This paper deals with an observer design for a p-cell chopper. The goal is to reduce drastically the number of sensors in such system by using an observer in order to estimate all the capacitor voltages. Furthermore, considering an instantaneous model of a p-cell chopper, an interconnected observer is designed in order to estimate the capacitor voltages. This is realized by using only the load current measurement. Simulation results are given in order to illustrate the performance of such observer. To demonstrate the validity of our approach, experimental results based on Digital Signal Processor (DSP) are presented.
Electrical circuits with state-feedbacks are addressed. It is shown that by suitable choice of the gain matrices of state-feedbacks it is possible to obtain the closed-loop system matrices with nilpotency indices equal to two and their state variables are linear functions of time. The considerations are illustrated by linear electrical circuits.
In the paper modeling of main inductances for mathematical models of induction motors is applied to study the effects caused by a rotor eccentricity and saturation effects. All three possible types of eccentricity: static, dynamic and mixed are modeled. The most important parameters describing rotor eccentricity include self and mutual inductances of the windings. The structural changes of the permeance function as a result of eccentricity appearance and the Fourier spectra of inductances in occurrence of saturation for each case are determined in the paper. The presented algorithm can be used for the diagnostically specialized models of induction motors.
The paper presents the probabilistic model of fibrillation currents containing two components with different frequencies. An analysis was conducted of the threat of ventricular fibrillation which occurs in consequence of the electric shock with the highest permissible contact shocking voltage of the network frequency (50 Hz), taking into account the threat caused by the second component of the voltage which has the frequency higher than the network frequency. The sample results of calculations apply to the probability of the ventricular fibrillation in case of a shock caused by the highest permissible contact shocking voltage, for the defined time of shock duration, without and with the participation of an additional voltage component with higher frequency. The formula has been presented for the calculation of the highest permissible contact shock voltages with taking into account the voltage component of the frequency higher than the network frequency. The results of calculations indicate that a considerable reduction of the highest permissible contact shock voltage is necessary in order to compensate for a growth of the ventricular fibrillation threat caused by the presence of an additional component with the frequency other the network frequency. This applies in particular to the long shock duration times and low frequencies (up to 500 Hz) of an additional component of the shocking voltage.
The paper describes high output induction motors driving large applications of heavy starting conditions. Heavy start is characterised by long accelerating time and occures in drives of hudge inertia torque, esspecially when performed at full load. The reliable operation of the motors depends on proper design and quality of rotor's cage. The aspects of thermal behaviour and electrodynamic forces have to be considered during the design of the motor for hard working conditions. In the paper the rotor with idle bars is investigated.
Results of 3-D of discharge channel displacement simulation, acquired by means of the Fluent program during one current half-period of AC arc, indicate that the obtained images of the phenomenon are qualitatively similar to those, recorded with a high-speed digital camera, while the computer simulation enables much a more comprehensive analysis of the acquired data. In addition to selected arc simulation frames and corresponding distributions of mass velocity vectors and current density vectors on a plane, the distributions of temperature, current density and mass velocity values are presented on the axis of the electrode arrangement model. The composite motion (continuous and jumping) of discharge channels was analyzed, taking into account mass displacement and matter state changes.