According to Marie Skłodowska-Curie Actions guide: "Secondment is a period of research training with another beneficiary or a partner organization implemented to further enrich the training experience of a researcher."
In my case, the secondment at the SIEMENS was planned for May 2020, and the main subject was defined as "practical experience in semiconductor environment." However, due to COVID 19, several plans and visits to the UK were canceled. Therefore, to complete the industrial secondments in accordance with my contract time. There was an agreement between the parties, and my secondments at the SIEMENS were carried out virtually.
Initially, many conversations with Mr. Lonsdale from SIEMENS were carried out to define a scope for secondments. The fisrt proposal considered to provide a report, covering (see also Figure 1):
• complete detailed process to model the common mode choke (CMC) and windings (cases for 1 and 2 windings) based on COMSOL. Furthermore, the complete detailed process for impedance extraction.
Figure 1 - Illustration of CMC modelling with COMSOL.
Nevertheless, after the second round of conversation with Mr. Lonsdale from SIEMENS, the topic of leakage inductance was defined. However, looking in finding formulas or rules for estimating leakage inductance toroidal chokes.
A report was developed with an emphasis on leakage inductance models. Some leakage inductance models were analyzed based on renowned journal papers (high number of citations). The main aspects of each simulated model were compared with real leakage inductance measurements, and the models' errors for different wire diameters of the winding coil were presented.
As the main conclusion, the report highlighted that the Nave model does not accurately predict leakage inductance over large numbers of turns. Thus, from the perspective of the analogy between reluctances and capacitances, the Ren model proposes a leakage inductance model to improve the accuracy when the CMC has a large number of turns. Figures below (from left to right) show a comparison between the error of the models.
In order to consolidate the activities carried out and presented in the report, a virtual meeting was held with the SIEMENS simulation team on March 25th. In the meeting, as directions for further developments, I recommended:
• H-E fields evaluation for a CMC;
• Modelling process development for a capacitor (the same steps used for the CMC);
• Complete prototyping evaluation of an EMI filter (modelling and measurements);
• Stray capacitance and leakage inductance evaluation (modelling and measurements).
Although I am approaching the end of my period in the SCENT project. Much was discussed with Mr. Lonsdale from SIEMENS about future cooperations. One idea under development is the donation of CMC to Douglas Nascimento (ESR 9 of the ETOPIA Project) to carry out some measurements.