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 Post Posted: Sat Oct 17, 2009 12:17 am 
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Joined: Fri Jul 24, 2009 4:30 pm
Posts: 3
Location: Dartmouth
Our (Dartmouth's) experience with Kelly controllers (KDH14501B) has had ups and downs. We've had a few issues which we strongly suspect are linked to our controllers:

- Regen doesn't work. We got a model with regen, but have been unable to get anything to happen.
- Our two motor controllers are not matched, the left controller will spin the left wheel, but the right one will not since it appears to put out less power.
- The RS-232 port on the connectors is not wired, we'd put it in our wiring harness, but it doesn't do anything.
- There is a 220K resistor between high and low voltage (confirmed by Kelly), meaning that with 2 we have 110K, putting us way closer than we would like to be to a ground fault. We did get this OKed by somebody at FH.
- There is no CAN, despite references to optional CAN.

If any of you have recommendations for controllers that have worked well for you and support regen, that would be appreciated.

As a final note, if you are looking for a brushed motor controller that doesn't have regen, we're had good luck with the Zilla.

Adam


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 Post Posted: Sat Oct 17, 2009 1:03 am 
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Joined: Tue Oct 30, 2007 6:50 pm
Posts: 78
Location: Illinois Tech
If your RS232 is not working how did you guys program your controllers? I don't know if you can see it in the pictures I have posted already but I don't think the RS232 is wired properly. Of course we were using an older model than yours so I don't know if anything has changed. But when we were using ours we had to use a "special" adapter for the serial communication. If you want I can open up the one we have and let you know what's inside.

Sigmadrives from PGDT are a good bet all though the more we work with them the more weaknesses we find. But overall they are a better bet than the Kelly's minus the lack of torque control for brushed DC motors.


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 Post subject:
 Post Posted: Sat Oct 17, 2009 5:09 pm 
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Joined: Fri Jul 24, 2009 4:30 pm
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Location: Dartmouth
There are supposed to be 2 connections, the proper port and one to connect into the wiring harness. Only the DB-9 worked, but we designed our wiring and layout assuming the other one would work.

Has anybody else used the SigmaDrives? I know I saw one team using them with both a dc motor and with one of Perm's brushless motors.


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 Post subject:
 Post Posted: Sat Oct 17, 2009 5:32 pm 
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Joined: Tue Oct 30, 2007 6:50 pm
Posts: 78
Location: Illinois Tech
Adam wrote:
There are supposed to be 2 connections, the proper port and one to connect into the wiring harness. Only the DB-9 worked, but we designed our wiring and layout assuming the other one would work.

Has anybody else used the SigmaDrives? I know I saw one team using them with both a dc motor and with one of Perm's brushless motors.


That was us. The drives worked great at the competition and they are relatively easy to configure. But they lack some features that we would like to have.


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 Post subject: To Antoant
 Post Posted: Mon Oct 19, 2009 4:58 pm 
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Joined: Tue Oct 06, 2009 4:00 pm
Posts: 38
Location: Florida State University
antoant wrote:
Adam wrote:
There are supposed to be 2 connections, the proper port and one to connect into the wiring harness. Only the DB-9 worked, but we designed our wiring and layout assuming the other one would work.

Has anybody else used the SigmaDrives? I know I saw one team using them with both a dc motor and with one of Perm's brushless motors.


That was us. The drives worked great at the competition and they are relatively easy to configure. But they lack some features that we would like to have.


Hi, besides your motor controller, do you still need another MCU as a central controller? you know, motor controller just got e.g. torque command from outside, while what this torque command should be, would really depends on some kind of functions which collect all the component information including brake pedal position/acceleration pedal position. the problem for such a configuraton, which I guess, is lots of
programming work in this controller, do you think so?


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 Post subject:
 Post Posted: Mon Oct 19, 2009 8:22 pm 
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Joined: Tue Oct 30, 2007 6:50 pm
Posts: 78
Location: Illinois Tech
@Julius

It depends on the level of sophistication you want your car to have. For example you can have a parallel hybrid that does not even include a motor controller. You just have an on-off switch that connects the motor directly to the batteries and your motor acts as a boost switch while you drive the engine the same way as a regular FSAE car. On the other hand you can have a very sophisticated car that has a central controller that acts as both an ECU and motor controller while taking into consideration SOC of the batteries, load, torque demand, wheel slip and anything else you can think of. And in that case you are right you will have a very complicated programming task in your hands, and if you manage to get it right you will probably have a much better car, from a system control point of view, than the very simple car described above. It is up to you to decide on the sophistication of your control system and if it makes sense to spend the extra time to perfect it while a less sophisticated solution will give you as good a result.

In our case we did have a central uC that took the driver's input and translated it to commands for both of our motor controllers and our engine based on the current of the batteries and the voltage of the DC bus. It was not as complicated as it sounds but in retrospect a simpler drivetrain configuration with a simpler controller might have been a better choice.


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 Post subject: to antoant
 Post Posted: Wed Oct 21, 2009 3:10 pm 
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Joined: Tue Oct 06, 2009 4:00 pm
Posts: 38
Location: Florida State University
Thanks,
another question, you know , we are going to use PMG-132 as the drive motor, which is 7.2kW at
3480 RPM, I saw IIT also use PMG-132 as drive motor while you mentioned in the 2009 program pdf
17.5HP(13kW) @ 3500 RPM, I assume you were using two PMG-132, right?
If that is it, are you using them as simple parallel 2 motors or you use one to drive left wheel, another to
drive right wheel?


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 Post subject:
 Post Posted: Wed Oct 21, 2009 6:55 pm 
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Joined: Tue Oct 30, 2007 6:50 pm
Posts: 78
Location: Illinois Tech
julius wrote:
Thanks,
another question, you know , we are going to use PMG-132 as the drive motor, which is 7.2kW at
3480 RPM, I saw IIT also use PMG-132 as drive motor while you mentioned in the 2009 program pdf
17.5HP(13kW) @ 3500 RPM, I assume you were using two PMG-132, right?
If that is it, are you using them as simple parallel 2 motors or you use one to drive left wheel, another to
drive right wheel?


We were using one PMG-132 as a drive motor and one as a generator on our parallel car. On our series car we use one motor on each front wheel with its own separate controller in order to have better control of the differential action. The power that we put in the program was the peak power of a single PMG-132 for a 10 minute interval assuming you have enough of a voltage to push 200 amps through the motor when it is spinning at 3500rpm. In reality the motor is able to produce a lot more power than what we put in the program or what the company advertises but that extra power can only be had for a few seconds. To be exact, the power developed by a permanent magnet brushed DC motor is limited by three factors:
1. HEAT. The heat the windings can take before they burn and the heat the magnets can take before losing magnetization
2. CURRENT & VOLTAGE. The amount of current you are able to push through the windings and as a consequence the difference in voltage between your power source and the motor's back EMF
3. The mechanical limitations of bearings, rotor, etc.
There might be a fourth limiting factor which is flux saturation but I am not sure if this applies to PMDCs.

An obvious example of how a PMG-132 can produce more power than advertised is the winning car of 2009, namely Texas A&M.
If you use the advertised weight of the car which is 250kg and use a 50kg driver and use the best electric acceleration time they had, which is close to 7sec, you can calculate that the average power produced by the motor must be 9.5kW.


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 Post subject:
 Post Posted: Wed Oct 21, 2009 8:29 pm 
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Joined: Wed Jun 03, 2009 1:29 am
Posts: 117
Location: Texas A&M
antoant wrote:
julius wrote:
Thanks,
another question, you know , we are going to use PMG-132 as the drive motor, which is 7.2kW at
3480 RPM, I saw IIT also use PMG-132 as drive motor while you mentioned in the 2009 program pdf
17.5HP(13kW) @ 3500 RPM, I assume you were using two PMG-132, right?
If that is it, are you using them as simple parallel 2 motors or you use one to drive left wheel, another to
drive right wheel?


We were using one PMG-132 as a drive motor and one as a generator on our parallel car. On our series car we use one motor on each front wheel with its own separate controller in order to have better control of the differential action. The power that we put in the program was the peak power of a single PMG-132 for a 10 minute interval assuming you have enough of a voltage to push 200 amps through the motor when it is spinning at 3500rpm. In reality the motor is able to produce a lot more power than what we put in the program or what the company advertises but that extra power can only be had for a few seconds. To be exact, the power developed by a permanent magnet brushed DC motor is limited by three factors:
1. HEAT. The heat the windings can take before they burn and the heat the magnets can take before losing magnetization
2. CURRENT & VOLTAGE. The amount of current you are able to push through the windings and as a consequence the difference in voltage between your power source and the motor's back EMF
3. The mechanical limitations of bearings, rotor, etc.
There might be a fourth limiting factor which is flux saturation but I am not sure if this applies to PMDCs.

An obvious example of how a PMG-132 can produce more power than advertised is the winning car of 2009, namely Texas A&M.
If you use the advertised weight of the car which is 250kg and use a 50kg driver and use the best electric acceleration time they had, which is close to 7sec, you can calculate that the average power produced by the motor must be 9.5kW.


The amount of power your PERM will put to the ground depends significantly on gearing (because it affects RPM), accumulator voltage, and accumulator current. PMDC motors are pretty easy to simulate, and if you want peak performance, even a simple simulation (I wrote one in C++, but any language, like Maple or Matlab, would work) is very useful

_________________
- Texas A&M 2009 FH Crew Chief
- 1st place FH '09: 981 pts


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 Post subject:
 Post Posted: Wed Oct 21, 2009 9:08 pm 
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Joined: Tue Oct 30, 2007 6:50 pm
Posts: 78
Location: Illinois Tech
Well the amount of torque you put through is affected by gearing not power. You can still produce 7.2kW with a higher gear ratio but you will not go as fast in the end, given the same voltage. But I do agree with Mojave, that it is very easy to simulate a PMDC. Get a book on motor design, or even controller design, from your school's library and use the equations in it, or look for them on google.


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 Post subject:
 Post Posted: Wed Oct 21, 2009 9:21 pm 
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Joined: Wed Jun 03, 2009 1:29 am
Posts: 117
Location: Texas A&M
antoant wrote:
Well the amount of torque you put through is affected by gearing not power.


HP = (torque * RPM) / 5252

So I'm really not sure what you mean with that statement. Did you mean peak power?

antoant wrote:
You can still produce 7.2kW with a higher gear ratio but you will not go as fast in the end, given the same voltage. But I do agree with Mojave, that it is very easy to simulate a PMDC. Get a book on motor design, or even controller design, from your school's library and use the equations in it, or look for them on google.


If you are talking acceleration times, and thus average power over an acceleration run, gearing absolutely has an affect.

_________________
- Texas A&M 2009 FH Crew Chief
- 1st place FH '09: 981 pts


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 Post subject:
 Post Posted: Thu Oct 22, 2009 1:42 am 
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Joined: Tue Oct 30, 2007 6:50 pm
Posts: 78
Location: Illinois Tech
Well you said that the amount of power your motor puts to the ground depends on gearing. That is not true. As you pointed out

Power = torque * rpm / 5252

If you gear your motor down you are decreasing your RPM but equally increasing your torque. Thus the power you are delivering is the same.

"You can still produce 7.2kW with a higher gear ratio but you will not go as fast in the end" By that I mean that your top speed will decrease given the same voltage and enough time and distance to achieve that top speed. You are right acceleration times will be affected by gearing but the power that your motor can produce will not, that was my point.


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 Post subject: Did the Mosfets fail?
 Post Posted: Tue Mar 09, 2010 11:33 am 
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Joined: Tue Oct 06, 2009 4:00 pm
Posts: 38
Location: Florida State University
antoant wrote:
Last year we used one on our car. We were running a 72V bus so I cannot comment on their 144V+ models but even the model we had was not all that good. We managed to burn it while doing regen and got another one which functioned fine for a while until the ends started popping off. In general I think their enclosures are poorly build. The ends are made out of plastic and are glued to the aluminum housing, or just pressed in. (One end had glue marks on it the other did not.) As far as the hardware inside the enclosure, well I can't really comment on the quality of the components since they are all covered with some sort of black paint, (to deter someone from copying/fixing the circuit?) but the setup used is not exactly professional. They use multiple mosfets in parallel in order to get the amp rating they want and multiple electrolytic capacitors to get the capacitance they need to run properly. The problem with that setup is that not all mosfets are created equal, manufacturing variations will cause different resistances, turn on and off times which can cause some of them to get hotter than the others and if one of them fails the rest will follow soon after.

However, in May I saw that Dartmouth was using them and they told me they did not have any problems with them. They even pointed out that the Kelly controllers will do torque control, which is a nice feature and one that most other controllers (if not all of them) do not have. Also to their defense I have not opened up the controllers that we used this past May to see what kind of setup they use, but then again I didn't have to because they did not burn.


Hi, There,

you said the Kelly controller failed during regen. , you know, the controller is actually just a half bridge circuit inside which include high side Mosfets and low side Mosfets, since you have removed the package, I guess you can measure if either of them got short-circuit, If all those Mosfets G, D, S are not short-circuited, I will suppose the driver for the Mosfets or the control chip got burned , but they may got black-painted and hard to measure as you mentioned.
anyway, I am just very cute about the regen. failure since we also want to implement regen. function in our car.


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