The Application Research Of Synthetical Technique In DTC System

The direct torque control (DTC) system has the excellent dynamic and static performance, as the electromagnetic torque is controlled directly in the IM (induction motor) speed adjusting system; while the digital signal processor (DSP) can provides stable hardware foundation for advanced controlling methods, so this paper is about the whole digital DTC experiment with TMS320LF2407A of TI Company as center processor.In the DTC, the electromagnetic torque and flux are calculated and controlled in the stator coordinate, and the optimal pulse width modulation gating signals are generated to control the inverter according to the output of the dispersing regulator. The DTC technology is a high-performance speed adjusting method with fast torque response, while there are some question, such as flux drift and torque ripple. The problem is that the traditional DTC has only 6 discrete space vectors to choose, which results in the torque increases or decreases rapidly, the torque ripple beyond the regenerative error, and vibration and noise of motor come out.So, based on the research on the traditional DTC system, the space vector pulse width modulation (SVPWM) technique combined with subdividing voltage space-vector and DTC is adopted. The torque three-point regulator is also used in the system. By these controls, the flux trace is approximate circle, the flux and torque ripple is decreased and the performance of system is improved.The paper introduces the realization of the digital DTC based on SVPWM and subdividing voltage space-vector in the TMS320LF2407A DSK platform with the IM as the control target, including the controlling construction, function of every module and mix programming of C and assemble language. The software of the system is developed through embedding assemble language in C program, which makes the software easy to read and transplantable. The experimental results indicate that the flux and torque ripple is decreased efficiently; the system has stable performance and practicability.