Study on None Speed Sensor Direct Torque Control
System Based On DSP
Abstract:Namely along with the rapid development of power electronics technology,computer technology and automatic control technology,the electric transmission technology is being faced with a history revolution,it has become development trend that AC transferring speed replaces direct current speed and computer digital control technology replaces the simulating control technology . Frequency conversion is generally acknowledged by the home and abroad that it has a great future with excellent speed ,extensive scope of application and other many merits. Based on an overall review of related papers published at home and abroad, this dissertation is devoted to the control strategies and implementation of the fully digital AC motor drive system, including the design of control system hardware and software and intelligent control.
In this thesis, none speed sensor DTC system is studied, which based on DSP of TI inc.-TMS320F2407. Fundamental principle and implementation method of DTC are introduced in detail in this paper. In DTC system, the concept of space vector is introduced to analyze and control the AC motor, the electromagnetic torque and flux are calculated and controlled in the stator reference frame, and the optimal PWM gating signals are generated to control the inverter according to the output of the Bang-Bang regulator In this paper the DTC system is designed based on DSP.A speed estimation method is derived detail and the no a speed close-loop control is conducted. In this system, there are some problems, such as flux drift and torque ripple. To resolve these problem, a modified flux calculation method and some measures such as speed LPF, torque slide filtering are adopted. The system performance is enhanced by these method.
The system control software is designed in assemble language based on the hardware fundament with using TMS320F2407 as core and no a speed sensor DTC algorithm is realized. The experimental results indicate that the design of this system is successful. The system has stable performance with fast response, so to some extent it is a practical useful system.
Key Words:direct torque control; none- speed- sensor;digital signal processor;
speed estimate