S. Lisauskas

Design of Observer for Direct Current Drive

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.

Electric Multi-Module Catapult Dynamics

Electric catapults can be used for automatic information storage in radioactive environment. Dynamics of a transport system with the potential of route flexibility was investigated. This system is made up of stand-alone modules, therefore further expansion is possible. Modules consist of mechanical part (rails for the cart), electrical part (inductor of a linear induction motor (LIM) and electromagnetic brake) and electronic part (thyristor commutator). Cargo cart is mounted on the LIM’s secondary unit that can be catapulted from any station (module) to another. First LIM’s inductor starts the secondary, ejects it out of primary’s range. Inertia of the cart allows it to reach the next station which in turn can either accelerate it or stop it. Position detectors (Hall effect sensors) are used for estimating cart movement. Electromagnetic brakes are used as dynamic braking is not effective in this case. A computer model was designed and various operating modes are simulated (upon non-zero initial conditions).

Model of a Sensorless Induction Drive

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.