Study Of The Novel Arithmetic Of The Speed Sensor-Less Control System For Freqency Modulation Based On DSP

Based on the TI Company's TMS320F240 DSP, this paper designs a novel speed-sensorless system for frequency modulation with a new method of speed estimation.Speed sensor has the limitation of high cost, taking up more space, low reliability and high dependency of working condition. Speed--sensorless frequency modulation system avoids those defects and can meet the need of high performance of AC motor driving which is a stress field. However, the current method of estimating and controlling speed has one or more of these serious disadvantage: complicate structure, difficulty to realize or high dependency of the parameter of motor which will result in the inaccuracy if the motor runs for a long time. In order to solve those questions, the author brings forward a novel method of speed estimation with the aid of Lin Zhongyue professor.Based on analyzing the math model and running character of motor, this paper educes a method of estimating the real torque of motor by a way of energy conversion. By measuring the stator's current, voltage and the power factor of the motor, we can calculate the input power of the motor, and then we can get the electromagnetism power and the real electromagnetism torque. Comparing the real electromagnetism torque and the ideal electromagnetism torque, we can find the trend of the speed variation, and then we can control the motor properly. This method is simple and facile, moreover, it dose not depend the motor parameter badly.Following analyzing the theoretics, the author workouts the control programme using the assembly language and realizes the speed-sensorless frequency modulation system base on F240.This system controls a 1.1 KW asynchronous motor. The result of the experiment verifies the system's validity and practicability.