Peter Christy Posted June 14, 2020 Share Posted June 14, 2020 A bit of background: I've been converting vintage helicopters to electric, and for the last two conversions I've used Neuron escs because of the telemetry they provide. I had trouble with the esc overheating in my first conversion - A Schluter HueyCobra - which turned out to be caused by the drab olive green camouflage paint absorbing a lot of sunlight! That just had an ordinary speed controller, hence my desire to adopt the Neuron for my next conversions! My first issue was getting the wrong rpm readings for the motor. I guessed that the esc needed to know the number of poles, but couldn't see where this was adjusted. Chris Bott kindly pointed me in the right direction, and my Lark conversion (Neuron 40S) seems to be giving the right reading once the number of poles was set. Moving up in size, my Schluter DS-22 did NOT seem to be giving the right readings, despite having the correct pole count set (Neuron 80). This is important on this machine, as it has an early collective pitch head, and needs to be run at around the right rpm. The head-speed is too low to measure on a conventional tach, so I needed to get reasonably accurate rpm readings from the motor. The tail rotor has a 3:1 reduction from the motor. This morning, I ran it up in the garden without the rotor-head, set the motor speed to an indicated 3000 rpm and tach'd the tail. It should have read 1000 rpm. It actually read 2000 rpm! In the telemetry set-up, in addition to the pole count there is a setting for "multiplication factor", which defaults to 1. I set this to 2, and now I get the correct readings! Can someone please explain what determines if this "multiplication factor" needs to be changed? There must be some reason for it being there, but nothing is mentioned in the (rather skimpy) manual, and I have been unable to find any guidance anywhere! Why does my DS-22 need it and not my Lark? (admittedly very different motors) If setting up a system from scratch, how do you know if it is needed or not, other than by guesswork or trial and error? Surely there must be some kind of logic to work this out! Over to you guys! -- Pete Quote Link to comment Share on other sites More sharing options...
Geoff S Posted June 14, 2020 Share Posted June 14, 2020 That's very interesting, Peter, because I was surprised at the rpm readings I was getting last evening with my Neuron 80 esc. I was in artifiial light so I was unable to check with an an optical tacho but I tried it this morning and the tacho shows 8k rpm and the Neuron 5.5k rpm. Unfortunately, I have no idea how many poles my motor has. It's an XYH 5055 I bought some years ago (from Giant Cod who haven't been trading for years!) but I think it's similar to the Ripmax QuantumII 61. Unfortunately, Ripmax (like some other suppliers) don't publish a spec. - not even a maximum continuous current rating. I thought the motor had a kv of 700 rpm/volt but, with the optical tacho it seems nearer to 600. The telemetry blades/poles is showing 10 with a multiplier of 1, which I guess is the default. I'm guessing there are more poles than 10, so perhaps I'll try 8 Geoff PS that still under read rpm slightly and setting to 7 poles was much nearer. Can you have an odd number of poles? I'm afraid I didn't tke a lot of interest in motors when I studies HNC electronic/electrical engineering in the early 60s and in any case brushless motors of the type we use now weren't around. Edited By Geoff S on 14/06/2020 12:42:06 Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted June 14, 2020 Share Posted June 14, 2020 I think I must be using magnet pairs as my UltraStick and Deuces Wild are set up as a multiplier of 7 though the logs are complete garbage as my RTC was flat when the last logs were recorded so I can't see what was true values were. I do remember that the telemetry widget looked about right when spinning up the motors. I'm not confident of the logs when session times are showing -16k lengths! Edited By Bob Cotsford on 14/06/2020 12:52:56 Quote Link to comment Share on other sites More sharing options...
Dickw Posted June 14, 2020 Share Posted June 14, 2020 Posted by Geoff S on 14/06/2020 12:29:27:.................................. PS that still under read rpm slightly and setting to 7 poles was much nearer. Can you have an odd number of poles? I'm afraid I didn't tke a lot of interest in motors when I studies HNC electronic/electrical engineering in the early 60s and in any case brushless motors of the type we use now weren't around. Edited By Geoff S on 14/06/2020 12:42:06 I don't think an odd number of poles is likely as it is the magnetic poles we are counting so the number should go up in multiples of 2. A motor with (e.g.) two south poles adjacent sound very unlikely to me. Don't forget if you are checking rpm "off load" against volts x kv that the motor will never actuall reach that speed. Dick Quote Link to comment Share on other sites More sharing options...
Peter Christy Posted June 14, 2020 Author Share Posted June 14, 2020 Hi Geoff, My motors were both Overlanders, and they do publish the number of poles. I have a feeling that the number of poles - which I assume refers to the electromagnets - does not have to be the same as the number of permanent magnets, and that could be why a multiplier is needed. However, I'm far from an expert on brushless electric motors! If its any help, my DS-22 uses a 14 pole motor and needed a multiplier of 2. My Lark also uses a much smaller 14 pole motor, but doesn't seem to need a multiplier. It has a much higher kV rating, so I'm guessing its to do with the number of poles vs the number of permanent magnets. 5055 usually refers to the can size. The motor in my DS-22 is a 5055/06, 580kV motor. Maybe try the figures I've used (14 poles and X2) and see if that gives a closer reading? Until someone more knowledgeable comes along, I'm running by guesswork here! -- Pete Quote Link to comment Share on other sites More sharing options...
Mike Blandford Posted June 14, 2020 Share Posted June 14, 2020 My understanding is the Neuron provides the number of flux reverse cycles per second (not flux reversals which is twice as many). On the Neuron I'm using I have to divide the raw value from the ESC by 7 to get the correct RPM. Mike Quote Link to comment Share on other sites More sharing options...
Dickw Posted June 14, 2020 Share Posted June 14, 2020 Posted by Peter Christy on 14/06/2020 12:57:33: Hi Geoff, My motors were both Overlanders, and they do publish the number of poles. I have a feeling that the number of poles - which I assume refers to the electromagnets - does not have to be the same as the number of permanent magnets, and that could be why a multiplier is needed. However, I'm far from an expert on brushless electric motors! ........................................ Pete Pete The brushless rpm monitoring devices I have used so far have taken the "poles" to be the permanent magnetic poles and not the "wound" poles. I have no experience with the Neuron so have no idea if it is the same. I recently used an EDF unit which came fitted with a motor described as "9 pole" by the manufacturer. I eventually determined that it is 9 wound poles, but 6 permanent magnetic poles, so set the brushless rpm sensor for 6 poles and get reaslistic rpm results from that. None of my brushless rpm sensors have a "multiplier", so the Neuron may work differently. Dick ps - Mike's reply is interesting. Edited By Dickw on 14/06/2020 14:21:49 Quote Link to comment Share on other sites More sharing options...
Geoff S Posted June 14, 2020 Share Posted June 14, 2020 Posted by Peter Christy on 14/06/2020 12:57:33: Hi Geoff, My motors were both Overlanders, and they do publish the number of poles. I have a feeling that the number of poles - which I assume refers to the electromagnets - does not have to be the same as the number of permanent magnets, and that could be why a multiplier is needed. However, I'm far from an expert on brushless electric motors! If its any help, my DS-22 uses a 14 pole motor and needed a multiplier of 2. My Lark also uses a much smaller 14 pole motor, but doesn't seem to need a multiplier. It has a much higher kV rating, so I'm guessing its to do with the number of poles vs the number of permanent magnets. 5055 usually refers to the can size. The motor in my DS-22 is a 5055/06, 580kV motor. Maybe try the figures I've used (14 poles and X2) and see if that gives a closer reading? Until someone more knowledgeable comes along, I'm running by guesswork here! -- Pete I suppose my 'crude' experiment of adjusting the number of poles until the optical tacho reading and the Neuron reading were the same and arriving at 7 may well be similar to adopting 14 poles and multiplying by 2 and doing that has resulted in a closer correlation. However the reading isn't super steady but is a reasonable indication. Perhaps it works through measuring the time for a single revolution which can vary. In another life I designed speed measurement systems for use on test beds and rigs from once/rev pulses and using a phase-locked loop to even things out so perhaps this is similar. I originally bought this motor to power an Ezee Pezee trainer which required a 60 size glow in its liquid fuelled incarnation. I took it out and replaced with an old Laser 62 I'd 'found' in the club hut and got running with new bearings etc (I don't mind messing with engines. I'm just not so keen to use them). It was first foray into 4s LiPo. I think XYH manufacture motors for a variety of labellers - or used to. I know the 5055 refers to physical size but it's the only identifier I have. I'm now getting 8000 rpm with a 14x7 prop for a current draw of 43 amps. I hope it will be enough to fly the Pup at only about 600 watts for what I suspect will be 8lbs of biplane. Geoff Quote Link to comment Share on other sites More sharing options...
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