05-04-2016, 07:34 PM | #1 |
Gone Wild
Join Date: Dec 2015
Location: Texas
Posts: 526
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EMP Motor
Ordered an EMP motor this week. Hope all goes well.
The cart has been out of commission for about 3 weeks now. New XCT controller and new motor from EMP on the way. Can't wait to get everything running again and hopefully will provide some good times. Sent from my Nexus 6 using Tapatalk |
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05-04-2016, 07:35 PM | #2 |
Happy Carting
Join Date: Dec 2007
Location: Southern California
Posts: 73,358
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Re: EMP Motor
Ask EMP which field map should be installed for the motor you are getting and keep us posted
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05-04-2016, 08:53 PM | #3 |
Gone Wild
Join Date: Dec 2015
Location: Texas
Posts: 526
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EMP said he would be sending me a couple of field maps
I will update this message thread as things progress. Sent from my Nexus 6 using Tapatalk |
05-05-2016, 07:18 AM | #4 |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: EMP Motor
subscribed to thread.
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05-05-2016, 08:25 AM | #5 |
Gone Wild
Join Date: Sep 2015
Posts: 572
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Re: EMP Motor
A couple of field maps for the same motor? I was under the impression that how the motor is built deturmines the ideal field map. From there you program the controller that will stay within the confines of the field map.
I think JohnnieB needs to explain. |
05-05-2016, 10:38 AM | #6 |
Gone Wild
Join Date: Dec 2015
Location: Texas
Posts: 526
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Just to add to the information...
I have a DCS 36volt cart with stock tires. I have an XCT 400 and 2 gauge cables. I wanted 23 or so mph. So they will target 24mph. I filled out a thorough questionnaire about my cart and where I would be driving it. They gave me 3 options...one being a OEM motor with their enhancements and the other 2 options being aftermarket motors with their enhancements. I decided on one of the aftermarket motors, with high speed banding as well. They said the high speed banding was not really necessary with my speed requirements, but i thought why not if it offers a little protection. Will add more as it goes along. Sent from my Nexus 6 using Tapatalk |
05-05-2016, 11:50 AM | #7 | |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: EMP Motor
Quote:
Basically, a field map is a lookup table that tells the controller how many amps to send through the field windings when the armature is drawing a given amount of amps. IE: If the armature is drawing 450A, the map might tell the controller to send 30A through the field while when the armature is drawing 100A, the field might only get 3A. The closer the armature amps vs field amps ratio is, the higher torque the motor produces for the RPM it is spinning at. The greater the numerical ratio, the higher RPM is reached for the voltage applied to the armature. (If the field amps are reduced too much relative to the armature amps, the motor's efficiency takes a nosedive and the motor gets really hot really fast.) Therefore, I suspect how a motor is used as well as what it is used in, also determine the ideal field mapping. If the cart is used on-road, it probably would have have different field weakening requirements than one used off-road. If the cart had tall tires, I suspect the field weakening requirements would be different than it would be for a cart with short tires. With a DCX controller (older technology), I suspect the filed map loaded into the controller is implemented with little, if any, interpretations or adjustments for anything except armature amp draw. That could mean that different field maps would work better in different applications the same motor was used in. On the other hand, I suspect the XCT (newer technology) mitigates what the lookup table says with motor RPM and maybe some other factors. With a 32 bit CPU, the XCT ought to have enough computing power to do a bit of AI. I did pose a question the XCT along these lines to an Alltrax vendor, who was going to ask Alltrax, but haven't heard back yet. |
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05-05-2016, 02:44 PM | #8 |
Gone Wild
Join Date: May 2012
Location: Rio Verde, Az
Posts: 7,123
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Re: EMP Motor
I think the Field map should be based more on RPM then Armature AMPS but it may be based on both. I have never seen a technical explanation of the Field map used in the Alltrax controller. They are not human readable either.
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05-05-2016, 04:02 PM | #9 | |
Techno-Nerd
Join Date: Jun 2011
Location: West Virginia
Posts: 19,654
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Re: EMP Motor
Quote:
I think armature amps should be the hard bottom on field weakening and above that safety net, RPM ought to be factored in and weighted heavily, and I suspect RPM is a factor in the XCT as well as some other stuff. The DCX doesn't use a speed sensor and doesn't know the motor RPM, so I'm pretty sure it's just a lookup table, but it might be looking at the throttle position. (More correctly, the duty cycle of the PWM to the armature) The field maps for the DCX have a ".hex" extension on the files, so I've thought about taking a look using a Hex-Editor, but all I've got are some old DOS based programs that won't run under Windows-98 or later. I've got an old Toshiba laptop with Win-95C loaded, but it doesn't do wireless and I've misplaced the dongle need to hard-wire it to my home network and none of my computers that are on my network have a 1.44mb floppy drive, so I cannot sneaker-net the hex file to the old laptop ether. |
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05-05-2016, 06:50 PM | #10 | |
Stay thirsty my friends!
Join Date: Jan 2007
Location: Suburban Chicago
Posts: 24,283
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Re: EMP Motor
Quote:
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