Jarosław Rolek

Analysis of multipulse rectifiers with modulation in DC circuit in vector space approach

Rectifiers consisting of parallel connected 6-pulse bridges with modulation in DC current circuit show properties of 24-, 36-pulse or multipulse rectifiers. The analysis of such rectifiers was conducted by means of the space vector method. A load unbalance of the component bridges of 12-pulse rectifier generates the intermediate position of space vector on a complex plane. An increase in the number of the intermediate positions approximates the space vector to the case of rotating one. In this paper topologies of multipulse rectifiers with modulation in DC current circuit are presented. The simulation results of investigations were obtained by means of the space vector for control of modulators.

Estimation of electromagnetic parameters of an induction motor multi-loop equivalent circuit based on the machine inductance frequency characteristic

The variability of electromagnetic parameters of induction motors with deep-bar cage or solid rotors is represented, with a satisfactory approximation, by the machine secondary multi-loop equivalent circuit with constant lumped parameters. An estimation procedure of electromagnetic parameters of such an equivalent circuit is presented in the paper. The procedure is carried out using the measured frequency characteristic determined on the basis of instantaneous values of investigated induction motor electromechanical quantities. The study has been subjected to an induction motor with a solid rotor manufactured from the magnetic material, i.e. a machine characterized by a significant skin effect occurring in rotor solid conductive elements.

Induction motor electromechanical quantities estimation based on the inductance frequency characteristic — Simulation studies

The estimation methodology of electromechanical quantities of an induction motor has been presented in the paper. The investigated estimation algorithms are based on the motor inductance frequency characteristic and the machine secondary multi-loop equivalent circuit, reproducing this characteristic in the analyzed frequency range. The conducted simulation studies indicate the possibility of using the proposed algorithms in an estimation process of considered electromechanical quantities of an induction motor.

Magnetic Composites in Electric Motors

Magnetic composites are manufactured as magnetic powder bonded by dielectric material, which bond and insulate powder grains. Magnetic composites are applied in electric machines due to their favorable magnetic and mechanical properties as well as possibility of tailoring their physical properties. The paper is a review of soft and hard magnetic composites, their internal structure, properties, and advantages resulted from their application on magnetic circuits of electric motors.

A methodology for electromagnetic parameter estimation of an induction motor equivalent circuit based on the load curve test

The paper presents the methodology for electromagnetic parameter estimation of the considered equivalent circuits of induction machines, enabling the more effective usage of information obtained as a result of realisation of the measuring procedure “Load curve test” described in the standard PN-EN 60034-28: 2013. An evaluation of adequacy of electromagnetic parameters estimated in accordance with the aforementioned standard and the presented methodology has been performed on the basis of the comparison of impedance frequency characteristics of the tested induction motor derived from measurement with the corresponding characteristics calculated by means of motor mathematical models resulted from the studied equivalent circuits with estimated parameters. Additional verification of correctness of estimated electromagnetic parameters has been realized by confronting the steady-state power factor-speed, stator current-speed and torque-speed characteristics of the tested induction motor determined experimentally and through the machine operation simulations carried out with the use of the considered equivalent circuits.

Angular velocity estimator based on the inductance frequency characteristic for an inverter fed induction motor — Simulation studies

The selected simulation results of the angular velocity estimator, whose operation algorithm has been elaborated basing on the inductance frequency characteristic of the considered induction motor (IM), have been presented in the paper. The simulations have been conducted at specified operating frequencies of the scalar-controlled induction motor drive with a modulator employing the space vector pulse width modulation technique. This allowed for the indication of the influence of the IM current distortion on the accuracy of the IM angular velocity estimation process and thereby the efficiency of the considered IM drive. The impact of the estimator input signals filtering on the level of angular velocity estimation and tracking errors has been also investigated in the paper. The analysis has been conducted for the mathematical model of the four-pole induction motor of Sg 132S-4 type with a solid rotor manufactured from the magnetic material S235JR.