# Get Field Map of Motor



## amesmich (Nov 17, 2009)

I have a motor Sep EX (Schaeff Model no 7600088 MVX4003 Class H) that I need to get a field map for. Is there some place online I can get this? I cant find any info online for this motor nor can I cross it over although I have not spent much time looking for a crossover. 

Can I calculate this or figure it out with a scope and a function generator? I measured the field resistance to be 1.1 ohms.

If I cant get this info will it matter much when trying to fit a controller? I knwo it will matter but by how much? My other question is how much current can a field take? Without any info can I just look at the coils and guess based on the wire size of the field coils. The motor I have weighs 83 pounds a picture is located here. http://amesweb.net/photos/main.php?

Do you think 50-80 amps would be too much? Any input is helpful since I am trying to learn.


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## major (Apr 4, 2008)

amesmich said:


> I have a motor Sep EX (Schaeff Model no 7600088 MVX4003 Class H) that I need to get a field map for. Is there some place online I can get this? I cant find any info online for this motor nor can I cross it over although I have not spent much time looking for a crossover.
> 
> Can I calculate this or figure it out with a scope and a function generator? I measured the field resistance to be 1.1 ohms.
> 
> ...


Hi ames,

I remember lots of discussion on this subject. Use the search function and you can find and review much of it. Here is an example. http://www.diyelectriccar.com/forums/showthread.php?t=42896&highlight=saturation+curve This should show the results of the search I used to get to that thread. http://www.diyelectriccar.com/forums/search.php?searchid=333706 Also search for SepEx, Field Map and stuff like that. Do some back ground and I'll help out. What controller do you have?

Regards,

major


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## amesmich (Nov 17, 2009)

I just read your posts in the other thread. The concepts in those threads are the uper limits of what I know. I taught 4 levels of electronics at the high school level. The post you made (#10) was spot on and I followed it with no problems. The others posts I followed but could not fully comprehend even though I knew the terms and concepts. 

I dont have a controller yet. I am thinking on getting a Kelly HSE 12101 http://kellycontroller.com/hse121011000a120vsep-ex-with-regen-p-899.html

When ordering a controller I remember being asked for the field current. I had no answer or any clue. Now I know more and realize I need a better understanding. A rep from kelly asked for the resistance of the field so I measured the resistance of the field coil and its 1.1 ohms. I am well versed in electrical calculations and can calculate what I need however I am not sure how this will apply. I am not sure what my feild current should be. I suppose I could guess based on the size of the wire used in the field coil but that does not seem right to me since counter EMF and inductance vary the actual current in the coil. My other question is what does the field map actually show. I knwo its the characteristics of the coils but what imformation is extracted from it and applied. Is it used to fully optimize a controller for peak performance or is it critical to making it work properly regardless fo efficiency? 

So I need to educate myself about field mapping so I can apply it to figure out what I need. 

Thanks for your response.


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## DavidDymaxion (Dec 1, 2008)

Search archives for Major's post on determining the field map. Basically spin the motor and measure the voltage it produces for various field currents.

Does the motor have a data plate or any published specs?

The Curtis website lets you download the manual for their sepex controllers. There is a section that suggests how to start and tune if you aren't sure of the motor parameters a priori.


amesmich said:


> I just read your posts in the other thread. The concepts in those threads are the uper limits of what I know. I taught 4 levels of electronics at the high school level. The post you made (#10) was spot on and I followed it with no problems. The others posts I followed but could not fully comprehend even though I knew the terms and concepts.
> 
> I dont have a controller yet. I am thinking on getting a Kelly HSE 12101 http://kellycontroller.com/hse121011000a120vsep-ex-with-regen-p-899.html
> 
> ...


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