|SinusLeistungsSteller - FuriaOne 2012|
FuriaOne at the Frisian Solar Challenge 2012
From the 8. until the 14. of July 2012 the Frisian Solar Challenge took place. We were also there, represented by the SLS-60-200-1PM. The solar boat of the Private Energy Solarboat Team around Gerard van der Schaar from MG-Electronics equipped with our SLS reached the second place!
The 1. place was possible for sure, but .......... we will explain the details from the beginning:
Gerard van der Schaar was in contact with us for a longer period of time regarding the SLS-60-200. In the beginning of June 2012 (so less than 4 weeks before the beginning of the Solar Challenge) the new TORQSTAR- Motor from Lehner was available and ready to be tuned on the SLS. The problem was: how to tune the motor under these circumstances, without transporting the 7m long solar boat from Holland to Würzburg? ... and everything under huge time pressure? For that we had to improvise! :-)
But first a few details about the motor:
The TORQSTAR is Lehners first outrunner and we were curious if this motor also would have had the for Lehner-motors known
(and for SLS ideal) sine shaped generator voltage. ...in short: IT HAS!
The remaining characteristics of the motor also show that we have a "real Lehner" in front of us:
The prewound (and formed?) windings are positioned in the rectangular stator slots (pressed in?) and are held there by the resin. The interconnection of the individual windings is accomplished via a multilayer-FR4-PCB. By that, it should be possible to carry out different kinds of interconnections. Between the shaft and the stator core lies a embedded aluminum ring, which has a air troughlet under each winding. The integrated (centrifugal-) fan assures that these troughlets are supplied with fresh air, so the "bad- cooled-stator-problem" usually occuring on outrunnes is not a problem for this motor. The longer this motor is studied, more and more nice details appear! Overall this motor gets the best rating from us!
To tune the Torqstar with load, we mounted the motor on our test-bench with a 1m propeller. With the right pitch setting, we were able to approach the point of load which Gerard told us. After 1 minute at 100Aac the winding reached 90°C (start at 30°C)...
Meanwhile Gerard´s team works on the drive train of the new solar boat. All had to be constructed preferably with little resistance and designed sleekly ... every Watt of power, which does not need to be invested in friction is additionally available for the motor and makes the boat faster! The against each other rotating screws should avoid the undesireable (useless) twist of the accelerated water and convert it to additional thrust.
End of June everything was ready: motor and SLS got their place in the solarboat and the first test drives were done.
... and than the Solar Challenge begun:
The actual challenge: Besides a sprint more day stages of overall 220km need to be completed. For this, only the energy produced by the solarcells (plus the stored energy of a small buffer accumulator) is allowed to be used. For both disciplines (sprint and cruising) the preconditions are actually ideal for the SLS, because it is designed for highest efficiency (especially in partial load situations). The weather forecast was rather mixed, so strict householding of the energy in the accumulator was important. The determined motor stability for the sprint at max. power seemed more than adequate and the new airfoil-concept had proven itself during test drives with amazing speeds up to 38km/h.
Everything was fine ... actually ...
... but something goes always wrong:
The 3. day (being first in the overall results!) the motor catched fire! Presumably a single (winding) wire detached in the casted resin and was caught in the air gap. All ended with a chain reaction ..... A moment later the motor was under fire! ... the leading position was lost!
Nevertheless: the SLS-60-200-1PM remained undamaged! Despite the short circuit in the motor the controller remained fully functional! The following day was planned for resting ... so a vague possibility remained to replace the motor and to drive on the 5. day. There was nothing damaged besides the motor ...
The same evening Gerard wanted to fly to Munich, in the hope that Lehner has a identical motor on stock. By the last call attempt to Lehner (before boarding the plane to Munich) all hope was gone: unfortunately no identical motor is currently available! ........ Gerard calls me at 9pm on the cell phone and asks me, if it is possible to rewind the motor. I had my concerns regarding the parameters, I thought it is impossible, because the original winding is pressed. So reproducing it without this pressing process can not be done. Variations in wire size or the number of turns would no longer match the data stored in the SLS like motor inductance- or resistance values. The SLS - certainly - can compensate some variations, but were is the limit? This way the SLS would have a hard time controlling the motor correctly ... and with incorrect parameters everything is possible, even a hardware failure; unfortunately we experienced this before! ... Gerard hung up with a disappointing sounding "good night" ... I thought myself: it's over!
... In the afternoon of the following day I hear, that Gerard found a company in the Netherlands, which can rewind the motor a (I still believe it is not possible to reproduce the winding exact as the original). The 5. day I expected the message about a defect SLS ...
... but again everything developed differently!
The next day I read about the unbelievable results result list of the 5. day , "our" boat with the start number T83 crossed the finish line with only 1 minute delay to the second position! The motor works again and the SLS handles it (howsoever this can be)! Gerard tells me the same day, that the motor did not operate optimally (apparently the magnets have been damaged during the burning) and the full power can not be achieved. But it works!
Until the end of the Solar Challenge our boat fights up to the 2. place and even wins the closing stage!
Where would it all have ended, when this little wire just stayed where it belongs? ;-)
Some consolation for Gerard: 1. place won his old solar boat, which Joop Steenman borrowed for this challenge.
Gerard thus defeated himself! ;)
Following, some great impressions of this great event (No. T83 is our boat!):
The next time I will experience it live! ... but you should know a bit Dutch ...;-)
(09. July 2012)
(10. July 2012)
(11. July 2012 - including the repair of the Lehner-Motor!)
(12. July 2012)
(13. July 2012)
(14. July 2012)
(Many thanks to Gerard van der Schaar for first-hand pictures and info!)