Abstract
The transition to electric vehicles (EVs) has received global support as initiatives and legislation are introduced in support of a zero-emissions future envisaged for transportation. Integrated on-board battery chargers (OBCs), which exploit the EV drivetrain elements into the charging process, are considered an elegant solution to achieve this widespread adoption of EVs. Surface-mounted permanent-magnet (SPM) machines have emerged as plausible candidates for EV traction due to their nonsalient characteristics and ease of manufacturing. From an electric machine design perspective, parasitic torque ripple and core losses need to be minimized in integrated OBCs during both propulsion and charging modes. The optimal design of EV propulsion motors has been extensively presented in the literature; however, the performance of the optimal traction machine under the charging mode of operation for integrated OBCs has not received much attention in the literature thus far. This paper investigates the optimal design of a six-phase SPM machine employed in an integrated OBC with two possible winding layouts, namely, dual three-phase or asymmetrical six-phase winding arrangements. First, the sizing equation and optimized geometrical parameters of a six-phase 12-slot/10-pole fractional slot concentrated winding (FSCW)-based SPM machine are introduced. Then, variations in the output average torque, parasitic torque ripple, and parasitic core losses with the slot opening width and the PM width-to-pole pitch ratio are further investigated for the two proposed winding layouts under various operation modes. Eventually, the optimally designed machine is simulated using analytical magnetic equivalent circuit (MEC) models. The obtained results are validated using 2D finite element (FE) analysis.
Highlights
This paper is limited to Surface-mounted permanent-magnet (SPM) machines as the optimization problem will invoke more parameters in the case of IPM machines, which will be the target for future studies
It can be noted that the maximum average torque and minimum torque ripple cannot be achieved at the same slot opening width
This paper thoroughly presents the performance of a SPM machine with two winding arrangements under both the propulsion and charging modes of operation
Summary
When designing an electrical machine for EV applications, the main criteria, in addition to cost, are maximum torque density, minimum losses, low torque ripple, and constant power speed range (CPSR) [13] In this regard, fractional slot concentrated winding (FSCW). The torque performance (i.e., the average torque production and torque ripple) and core losses are significantly affected by the design parameters of the employed propulsion motor such as the slot opening width and PM width-to-pole pitch ratio [19,20]. The main contribution of this paper is to present the performance of the EV traction machine under the charging process, shedding light on the influence of various design parameters, namely the slot opening width and PM width-to-pole pitch ratio, on the torque ripple and core losses under both modes of operation. This paper is limited to SPM machines as the optimization problem will invoke more parameters in the case of IPM machines, which will be the target for future studies
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