Papers by Author: Andrius Petrovas

Abstract: The paper deals with modeling, simulation and analysis of speed observer for induction drive. Mathematical model of observer is presented and its computer model is elaborated. Speed measurement results are compared with those obtained during simulations with induction motor model. Development and implementation of speed observer requires measurement of motor current and supply voltage. Simulated values of current and voltage are used in the proposed observer model instead of the real ones. Model of induction motor is developed on the basis of motor equations in stationary reference frame. Model of observer relies on nonlinear differential equations, describing performance of induction motor, additionally making use of the space-vector theory. The speed observer developed by means of direct synthesis from state equations is robust with respect to parameter and load variations.

Abstract: The paper presents the model of vector controlled induction motor. Induction motor model is carried out in reference frame, fixed on stator. Elaborated model of the drive is suitable for investigation dynamics because output signals appear as real currents, flux linkages and other variables. Vector control law model is implemented for variables in synchronous reference frame; therefore controller operates with transformed variables. Structure of designed model reflects the real variable speed drive. Model of vector controlled induction drive comprise model of induction motor, feedback signals and blocks as well as speed and flux reference blocks and controllers for producing motor supply signals. Feedback blocks are used for calculation stator current vector in the rotor flux linkage reference frame. For flux and speed control are designed lag controllers. Between advantages of that model is additional simulation of current channel law.

Abstract: Control theory proposes to apply observers in systems with uncertain plant parameters. Observers can be used for calculation of feedback gains and getting desired, even strictly determined response requirements. The paper considers design of controller for direct current drive. As state space variables are chosen armature current and angular speed of motor. Mathematical model of the motor, operating with load which is assumed as disturbance, is elaborated. Full order Luenberg observer is designed according to desired characteristic equation of system. The results of simulation are presented and discussed.

Abstract: A model of the AC induction motor, which allows us to analyze all operation modes of motor supplied by the frequency converter, has been developed. A simulation of the inverter of the frequency converter and the AC induction motor interaction on the basis of the developed motor model, using software MATLAB, was performed and a motor regenerative braking mode was investigated. The results of investigation are used for the development of fault protection of the inverter.