# Interesting regen method for series motors



## JRP3 (Mar 7, 2008)

I don't remember seeing this technique before. Dividing and switching the pack to parallel on regen to cut voltage in half, which should avoid arcing the brushes:
http://www.russcoev.com/oj_regen.html

Probably not as effective at higher voltage.


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## Tesseract (Sep 27, 2008)

Yeah, I remember stumbling on that link awhile ago and thinking wtf?! 2V at _200A_??? That'll be a tricky power supply to design or buy.

Also, with a fixed field strength, the armature voltage will vary directly with RPM so this is not so fun for the batteries, either.

Rumor has it that if you change over from motoring mode to regen mode before the field collapses (the time depends on the field inductance and current, but I'd guess 50us at a minimum) that you can dispense with having to energize the field separately.


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## DIYguy (Sep 18, 2008)

Check out what this guy did.... I really like it. 
http://www.northrim.net/wyanders/ev/

I am planning to do the same. I may have a bit of a challenge getting the voltage high enough for my 192 volt pack.... but, I'm gonna take a crack at it. I have the electric clutch modified and mounted on my motor already. Haven't got the alternator yet. I had this in mind...and did some searching. Came up with this thread. I had some PM with this dude. He said that he can break the tires loose with regen if dumping power with high motor rpm. It really slows him down.


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## JRP3 (Mar 7, 2008)

Yeah that's the "old school" method, basically cheating  I've read his page before, and that's what Roland Wiench did on his Rover and El Camino, some other people as well. I'm not sure why he chose to mount the clutch on the motor and go through the trouble of reversing the torque bars instead of using the clutch on the alternator and leaving it alone? Might be a slight energy savings his way since the belt won't be turning till the clutch locks up.


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## jackbauer (Jan 12, 2008)

My idea on that would be to just drive the alternator continuously and switch the rotor in and out for regen. I know there would be a slight loss in driving the belts.


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## DIYguy (Sep 18, 2008)

JRP3 said:


> I'm not sure why he chose to mount the clutch on the motor and go through the trouble of reversing the torque bars instead of using the clutch on the alternator and leaving it alone? .


I believe this chap assumed that the "torque bars" were mounted in this fashion to better handle the load in the direction of rotation. After studying mine for a short while... I would contend that there is another reason for this design. The electro-magnetic coil pulls the front face of the unit in, towards the pully unit and the surface area is enough friction to drive it. In order for the movement of this unit, there needs to be flexion in the mount. These "torque bars" are elongated to enable this. If they were straight from their mount towards the centre, they would be quite short and not able to flex appropriately for function.



JRP3 said:


> Might be a slight energy savings his way since the belt won't be turning till the clutch locks up.


Yes, this is correct. Why spin it if you don't need to. This energy is enough to warrant the design I believe. 

I'm interested in the braking effect more than the regen... but I'll take the energy for sure....


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## JRP3 (Mar 7, 2008)

DIYguy said:


> If they were straight from their mount towards the centre, they would be quite short and not able to flex appropriately for function.


But he didn't change the length or angle, he just reversed the angle.


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## Tesseract (Sep 27, 2008)

jackbauer said:


> My idea on that would be to just drive the alternator continuously and switch the rotor in and out for regen. I know there would be a slight loss in driving the belts.


I think this is the best method, too. Modern toothed belt drives are extremely efficient and even V-belts aren't too bad as long as they are tensioned properly (IIRC, the average efficiency of each belt type is 96% and 88% respectively... SDP-SI has a lot of info on this).

Also, you need to control the rotor current, anyway to make regeneration at all useful...


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## DIYguy (Sep 18, 2008)

JRP3 said:


> But he didn't change the length or angle, he just reversed the angle.


Yes, he reversed the angle because he felt that they needed to be in tension not compression. Spinning the clutch the opposite way puts them in compression. Thinner materials in compression could cause issues of course. It's my thought that perhaps the main reason they are mounted on an angle is to make them long enough to flex adequately... not necessarily the tension/compression issue.


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## DIYguy (Sep 18, 2008)

Tesseract said:


> I think this is the best method, too. Modern toothed belt drives are extremely efficient and even V-belts aren't too bad as long as they are tensioned properly (IIRC, the average efficiency of each belt type is 96% and 88% respectively... SDP-SI has a lot of info on this).
> 
> Also, you need to control the rotor current, anyway to make regeneration at all useful...


Why would it be best to spin it if you don't have to? Did I miss something?


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## Tesseract (Sep 27, 2008)

DIYguy said:


> Why would it be best to spin it if you don't have to? Did I miss something?


Perhaps that the clutch requires electrical power to engage it - specifically, power that takes away from the amperage available from the dc/dc converter to run the other accessories like headlights, wipers, radio (assuming your controller doesn't spew so much noise you can actually use the radio... hmmm... that would be a good poll question) But I digress...


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## DIYguy (Sep 18, 2008)

Tesseract said:


> Perhaps that the clutch requires electrical power to engage it - specifically, power that takes away from the amperage available from the dc/dc converter to run the other accessories like headlights, wipers, radio ...


OK now I'm even more confused. The clutch would be engaged for regen only....whether mounted on the drive motor, or the regen alternator.



Tesseract said:


> (assuming your controller doesn't spew so much noise you can actually use the radio... hmmm... that would be a good poll question) But I digress...


Does this have anything do with it? Or are you trying to confuse me even more?? lol


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## Tesseract (Sep 27, 2008)

DIYguy said:


> OK now I'm even more confused. The clutch would be engaged for regen only....whether mounted on the drive motor, or the regen alternator.


Right... versus just having the drive motor spin the alternator all the time and only energize the alternator's rotor when regen braking is desired. The parasitic losses in spinning the belts/alternator all the time are probably on par with having to energize a clutch (like the type used on the a/c compressor) whenever you want to regen brake. I was just stating my opinion that there's probably little difference in overall efficiency, so why go to the extra trouble of adding a clutch?






> Does this have anything do with it? Or are you trying to confuse me even more?? lol


Nah, I was wandering off on a tangent


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## JRP3 (Mar 7, 2008)

I suppose you could measure how much power it takes to engage and hold the magnetic clutch in place for x amount of time verses the constant power loss of running the pulleys and belt full time. I'd think the former would be less than the latter.


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## Tesseract (Sep 27, 2008)

JRP3 said:


> I suppose you could measure how much power it takes to engage and hold the magnetic clutch in place for x amount of time verses the constant power loss of running the pulleys and belt full time. I'd think the former would be less than the latter.


I agree... but it's also analogous to worrying about people stealing pennies from the change cup on the counter while the employees are pocketing tens and twenties from the till.

We're talking differences in losses of around 1-10Wh range here... maybe running the belt continuously loses 10Wh while clutching it loses 8Wh... That's a seat-o-the-pants estimate, but it feels about right.

If we were talking about saving even 100Wh here I'd say go for it, but for a measly 10Wh or less? Nah...


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## Amberwolf (May 29, 2009)

DIYguy said:


> I may have a bit of a challenge getting the voltage high enough for my 192 volt pack....


Well, one option would be to use contactors to split the pack during braking only, reconnecting it as two parallel halves of the original. More wiring, more parts, a bit more resistance before getting the power to the controller, and one more set of parts to fail  but it could make any regen voltage more "usable" for your pack. 

EDIT: (a day later) Rescanning this thread I realized that I am an idiot, because this was the point of the OP's start of this thread.  Somebody smack me when I do that! 
________
HERBAL VAPORIZERS


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## jackbauer (Jan 12, 2008)

Take the 3 phase wires out of the alternator and feed em into a 3 phase voltage doubling rectifier. Job done.


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## DIYguy (Sep 18, 2008)

JRP3 said:


> I suppose you could measure how much power it takes to engage and hold the magnetic clutch in place for x amount of time verses the constant power loss of running the pulleys and belt full time. I'd think the former would be less than the latter.


I think u are right. The clutch magnet requires about 4 amps at 12 volts or 48 watts or .06hp. 

I'm not sure about the mechanical energy of driving the belt, alternator and clutch pulleys.... thinking out loud here.....
The statements about belt efficiency are interesting... They discuss "efficiency"....which is really not the heart of the matter here. The better belts (for efficiency) being cogged, are up around 98%. That means they loose 2 hp on a 100 hp application. V belts are less efficient ( but will handle higher hp loads) and loose more to torque and speed. It's been quite some time since I dabbled in these calcs.... but to do it correctly, you would have to take into account the bending forces of the belt, mass of the spinning objects and bearing efficiency...and probably a few other things. Pully diameters become a large issue, particularly with v-belts, for bending forces. Once you know all these things, the belt efficiency number could be used I think. Does that make sense?

Here is a real world example.... I designed and built a puck shooting machine (goalie dad ) I used a small DC motor, some bearing mounted shafts, with v-belt pulleys. I had to search out a high flex, smaller v belt for the pulley diameters I was using as the motor could not generate any speed with a standard belt on "smallish" pulleys. After changing the belt type, I was able to wind it up to high speeds without problem. The bending force required by the first belt was just too great. 

Either way, the comment made was that spinning the alternator all the time was the "best method". ... I'm not convinced of that yet.


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## DougM (Aug 3, 2009)

When I first seen this method of alterntaor re-gen. I liked it a lot, espescially controlling it from a remote switch. However I think you should be able to run the alternator direct off the aux tail shaft and only energize the rotor when demanding re-gen action. In this type of application you are best to rewind your stator coils to suit your pack voltage anyway so you could wind it to charge down below the 1000rpm range.
What think?


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## DIYguy (Sep 18, 2008)

DougM said:


> When I first seen this method of alterntaor re-gen. I liked it a lot, espescially controlling it from a remote switch. However I think you should be able to run the alternator direct off the aux tail shaft and only energize the rotor when demanding re-gen action. In this type of application you are best to rewind your stator coils to suit your pack voltage anyway so you could wind it to charge down below the 1000rpm range.
> What think?


I think you could drive the alternator all the time or by clutch, whatever you like. 
As for the voltage you have to wind it to get high enough voltage over your pack to drive current into it....unless you transform it somehow I suppose. 
As for the rpm range, I think you would mess with pully ratios to get this right. I think targeting 1000 rpm may be a bit low. I know this fellow could break the tires loose with too much field current and higher rpm. Like engine breaking, it would make sense to have the effect on the higher rpm I think. I was thinking of using an electric brake control for the field... maybe at least to figure it out. As least in my small brain.


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## DougM (Aug 3, 2009)

I understand,
I am working on my Mazda B3000, with a 9" Warp and I have seriously thought about doing this.
I think to break the wheels loose on a car or truck would be one heck of a load on the belts (cogged or "V" type) they can only hand about 10hp for the std automotive type. Anyway, I am thinking about the hills on my commute, long somewhat steep. Pumping even 700W into the pack over a 1km hill would be of some benifit, and I can't see 700W slowing a 4000lb truck down too much.
I guess it's a matter of how much re-gen you employ.


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## JRP3 (Mar 7, 2008)

Synchronous toothed belt drives can take a lot more than that, think of a belt drive on a dragster blower as one example. The one I run on my AMPhibian is rated around 30hp.


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## DIYguy (Sep 18, 2008)

DougM said:


> I understand,
> I am working on my Mazda B3000, with a 9" Warp and I have seriously thought about doing this.
> I think to break the wheels loose on a car or truck would be one heck of a load on the belts (cogged or "V" type) they can only hand about 10hp for the std automotive type. Anyway, I am thinking about the hills on my commute, long somewhat steep. Pumping even 700W into the pack over a 1km hill would be of some benifit, and I can't see 700W slowing a 4000lb truck down too much.
> I guess it's a matter of how much re-gen you employ.


Hey Doug,

I'm doing a B4000 and also live in Ontario. Where abouts are you? 
Auto worker eh? hmmmm too much in common here...lol

BTW, email the chap on the web page I referenced...he'll tell you how he can break the tires loose....


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## DougM (Aug 3, 2009)

DIYguy,
Being new here, I don't want to hyjack this posting but, I gotta show you my direct coupler.
I'll start my own posting soon.
Airport / 89 (Violet Hill)


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## DIYguy (Sep 18, 2008)

send you a PM


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## DIYguy (Sep 18, 2008)

U r near Shelburne on Hiway 89?


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