Design, Modeling, and Control of Rotating and Linear Electric Machines for Automotive Applications

1. Introduction

The automotive industry is one of the main employers in industrialized countries. Due to its bright image, car culture has spread over the entire world, and shaped not only the global economy but also the way of life of billions of people. Currently, the automotive market is very competitive, with big actors in nearly all continents, and they are required to constantly evolve and propose new solutions to current problems. The electric vehicle has been the main driver of this industry in recent years. Indeed, in order to address the problems of greenhouse gases and the polluting emissions of the classical internal combustion (IC) engine vehicles, governments all over the world are imposing new legislation which pushed the automotive industry to develop more hybrid vehicles or fully electric vehicles.

A large variety of electric machines and actuator topologies has been and is still being developed for automotive applications, by both the academic and industrial communities. Hence, this Editorial aims at presenting the motivations and a brief introduction to the Special Issue entitled “Design, Modeling, and Control of Rotating and Linear Electric Machines for Automotive Applications”. This Special Issue contains eight contributions, with authors from Asia, Europe, and the USA. Researchers with backgrounds in both academia and the automotive industry (Valeo, PSA-Stellantis, Mercedes-Benz, Schaeffler Group USA Inc., Fort Mill, SC, USA) have contributed with original research results covering different aspects related to rotating and linear electric actuators and machine design and control. The main objective of this Special Issue is to gather the ideas of the research community worldwide into a common platform and to present the latest advances and developments in the design, modeling, and control of electric machines and actuators for automotive applications.

2. Summary of Accepted Contributions

The accepted contributions are listed in the references section [1,2,3,4,5,6,7,8]. They can all be accessed through the following link: https://www.mdpi.com/journal/energies/special_issues/rotating_and_linear_permanent-magnet_Machines (accessed on 29 July 2023).

Among the eight accepted papers, seven are research articles [1,2,3,4,5,6,7], and one is a review paper [8]. Contribution [1] presents the control strategy of a fault-tolerant permanent magnet synchronous motor. The fault tolerance is insured by adopting a dual-winding permanent magnet synchronous motor (DW-PMSM), with each winding set being controlled by a separate, fully independent electronic control unit (ECU). The motor is used in an electro-hydraulic brake (EHB) system.

Contribution [2] compared two design methodologies for the multi-layer permanent magnet synchronous machines used for automotive applications. The two compared methodologies differ from the adopted modeling approach. Both modeling approaches are based on finite element computations, but one considers multiple rotor positions (which the authors called the “abc Model”), while the second only consider computations performed for the d-q axes (which the authors called the “dq Model”). Interesting conclusions are drawn from this comparison study.

In contribution [3], the authors presented the design study of an original squirrel cage induction motor with non-overlapping windings used for EV/HEV applications. The influence of major machine design parameters on the average torque, torque ripple, current density, machine losses, efficiency, and flux-weakening performance were examined.

Contribution [4] concerned the evaluation of an analytical modeling approach (which the authors called the “Harmonic Modeling Method”) for the analysis of high-speed machine performance. The authors considered the harmonics present in the armature currents due to the PWM technique used in the inverter supplying the machine. The authors validated the adopted approach by comparing its results with those obtained from a finite element model. While the results were more or less in line with finite element models, they obtained results from the adopted approach more quickly.

While contributions [1,2,3,4,6,7,8] concern rotating electric machines, contribution [5] is the only paper dedicated to linear machines. The authors analyzed different single-phase tubular linear permanent magnet machines, and compared different original structures with partitioned stators, and a passive mover was sandwiched between two stators. The authors highlighted that the proposed machines possess the merits of lighter mover mass and much lower magnet eddy current loss compared with the conventional single-phase short-stroke surface-mounted PM tubular machines (SPSS-SPMTM).

Contribution [6] is dedicated to the study of cooling fluids for direct oil-cooled electric traction drives. The study is based on a thermal model of these drives. The cooling concerned both the stator and the rotor, which is equipped with a hollow shaft. An interesting experimental validation is presented. The authors obtained fair agreement between model-based comparisons and experimentally based comparisons.

In contribution [7], the authors presented a design study of an original eccentric rotor induction motor. While spinning, the rotor is allowed to touch the stator, hence the term “zero-airgap induction motor”, which is used in the title of the contribution. The authors claim that the use of such an eccentric rotor motor provides the possibility of removing the mechanical part that is typically found in the transmission oil pump, which allows for an increase in efficiency.

Finally, in contribution [8], the authors presented an interesting overview of the recent advances in multi-phase permanent magnet synchronous machines (PMSMs) and drive control techniques, with a focus on dual-three-phase PMSMs. A total of 201 relevant references were cited in this review paper. Aspects related to machine topologies, modeling, and control were addressed.