The model-based analysis of a switched reluctance machine, which has significant losses in the iron core, requires the machine to be represented by parameters that account for nonlinearities caused by both the magnetic saturation and the iron losses. This paper describes the methodology for determining the parameters of the equivalent electric circuit that includes the representation of iron losses. The parameters are derived from measurements performed under static conditions. The methodology is verified by comparing the dynamically measured results for the pull-out force against the results predicted by the model that is based on the equivalent circuit.

Experimental Determination of Equivalent-Circuit Parameters of a Tubular Switched Reluctance Machine With Solid-Steel Magnetic Core

A core loss model for switched reluctance motor (SRM) is introduced in which flux waveforms in different parts of the motor are predicted by carrying out a two-dimensional (2D) finite-element (FE) transient analysis using ANSYS FE software. Since the predicted flux waveforms are non-sinusoidal, the improved Steinmetz equation is used for core loss calculation. The core loss model is developed totally in ANSYS parametric design language as a parametric model and it can be used easily for different types of SRM. The developed core loss model is applied to an 8/6 SRM and the experimental results are presented for validation of the model.

Core loss model based on finite-element method for switched reluctance motors

SUMMARY The prediction of switched reluctance motor (SRM) performance requires knowledge of core losses. However, the calculation of iron losses in SRM is especially complex first because the flux waveforms are nonsinusoidal and different parts of the magnetic circuit have different waveforms and second because they are conditioned by the type of control used. This study proposes an analytical method for calculating core losses that comprises simulation of the SRM using finite element analysis to determine the magnetization curves, and SRM modeling, which enables transient simulations with the associated electronic power converter run under different control strategies. The flux density waveforms in the different parts of the SRM are derived from the flux density waveform of the stator pole that is obtained from the transient simulation. The specific core losses (in W/kg) are separated into three parts (hysteresis losses, classical eddy current losses and excess losses) and calculated using the waveforms and time derivatives of the local flux density. The core losses for each part of the SRM’s magnetic circuit can be estimated using the calculated values for specific hysteresis losses, specific classical eddy current losses and specific excess losses for each zone. Adding these individual losses yields the total core losses. The method was applied to three-phase 6/4 SRM, and the calculated results were compared with experimentally obtained measurements. Copyright # 2010 John Wiley & Sons, Ltd.

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Method for estimating core losses in switched reluctance motors

Switched reluctance machines have emerged as an important technology to be deployed in automotive electric drives; they represent a real alternative to conventional electrical machines in automotives. This paper reviews the technology status and trends in switched reluctance machines. It covers the various aspects of modeling, design, simulation, analysis, and control. Finally, it discusses the impact of switched reluctance machines technology on intelligent motion control.

Switched reluctance machine in automotive applications — A technology status review

A fast method to calculate the iron loss of switched reluctance motor (SRM) is proposed. The key of the method is that the flux density waveforms in different parts of the motor can be obtained quickly. First, the static flux density data varying with phase current and rotor position in various parts of SRM are obtained by finite element method (FEM). Then, the static flux density data are stored in 2D look-up tables in Matlab/Simulink to get the flux density waveforms by look-up table method, and the obtained flux density waveforms are verified by FEM results. Since the flux waveforms are non-sinusoidal and non-linear, an accurate and fast model for the iron loss prediction is presented, and different modified factors are applied to calculate the hysteresis loss according to the classification of flux density waveforms. Based on that, the calculation model is established in Matlab/Simulink, and iron losses of a three-phase 6/4 structure SRM under different turn-on and turn-off angles and load conditions are calculated and analysed. Finally, measured results are presented to verify the precision of the calculation model.

https://ietresearch.onlinelibrary.wiley.com/doi/epdf/10.1049/iet-epa.2016.0808

A fast iron loss calculation model for switched reluctance motors

An improved dynamic model of the switched reluctance machine for use in design has been developed. The specific requirement was for the incorporation of iron losses, but a secondary benefit has been the inclusion of the magnetic interaction between phases. The work is described in two stages: (i) modelling of iron loss and its effect on current waveform in a rudimentary one-phase static SR machine, and (ii) the development of a dynamic model, including instantaneous torque, of a three-phase machine with eddy-current, hysteresis and additional iron losses. Both stages include experimental verification. Coupling between the phases through shared portions of the magnetic circuits and also through 'leakage flux' is included. Model results are compared with measured values for a three-phase, 12/8-pole motor.

Dynamic modelling of switched reluctance machines with iron losses and phase interactions

The authors are engaged in a programme of work to develop an improved model of iron loss for the use in the design of switched reluctance machines. This has necessitated (i) the development of equipment to measure iron loss in samples of steel over a wide range of frequencies for a variety of impressed flux waveforms, including a DC bias, and (ii) measurements of the loss in a static basic 2-pole switched reluctance machine. The paper gives details of these systems and results demonstrating the agreement with the new model. Two interesting effects which have emerged are also explained - the first shows the unexpected effect of the nonlinear magnetisation curve on the relationship between mean flux and mmf and the second concerns the decay of flux and eddy currents under conditions of discontinuous excitation

S.P. Randall

Papers

Dynamic modelling of switched reluctance machines with iron losses and phase interactions

Iron loss measurement technique and experience for flux including DC offsets