Gorazd Štumberger

Evaluation of saturation and cross-magnetization effects in interior permanent-magnet synchronous motor

The paper presents the evaluation of saturation and cross-magnetization effects in interior permanent magnet synchronous motor (IPMSM) over the entire range of direct and quadrature axis excitation. The conventional two-axis machine model is modified in order to include the influence of saturation and cross-coupling effects on the variation of self and cross-coupling inductances in the direct and the quadrature axis. The two-axis machine model parameters are evaluated by experiments performed on a IPMSM using a controlled voltage source inverter and are compared with parameters values evaluated by the finite element method. The evaluation of two-axis machine model parameters reveals significant saturation and cross-magnetization effects in both axes, especially in the flux-weakening regime.

Parameter Identification of the Jiles–Atherton Hysteresis Model Using Differential Evolution

In this paper, parameters of the Jiles-Atherton (J-A) hysteresis model are identified using a stochastic search algorithm called differential evolution (DE). The J-A hysteresis models parameters are identified by DE in such a way, that best possible agreement is obtained between the measured and model calculated hysteresis loops. This agreement is furthermore increased by improving the J-A hysteresis model. The improvement is achieved by replacing a constant pinning parameter in the J-A hysteresis model with a variable one. Here, the variable pinning parameter is written as a function of a magnetic field. By DE identified parameters are used in the J-A hysteresis model, which is included in the dynamic model of a single-phase transformer. The effectiveness of the improved J-A hysteresis model and parameters identification approach is verified with experiments and simulations.

Maximum Efficiency Trajectories of a Two-Axis Sun Tracking System Determined Considering Tracking System Consumption

This paper deals with the two-axis sun tracking system for a photovoltaic system. The trajectories of the sun tracking system are determined in an optimization procedure. The optimization goal is maximization of an electric energy production in the photovoltaic system considering the tracking system consumption. Determination of the tilt angle and azimuth angle trajectories is described as a nonlinear and bounded optimization problem, where the objective function is not available in the explicit form. A stochastic search algorithm called Differential Evolution is used as an optimization tool. In the optimization procedure, the objective function is evaluated by using the models of available solar radiation, tracking system consumption, and the efficiency of solar cells with the appropriate dc/dc converters. The problem bounds are given in the form of lower and upper bounds for both angles and time and angle quantization. The results presented in the paper show, that the optimal trajectories for the tilt and azimuth angle depend on the available solar radiation, solar cell efficiency, tracking system consumption and the optimization bounds.

Line-Starting Three- and Single-Phase Interior Permanent Magnet Synchronous Motors—Direct Comparison to Induction Motors

The performance comparison of three- and single-phase line-start interior permanent magnet synchronous motors (LSIPMSMs) and induction motors (IMs) with equal squirrel-cage design and symmetric four-pole stator windings is presented. The finite element method was employed in analysis of steady-state synchronous performance of LSIPMSMs. A magnetically linear lumped parameter model was employed in analysis of line-starting performance of LSIPMSMs, where the electrical and also the mechanical subsystems were considered. The procedure which was used for the LSIPMSM design was validated by comparison of calculation and measurement results. The performance of three- and single-phase LSIPMSMs and IMs with equal squirrel-cage design was directly compared and evaluated, thus emphasizing impacts of the permanent magnet breaking torque and reluctance breaking torque on the LSIPMSM performance in the asynchronous operation region.

Evaluation of experimental methods for determining the magnetically nonlinear characteristics of electromagnetic devices

The properties of magnetic material are normally described by the permeability tensor, while the magnetically nonlinear properties of electromagnetic devices (EMDs) can be described by the current-dependent characteristics of flux linkages. This paper presents and evaluates different experimental methods appropriate for determining the magnetically nonlinear characteristics of EMDs. The tested device is supplied by a controlled voltage source. Sinusoidal voltages, sinusoidal voltages with offset, and stepwise changing voltages are applied. Current-dependent characteristics of flux linkages are determined from the measured voltages and currents, either by numerical integration or by Fourier analysis and calculation of impedances.

Identification of linear synchronous reluctance motor parameters

The paper deals with the identification of parameters of a two-axis linear synchronous reluctance motor (LSRM) dynamic model. The model parameters are identified by experiments performed on an LSRM using a controlled voltage source inverter. The current dependent direct- and quadrature axis inductances are identified by experiments and calculated by the finite element method. The calculated inductances are compared with the inductances identified by experiments. As the translation range of the tested LSRM is limited, the proposed parameter identification procedure has been verified indirectly through the comparison of simulation and experimental results in the case of kinematic control. Compared are the reference and the actual position, speed, current and voltage trajectories obtained by experiment and by simulation. The agreement of the results is good.This paper deals with experimental methods for the identification of linear synchronous reluctance motor (LSRM) parameters. A magnetically nonlinear two-axis dynamic LSRM model is derived. This model accounts for the effects of slotting, saturation, cross-saturation, and the end effects. The parameters of the obtained model are not constant. They are given by the characteristics of the flux linkages, thrust, and friction force depending on the mover position and the direct (d) and quadrature (q) axis currents. These characteristics are determined experimentally by a controlled voltage-source inverter employing closed-loop current control in the d-q reference frame. The proposed model, experimental methods, and determined characteristics are confirmed through a comparison between the measured and calculated results. Two tests are performed: a test at the locked mover, and kinematic control at low speed. The effects of cross saturation under dynamic operating conditions and the effects of slotting can be clearly seen in the measured and calculated results.

Design and Finite-Element Analysis of Interior Permanent Magnet Synchronous Motor With Flux Barriers

The paper presents a finite-element method-based design and analysis of interior permanent magnet synchronous motor with flux barriers (IPMSMFB). Various parameters of IPMSMFB rotor structure were taken into account at determination of a suitable rotor construction. On the basis of FEM analysis the rotor of IPMSMFB with three-flux barriers was built. Output torque capability and flux weakening performance of IPMSMFB were compared with performances of conventional interior permanent magnet synchronous motor (IPMSM), having the same rotor geometrical dimensions and the same stator construction. The predicted performance of conventional IPMSM and IPMSMFB was confirmed with the measurements over a wide-speed range of constant output power operation.

Determining Parameters of a Line-Start Interior Permanent Magnet Synchronous Motor Model by the Differential Evolution

The line-starting performance and synchronization capability of a line-start interior permanent magnet synchronous motor (LSIPMSM) has to be evaluated by considering different loads and different values of supply voltages, which requires the usage of a reliable dynamic model. In this work the parameters of a magnetically linear lumped parameter LSIPMSM dynamic model were determined by the differential evolution (DE). The optimization objective was the best possible agreement between the measured and by the model calculated time-behavior of model variables. Parameters determined by the DE are used in the LSIPMSM dynamic model, improving agreement between measured and calculated responses of currents and motor speed.

Impact of magnetic nonlinearities and cross-coupling effects on properties of radial active magnetic bearings

The impact of magnetic nonlinearities and cross-coupling effects on the properties of the discussed radial active magnetic bearings (AMBs) is evaluated in the entire operating range. The characteristics of flux linkages and radial force are all determined by finite element computation, while the current and position dependent partial derivatives of the flux linkages are calculated by analytical derivations of the continuous approximation functions. Calculated current and position-dependent partial derivatives, as well as the radial force characteristics are incorporated into the proposed dynamic AMB model. The results presented show that the magnetic nonlinearities and cross-coupling effects can change the electromotive forces and the radial force considerably. These disturbing effects have been determined and can be incorporated into the real-time realization of nonlinear control in order to achieve cross-coupling compensations.

Differential-Evolution-Based Parameter Identification of a Line-Start IPM Synchronous Motor

This work deals with the differential-evolution (DE)-based method for simultaneous identification of the electric, magnetic, and mechanical subsystem parameters of a line-start interior permanent magnet synchronous motor (LSIPMSM). The parameters are determined in the optimization procedure using the dynamic model of the LSIPMSM; the time behavior of voltages, currents, and speed measured on the tested LSIPMSM; and the DE, which is applied as the optimization tool. During the optimization procedure, the DE changes the parameters of the LSIPMSM dynamic model in such a way that the differences between the measured and calculated time behaviors of individual state variables are minimized. This paper focuses on the objective function definition, the constraint settings for individual parameters, the normalization of parameters, and, above all, the test and measurement procedures performed on the LSIPMSM, which all together make it possible to determine the LSIPMSM dynamic model parameters valid for a broad range of operation, thus ensuring proper evaluation of the LSIPMSMs line-starting capability. Some of the LSIPMSM parameters that can be determined by finite-element analysis and experimental methods are compared to the values obtained by the DE, thus validating the DE-based approach.