SinusLeistungsSteller - SLS Development/2008 |
In this section we provide frequently news on development and progress ... Details about the SLS are found here (click...) 18.10.2008: We think about electric road-cars, since the further increase in fuel prices in the past few months. The SLS is from sight of power capability (10KW), perfectly suitable for smaller and lighter cars. Because the SLS is only able to work with brushless motors without sensors at the moment, a clutch is needed for start (sensorless operation only allows low torque at very low RPM). So, in the future we want to develop SLS with sensor inputs, which do not require a clutch. As a first approach in this direction (still with centrifugal clutch) we want to show the Elektro-Quad of Markus Landeck. 08.10.2008: Within a industrial project we confirmed flawless operation of the SLS over a 70 meter(!) long DC-supply line. A SLS-60-100 was operated more than one hour with up to 1.500Watt - without any interruption! More power was also possible, but the used voltage-source did not allow more. The voltage drop over the line already was about 10V. No additional capacitors were used along the supply line, which is done and required by other controllers, even at short distances. The SLS alone (at the end of the power line), has no additional electolytic caps built in - just the two 1000ĩF, which are standard parts of the SLS. 03.07.2008: ... SLS at land - SLS at air - and now also SLS at water! ... man-carrying, of course! We visited the ship engine manufacturer Bieschewski (www.e-jet.org) and were able to test 2 different boats right away (the Bieschewski-solarboat and the "Brummer" of Torsten Wernecke ) on a lake ... during the hottest day of the year, so far! The last test of an outborder of a 3. boat had to be done (due to a intense thunder storm!) inside a tank in a hall. The present combination of motor+propeller could not completely show what would be really possible, but even in the already tested partial load range it makes a lot of fun. ![]() ![]() ![]() 04.06.2008: From now on the digital Servotester ST is ready for purchase! 08.05.2008: At the beginning of the year we provided the power module (PM) with "tabs", to make it easier, to mount extern heatsinks on the SLS. The user can choose between the cooling methods (fan, water-cooling, external heatsinks). For this purpose the SLS provides a mechanical interface of 4 mounting points (hole size 74.0mm x 17.0mm) for each power module and ensures optimal cooling. The modifyed potting mold is also available now - the first potted SLS with 2 PMs and tabs can be seen in the picture. This "full configuration" weighs only 500g - incl. the new milled copper bars (they are already designed for the planned 300A+ versions!) and both capacitors. we can also build the SLS version with only one PM, with tabs (see below). Thanks to the new potting mold the SLS is also 4mm flatter (The SLS with 2 PMs is 19,0mm thick, and with one PM only 15,0mm). And accordingly weighs only about 350g. I would also like to draw your attention to our new digital Servotester ST, which we will deliver most likely at the end of May for the SLS or controllers from other manufacturers. ![]() ![]() ![]() ![]() 14.03.2008: Just in time, for the start of the paragliding season, we got Werner Eckīs new motor for fine tuning on our SLS. Werner flys this motor with a propeller (optimized for paragliding) with a diameter of 1,40m. The motor is designed for a speed of about 2000 RPMs at 14S-LiPo and runns the propeller directly - without any gear! The resulting benefits in terms of noise and efficiency are easy to understand ... Unfortunatelly our test-rig has limited ground clearence. Therefore we were only able to use our 40"-Propeller for testing. By increasing the pitch up to 38° "step by step", we were able to reach the power-level of the 1,40m propeller at desired RPM. During the end of our tests, we achieved power-levels over 8KW. For the tests we used the SLS-60-200 with only one power module + a external heatsink. With this setup the motor did well: he never showed a temperature increase over 50K compared to the ambient temperature ... A SLS with 2 PMs more likely has the chance to reach the motor limits - but than we talk about 16KW!!! Where is the power supply for such a thing and seriously, who needs this? ;-) In the last image we see the AC-motor current at the maximum speed of 1.965rpm at 51Vdc. The field-frequency (calculated back to a 2-pole-motor) is almost 42.000rpm. The amplitude of the current is scaled 1mV/A. ![]() ![]() ![]() ![]() 20.02.2008: My vacation is unfortunatelly already over ... but I am looking forward to the work ahead, because in the following time new projects are on our to-do-list :-) ... New: The "Aktive Vorladeschaltung" AVS is available now in a new version with SMD-LEDs. By that, the AVS will be more compact and the LEDs can be seen better in sunlight. 21.01.2008: Peter Schmalenbach visited us with his TF8000 during weekend. The 145mm-impeller is equipped with a LMT3060-14-8 (Kv=860RPM/V with delta connenction), which can not use the full motor power. Actually it should be a LMT3060-18-10, but it was available here ... This suboptimal design reached with 26.500rpm (that are only 70% of the max. RPM) with a motor current of 200Aac, the AC-current-limit of our SLS-60-200 (no heatsink, no airflow). At a simulated 12S-LiPo-pack (44,4Vdc) and a battery current of 160Adc at least more than 7.000W! With the right motor, 10kW should be possible ... You can see in the diagram, we redirected the airflow between the SLS peaks for additional cooling in order to shorten the wait-times till the next measurement. The temperature dropped down immediatelly! In Peterīs next project ("Panther" with 1,85m wingspan!) are enough opportunities, to cool down motor as well as the SLS :-) ... we are looking forward to it! By the way when comparing the TF8000 with our self-made impeller (see below) he had no problems with unbalance or vibrations! He could directly be mounted on the the test-rig surface. Thanks to the open constructed motor carrier, he came never in critical temperature range... a very good impeller! ![]() ![]() ![]() ![]() 18.01.2008: In the new year we continued a test series with a 125mm impeller-drive, started in December. The tests in the previous year failed at about 27.000rpm ...some stator blades detached and flew like bullets towards us. The impeller was most likely not designed for such a high RPM. So we decided to completely rework the impeller: all CFK-parts were seperated from each other and cleaned. The contours of the junctions were then drilled and each part sewed with Kevlar cord. Than we fixed these seams with resin, to stabilize it during operation. In order to dampen mechanical oscillations in the tube, it was reinforced on the outside with a layer of Kevlar and resin. The impeller was mounted at the test bench board, via slightly flexible synthetic fiber cord, for decoupling mechanical vibrations. This method works very well, but the thermal image showed a noticeably high cord temperature, which could harm and damage the cord! Today we came to a max. of 32.000rpm at 145Aac. This means about 160Adc at 30Vdc (=4,8kW) on the DC-side. During the whole test neither the SLS nor the motor exceeded 60°C. We used a SLS-42-220 with one power module with a external heatsink. The motor was cooled (with a self-made heatsink-star) by airstream. This time, the SLS was not placed in the airflow! |