Nyhetsflöde

Dear students,

Below is important information about the study visit to ABB Corporate Research, ABB LV Motors and ABB Machines.

Who can attend: The bus takes 49 passengers. The registered students are listed here. If your name is marked in yellow, you can only attend if students higher up on the list don't show up. 

Date: Wednesday Nov. 16th.

Time and place: The bus leaves from Lindstedtsvägen 3 at 7.50 SHARP. Be there on time or you will not participate. 

Lunch: ABB Corporate Research serves a salad lunch to each participant.

Best,

Oskar

Dear students,

Eq. (1) in Project 3's project description contains a typo. The correct expression should be:

$$T_e\!=\!\frac{3p}{4}\left(\psi_di_q-\psi_qi_d\right).$$

Here is the project description without the typo.

Sincerely,

Oskar

Dear students,

Petter Eklund provided the following neat tips regarding how the code for Project 1 can be made faster:

In Geometry.m: 

Change line 7 to:
mi_probdef(SlipFreq,'meters','planar',1e-8,ActiveL,30,1);

The last parameter (=1) causes the solver to use Newton-Raphson which will render the solving times considerably shorter.

Thanks Petter!

Best,

Oskar

Dear students,

After yesterday's two lectures, the complete course content has been covered. To really grasp the more advanced aspects covered in Chapter 8 (the interaction between eddy-current and hysteresis losses and Tellinens's hysteresis model) you absolutely have to spend some time with the text in your study chamber.

Further, Claes pointed out an error on one of the lecture slides (the missing \(j\)). Here is the corrected slide (the error is not present in the course book).

Looking forward to discuss with you during the coming project tutorial sessions.

Sincerely,

Oskar

Dear students,

Some input regarding Project 1 following the discussions during today's project work:

• When computing the rated torque using FEMM and comparing with the motor rate plate data, it is reasonable to assumed that the rotor bars are not at room temperature; 100 degC is more close to reality.
• Remember also to take the short-circuit ring into account when setting the conductivity for the rotor bars (as outlined in the course book).
• The air-gap length is close to \(\delta\!\approx\!0.3\) mm (rather than 0.4 mm I saw that some used in their code).

Best,

Oskar

Dear students,

Here is a photo of the motor template for the motor used in Project 1 and 2.

Best,

Oskar

Dear students,

After today's lecture, Chapter 5 and Chapter 6 have now been covered in complete. On the two coming lectures, I plan to cover Chapter 7 (first lecture on Tuesday Sept. 27th) and Chapter 8 (second lecture on Tuesday Sept. 27th). 

Best,

Oskar

Dear students,

Today, I covered Section 6.1 to Section 6.7.2 in the course book. During next lecture, I aim to cover Chapter 6 in complete and conclude with the remaining FEM theory in Chapter 5.

Best,

Oskar

Dear students,

In Project 1, assignment 2.1 b), you may learn more by plotting the radial flux density from FEMM using a material in the rotor and stator laminations with very high relative permeability (e.g., \(\mu_r\!=\!10000\)). In this way, the impact of magnetic saturation will be removed and the agreement with the theory developed in Chapter 1 will be better. In summary, for assignment 2.1 b), it is ok to use a "linear steel" when comparing with theory.

Best,

Oskar

Dear students,

For Project 1, I have received some questions about how to add a contour in the whole air gap in order to plot, e.g., the air-gap flux density. It can be done in several ways but this is how I implemented it in Matlab:

%Clear all selected contours (if any)
mo_clearcontour;
%Define a contour in the middle of the air gap
mo_addcontour(0,-RotorRad-AirGapHeight/2);
mo_addcontour(0,RotorRad+AirGapHeight/2);
mo_bendcontour(180,5);
mo_addcontour(0,RotorRad+AirGapHeight/2);
mo_addcontour(0,-RotorRad-AirGapHeight/2);
mo_bendcontour(180,5);

Best,

Oskar