, we can select the proper voltage vector by the position and magnitude of stator flux as well as the magnitude of torque.Because direct torque control requires very high performance of Real-time, the popular microcomputer core DSP is used as controller in the design of hardware. Its high speed of running is suitable for the experiment. In the main circuit, there is a highly integrated power element: IPM as inverter, which includes seven IGBT, has high switch frequency and fault diagnosis function. IPM greatly decreases the bulk of system. The system software is implemented by assemble language under the CCS environment.
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