Francisco J. Márquez-Fernández

Design, optimization and construction of an electric motor for an Electric Rear Wheel Drive unit application for a hybrid passenger car

An Electric Rear Wheel Drive -ERWD- unit is a cost effective solution for the electrification of passenger cars. While the conventional front-wheel transmission is kept, the ERWD unit provides electrical torque to the rear wheels and regenerative braking capabilities. In this article the design, optimization, construction and testing of an electric motor for such unit is presented. The experimental test results are compared to the FE simulation results from the design stage in order to validate the design tool.

Dynamic evaluation of the overloading potential of a convection cooled permanent magnet synchronous motor

In order to obtain the maximum efficiency from a hybrid driveline it is crucial to optimize the power distribution between the electric drive and the internal combustion engine. An accurate estimation of how much electric power can be delivered at any instant of time is therefore of great interest. Such estimation is dependent on several factors, as the state of charge of the battery, the temperature and the cooling conditions of the motor and the power electronics at that particular moment. This article proposes a method for evaluating the overloading potential of the electric drive dynamically at any time, based on a previously developed thermal model. Alternative modelling techniques are discussed and the resulting thermal model is validated against experimental measurements.

Heat transfer analysis of a traction machine with directly cooled laminated windings

A directly enhanced cooled winding in an electrical traction machine has the potential to extend the operation range, which is in particular attractive for a traction application when operating near peak power for extended periods of time. This paper presents the heat transfer analysis of a modular machine segment with a laminated winding. The laminated winding has a great potential when it comes to production of the winding and the thermal management of the excessive power losses in the winding. The prototype is built and assessed based on experimental measurements and finite element analysis. The results indicate some practical challenges of integrating the combined heat exchanger and winding and controlling the coolant flow through the machine construction. The prototype machine shows a limited enhanced cooling capability mostly due to flow leakage while the results from the simulation models indicate the great potential of direct cooled windings.

Scalable performance, efficiency and thermal models for electric drive components used in powertrain simulation and optimization

A methodology for designing and scaling the performance and thermal characteristics of electric powertrain components is presented. This methodology is aimed at finding optimum component combinations based on a set of requirements. Both drive-cycle performance and specific operating modes such as curb-climbing and maximum wheel speed are considered. This allows the selection of electrical machine topology, the design and sizing of the related gearbox, as well as the power-electronic converter needed to fulfill the wheel torque and speed requirements for all operating points, including overloading. Utilizing subsystem-models inside an optimization loop, the powertrain components can be sized using a number of goals such as lowest cost, size, weight or combinations of these, while still fulfilling the target specifications for a number of powertrain layouts.

Electric roads: The importance of sharing the infrastructure among different vehicle types

Electric Road Systems (ERS) are analysed here as a feasible solution for the electrification of heavy traffic, where the predominant approach for passenger cars based only on batteries and a network of fast-charging stations combined with slower overnight charging becomes unrealistic due to the large amount of batteries required. Nonetheless, this study shows that in most cases, building such ERS so that they can be used by both types of vehicles results in added value to society.

Electric roads: Reducing the societal cost of automotive electrification

In this article five scenarios for fully electric road transport in Sweden are compared, looking at the total system cost for different combinations of battery systems, vehicle equipment and charging solutions, including the use of Electric Road Systems (ERS). The main objective of this work is not to provide accurate price estimations, but to help understanding the main cost drivers of transport electrification and to illustrate how the final system cost is influenced by the different parameters considered. The main conclusion obtained is that, despite the substantial initial investments required for the deployment of electric roads, a system featuring only static charging and vehicles with large size batteries results in a higher total system cost. Moreover, due to the much larger number of light duty vehicles in the fleet, the deployment of an ERS system that can be used by both long-haul and light duty vehicles is substantially more advantageous than a solution restricted only to long-haul vehicles.

Optimization of Electric Powertrains Based on Scalable Cost and Performance Models

This work presents a methodology for modeling, designing, and scaling the electromagnetic, mechanical, and thermal characteristics of the main components in an electric powertrain (excluding the battery), i.e., a power electronics converter, an electrical machine, and mechanical transmission. Additionally, a framework for estimating the cost of these components is described. This framework takes into consideration not only the material cost, but also all major manufacturing steps required for the production of a component and their dependence on expected production volumes. Moreover, a procedure to optimize the design of an electric powertrain, taking advantage of the aforementioned models, is proposed. Finally, the powertrain for a passenger electric vehicle is optimized using the proposed methodology, and the results are compared in terms of the electrical machine topology, powertrain concepts, cost, weight, gear ratio(s) in the transmission, and overloading capabilities.

Experimental Validation of a Thermal Model for High-Speed Switched Reluctance Machines for Traction Applications

This paper presents the experimental validation of a novel cooling concept applied to a high-speed switched reluctance machine topology for traction applications. By circulating the coolant between the coils and the stator poles, the winding and the stator iron are virtually thermally decoupled. A number of test motorettes are used to demonstrate the potential of the cooling concept at current density values up to 27 A/mm2 continuously. The measurements are also used to validate a thermal model of the machine, and further improvements of both the model and the experimental setup are proposed.

Dynamic charging solutions in Sweden: An overview

Dynamic Charging, meaning supplying electric energy to electric vehicles while moving and also referred to as Electric Road Systems (ERS), can be implemented in a number of different ways. In Sweden, no less than four different technologies are being developed and/or demonstrated. This is, in an international comparison, unique. This paper represents an effort to describe these different technologies and their known and expected properties.