## Wednesday, 27 June 2018

### Coupled coils and coupling coefficient: from fraction of total flux to inductance definition

It is possible to relate the coupling coefficient $$k$$ to both the total ($$\phi_{1}$$ or $$\phi_{2}$$) and shared flux ($$\phi_{12}$$ or $$\phi_{21}$$) or to the self ($$L_{1}$$ and $$L_{2}$$) and mutual ($$M$$) inductances: $k = \frac{M}{\sqrt{L_{1} L_{2}}} = \frac{\phi_{12}}{\phi_{1}} = \frac{\phi_{21}}{\phi_{2}}$

Simple proof:

## Sunday, 3 June 2018

### Publication List using BibTeX and BibTeX-js

Sometimes it is useful to display a list of publications on a personal website.

There are many ways to do that, with the easiest being to write down each one by hand. While it is quite simple, it is also quite annoying and probably would leave the list not updated after few days (not a big issue for my few publications, but this is a different story).

One of the ways to deal with references is using BibTeX and the associated .bib files, which are the standard for $$\LaTeX$$ and used also by JabRef as the default database format.

There is a nice Javascript library, BibTeX-js, which is able to parse and display .bib files, with the rendering done on the client side when the page is loaded. The only thing to do is to keep an updated .bib file, which is not too demanding, since it is also used for references in the papers.

I therefore decided to share my template, which I personally feel quite clean and nice and would be maybe useful to someone else. It is responsive and the bib link acts as a button to show the bibtex code of the single entry. The books, journal papers and conference papers are separated automatically and ordered by the year, with the newest being first. The clickable link on the DOI is automatically added using the doi value, while the link on the publication title is retrieved from the url value.

As an example see my publication list (Alex Pacini's Publications).

## Wednesday, 10 January 2018

### Appunti Laurea Magistrale e Triennale, Ingegneria Elettronica, Università di Bologna, Cesena

A volte le vacanze natalizie sono utili per riordinare un po' e così, per liberare spazio, ho deciso di digitalizzare gli appunti. In realtà solo quelli più decenti, quindi non sono tutti i corsi ma solo alcuni.

Meglio sempre prendere il contenuto con senso critico, non dovrebbero esserci errori, ma nel caso lasciare un commento 🤓. Se pensate vi siano stati utili, accetto ben volentieri una birra! 🍻

## Wednesday, 6 December 2017

### Load- and Position-Independent Moving MHz WPT System Based on GaN-Distributed Current Sources

This paper describes the modelling, analysis, and design of a complete (dc-to-dc) inductive wireless power transfer (WPT) system for industrial moving applications. The system operates at 6.78 MHz and delivers up to 150 W to a load moving along a linear path, providing a quasi-constant dc output voltage and maintaining a zero voltage switching operation, regardless of position and load, without any retuning or feedback.

The inductive link consists of an array of stationary transmitting coils and a moving receiving coil whose length is optimized to achieve a constant coupling coefficient along the path. Each Tx coil is individually driven by a constant amplitude and phase sinusoidal current that is generated from a GaN-based coupled load-independent Class EF inverter. Two adjacent transmitters are activated at a given time depending on the receiver's position; this effectively creates a virtual series connection between the two transmitting coils. The Rx coil is connected to a passive Class E rectifier that is designed to maintain a constant dc output voltage independent of its load and position.

Extensive experimental results are presented to show the performance over different loading conditions and positions. A peak dc-to-dc efficiency of 80% is achieved at 100 W of dc output power and a dc output voltage variation of less than 5% is measured over a load range from 30 to 500 Ω.

The work in this paper is foreseen as a design solution for a high-efficient, maintenance-free, and reliable WPT system for powering sliders and mass movers in industrial automation plants.

This paper is published with Open Access on IEEE Xplore:

A. Pacini, A. Costanzo, S. Aldhaher and P. D. Mitcheson, "Load- and Position-Independent Moving MHz WPT System Based on GaN-Distributed Current Sources," in IEEE Transactions on Microwave Theory and Techniques, vol. PP, no. 99, pp. 1-10. doi: 10.1109/TMTT.2017.2768031

## Wednesday, 25 October 2017

### PhD Tutorial: Position and Load Independent DC to DC Wireless Power Transfer System for Moving Applications

In order to pass to the third year of the PhD at the University of Bologna, it is required to give a 40 minutes presentation to first introduce your field, in the form of a tutorial, and then briefly show your research.

The presentation is organized as follows

• Tutorial
• Introduction to Wireless Power Transfer (WPT)
• Inductive Power Transfer (IPT)
• Class E Resonant Inverter
• Advantages of Wide Bandgap Semiconductors (WBG)
• Research Contribution
• Geometry Optimization of Sliding Inductive Links for Position-Independent Wireless Power Transfer
• Design of a Position-Independent End-to-End Inductive WPT Link for Industrial Dynamic Systems