http://groups.yahoo.com/group/lrk-torquemax/ building high-torque brushless e-motors Fri, 06 Nov 2009 21:47:29 GMT ryanbiffard http://groups.yahoo.com/group/lrk-torquemax/message/12469 http://groups.yahoo.com/group/lrk-torquemax/message/12469 If you are designing your own motor, you can use FEMM to simulate the motor and calclulate the KV, there are tutorials on how to do that in the FEMM examples. Fri, 06 Nov 2009 11:17:40 GMT Christo van der Merwe http://groups.yahoo.com/group/lrk-torquemax/message/12468 http://groups.yahoo.com/group/lrk-torquemax/message/12468 You might be wondering what the use of Kv is, if it doesn't tell you the RPM under load.. Well, Kv is one of the 3 motor constants that's used to simulate a Fri, 06 Nov 2009 11:03:48 GMT jcroxall@... http://groups.yahoo.com/group/lrk-torquemax/message/12467 http://groups.yahoo.com/group/lrk-torquemax/message/12467 If possible how can I calculate the KV constant? [Non-text portions of this message have been removed] Fri, 06 Nov 2009 10:54:58 GMT Christo van der Merwe http://groups.yahoo.com/group/lrk-torquemax/message/12466 http://groups.yahoo.com/group/lrk-torquemax/message/12466 The Kv rating is the constant relating the motor's unloaded RPM to the peak (not RMS) voltage on the windings. E.g. a 100Kv motor will spin at 600RPM on 6V, Fri, 06 Nov 2009 09:51:17 GMT jcroxall@... http://groups.yahoo.com/group/lrk-torquemax/message/12465 http://groups.yahoo.com/group/lrk-torquemax/message/12465 What is the significance of RPM per Volt? Is this RPM that would be achieved with the bare minimum load at the maximum current flow dictated by the windings Fri, 06 Nov 2009 07:00:31 GMT Christo van der Merwe http://groups.yahoo.com/group/lrk-torquemax/message/12464 http://groups.yahoo.com/group/lrk-torquemax/message/12464 Scorpion motors are available as kits. It's much easier than trying to disassemble a motor. There are various websites i.e. www.innov8tivedesigns.com that give Thu, 05 Nov 2009 20:58:57 GMT ryanbiffard http://groups.yahoo.com/group/lrk-torquemax/message/12463 http://groups.yahoo.com/group/lrk-torquemax/message/12463 Since it is on a prop, sensorless will be fine. My understanding of fluid dynamics makes me think that the torque a prop needs increases with the square of the Wed, 04 Nov 2009 23:11:38 GMT Louis FOURDAN http://groups.yahoo.com/group/lrk-torquemax/message/12462 http://groups.yahoo.com/group/lrk-torquemax/message/12462 Hi A BLDC sensorless has a starting algorithm before getting a roughly constant speed During that period, torque is very irregular (could be back and forth Wed, 04 Nov 2009 21:51:39 GMT Christo van der Merwe http://groups.yahoo.com/group/lrk-torquemax/message/12461 http://groups.yahoo.com/group/lrk-torquemax/message/12461 Mark An electric motor produces full torque right from zero RPM, or shall I say, right from the moment it starts turning. Christo ... From: Mark Mickelsen To: Wed, 04 Nov 2009 20:54:23 GMT Plpastore http://groups.yahoo.com/group/lrk-torquemax/message/12460 http://groups.yahoo.com/group/lrk-torquemax/message/12460 Ok   I am read this messages, then I like to ask:   This external rotor the brushless DC motor your speed is low and very torque with linkage delta, ok, to Wed, 04 Nov 2009 20:45:45 GMT Mark Mickelsen http://groups.yahoo.com/group/lrk-torquemax/message/12459 http://groups.yahoo.com/group/lrk-torquemax/message/12459 I want to use it to direct drive the prop in a large model submarine. I don't think that that would require as much startup torque as a car or truck, but you Wed, 04 Nov 2009 19:42:47 GMT ryanbiffard http://groups.yahoo.com/group/lrk-torquemax/message/12458 http://groups.yahoo.com/group/lrk-torquemax/message/12458 I forgot to comment on the size and torque you mentioned. If you are talking about high startup torque, you will want sensored controller, sensorless doesn't Wed, 04 Nov 2009 19:20:46 GMT ryanbiffard http://groups.yahoo.com/group/lrk-torquemax/message/12457 http://groups.yahoo.com/group/lrk-torquemax/message/12457 As the others have stated, all brushless DC motors are variable speed, when coupled with the appropriate controller. As far as a good place to start Tue, 03 Nov 2009 12:52:47 GMT Mark Mickelsen http://groups.yahoo.com/group/lrk-torquemax/message/12456 http://groups.yahoo.com/group/lrk-torquemax/message/12456 Could you point me in the right direction as to where to start studying to learn how to design such a motor and where to find the type of esc I would need? Tue, 03 Nov 2009 07:27:51 GMT Christo van der Merwe http://groups.yahoo.com/group/lrk-torquemax/message/12455 http://groups.yahoo.com/group/lrk-torquemax/message/12455 Yes, it can be done. ... From: Mark Mickelsen To: lrk-torquemax@yahoogroups.com Sent: Tuesday, November 03, 2009 9:13 AM Subject: Re: [lrk] Variable speed out