A Parameter Identification Method of Inverter-Fed Induction Motor for Direct Vector Control

Abstract

ABSTRACT A Parameter Identification Method of Inverter-Fed Induction Motor for Direct Vector Control

In industry, range of use of the induction motor that vector control algorithm is used has gradually been expanding in area that high performance is requested. The research objective of torque control of the induction motor that vector control is applied is to realize that torque can be accurately controlled in actual operation condition. For this reason, parameter values of the motor must be accurately estimated. These parameter values can be identified from the nameplate attached on the motor or the datasheet offered from the company. Also, to obtain the parameter values of the induction motor, traditional methods can be used such as no – load and rotor locked tests. But there are many differences between values obtained from the traditional tests and actual values. And there are drawbacks that additional equipment and cost are required for the experiment. So, parameter estimation methods that do not need separate measuring devices or sensors have been studied. Among them, many studies about the estimation method using the PWM inverter used for drive control have been conducted. To implement this estimation method, we need to understand the control system of the motor and analyze the cause of estimation errors and study the compensation methods about errors. For the accurate parameter estimation, studies about nonlinearity of dead time, voltage drop in the inverter, implement of synthesis of the accurate voltage, the accurate measurement of average current considering switching characteristics and the accurate estimation of the parameter values under various operation conditions have been studied. In thesis, the methods that can obtain the parameter values used for direct vector control are presented in standstill, while ensuring the reliability of the same level as much as the traditional tests. For this, the compensation methods for the synthesis of the accurate output voltage are discussed by analyzing the dead time and voltage drop of the inverter. The validity and usefulness of this method are verified by experimental results.