On 09/30/2011 07:52 PM, emc-users-requ...@lists.sourceforge.net wrote: >> > Is there any chance that I have to set something that is not 8? That >> > Keling's spreadsheet says that motor has 8 poles. It took me a while to find this web page:
http://www.southernsoaringclub.org.za/a-BM-motors-3.html The topic covered is using stators from old CDROM motors to wind new powerful outrunner motors, which are a type of brushless DC motor. There are 5 pages in this series, and they give a comprehensive look at winding and driving brushless DC motors (at least the RC type. Though there may be an exception to the rule, the rule is that all BLDC motor controllers for RC vehicles are designed to drive 3 coils, or phases. RC controllers are meant to drive a motor at reasonable speeds so that they can get the motor going in an asynchronus manner, and when it gets moving fast enough they can check winding voltage to find out when to switch the electronic commutation. The motor will have stators with poles in multiples of 3. For a 9 pole stator, generally each coil will be wound around 3 poles equally spaced apart. For a servo motor a lower limit even as low as 300 RPM would be too much for the application, so BLDC servo motors have hall sensors, or incremental encoders to provide feedback for commutation. If the motor comes with 3 hall sensors, then it "should" be intended to be driven with a 3 phase driver. Inside it could have 3, 6, 9, 12, 15, or 18 poles (or perhaps more), but it will still only have 3 distinct coils, and 3 phases of drive. If Keling says there are 8 poles, perhaps there are, but that would probably require a four phase controller, and that would be unusual. * The final word, if there are only 3 hall effect sensors, you should only have to be concerned about 3 phases.* Check out the chart on the web page above. Also recommended, even if you are not planning to fly an RC airplane with the guts of your defunct CDROM drive, are the other 4 pages of this series. They may give you more insight into what's happening under the case of that expensive servo motor that you wouldn't want to take apart. ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2dcopy2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
