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Research and Realization of Strategies in Asynchronism Motor Direct Torque Control Based on DSP

Author: WuDeXiang
Tutor: ZhangAiLing
School: Taiyuan University of Technology
Course: Motor and electrical
Keywords: Flux priority u-n model Start Weak magnetic SVM-DTC
CLC: TM343
Type: Master's thesis
Year: 2010
Downloads: 86
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Abstract

Relative to the vector control strategies, Direct Torque Control system of induction motor structure concise, fast torque response, and thus subject to the general concern, and has been developing rapidly. The in-depth study of asynchronous motor torque ripple of direct torque control system, the flux observer starting methods, weak magnetic speed. Pulsating larger problem for based on the low-speed the switch direct torque control system (ST-DTC), at home and abroad to carry out a large number of studies, one of the ways is to reduce the torque ripple torque prediction (TP-DTC); method using space vector modulation method instead of the switch table, the study results show that the method to overcome the above disadvantages. In this paper, a space vector modulation method, based on direct torque control torque and stator flux error to establish a dual linear equation solution should be applied to the reference voltage vector, and then use the space vector pulse width The modulation method of synthesis of the vector, this method is called SVM-DTC. The experimental results show that the TP-DTC can reduce low speed torque ripple, SVM-DTC torque ripple at full speed range can be reduced to improve steady-state performance and dynamic performance, improve current and flux waveform to reduce the noise when the motor is running and vibration. Flux observer model in-depth study, in particular, the the two un model is able to run at full speed range studied flux model selected state variables and discrete methods for solving equations problem and should pay attention to the programming discretization methods and discretization step analysis of the experimental results show that the model can more accurately un flux observer to achieve the full speed range. Flux priority and ramp function two starting methods, experimental results show that the flux priority method can not only improve starting performance can also reduce the steady state flux and torque ripple; the ramp function method can limit the starting current and speed control, reversing, parking the same work. Weakening control principle is described, developed two weakening control program. The simulation results show that the two programs can be the governor of the field-weakening range, including open-loop to the titration programming to achieve relatively simple and effective, and only need to find a given value depending on the speed of the flux corresponding to a given value; closed-loop Tuning Method not only be on the basis of the original program with the PI regulator such procedures, and the need to adjust the parameters of the PI regulator. In this paper, based on simulation studies on the DSP chip TMS320LF2407A AC motor control core experimental platform direct torque control strategy compared with the ST-DTC, TP-DTC, SVM-DTC three kinds of control. Experimental results show that the SVM-DTC than the other two can be effective to reduce the torque ripple, to improve the current and flux waveforms.

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