[EVDL List]

My question, will I get regen braking with my circuit as a I drew it?
I have a Jack & Heintz G-29-88 shunt motor mounted to a 1995 geo metro
transmission. Have driven it a few times 9 miles with a 48V contactor
controller, on and off. Anyways, I have ordered a controller for this motor.
Should have it in 3 weeks from now. It will be powered by 72V battery pack.
Also, there will be a 24V separate battery pack for the field to be powered
100% of the time. Negative on 24V battery goes to negative on armature on
motor and positive will be attached to field positive on shunt motor. There
are four terminals, two for armature, two for field, but one will not be
used on the field.

I have envisioned a few ways to get regen with this motor generator. I
happen to have a few 650 amp 400V rectifier diodes to allow current to flow
in only one direction and several SW180B contactors. The simplest way to
wire this up is for downshifting the transmission to rev motor and thus slow
vehicle down. I know this might work, but the problem I am having in
justifying the circuit I drew as accurate. See on the circuit I have a
negative from battery going into the controller, then a negative from
controller going into the motor. My problem when controller is not engaged
battery negative will not be connected to motor. However, in my circuit the
positive of battery will still be connected and current can only flow one
way back into the battery. So will regenerative braking take place when I
downshift and rev shunt motor?
I suppose I could hook it up and see, but rather ask first.

Here are some links to the circuit I drew.
http://www.host-images.com/show.php/3645_shuntregencircuit.jpg
http://img207.imageshack.us/img207/5061/shuntregencircuitbj1.jpg
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[EVDL List]

Hi ampaynz1,

Looks to me like you do not need any additional diodes
or switches. And the controller will have a diode in
parallel (reversed biased) with the main transistor.
All you need to do is get the armature speed high
enough while maintaining field current to regenerate.
No extra parts required.

Hopefully some others will confirm this.

Jeff M

--- ampaynz1 <[email protected]> wrote:

>
> My question, will I get regen braking with my
> circuit as a I drew it?
> I have a Jack & Heintz G-29-88 shunt motor mounted
> to a 1995 geo metro
> transmission. Have driven it a few times 9 miles
> with a 48V contactor
> controller, on and off. Anyways, I have ordered a
> controller for this motor.
> Should have it in 3 weeks from now. It will be
> powered by 72V battery pack.
> Also, there will be a 24V separate battery pack for
> the field to be powered
> 100% of the time. Negative on 24V battery goes to
> negative on armature on
> motor and positive will be attached to field
> positive on shunt motor. There
> are four terminals, two for armature, two for field,
> but one will not be
> used on the field.
>
> I have envisioned a few ways to get regen with this
> motor generator. I
> happen to have a few 650 amp 400V rectifier diodes
> to allow current to flow
> in only one direction and several SW180B contactors.
> The simplest way to
> wire this up is for downshifting the transmission to
> rev motor and thus slow
> vehicle down. I know this might work, but the
> problem I am having in
> justifying the circuit I drew as accurate. See on
> the circuit I have a
> negative from battery going into the controller,
> then a negative from
> controller going into the motor. My problem when
> controller is not engaged
> battery negative will not be connected to motor.
> However, in my circuit the
> positive of battery will still be connected and
> current can only flow one
> way back into the battery. So will regenerative
> braking take place when I
> downshift and rev shunt motor?
> I suppose I could hook it up and see, but rather ask
> first.
>
> Here are some links to the circuit I drew.
>
http://www.host-images.com/show.php/3645_shuntregencircuit.jpg
>
http://img207.imageshack.us/img207/5061/shuntregencircuitbj1.jpg
> --
> View this message in context:
>
http://www.nabble.com/Shunt-motor-regen-braking-with-alltrax-7245.-tf4343196s25542.html#a12372789
> Sent from the Electric Vehicle Discussion List
> mailing list archive at Nabble.com.
>




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[EVDL List]

I'll try to answer, but you might want to wait for some
corroboration and/or better responses.

--- ampaynz1 <[email protected]> wrote:
>
> My question, will I get regen braking with my circuit as a I drew
> it?

You might, but the diode on the right should be just a straight
connection. It doesn't need to be a diode at all as there is one
(or several in parallel) in the controller the allows the freewheel
current to flow internally from your Motor - to your B+.

> Also, there will be a 24V separate battery pack for the field to
> be powered 100% of the time.

> Negative on 24V battery goes to negative on armature on
> motor and positive will be attached to field positive on shunt
> motor. There are four terminals, two for armature, two for
> field, but one will not be used on the field.

I think you want to have the 24V pack connected to >both< field
terminals, although you should check the resistance of the field
winding to make sure you can have 24V full time and not burn it up.
Check polarity for direction of rotation. And you don't want to
connect the 24V pack to M-.

> I have envisioned a few ways to get regen with this motor
> generator. See on the circuit I have a negative from
> battery going into the controller, then a negative from
> controller going into the motor. My problem when controller is
> not engaged battery negative will not be connected to motor.

Actually, there is a connection through the parasitic diodes in the
MOSFETS in the controller. When the motor is in generator mode the
current will flow back up through these diodes from B- to M-.

> However, in my circuit the
> positive of battery will still be connected and current can only
> flow one way back into the battery.

I believe that the other diode is not necessary either. As I
mentioned above the current will flow through the parasitic diodes
in MOSFETS in the controller. Although I suppose it wouldn't hurt
to add one in parallel to them between B- and M-. (Positive on B-,
band on M-)

> Here are some links to the circuit I drew.
> http://www.host-images.com/show.php/3645_shuntregencircuit.jpg
> http://img207.imageshack.us/img207/5061/shuntregencircuitbj1.jpg

Hope that helps. Others will probably add more.

Chet

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[EVDL List]

I think that if you downshift and hook up the motor's EMF to the battery
through your diodes, you will get very rapid, uncontrolled braking. If you
have 120V of back emf and a 72V battery, you'll get a huge burst of current
and deceleration. The huge current could hurt the parasitic diodes in your
controller's mosfets. Regen would work better if you had it more gradual.
Downshifting just the right amount would work, but it could be a pain.

Also, I think that your setup with the diodes and switches might not be
necessary. All you're doing is controlling which way the current is allowed
to flow. A simpler circuit would be the controller+ directly connected to B+
and a left-facing diode in parallel with a switch between the controller and
M+. That way, in normal operation, the switch is pressed and the motor is
directly connected to the controller. In regen operation, the switch is open
and current can only flow from M+ to the battery.

I also advise you to find someone more experienced.
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[EVDL List]

I was looking over all the comments, thanks. However, I forgot to include the
precharge resistor over the contactor labeled SW1. So when the regen is
taking place, the controller will get a little of the 120 volt current
through the precharger resistor.

My question: Would this ruin the controller as the voltage climbs through
this little 200 ohm 10W resistor?
One solution would be to run it all at a lower voltage of say 60V or 72V.
The controller I am using can run as high as 84V constantly, and has
tolerance for 100V for a while. Actually, don't have it yet, but it has been
ordered.

I suspect it wouldn't ruin the controller since it isn't on technically. It
does have over voltage protection, so it might just shut it off. Or maybe
the batteries will sink all this current and voltage instantly and
controller would never see it. The regen will only happen if I downshift, so
with newly charged batteries I'd just not downshift. andrew payne


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[EVDL List]

Andrew,

I'd leave SW1 closed. Take it off a foot switch and
use the key switch. I don't think it should matter if
the controller is on during regen. If you run a 72
volt battery, you should never see 120 V. That would
probably put your face into the windshield. Your max
regen voltage should be about the same as your highest
charge voltage.

Now, I am not familiar with the Alltrax. You should
check with them. Or perhaps someone here can verify.
During regen, current will be reversed thru the
controller current sensor. I don't think that is a
problem, but I don't know for sure how the control
electronics work in there.

As far as your basic regen scheme, down shifting to
raise motor speed is pretty primitive type of control.
There would be no voltage or current control if you
leave the full voltage on the field. Therefore, it
would be advisable to have a means to reduce field
current to control the regen torque and therefore
voltage and current.

I think you said you were driving it now, just 48
volts, no controller. Does it regen now if you go
downhill?

Anyway, sounds like you're having fun. Keep at it.

Jeff M.

--- ampaynz1 <[email protected]> wrote:

>
> I was looking over all the comments, thanks.
> However, I forgot to include the
> precharge resistor over the contactor labeled SW1.
> So when the regen is
> taking place, the controller will get a little of
> the 120 volt current
> through the precharger resistor.
>
> My question: Would this ruin the controller as the
> voltage climbs through
> this little 200 ohm 10W resistor?
> One solution would be to run it all at a lower
> voltage of say 60V or 72V.
> The controller I am using can run as high as 84V
> constantly, and has
> tolerance for 100V for a while. Actually, don't have
> it yet, but it has been
> ordered.
>
> I suspect it wouldn't ruin the controller since it
> isn't on technically. It
> does have over voltage protection, so it might just
> shut it off. Or maybe
> the batteries will sink all this current and voltage
> instantly and
> controller would never see it. The regen will only
> happen if I downshift, so
> with newly charged batteries I'd just not downshift.
> andrew payne
>




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