Dynamic Vector Modeling of Three-Phase Mutually Coupled Switched Reluctance Machines with Single dq-Quadrant Look-up Tables

Peter Azer,Shamsuddeen Nalakath,Ali Emadi,Brock Howey,Berker Bilgin

doi:10.1109/ojies.2020.3028059

Peter Azer, Shamsuddeen Nalakath + Show 3 more

Open Access

https://doi.org/10.1109/ojies.2020.3028059

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Abstract

This paper presents a dynamic modeling method for a 3-phase mutually coupled switched reluctance machine (MCSRM) considering spatial harmonics, and saturation. The conventional modeling methods of MCSRMs are based on 3D look-up tables (LUTs), where the phase flux linkages are considered as state variables. These 3D LUTs describe the phase currents with respect to phase flux linkages, and rotor position. The 3D LUTs represent two $dq$ quadrants, and are obtained from finite element analysis (FEA) by multi-phase excitation where the excitation currents cover two quadrants in the $dq$ synchronous reference frame. The LUTs used in the proposed method represent the phase current, and electro-magnetic torque as vectors. The magnitude, and the angle of these vectors are represented by the sine, and cosine Fourier coefficients. Hence, rotor position is not an input to the LUTs, and the proposed method uses 2D LUTs. Additionally, the flux linkages in the four $dq$ quadrants possess symmetry for MCSRMs. Therefore, LUTs corresponding to only one $dq$ quadrant are required. The single-quadrant based LUTs reduces the number of FEA steps, and the size of the LUTs by 50% compared to the two-quadrant LUT based models. Finally, the proposed method is validated using FEA, and experiments for a 12/8 MCSRM.

Highlights

S WITCHED reluctance machines (SRMs) have a simple, robust, and low-cost structure due to the absence of magnets and rotor winding
The symmetry of the flux linkage is due to the absence of the rotor magnets and rotor winding in mutually coupled switched reluctance machine (MCSRM)
The proposed method utilizes two-dimensional look-up tables (LUTs), which describe a single quadrant of the dq synchronous reference frame

Summary

INTRODUCTION

S WITCHED reluctance machines (SRMs) have a simple, robust, and low-cost structure due to the absence of magnets and rotor winding. The existing magnetic circuit modeling methods for MCSRM model the mutual inductance for two phases of equal instantaneous currents [17], [18], so that the two excited phases are considered as a single-phase excitation. Results in [21] are for two-phase excitation with equal currents and they have large error when compared to FEA results even in the linear magnetic region This method cannot describe motor dynamics when the two excited phases have different instantaneous currents. This paper introduces a dynamic modeling method for a 3-phase MCSRM, where the required LUTs from the FEA model describe only a single quadrant of the synchronous reference frame. THE PROPOSED DYNAMIC MODEL A higher mutual inductance is desired in MCSRMs. Stronger mutual coupling between phases is achieved by applying multi-phase excitation and by changing the flux paths through changing the winding configuration. To make the sine Fourier coefficient similar to the q-axis component, the Fourier series can be represented as:

MODELING OF THE PHASE CURRENTS

MODELING OF THE ELECTRO-MAGNETIC TORQUE

EXPERIMENTAL VALIDATION

Findings

CONCLUSION