Bojan 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.

Analysis of iron loss in interior permanent magnet synchronous motor over a wide-speed range of constant output power operation

The paper presents the analysis of iron loss in interior permanent magnet synchronous motor over a wide-speed range of constant output power operation. The analysis is based on finite element method and uses the information on local flux density variation in the motor components. The total iron loss is calculated by summing up separately the hysteresis, classical eddy current and excess losses for each element of discretization over one electrical cycle of magnetic field variation in all parts of motor iron. The results of iron loss calculation were compared with the results obtained from experiments on the actual machine.

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.

Analysis of interior permanent magnet synchronous motor designed for flux weakening operation

The paper presents a finite element method (FEM) based analysis of interior permanent magnet synchronous motor, designed for flux-weakening operation. Flux-weakening performance determined from the FEM analysis on the proposed permanent magnet motor structure is presented in order to verify the suitability of the design concept for flux-weakening operation. The influence of iron losses on the output power capability is included in the analysis by posterior iron loss calculation. The presented interior permanent magnet motor shows an extremely wide constant-power speed range which exceeds 5:1.

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.

Torque Analysis of an Axial Flux Permanent Magnet Synchronous Machine by Using Analytical Magnetic Field Calculation

This paper presents a torque analysis of an axial flux permanent magnet synchronous machine (AFPMSM) based on analytical analysis of magnetic field. The proposed method for torque analysis requires less computational time and is more flexible than finite element method (FEM). This is important advantage, especially for the early stages of the design process. Torque measurements on prototype AFPMSM confirm the validity of the torque analysis method.

Determination of parameters of synchronous motor with permanent magnets from measurement of load conditions

The paper describes the determination of the parameters of the two-axis model of a synchronous motor with permanent magnets using the results of the measurement of load conditions at different sine voltages and constant frequency. For the determination of parameters of the two-axis model the modified conventional method was used. The machine parameters are determined from measurement data by the results of the calculation of the induced voltage E/sub i/ and internal load angle /spl delta//sub i/. Computational difficulties at parameters determination owing to random inaccuracies in the measurements data are overcome with use of orthogonal polinoms approximation. Detailed determination of parameters values reveal an important influence of the interaction of the direct and quadrature axis excitation on the parameters variation.

Analytical Analysis of Magnetic Field and Back Electromotive Force Calculation of an Axial-Flux Permanent Magnet Synchronous Generator With Coreless Stator

This paper presents the analytical analysis of magnetic field and back electromotive force (back EMF) calculation in an axial flux permanent magnet synchronous generator (AFPMSG) without stator core. For the verification, the numerical analysis [finite element method (FEM)] of magnetic field is accomplished and comparison between analytical and numerical solution of magnetic field is presented. Both analytical and numerical solutions are obtained via magnetic vector potential, respectively. This paper also presents the comparison between analytical solution and numerical (FEM) solution of back EMF using Faradays law. The verifications show that good agreement between analytical and numerical solution of magnetic field and back EMF is obtained. The validity of the proposed analytical method is additionally confirmed with measurements of back EMF on prototype AFPMSG with coreless stator.

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.