mac motor pumping under high load

izeman

1 GW
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Jun 21, 2011
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Location
Vienna, Austria
i just had my first test ride with my middrive conversion. http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=55215
motor used is a mac with 40a max @48v. so around 2kw load.
when accelerating in low gear everything is fine as long as it's not very steep. if in higher gears using full power makes the motor PUMP. it finally reaches full speed, but not smooth. it seems it lacks power.
controller is a heavy modded xie chang 9fet controller. double shunt and programmed as eb312.
i use a ca-v3 but removed all limiting and throttle is in pass-thru mode.
any ideas what could cause this? should i recheck halls?
 
What's no load (free spinning) Amps? Lesss than 2A is a proper combination. Anything higher should be investigated.

My recent experience mating a geared hub motor to a new controller is that geared motors may be somewhat deceiving IMO with regard to Hall/Phase combination.
 
high gear? What speed are you at in this gear?
 
izeman said:
don't know. it's independent from speed. load is the problem. this can happen in first gear on a 15% grade and in 8th gear at 20km/h. if i need 40a it's pumping.

And what exactly do you mean by pumping? is that surging torque?
 
Phase current is proportional to torque (load).
The surging is likely caused by the way your controller is regulating the phase current when it reaches the upper phase current limit.

How old is your controller ?
Because of their low inductance, I found Mac motors were often a problem for the older (digital) Infineon controllers, surging would result when phase current limiting was in operation.

More recent controllers I bought from EM3Ev (within the last 18 months) seem to work OK with the Mac motors. I think they must have updated the firmware to sort this problem.


You could try playing with the phase current limit to see if it makes a difference, but be careful not to smoke your FETs :eek:
 
sound reasonable. to answer your question it's a 309 and not a 2xx series. had one of them some time ago. now it's only 3xx.
i will experiment with the phase amps and see if it help. they are not too high at the moment to be easy on gears and chain. it's 40a battery and maybe 90a for phase.
 
It is possible that one of the phase wires inside the motor has lost connection. Basically the phase wires split into two inside the motor so it is possible that only half of the windings for one of the phases is still connected.
 
i guess i have to reopen the topic.
had a test ride yesterday. everything was more or less fine, but suddenly during a climb the motor stopped. i wasn't able to move on. disconnected the battery, reconnected but only a short movement of thr axle. only some degrees.
back home i removed all connections between the motor and controller, reconnected them and the motor worked again.
this sounds like a connection problem, but the plug looks good. no loose pins etc ...
i opened the motor to check the hall sensors. they look fine as well.
so what else could i check? how to i check that the windings are connected correctly (other then visually)?
 
John in CR said:
izeman said:
...modification and not 100% aligned axle and bearings.
there's a big clue, and bad bearings would make it all much worse under heavier loads.
the bearings itself are highest quality SKF 2RS. the factory installed ones were chinese crap. we will see how the new axle performs.
 
izeman said:
can someone tell me how to check if the windings are wired correctly? measuring resistance is useless imho, as i get 0-2ohm for all combinations between phases.
did you re-wire ? A simple test is, at constant rpm the voltages between the 3 windings should be equal (measure with the AC setting of the multimeter)
 
Lebowski said:
izeman said:
can someone tell me how to check if the windings are wired correctly? measuring resistance is useless imho, as i get 0-2ohm for all combinations between phases.
did you re-wire ? A simple test is, at constant rpm the voltages between the 3 windings should be equal (measure with the AC setting of the multimeter)
thanks a lot! yes, i installed new phase wires. removed the old ones, took new 10awg silicone wire, wrapped with single strand 22awg copper wire, soldered and heat shrinked. just as you learn in school :) i will measure voltage as this is easy to do.
 
izeman said:
Lebowski said:
izeman said:
can someone tell me how to check if the windings are wired correctly? measuring resistance is useless imho, as i get 0-2ohm for all combinations between phases.
did you re-wire ? A simple test is, at constant rpm the voltages between the 3 windings should be equal (measure with the AC setting of the multimeter)
thanks a lot! yes, i installed new phase wires. removed the old ones, took new 10awg silicone wire, wrapped with single strand 22awg copper wire, soldered and heat shrinked. just as you learn in school :) i will measure voltage as this is easy to do.
if you connected it all OK, the 3 measurements should give the same results. If one is 70% larger than the others, the phase not involved with the 70% higher measurement is wrongly connected...
 
i can't imagine what could have gone wrong soldering new phase wires. but it will test it just to be sure.
i am unsure if the hall sensors work correctly. they work fine with low rpm, they give correct readings on the lyen motor tester. could it be that they behave weird under high rpm/high voltage?
 
Lebowski said:
it's a pity postage is so high (30 euro probably) else I'd send (loan) you a controller to try... (the big lebowski controller is on the shelf doing nothing....)
postage from switzerland to austria should be around the same as vice versa, and it's 10€ in one direction for one kilogramm. so not that bad. what's the dimension size/weight of your controller?
 
izeman said:
Lebowski said:
it's a pity postage is so high (30 euro probably) else I'd send (loan) you a controller to try... (the big lebowski controller is on the shelf doing nothing....)
postage from switzerland to austria should be around the same as vice versa, and it's 10€ in one direction for one kilogramm. so not that bad. what's the dimension size/weight of your controller?
I had a second look and found similar prices, I'll weigh it this evening to see...
 
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