Dynamic Identification of Rotor Magnetic Flux, Torque and Rotor Resistance of Induction Motor

Pavol Fedor,Daniela Perdukova,Viliam Fedak,Petr Palacky,Peter Bober

doi:10.1109/access.2020.3013944

Abstract

In the modern high-performance drive applications, a high-precision and efficient control of the induction motor depends on the accuracy of parameter values. However, the motor parameters may change due to the winding temperature fluctuations, flux saturation and skin effect. Any discrepancy between the values of the motor’s actual parameters and the ones used for the design of the controllers may result in degradation of the drive performance. In this work, a new identification method of hardly measurable internal quantities of the induction motor, such as components of the magnetic flux vector and electromagnetic torque, is outlined. Commonly, the measurable quantities of the induction motor like stator currents, stator voltage frequency and mechanical angular speed are used to determine a feedback effect of the rotor flux vector on the vector of the stator currents of induction motor. Based on this feedback, it is also possible to identify the actual value of the rotor resistance, which may alter during the induction motor operation. This has a significant impact on the precision of the identified quantities as well as on the master control of the induction motor. Stability of the identification structure is guaranteed by the position of roots of characteristic equation of its linear transfer function. Simulation and experimental results are given to highlight the quality, effectivity, feasibility, and robustness of the proposed identification method, which is working reliably within the whole range of the motor angular speed.

Highlights

The use of the induction motor (IM) in the electric drives introduces indisputable advantages consisting of their simple design, maintenance, operational reliability and efficiency
It is necessary to identify respective motor parameters and internal quantities that are changed during the operation of the electric drive system, for example due to the temperature fluctuations or the magnetic flux saturation
In [11], [12], a finite element method is used to identify the parameters of the IM and its dynamic behavior

Summary

INTRODUCTION

The use of the induction motor (IM) in the electric drives introduces indisputable advantages consisting of their simple design, maintenance, operational reliability and efficiency. On the basis of the measurements of the rotor speed, stator currents, and voltages a nonlinear adaptive on-line observer with exponential convergence properties is designed to identify magnetic flux, as shown in [24]. It utilizes reduction of variations of the three critical parameters (load torque and motor resistances). This article proposes a new high-quality dynamic identification structure for IM based on its mathematical model and allowing to identify rotor magnetic fluxes and IM electromagnetic torque simultaneously with an on-line adaptation of the rotor resistance. A comparison of the results with existing methods and conclusions are presented in the Section 7

MATHEMATICAL MODEL OF INDUCTION MOTOR

IDENTIFICATION OF ROTOR FLUXES AND TORQUE OF

ADAPTATION OF IDENTIFICATION STRUCTURE TO CHANGE OF ROTOR RESISTANCE

Findings

VIII. DISCUSSION AND CONCLUSION