Pro or Con on Sepex!!!

SAcharlie · 02-02-2009, 03:23 PM

Read a discussion on Sepex motors at the Curtis website.
They said that a sepex was more efficient than a series by a ratio of 4 to 1...and no gain form regen was used in that ratio.

Also in regard to more torque of one over the other. They said that when an electronic controller is used neither one has more torque over the other...but if hooked directly to an unlimited power supply then the series has an advantage.

I like the efficiency factor...should be good when slow cruising.

Monsterezgokid · 02-02-2009, 05:27 PM

By a factor of 4:1 i dont know about that

.

But in general the sepex system is more efficent because of its regen capabilites. But not by a factor of 4:1 more like around 25ish% more effecient, about 20-30% more run time in general, because of the whole system setup. The sepex is kinda like a fake AC drive, where the controller controlls the field around the motor. But there is still a communicator, and center windings.

Torque wise, it all depends on the motor. As far as golf carts are concerned, there is a bunch more torque motors out there for series systems, however regen torque motors are becoming more popular. The sepex/regen system, when tuned right can get you some nice results, with just controller modifying. But the series setup has some pretty hot modified motors out there right now.

Quote:

Originally Posted by SAcharlie

but if hooked directly to an unlimited power supply then the series has an advantage.

The reason they say that is because a series motor can technicaly be hooked up directly to a power source, where as a sepex requires a controller, thus no limit to the ammount of amps it can get

Nate · 02-03-2009, 09:57 PM

Did they specify how they came to the 4:1 efficiency number? I would also need to know what kind of Sep-Ex motor they compared to what kind of Series motor. To get high torque each motor must over current the field. This is not a problem if the time of over current is kept within wire specs. A series motor automatically adjusts the field current as RPM increases. The sep-ex motor requires the controller to adjust current. If the field current is to high the field can burn up, if the field current is to low the armature can burn up.

SAcharlie · 02-04-2009, 09:22 PM

They were talking of losses in the field winding. Here is the link: about 2/3s down they discuss Sepex.

http://curtisinst.com/index.cfm?fuse...otorControlles

Nate · 02-04-2009, 10:31 PM

That was the info I needed, yes they are correct with the I2R formula. This is a maximum value, neither motors run at this current for extended times. A series motor typically runs 53 amps or less at 15 MPH. I don't know what a sep-ex motor runs but I am willing to bet the wattage used is very similar at 15 MPH. They also are talking stock controllers when they say the controller limits the current of a series motor.

Sep-ex does have advantages but the controllers cost more because they have to control more. Series motors do work or no one would buy them. If you want regen braking then a sep-ex is definitely a better choice. The choice of which motor to use would depend on what the user wants the end results to be and is willing to spend.

SAcharlie · 02-06-2009, 05:39 PM

Nate, this is what D&D sent in reply to the high torque sepex ES-9B-50.

Peak hp/torque for 48v with 500amp controller
500amp armature
20amp field
1200rpms
15.5hp
68ft/lb

I also asked for RPMs 40 to 50amps & reply was:
46amps armature
5amps field
2575rpms
2.4hp
5.0ft/lb

I guess ya could play with the field some and change both speed and torque. For my needs that looks good.

Also got a local GC shop to swap out all the gears of my GEM h-12 10.31 ratio to EZGO 12.44 ratio.

Nate · 02-06-2009, 08:30 PM

Charlie, to get a direct comparison you would need to have two motors with the same type of armature. Then you would need the case and shoes to be the same dimension and weight.
Now for the field, it comes down to amp turns that build the magnetic field.
The series motor would have 10 turns at 100 amps that is 1000 amp turns.
The sep-ex motor would have 50 turns at 20 amps to keep the same 1000 amp turns magnetic field. If you ran the sep-ex armature at 100A you would have the same ratio of armature amps to filed amp turns as the series motor. Each would be a 100A armature in a 1000 amp turn field. Now my question would be which motor is more efficient? You have the I2R going against the series motor but you would have 100 armature amps plus 20 field amps going against the sep-ex motor. I have not done the actual test, although I would like to.

Hmmm, 46 armature amps plus 5 field amps for 51 amps total, that's dang close to the 53 amp tag on stock series motors... Thanks for the info, I was just noticing the numbers.

Looks like the choice of which motor to use depends on what features the user wants, they are as different as they are similar. I can't say one is better than the other.

SAcharlie · 02-06-2009, 08:43 PM

Yeah as for choise between sepex or series; 1st issue for me is safety and the sepex wins as my cart will only have brakes on the front wheel drive.
2nd issue it is scratch built and all upgrades will be done initially where as gradual or experimentation favors the series.

02-02-2009, 03:23 PM	#1
SAcharlie Not Yet Wild Join Date: Feb 2007 Location: here in TX Posts: 37	Pro or Con on Sepex!!! Read a discussion on Sepex motors at the Curtis website. They said that a sepex was more efficient than a series by a ratio of 4 to 1...and no gain form regen was used in that ratio. Also in regard to more torque of one over the other. They said that when an electronic controller is used neither one has more torque over the other...but if hooked directly to an unlimited power supply then the series has an advantage. I like the efficiency factor...should be good when slow cruising.

02-03-2009, 09:57 PM	#3
Nate Gone Wild Join Date: Dec 2006 Posts: 679	Re: Pro or Con on Sepex!!! Did they specify how they came to the 4:1 efficiency number? I would also need to know what kind of Sep-Ex motor they compared to what kind of Series motor. To get high torque each motor must over current the field. This is not a problem if the time of over current is kept within wire specs. A series motor automatically adjusts the field current as RPM increases. The sep-ex motor requires the controller to adjust current. If the field current is to high the field can burn up, if the field current is to low the armature can burn up.
Nate Gone Wild Join Date: Dec 2006 Posts: 679

02-04-2009, 09:22 PM	#4
SAcharlie Not Yet Wild Join Date: Feb 2007 Location: here in TX Posts: 37	Re: Pro or Con on Sepex!!! They were talking of losses in the field winding. Here is the link: about 2/3s down they discuss Sepex. http://curtisinst.com/index.cfm?fuse...otorControlles

02-04-2009, 10:31 PM	#5
Nate Gone Wild Join Date: Dec 2006 Posts: 679	Re: Pro or Con on Sepex!!! That was the info I needed, yes they are correct with the I2R formula. This is a maximum value, neither motors run at this current for extended times. A series motor typically runs 53 amps or less at 15 MPH. I don't know what a sep-ex motor runs but I am willing to bet the wattage used is very similar at 15 MPH. They also are talking stock controllers when they say the controller limits the current of a series motor. Sep-ex does have advantages but the controllers cost more because they have to control more. Series motors do work or no one would buy them. If you want regen braking then a sep-ex is definitely a better choice. The choice of which motor to use would depend on what the user wants the end results to be and is willing to spend.
Nate Gone Wild Join Date: Dec 2006 Posts: 679

02-06-2009, 05:39 PM	#6
SAcharlie Not Yet Wild Join Date: Feb 2007 Location: here in TX Posts: 37	Re: Pro or Con on Sepex!!! Nate, this is what D&D sent in reply to the high torque sepex ES-9B-50. Peak hp/torque for 48v with 500amp controller 500amp armature 20amp field 1200rpms 15.5hp 68ft/lb I also asked for RPMs 40 to 50amps & reply was: 46amps armature 5amps field 2575rpms 2.4hp 5.0ft/lb I guess ya could play with the field some and change both speed and torque. For my needs that looks good. Also got a local GC shop to swap out all the gears of my GEM h-12 10.31 ratio to EZGO 12.44 ratio.

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02-06-2009, 08:30 PM	#7
Nate Gone Wild Join Date: Dec 2006 Posts: 679	Re: Pro or Con on Sepex!!! Charlie, to get a direct comparison you would need to have two motors with the same type of armature. Then you would need the case and shoes to be the same dimension and weight. Now for the field, it comes down to amp turns that build the magnetic field. The series motor would have 10 turns at 100 amps that is 1000 amp turns. The sep-ex motor would have 50 turns at 20 amps to keep the same 1000 amp turns magnetic field. If you ran the sep-ex armature at 100A you would have the same ratio of armature amps to filed amp turns as the series motor. Each would be a 100A armature in a 1000 amp turn field. Now my question would be which motor is more efficient? You have the I2R going against the series motor but you would have 100 armature amps plus 20 field amps going against the sep-ex motor. I have not done the actual test, although I would like to. Hmmm, 46 armature amps plus 5 field amps for 51 amps total, that's dang close to the 53 amp tag on stock series motors... Thanks for the info, I was just noticing the numbers. Looks like the choice of which motor to use depends on what features the user wants, they are as different as they are similar. I can't say one is better than the other.
Nate Gone Wild Join Date: Dec 2006 Posts: 679

02-06-2009, 08:43 PM	#8
SAcharlie Not Yet Wild Join Date: Feb 2007 Location: here in TX Posts: 37	Re: Pro or Con on Sepex!!! Yeah as for choise between sepex or series; 1st issue for me is safety and the sepex wins as my cart will only have brakes on the front wheel drive. 2nd issue it is scratch built and all upgrades will be done initially where as gradual or experimentation favors the series.

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