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Direct Vector Control For Induction Machines And Its Rotor Resistance Estimation

Posted on:2005-04-19Degree:MasterType:Thesis
Country:ChinaCandidate:B HuangFull Text:PDF
GTID:2132360152468021Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
By decoupling between the magnetizing current and the torque current, the vector control strategy of induction machines can achieve excellent dynamic performances. However, the estimation of the rotor resistance has always been one of the key problems for the high-performance induction machine drive. Many scholars have investigated this problem and brought forth so many methods to solve it. The development situation of rotor resistance estimation is summarized in this paper. A full digital induction motor drive system based on direct vector control is developed. Flux and speed closed loops are used. The current model flux estimator is adopted to calculate the rotor flux. The frame of system and the control circuit are designed. TMS320F240 digital signal processor that is selected as the main CPU in the system realizes the full digital vector control system. Based on the speed and current detected, the estimation of rotor flux's magnitude and angle can be accomplished. By regulating the speed, flux and current, the optimal voltage vectors can be obtained. And then through the SVPWM algorithm, the desired stator voltages are exerted to the induction machine. The software of the control system is compiled with assembly language. To compensate the error of rotor resistance, a novel rotor resistance estimation method based on the instantaneous reactive power (IRP) model MRAS is proposed. This method uses the IRP calculated from the stator voltage equations in the static reference frame as the reference model, uses the IRP calculated from the rotor voltage equations in the synchronous reference frame as the adjustable model, and regulates the error between these two models to get the suitable rotor resistance value. The principle of this method with an illustrating graph is introduced in detail, and the adaptation mechanism has been studied in this paper. Some simulations have been made and the results show that this method is valid. To improve the estimation speed of this method under the condition of low load torque, a modified method is provided, the simulations prove that this modified estimation method is effective and its robustness has been enhanced.With the 4kW drive system prototype developed in the lab, some experiments have been done. The experimental results prove that the estimation strategy and its modified one are feasible and the algorithm has good steady and dynamic performances. In the end, the problems left in the system are analyzed, and the advice for farther improvement is raised.
Keywords/Search Tags:direct field-oriented vector control, rotor resistance estimation, model reference adaptive system (MRAS), instantaneous reactive power
PDF Full Text Request
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