The article presents measurement methods serving to determine electric and magnetic properties of rails (60E1) used to construct railroad turnouts. Knowledge of a rail's electric and magnetic properties is necessary to analyse the phenomena in the rail's internal structure when under impact of a powerful electromagnetic field. The electric and magnetic properties will also help to develop a simulation model of Turnhout induction heating in 2D and 3D space.

A new observer of induction motor state variables is proposed in the paper. A nonlinearity of the main magnetic path is expressed as a function of a properly chosen parameter versus the position vector length. The value of the mutual inductance received n the identification algorithm is calculated exploiting the estimated values of the state variables. The coefficients appearing in the differential equations of the observer system are modified in each step of the algorithm on the basis of the calculated mutual inductance. The analysis of convergence of the identification algorithm is shown in this paper.

This paper presents a method of calculation of steady-state processes in threephases matrix-reactance frequency converters (MRFC's), in which voltages and currents are transformed by control signals with two pulsations. A solution of nonstationary differentia equations with periodic coefficients that describe this system is obtained by using Galerkin's method and an extension of equations of one variable of time to equations of two variables of time. The results of calculations are presented in an example of three-phases MRFC with buck-boost topology and compared with a numerical metod embedded in the program Mathematica.

The modified air gap torque method to determine the efficiency of squirrelcage induction motor was presented. of testing which continues the authors' work on application of AGT method to estimating induction motor's efficiency are discussed. The proposed method is verified in a number of selected low-power motors.

The paper presents a laboratory prototype of the three-phase transformer less voltage outages compensator with an energy storage based on high voltage supercapacitors. The system described is able to protect an isolated grid e.g. in industry against short voltage interruptions, dips and sags. An idea of a control method as well as a Digital controller has been presented, too.

The paper presents the mathematical models of dual stator squirrel-cage induction motor, formulated in phase coordinate system and in general transformed space vector form. The two types of models of dual stator induction motor are considered. The control systems of field-oriented control (IFOC and DFOC) and direct torque control (DTC) of the dual stator induction motor have been described and discussed.

The paper presents the method of control of an induction squirrel-cage machine supplied by a voltage source converter. The presented idea is based on an innovative method of the voltage source converter control, consisting in direct joining of the motor control system with the voltage source rectifier control system. The combined control system gives good dc-bus voltage stabilization. In the applied control system the limits of the reference variables have been introduced. A correction of the estimated machine load torque is proposed. The new proposed solutions are confirmed by mathematical dependences, simulation and experimental results.

This paper briefly describes direct power control methods for two- and threelevel AC/DC converters and their modified DPC 3H 2-? and the DPC 5H2-? algorithms. It also presents two new control methods DPC-3Am (direct power control 3 areas with modification) and the DPC-3L-3Am (direct power control 3 levels 3 areas with modification). The research results were used to compare the described methods. The comparison was based on an average value of switching frequency and current distortion coefficient. Experimental investigations into the methods have shown that the use of the modified DPC methods reduces the number of switchings by more than 70% compared with the standard DPC method.

The presented paper concerns the issues of communication networks applied to monitoring and control of reactive power compensator for small hydroelectric plants installed in areas distant from urban agglomerations. Ethernet, CAN, Modbus and GPRS transmission protocols has been used. Industrial programmable controller as a data collector has been used also.

Department of Electrical Drive and Industrial Equipment University of Science and Technology (AGH) The article describes the method of determining mechanical losses and electromagnetic motor torque on the example of a flywheel energy storage system utilizing BLDC motor. The description of the test stand contains: the topology of power factor correction boost rectifier, an inverter supplying the BLDC motor, and the measuring system. The detailed experimental results are included in the paper.