Comparative analysis of axial flux SRM topologies for electric vehicle application

Abstract

In-wheel motors for electric vehicles (EVs) have a high outer diameter (D) to axial length (L) ratio. In such applications, axial flux machines are preferred over radial flux machines due to high power density. Moreover, permanent magnet (PM)-less machines are gaining interest due to increase in cost of rare-earth PM materials. In view of this, axial flux switched reluctance motor (AFSRM) is considered as a possible option for EV propulsion. Two topologies namely, toothed and segmented rotor AFSRM are designed and compared for the same overall volume. These topologies have a three-phase, 12/16 pole single-stator, dual outer-rotor configuration along with non-overlapping winding arrangement. Analytical expressions for phase inductance and average torque are derived. To verify the performance of both the topologies a finite element method (FEM) based simulation study is carried out and its results are verified with the analytical values. It is observed from simulation that the average torque is 16.2% higher and torque ripple is 17.9% lower for segmented rotor AFSRM as compared to toothed rotor AFSRM.

Evaluation of axial SRM for electric vehicle application

“…As mentioned, the external radius and the axial length are the same in order to have the same volume (equations (2) and 3).…”

“…In order to choose the appropriate structure for electric traction, comparisons between axial and radial SRM are essentially presented. Except some works like [2]- [4], the majority of studies on switched reluctance motor for an electric traction has been made by considering a radial structure [5]- [13]. Therefore, this work focuses on the axial structure for an automobile application.…”

Reluctance Machine for a Hollow Cylinder Flywheel

“…Although reduced torque ripple is not important for the flywheel rotor itself (since these generally have a high moment of inertia), secondary benefits include decreased losses, decreased vibration and more constant charging and discharging rates. The characteristic ripple torque of axial flux SRMs has been a subject under study [44][45][46].…”

Comparative Study of Conventional, Fuzzy Logic and Neural PID Speed Controllers with Torque Ripple Minimization for an Axial Magnetic Flux Switched Reluctance Motor

“…From literature, it can be observed that many works are related to radial flux SRM; however few works are related to axial flux SRM [3]. Some of them refer to axial flux SRM with two stators [4]- [6], but in this paper the motor has only one stator. With respect to the control strategies, several strategies are reported [7]- [9].…”