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this forum hasn't been of much help for much of anything. I figured someone would have known yes or no simply. it's a pretty straight forward question, are PMAC motors held in flux or is it okay to disassemble them
PMAC motor disassembly question.
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in my younger years I ruined some stepper motors by taking them apart. Will the permanent magnets in a motenergy PMAC loose any flux (?) like a stepper. Id like to peak inside and make any inprovements as I see fit.
for example replacing standard socket head screws with ones with corrosion plating like zinc or chrome. double checking epoxy points on windings, copper work hardens and id like to mitigate any movement to prevent. breakage down the road. one of the rubber seals has a proper lip on all but 1 side so that may get some schmoo to seal it up better. also there's lots of sharp milled edges I'd like to knock down for ease of handling.
for example replacing standard socket head screws with ones with corrosion plating like zinc or chrome. double checking epoxy points on windings, copper work hardens and id like to mitigate any movement to prevent. breakage down the road. one of the rubber seals has a proper lip on all but 1 side so that may get some schmoo to seal it up better. also there's lots of sharp milled edges I'd like to knock down for ease of handling.
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With that attitude, don't expect much help with anything, from anyone.
And there's the key: while people salvaging old forklift motors do take them apart, there's no reason to disassemble a working PM AC motor... and the ones salvaged from modern EVs generally don't stop working. Small junk motors from some random source are probably a different matter, but they're typically not suitable for driving a car.
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yeah I must have mistaken the DIY part of this forum for paying a specialist.
the motor in question is a motenergy formally Mars, not high quality but not junk either. like I stated, there IS good reason to disassemble for just the poorly designed seal by itself. motor companies cheap out and may not properly affix the windings and with continuous vibration(motorcycle) they will fail. this is common on cheaper motors especially power tools (not the same kind of motor no, but still has windings and vibrates) if a quick dab of better epoxy will mitigate that then thats what I'm going to do, I'm going to do it myself...DIY....
the motor in question is a motenergy formally Mars, not high quality but not junk either. like I stated, there IS good reason to disassemble for just the poorly designed seal by itself. motor companies cheap out and may not properly affix the windings and with continuous vibration(motorcycle) they will fail. this is common on cheaper motors especially power tools (not the same kind of motor no, but still has windings and vibrates) if a quick dab of better epoxy will mitigate that then thats what I'm going to do, I'm going to do it myself...DIY....
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314 Posts
Check out Ripperton's efforts with his re-building of the Moteneregy motors. While not much can go wrong with a PMAC, when it does go wrong it's a big job to fix it. Pretty sure he had them rewound but he also put different magnets in, and liquid cooled them.
In the Electric track bike thread.
In the Electric track bike thread.
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I am not sure if you are talking about the ME models like 1114 1115 or the other similar ones.
These are DC, but similar principals apply.
We made a special shaft puller/pusher to remove the
outer housings. If you try with a pry bar , screw drivers or other cave man like
instruments the chances or cracking the rotors is very high. By the way we
know someone else who did that..
Press and pull the shaft out/in of the bearings and housing.
The magnets will degrade over a period of time if they are not left in flux with
a steel plate. That is why it is good practice to leave magnets stuck to them
selves or metal over a long time, I have been told. These are very strong magnets
so put something non magnetic between them. Used plastic cutting boards work good and there fairly cheap.
Around 5mm thick is ok.
Hope that helps someone.
Mark
These are DC, but similar principals apply.
We made a special shaft puller/pusher to remove the
outer housings. If you try with a pry bar , screw drivers or other cave man like
instruments the chances or cracking the rotors is very high. By the way we
know someone else who did that..
Press and pull the shaft out/in of the bearings and housing.
The magnets will degrade over a period of time if they are not left in flux with
a steel plate. That is why it is good practice to leave magnets stuck to them
selves or metal over a long time, I have been told. These are very strong magnets
so put something non magnetic between them. Used plastic cutting boards work good and there fairly cheap.
Around 5mm thick is ok.
Hope that helps someone.
Mark
Seems to be some on here with knowledge of motor theory.
A group of us have been trying to get a Motenergy 3031 pmac running properly for some time. Sevcon gen4 controller.
I have dld and two dcf files. One from motor testing and one with some tuning done by John at motenergy for testing in a golf cart.
The first company that attempted tuning was little help except for separating us from our money. He left us running rough, low power, and hot, but 7000rpm.
Second did a lot but did not have time to dig deep.
Third is a freelance Sevcon tech that gave us on-site assistance. He has done as much as he believes possible. He limited us to 4000 rpm which helps with overheating, but it still runs very hot. Over 4000rpm it overheats in a couple minutes or less.
Tech tells us, "that's it" won't run cool and won't run over 4000rpm.
We plan to give up soon and run heavy 8kw induction motors. They are running fast and cool way over 7000rpm.
Golf cart test platform is crazy fast. 10:1 and little 17" tall tires. Spins tires and front end gets light at 15mph. Theoretical >40mph but not safe to test top speed in this feather weight.
Any insight into pmac performance is appreciated. There may be extra motors available as test samples, or when we give up completely.
6:1 gears are ordered, but even at 4000 we have too much heat.
tnx in advance
A group of us have been trying to get a Motenergy 3031 pmac running properly for some time. Sevcon gen4 controller.
I have dld and two dcf files. One from motor testing and one with some tuning done by John at motenergy for testing in a golf cart.
The first company that attempted tuning was little help except for separating us from our money. He left us running rough, low power, and hot, but 7000rpm.
Second did a lot but did not have time to dig deep.
Third is a freelance Sevcon tech that gave us on-site assistance. He has done as much as he believes possible. He limited us to 4000 rpm which helps with overheating, but it still runs very hot. Over 4000rpm it overheats in a couple minutes or less.
Tech tells us, "that's it" won't run cool and won't run over 4000rpm.
We plan to give up soon and run heavy 8kw induction motors. They are running fast and cool way over 7000rpm.
Golf cart test platform is crazy fast. 10:1 and little 17" tall tires. Spins tires and front end gets light at 15mph. Theoretical >40mph but not safe to test top speed in this feather weight.
Any insight into pmac performance is appreciated. There may be extra motors available as test samples, or when we give up completely.
6:1 gears are ordered, but even at 4000 we have too much heat.
tnx in advance
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1,954 Posts
in my way of thinking, the so-called stepper "motor" is not really a motor at all--it is just a position-holding device. It makes it's highest torque when not moving, and makes little or no mechanical torque when moving. It will stall and skip steps when loaded or trying to "run" at high step rates. Put one on a dyno and try to test it under load. The older versions used magnitized stacks of iron laminations as rotor magnets, and if the rotor touched the stator during disassembly, it would be ruined.
Some older DC brush servo motors require the use of a "keeper" ring during disassembly. If the rotor is withdrawn from the stator without the keeper, then the magnet strength gets degraded severely every time it is done. This is determined by the type of material used to create the magnet, e.g. ferrite, alnico, samarium-cobalt, neodymium.
The Mote axial flux motors use PM on the rotor, which seemed to be of the neodymium variety and don't require the use of a keeper.
Post up a datasheet for the 3031 motor, maybe that will help understand the overheating issue.
Some older DC brush servo motors require the use of a "keeper" ring during disassembly. If the rotor is withdrawn from the stator without the keeper, then the magnet strength gets degraded severely every time it is done. This is determined by the type of material used to create the magnet, e.g. ferrite, alnico, samarium-cobalt, neodymium.
The Mote axial flux motors use PM on the rotor, which seemed to be of the neodymium variety and don't require the use of a keeper.
Post up a datasheet for the 3031 motor, maybe that will help understand the overheating issue.
After struggling to tune an ME1507 I had in a small EV, I have little faith in being able to get Motenergy brushless motors to function properly, I've had much better luck with their brushed motors. Where are you located at in Iowa? I am in Cedar Falls.
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