## 5 Conclusions  
In the latest years, it became clearer that new solutions for passengers and goods mobility must be adopted in a final attempt to limit the effects of global warming on the planetary ecosystem. All major actors in the automotive market have taken steps in gradually eliminating the current internal combustion engines and replacing them with electric propulsion systems.  
The current study shows that the process of retrofitting a light electric vehicle with a fully electric drive, starting from the requirements defined in the L6 European vehicle class and going through all the stages required to develop an EV drivetrain. The common drivetrain topologies were evaluated, resulting in a system consisting of a central EM connected to the wheels through a mechanical transmission. This was the most suitable solution and was further investigated. Several EM structures were evaluated, resulting in PMSMs providing the required performance for the given constraints set. Two vari  
Figure 13: Data from a test run.  
ants were considered for implementation, the Interior Permanent Magnet PMSM and the spoke-type PMSM.  
A prototype was constructed based on a design/FEM-simulation/optimization process, and some of the tests performed are described in this article. The FEM-estimated phase voltage is compared with the measured one, showing a very good accuracy both in wave form and value, validating the entire process. Similar results were obtained between the measured and estimated electrical parameters of the prototype, and these values were used to parameterize the commercial SEVCON power converter used for this application.  
The test bench that was constructed to test the PMSM prototype was presented in Section 3 of the article, allowing the emulation of WLTP drive cycle by using a DC Machine. It worked as a load when the PMSM was operating as a motor and worked as a motor when the PMSM was functioning as a brake/generator. Test results showed good accuracy between the imposed WLTP speed profile and the measured values; the variation of mechanical power and battery power was also presented, allowing an estimation of the vehicle's autonomy.  
Once the on-bench testing validated the estimated results, the PMSM prototype was integrated into a light vehicle and tested in real-life conditions, showing that the required operating regimes can be achieved. The main novelty of the article consists of the presentation of a full development process of a drivetrain for the light electric vehicle, specifically the Lee European class. Although similar PMSM structures using ferrite magnets [26; 27] were previously investigated in the literature, this paper provides a guideline for a full development process. It begins with the requirements, goes through the lengthy design-simulation-optimization-prototyping-testing process, and finally validates the procedure by integrating the drivetrain on a light EV and testing the prototype in real-life conditions.  
Conceptualization, S.B. and C.-A.O.; methodology, S.B., P.-D.T.; software, A.-M.P.; validation, M.D., M.C., A.-M.P., S.B. and C.-A.O.; writing--original draft preparation, S.B.; writing--review and editing, C.-A.O.; supervision, C.-A.O., P.-D.T.; project administration, C.-A.O.; funding acquisition, S.B. All authors have read and agreed to the published version of the manuscript.  
This paper was supported by the project \"Advanced technologies for intelligent urban electric vehicles--URBIVEL--Contract no. 11/01.09.2016\", project co-funded from the European Regional Development Fund through the Competitiveness Operational Program 2014-2020.  
Not applicable.  
Authors are grateful for the technical support given by [PERSON], Senior Applications Engineer at BorgWarner Southborough Inc.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.