[engineer_Bill]

Originally Posted by jbeatty

Hi Guys.... First off, I GUARANTEE you I am NOT Tommy in disguise :-) After all, if I was Tommy, how could I possibly avoid plugging my own hardware and telling you what a genius I am!

So, the morning after I had my online pissing match with Steven and made the post here, I received another email from him stating that he was going to send me a new controller. Now I don't know what to think. I somewhat confused about why he couldn't have just done that in the beginning and saved all the insults, but whatever. I'll keep you posted after I receive it and try it out.

Incidentally, on the configuration software, it is quite nice. There are a lot of adjustments, and for us it worked as shown on the kelly site (although we did have the trouble mentioned previously with the analog signal for regen).

Actually, while I'm at it, maybe you guys can help with the problem I was having.... Our car is 24V DC. We have the Mars 0709 Brushed DC Motor http://www.cloudelectric.com/inc/sdetail/2366 which should be over 6 hp peak (as I understand it, but granted I'm pretty new to this). Our batteries are deep cycle 55 Ah. I was told these batteries should be capable of 300 amps. From a dead stop, full throttle, we are only getting 130 amps MOTOR current. We've completely rewired our car and stripped out ALL unnecessary parts like cutoff switches, etc. We are running battery to contactor to controller. Nothing else. The controller is the Kelly KD36301, supposedly capable of 300 amps peak. What else could possibly cause us to get less than 1/2 peak current? Keep in mind we put the alltrax out of our other car in this one and immediately went to 180 amps. The alltrax is a 400 amp controller, so we're still not reaching peak, but our current did improve by 50% by pulling out the Kelly.

These are the questions that I asked Steven that he never answered :-)

Any help is greatly appreciated.

Jason

I would try a higher voltage the motor you showed in the link is 24-72 volts. You are running on the LOW end for this motor. The difference in current between the two controllers is most likely caused by a difference in internal resistance in the controllers. IGBT VS MOSFET? or different amount or voltage rating of drive components. Try 36 Volts and see if you get better performance. I'm using a Kelly controller for my EV. I've only bench tested it so far, but it is working good. I had trouble comunicating with it from a laptop, but from my desk top no problem. They sent a new interface cable that fixed the com problem when I called them.

[MindMil]

Originally Posted by engineer_Bill

I would try a higher voltage the motor you showed in the link is 24-72 volts. You are running on the LOW end for this motor. The difference in current between the two controllers is most likely caused by a difference in internal resistance in the controllers. IGBT VS MOSFET? or different amount or voltage rating of drive components. Try 36 Volts and see if you get better performance. I'm using a Kelly controller for my EV. I've only bench tested it so far, but it is working good. I had trouble comunicating with it from a laptop, but from my desk top no problem. They sent a new interface cable that fixed the com problem when I called them.

I agree with Bill. Low current might not be always a fault of controller. You cannot expect controller to produce the max current what is written in controller max specs. It heavily depends on setup.
Simplest way to test might be to connect the battery directly to the motor for very short period of time (like 1 to few seconds) and measure the current, lets call it Imax, to the the loaded motor. It is simplest but not safest as high currents and high torque motors might be very nasty.
So if you do it then do it at your own risk and liability and make sure to take precautions:
- Use loaded motor (otherwise it will runaway and likely destroy itself). Loaded doesn't mean clamped to be still. A good load is a dynamic one such as barely moving car or a propeller (I've seen guys actually testing this way)
- Use the circuit breaker of current nominal somewhat bigger than maximum rated current of the motor (otherwise you'll smoke the motor if battery is too powerful and current is unexpectedly high due to stalled motor)
- If you have battery stack then it would be much safer to connect fewer batteries first and work it up as you make your measurements.

After this testing you will have the current Imax that proper controller should able to reach in theory if you step on gas with heavy foot. If it is way below then controller has a problem indeed. Ideally in the same conditions the controller should be able to produce any current between 0 and Imax depending on throttle possition.

Couple of examples:
Exapmle A: You have 300Amp controller, motor model A and 24V battery. You measured Imax = 170 Amps with battery connected to the motor directly and max 150Amps through the controller. Then the controller is most likely OK since it produces about 88% of current range. The rest could be some expected heat dissipation.

Example B: You have 400Amp controller, motor model B and 48V battery. You measured Imax 300Amps directly and 150Amps through controller with throttle down with all controller temperatures initially OK. In this case controller has issues because it produces only 50% of the current available to it. You may also expect controller to heat up very quickly - be cautious.

A more scientific way is to measure four parameters: current from batteries to controller, voltage on batteries on controller input, current controller to motor, voltage on motor on controller output. Then it would be possible to estimate how much of available range the controller uses and what is it's energy loss (heat).

[Tesseract]

BTW - what's the verdict with regen on this controller. Does it work or not?

[engineer_Bill]

Originally Posted by Tesseract

BTW - what's the verdict with regen on this controller. Does it work or not?

It works on the test bench. I strapped down the motor and ran it with half the pack to full RPM then throttled down quickly. I got about half the maximum amps on the startup, back on the regen slow down. I'm still waiting on the coupler to attach to the car. I'll give an update when I'm finished.

[Tesseract]

Originally Posted by engineer_Bill

It works on the test bench. I strapped down the motor and ran it with half the pack to full RPM then throttled down quickly. I got about half the maximum amps on the startup, back on the regen slow down. I'm still waiting on the coupler to attach to the car. I'll give an update when I'm finished.

Very cool. It's quite difficult to get regeneration to work with a series wound motor because the transfer function has a potential infinity in it (a divide-by-zero). You don't by any chance happen to remember what the actual amps were and if you noticed the motor revert to coasting once it hit a particular rpm do you?

[saab96]

Originally Posted by Tesseract

Very cool. It's quite difficult to get regeneration to work with a series wound motor because the transfer function has a potential infinity in it (a divide-by-zero). You don't by any chance happen to remember what the actual amps were and if you noticed the motor revert to coasting once it hit a particular rpm do you?

Is this really going to work well with these tweaked forklift motors that have advanced brush timing? And if you leave the brush timing in a neutral position won't you have trouble getting enough power out of these motors to make it anything more than a NEV?

[TheSGC]

Originally Posted by engineer_Bill

It works on the test bench. I strapped down the motor and ran it with half the pack to full RPM then throttled down quickly. I got about half the maximum amps on the startup, back on the regen slow down. I'm still waiting on the coupler to attach to the car. I'll give an update when I'm finished.

Woah, wait- are you using a series wound motor and getting actual regen with juice going back into your pack???????!?!??!?!??!

I have a Kelly KDH09401 with REGEN, but I did not enable it because I was under the impression REGEN didn't work with series wound.

[Tesseract]

Originally Posted by saab96

Is this really going to work well with these tweaked forklift motors that have advanced brush timing? And if you leave the brush timing in a neutral position won't you have trouble getting enough power out of these motors to make it anything more than a NEV?

You are correct in that regen with an advanced brush motor is a disaster waiting to happen (same as trying to run such a motor in reverse).

And, as far as forklift motors go, yeah, you have to advance the brush timing to run them at a higher voltage (and extract much more horsepower out of them), but this means no reverse and no regeneration, unless you are ok with losing 60-90% of the brush life and/or possibly damaging the commutator segments from arc-over.

Thus, a controller that can do regen should always provide the option of disabling it!

[Tesseract]

Originally Posted by TheSGC

...
I have a Kelly KDH09401 with REGEN, but I did not enable it because I was under the impression REGEN didn't work with series wound.

Every motor is a generator, too. Some are just more suited to the task than others. (disclaimer: I still haven't figured out how to make a shaded-pole motor act as a generator, but theoretically it can).

The problem with the series wound motor is that the qualities that make it so attractive for "traction" applications, like being able to delivering tremendous amounts of torque at 0 rpm, also make it "unstable" as a generator.

For example, the current through a series wound motor skyrockets if you lock its rotor; conversely, the current will also skyrocket if you short-circuit a rotating series motor (and the rotor will quickly decelerate, too, unless a very high inertia load is attached to it... like a moving vehicle!). Unfortunately, because the field current and armature current are the same in a series motor, and the rpm it spins at is proportional to the voltage for a given load, the only way to turn a series motor into a generator is to short-circuit it briefly to allow the current to build up in the field/armature (extracting rotational energy in the process; i.e. - braking) and then release the short after a precise amount of time to allow the inductive nature of the motor to "flyback" and produce a higher voltage than the battery pack's. In SMPS terms, you need to change the controller from a buck converter to a boost converter to do regen with a series wound motor, and those two topologies have very different transfer functions... Because of this, it is not really practical for a strictly analog controller to operate in both modes because the compensation and control scheme for each is radically different: practically speaking, you would need two separate control circuits! It's a whole different story with a microcontroller, though...

Still tricky, mind you, which is why I was curious to see if the Kelly controller actually pulled it off. With reliable regen DC motors really can give 3-ph ac motors a serious run for the money.

[TheSGC]

Originally Posted by Tesseract

Every motor is a generator, too. Some are just more suited to the task than others. (disclaimer: I still haven't figured out how to make a shaded-pole motor act as a generator, but theoretically it can).

The problem with the series wound motor is that the qualities that make it so attractive for "traction" applications, like being able to delivering tremendous amounts of torque at 0 rpm, also make it "unstable" as a generator.

For example, the current through a series wound motor skyrockets if you lock its rotor; conversely, the current will also skyrocket if you short-circuit a rotating series motor (and the rotor will quickly decelerate, too, unless a very high inertia load is attached to it... like a moving vehicle!). Unfortunately, because the field current and armature current are the same in a series motor, and the rpm it spins at is proportional to the voltage for a given load, the only way to turn a series motor into a generator is to short-circuit it briefly to allow the current to build up in the field/armature (extracting rotational energy in the process; i.e. - braking) and then release the short after a precise amount of time to allow the inductive nature of the motor to "flyback" and produce a higher voltage than the battery pack's. In SMPS terms, you need to change the controller from a buck converter to a boost converter to do regen with a series wound motor, and those two topologies have very different transfer functions... Because of this, it is not really practical for a strictly analog controller to operate in both modes because the compensation and control scheme for each is radically different: practically speaking, you would need two separate control circuits! It's a whole different story with a microcontroller, though...

Still tricky, mind you, which is why I was curious to see if the Kelly controller actually pulled it off. With reliable regen DC motors really can give 3-ph ac motors a serious run for the money.

I just sent off an e-mail to Kelly asking them about the series motors and regen on their controllers. I don't want to blow my controller to hell without some verification. But if REGEN does work, that would be amazing.