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Review of Course at Narva

As some of you already knew that I finally made up my mind to take a position in the academia rather than in the industry, it’s always hard for me to explain why. I’m neither a enthusiastic speaker nor a percipient thinker. It can be challengeable for me to go towards a position in a university. I thought that I should have lost my mind at that time. It drives me to explore my internal desire for this decision.

Before that, let me say some good word for our group, from the perspective of a native Chinese PhD. I have to admit that I’m so lucky to work in the EMD group, which “pulls” me to develop my research area in the postdoc period. (Footnote: the reason why I used “pull” rather than “push” is that I need to be efficient and open-minded dealing with my project work while exploring more research area freely. I don’t feel pushed or stressed out, and receive lots of help and supports. “push” is a negative word rather than a neutral word in my language). My supervisor Luca gave me the freedom to investigate the challenge and difficulty in the industry so that it could show the direction of our future work. In other words, I could work closely with Zparq and ABB to gain more experience.

In fact, it’s Luca who decided to join this project/team (ExpSkills-REM), whose latese event was to give the course at Narva. The aim of ExpSkills-REM is to educate professionals who work or intend to work in the field of permanent magnets along the whole value chain, including recycling and motor applications: Raw Materials, Technological Magnets, Circular Economy and Electromobility coming together. In Narva Estonia, Neo Performance Materials is building a permanent magnet factory, making it the first of its kind in Europe and the Western world. I hope this magnet product will be used in the permanent magnet motor soon. 

For this course, thanks to the help and support of Luca, I had enough time to prepare our one-day module “Design and fabrication of REM-based devices and components” for this four-day course. Everything goes on well on those days except the heavy snow in Narva when we were visiting the factory.

Then, it became sunny again in the nex day.

For me, it’s the first time to give the course for the whole day. It is definitely a milestone in my life, but really tiring. Hence, I took a wonderful sauna after the course. There were always lots of interesting and useful discussion about some contents of the course, which inspired the teachers as well.

Coming back to the first question in this post, when comparing academia with industry, one of the major difference is that the position of the academia requires the duty of teaching and supervision, which is as important as the researching. I then realized that it’s also a great joy for me to discuss about the technical detail in the project as well as the philosophy of life. I hope to support my future friends (namely students) to freely explore their research and lifestyle. I already have been lucky enough to get this privilege at KTH and ZJU and I hope in the near future I also have the ability to share this luck/opportunity to those who believe in this way.

As this is my last weekend at KTH, I would like to say Hej då to all of you, EMD noblemen, project colleagues, and EPE friends. Take good care of yourself, as it is merely the deadline of the course, project, or paper, not the end of the world. Keep in touch and see you again.


Il Risorgimento

Il sole sorge all’orizzonte e splende attraverso la nebbia. Sto guardando una nuova alba. If you’re not speaking Italian, I don’t expect you to understand that, so here’s the translation: The sun rises on the horizon and shines through the fog. I’m watching a new dawn.

A pretty lousy start to a blog, even if you ask me. No other comparisons made, it reminds me of the sloppy technique that Christopher Nolan used in his not-so-well-acclaimed Covid-19 release Tenet, where the audience was asked to accept the story rather than to understand it. A clear breach of trust as directors should never underestimate their audience. But bear with me!

Because after all, you might recognize a few words; and they all have something in common. Let me guide you through this loose tangle of Italian (word-) threads. The first suspect is the word sorge, from sorgere, which means to rise. The Risorgimento, the resurgence, was an emblematic and formative historical period of the Italian state where the peoples on the Apennine Peninsula finally were united under the umbrella of the Piedmontese-Sardinian kingdom. The first functioning administration was in place in 1861 and a rudimentary Italian parliamentary monarchy was governing the young country from the Piedmontese city of Turin, within commuting distance from the city of Alba, meaning dawn, at the center of Piedmont. Alba is most famous for its wines, most likely made from the Nebbiolo grapes that is the dominant variety in Piedemonte. The word nebbia, fog, is by the way the stem for the name of this grape variety. And for good reasons! Autumn dusks and dawns are more likely than not bringing fog over the scenic landscapes of the Susa Valley (where Turin is located) and its surroundings.

Clouds and fog from the summit of Pian del Lupo in the Piedmontese Alps at one of my bike excursions.

I know this, as I have experienced it first-hand since the beginning of September last year. At that point in time, I started a six-month research exchange at the Politecnico di Torino. When I look out my studio’s window over the roof ridges of the north part of the city center of Turin to the southeast (in the direction of Alba), I not only spot some of the memorials from the first Italian kingdom. I have namely had my fair share of nebbia to gaze through. And it’s not because I wake up every morning from drinking too much red wine.

Autumn fog surrounds one of the famous buildings in Turin: la Superga.

The stay in Torino has been a fantastic experience for me in many ways; personally and professionally. First of all, I’ve been trusted to contribute to the research conducted at PoliTo on automotive permanent magnet synchronous machines (PMSMs) and their fault tolerance. This is one of the areas where the research team under Prof. Gianmario Pellegrino at PoliTo has contributed some significant results lately. So being involved in that research is both an honor as well as a good chance to pick some of the masters’ brains. It has also meant that I’ve had to temporarily change track from the variable phase-pole induction machine, which has been the main subject of study for me during my doctoral education at KTH. As I’m sure you have experienced, such changes of scenery tend to sharpen your senses. As a result, we soon came up with an idea of how to swiftly determine which initial conditions that ensure the permanent magnets to remain healthy and the shaft torque to stay within acceptable bounds during an active short-circuit of the PMSM. It means that the car safely can come to a halt, whereas the traction motor will function, even after a severe failure of some other subsystem in the car (which triggers the active short-circuit). As such, the method can serve as a foundation for car manufacturers in their development of so-called functional safety systems. We will present our results at the ICIT conference in Bristol in March, so stay tuned.

Afternoon sun over the rooftops of Turin.

I cannot give enough credit to the people who helped me plan for the exchange, accommodated me at work once I arrived, and make my spare time in the city enjoyable. I will get back to you with some more news from the south of Europe before the end of my stay at the beginning of March.

Ci vediamo a dopo!



Study @ conference IEMDC2023

It has been half a year since I participated in this international conference. Before I start to memorize the event at that conference, I would like to recommend some good conferences that are related to our research field (Maybe useful for fresh PhD and master students).  ECCE and ICEM are two of the most famous conferences in the field of electrical machines, I think. ECCE is held every year, while ICEM is held every two years. Besides, I would recommend ICEMS, PEMD, and IEMDC which attract lots of motor engineers. For the motor design, Intermag and CEFC are good conferences, where many conference papers can be published in the IEEE Transaction on Magnetics. Meanwhile, IECON is related to the field of motor control. As the transportation electrification is more and more popular nowadays, I think we can consider submitting the papers to VPPC and ITEC.

Let’s come back to the conference IEMDC 2023. Please allow me to copy the description of this conference from the official website ( so that I don’t need to summarizeit :). The 14th IEEE International Electric Machines and Drives Conference (IEMDC) was held May 15-18, 2023 in San Francisco, CA. IEMDC provides a forum to share technology advances and new developments in the design, operation, analysis, and applications of electric machines and drives. Contributions are invited from industry, academia, and other sectors. Accepted and presented papers will be published in the Conference Proceedings, which will be submitted to the IEEE Xplore® digital library. Papers presented at IEMDC may be submitted to IEEE Transactions on Industry Applications, IEEE Transactions on Energy Conversion, IEEE Transactions on Industrial Electronics, or IEEE Transactions on Power Electronics, according to the rules specific to each journal.

This year, I guessed that only two hundred participants, which is not as large as before. For me, I found two interesting trends from the tutorial of the conference. The first interesting topic is the application of hairpin winding. Still, lots of researchers are working on the improvement of the hairpin winding. The professors from the University of Nottingham gave excellent speeches to show their findings. The other interesting topic is the application of additive manufacturing (3-D print) on motor design. The Marquette University built a high power density motor equipped with additively manufactured windings and integrated with advanced cooling and modular integrated power electronics, which is fascinating. Of course, other tutorial topics are very interesting, but I cannot join as they were held at the same time slot.

Photo at the conference

At the conference, I met lots of famous professors from all over the world and engineers from well-known companies. I felt that we needed to know more about the accomplishments that the company has already achieved and try to fulfill the needs of the industry if we could (or we can focus). That will be beneficial to both academia and industry.

Last but the least, I would like to present our papers at this conference entitled ”Design Comparison of Outer- and Inner-Rotor Permanent Magnet Motors for Hydrofoil Boat”. It gives some comparison of different kinds of PM motors. I hope to extend this paper soon and submit it to the journals.

Finally, I would like to present some beautiful pictures of San Francisco. I love the weather there. Even though I was told that it was dangerous in the city center, I felt safe during my stay. Some pictures around the city.

By the way, I’m looking forward to seeing the post of IECON 2023, in which I was absent. I believe that Yixuan, Gustaf, and Xinpo had a pleasant time in Singapore. It is really nice to see that EMDers reunite somewhere. I cannot say that I didn’t envy you guys. Also, I hope to see you all soon.

Merry Christmas!

The Christmas and new year that you deserve

Dancing Santa Royalty Free Stock Image - Image: 16438156

(Search on Youtube for “holiday night fever commercial” before reading!)

There are reasons why you should be or not be happy that the Christmas holidays are coming and the year 2024 is looming. It all comes back to two simple questions: how do you judge your 2023? How do you see the incoming challenges in 2024?

This is a post on KTH pages related to work, so I guess it is about work that we should discuss. However I want to make clear one thing: there is no work satisfaction (or dissatisfaction) that should impede you from having a healthy, balanced, interesting life outside the office. Sacrificing your family, relations, and friends chasing your career is not going to work forever. Sooner or later you will pay it back, in one way or another. You are warned!

So how do we feel about EMD 2023?

I’ll speak for myself, then everyone else in the team can express their views in separate posts…

I have referenced to a Youtube video showing the latest advertisement for a US credit card. It is not about the credit card I want to discuss (throw that part away from the video) but of Santa Claus himself. Do you know who is Santa in the video? If you are not too young, you should have recognized John Travolta, stepping back years in his role as the Italian-American Tony Manero in “Saturday Night Fever” (1977). The sketch also retraces some of the initial sequences of the original movie.

I have always admired John Travolta’s dancing prowess and I think it combines well to Santa’s main character to create a cool happy dude. That’s the same I feel about the past year at EMD. But I cannot dance like that so I let someone do it better :-).

There are many things that make me think positive about what we did. For the first, we must underline that the overall funding situation for our field of research is not the best you can find out there, with funding agencies largely ignoring the importance of electrical machines, their design, and their control for the great goals of sustainability. But I stopped complaining too much about that because we managed anyhow, and there are reasons to be happy beyond that.

Teaching is going well, very well indeed. Every year I get a group of students who enter the course EJ2201 Electrical Machines and Drives completely unaware of what is coming and get out of the course overwhelmed – with knowledge 🙂 . I can see that many develop an interest in the subject after going through the course, which is a good sign. Others are there only because they are forced to, but still, they seem to have a reasonably good time. All in all, I think that this entry course is very important to establish connections.

For those bold students that decide to continue on the path, from 2023 I have been also appointed responsible for the course EJ2230 Control in Electrical Energy Conversion, which is essentially control of electric machines. I did not have much time to make modifications to its content in 2023, but I am now almost ready for the next 2024 round, and I am excited about that.

I have also received great help during these three last years to keep alive the course EJ2222 Design of Electrical Machines, which came under my responsibility after the passing of our dear colleague Oskar, but that I never had time to develop as it has always been overlapping with EJ2201. Mats has helped me significantly to keep it going, and I will always be grateful for that. Now the situation has changed: I have reshuffled the courses along the year so that EJ2222 does not clash any longer with any other course I am responsible for. So! Are you really interested in electrical machines and drives? Join the master of electrical engineering at KTH and you will be able to:

  • join EJ2201 in the first semester, period 1 and period 2, August to December;
  • join EJ2230 in the second semester, period 3, January to March;
  • join EJ2222 in the second semester, period 4, April to June.

And if you do not have enough of me for an entire year, then you can continue with individual project courses and the master thesis, of course :-).

For those who think that teaching is heavy and a waste of time, I have nothing to say. To me, it is a great source of inspiration, recruiting, and a way to send good students ambassadors to work in the industry – which pays back later on ;-).

I mentioned industries. Yes, Sweden has many in the field and the opportunities to collaborate are also significant. Here the strangest of things happen. I could find 100 things to work on in collaboration with interested companies that would support us. However, the financial side is always an issue: a KTH doctoral student – plus all the overheads – costs a lot of money, and companies do not feel like paying that much without an additional external financial support. I can fully understand them – we are so damn expensive. And so we find ourselves writing applications to funding agencies, with the hope that the latter will recognize the importance of our work… sometimes it goes through, sometimes it does not. We’ll keep trying!

However, there is one company that said no, we do not need to play this game – I will pay you all. Those guys at ABB that decided that are amazing and I am really grateful. And scared: because we have a big responsibility to show the value of the money they invested in us. To be continued in 2024!

Let’s not forget, however, that in 2024 we will run doctoral and post-doctoral projects with many involved companies with big names. ABB, Scania, Volvo Cars, CEVT, Inmotion Technologies, and the little but interesting Zparq AB will be around us. We will deliver and learn a lot from them too.

All of this is not possible without the people – it is always about the people. With the EMD people you go on the safe side: give them a task and they will not disappoint you. On the contrary, they will surprise you with the depth and understanding of their work.

There is too much I could write for each of them and this post would become endless. But I can say this: when I realize that I do not fully understand what they are explaining to me about their work, and therefore I need to search for technical details in my old books and notes, that’s the moment when I feel my mission accomplished. This person has turned into a Searcher (not a researcher… re-searchers are re-searching things, while Searchers bring new things). We have only Searchers at EMD – I can guarantee that. I am proud of their work and how they are growing into their role, and I will support their next steps whatever road they want to take.

Ah yes, on the side of everything else, I also accepted to become deputy head of our division Electric Power and Energy Systems. So far I have been taking care of the “social side” of the division, organizing coffee breaks with sandwiches and pastries (the Swedish “fika”!) and information meetings. In the future, who knows. But it is nice to get in contact with other doctoral students working in other research groups – it gives you perspective, and a feeling of an enlarged family.

Let’s hope we can still be all John Travoltas at the end of 2024. So far so good! Merry Christmas and happy New Year!

A Review of the Review Process

Greetings! We hope this post finds you well and that you have enjoyed the holiday seasons. In Sweden, it is (still) fairly common to send postcards for Christmas to your nearest and dearest friends and family. I always appreciate the nicely decorated cards and the warm wishes you get from people spanning from your mother to your old primary school teacher.

This year, a very special message reached my Ph.D. student colleague Yixuan and me in the days between Christmas and New Year’s Eve. Our paper, Pole-Transition Control of Variable-Pole Machines Using Harmonic-Plane Decomposition, was approved for publication in IEEE Transactions on Industrial Electronics and the associate editor and reviewers congratulated us for having successfully passed the scientific needle’s eye known as the scientific review process. %Indeed, this marked a cornerstone in our ongoing research.%

At this point, you may wonder what grants this process such an uncanny metaphoric epithet. This blog will try to give a glimpse of what Yixuan and I experienced in the past year and describe the scientific review process from a practical view. In other words, we’ll set out to review a review. Feel that meta-discussion!

All of us have personal experiences with reviews. As a matter of fact, we were reviewed every time we got an exam back at school. And most of us have gotten stuck in front of a product, film, or book review on Youtube or in a newspaper. The scientific review has similarities with these types of reviews, but also some distinguishing differences.

Let’s start with the similarities. Indeed, one part of the review is a score (humans love numbers – see the book Sifferdjur by prof. Micael Dahlén), or in other words, how well you have performed. Some journals or conferences hand out a grade based on the average of the reviewers’ opinions regarding e.g. technical content, novelty, and language. Others, like the review we just went through, give a summarizing statement on the opinion of the reviewers and a pass/fail type of judgment. Either you get a pass (accepted) or fail (declined), or you are informed that the paper has to go through a minor or major review to be accepted. In our case, we went through five agonizing rounds of revisions before the manuscript was accepted after more than a year.

That brings us to a major difference to, for example, a film review. Whereas the film review is carried out on the final product, a scientific paper review happens before the potential publication. Moreover, the reviewers are incognito to ensure their integrity. The reason for these differences is dumbfounding simple and reasonable. In the world of science, quality is less of a taste thing and more about complying with specific standards on how to conduct experiments, display results, and analyze their validity. In order to cross these bars, the reviewers’ jobs are to find flaws in your argumentation and iron out any uncertainties that may be caused by the way you present the results. The review is in a way also a coarse filter whose mesh density each journal can decide on, on their own. Perhaps, the journal has a very defined theme and a high citation score, which puts even higher demands on the scope, standard, and novelty of your paper. For those of you unfamiliar with the term citation score, you can think of it as a reputation rank. Being published in the journal with the highest citation score is for the researcher the equivalent of performing at Carnegie Hall for a violinist.

A third interesting aspect of a scientific review is the correspondence of ideas and arguments that go back and forth between the reviewers and the manuscript authors. Questions from the reviewers are not always answered directly by making a change in the manuscript. Rather, longer answers, arguments, opinions, and explanations may be attached in what is called a review letter.  This is a sophisticated way of settling disputes, although I would have liked to try the French combat way at some point.

An example of such an argument in our case was the presence of a small but evil ~100 Hz harmonic on the torque measurement. One reviewer highlighted that it was visible in one of our plots and shouldn’t be there if our proposed control was correct. However, Yixuan and I noticed that the ripple was caused by a resonance frequency in the mechanical structure of the test bench (it is very big and heavy). The first thing we did to try our hypothesis was to jump outside of our cell. When we did that, there seemed to be an amplification of the 100 Hz signal of the vibration we were causing. Then, we moved on to use a commercial drive and motor on our bench and we still observed the same ripple, independent of speed. So we conveyed these measurements to the reviewer and could settle this issue. After the review rounds, I was performing locked rotor tests at varying frequencies on our machine and it was peculiar to hear and feel the humming due to the resonance when I passed 100 Hz. At least, I know where it comes from. Otherwise, I would probably have become a bit bewildered.

In the end, did our paper get better from all the review rounds? The answer is undeniably yes, although the incremental improvements became smaller the further into the process we got. The system appears to work. Kudos to the reviewers!