Kelly Controller Pron, and a Call for Help

[shinyballs]

thank you baby, didn't know there are leds with only 2mA... will it be ok to use the 5v output for the throttle/brake to a resistorized led and not affect those controls?
I have a bunch of regular 20mA leds and it'll make a Kelly's status light much brigher to see in daytime.

 

[Tiresias]

Are Kelly Controllers programmable? Sorry but I didn`t understood all of the description on their homepage. I need a controller for my Heinzmann Brushed hub. If the controllers are programmable, can I decide how much ampere runs through?

 

[shinyballs]

Kellys are generally configurable although I haven't tried there Brushed controllers. You can limit the current and voltage feeding the motor through its configuration software. It really doesn't matter what brushed type you picked as long as its within the voltage range.
Besides price, other things you would consider is size and regen.

For the Heinzmann, there small ones can handle it...
http://www.kellycontroller.com/mot/Brushed-Motor-Speed_Controller.html

Are Kelly Controllers programmable? Sorry but I didn`t understood all of the description on their homepage. I need a controller for my Heinzmann Brushed hub. If the controllers are programmable, can I decide how much ampere runs through?

 

[shinyballs]

I've just gotten a bmc 600 rear hub for my existing 74v 16Ah LiFePO4. Careful of not frying this motor, I'll run it at 48v by changing the top speed setting in the config program to 70%.

Emailed Kelly regarding how exactly does the Controller limit top speed when you change the value of "top speed[1]", response is: Basically you can limit the output voltage to motor, so limit the max speed of motor.

How does one verify if it really is putting out 70%(51v) to the motor?

If this setting works, I don't need to reconfigure my packs, wirings. Have to also limit current to 30A and disable regen.

 

[methods]

Set to 100%
read MPH from Cycle Analyst

Change Kelly to 70%
read MPH from Cycle Analyst

New speed will be 70% of old speed
That is the answer to your question - how to confirm that it works

Now I will say, that is sort of a weird way to go about "not frying your motor"
No reasonable amount of voltage (or top speed) is going to "fry" your motor.
Heat is what will fry your motor and heat comes from current.
Unless the bike goes to fast for your liking, set the speed to 100% and limit the current

Current limiting is what you want to use to protect your motor 99% of the time.
You will notice that once you get up to the top speed of your bike, the motor will be drawing very little current.
It is the period at which you are accelerating that is stressing the motor, not the top speed you attain.

-methods

EDIT: When they tell you that a motor is "rated for 48V" they are assuming that you are not using current limiting. You can apply whatever voltage you like to the motor so long as you control current. Current and voltage are related by V=I*R so regulating (or lowering) current will regulate (or lower) voltage.

 

[oatnet]

I've just gotten a bmc 600 rear hub for my existing 74v 16Ah LiFePO4. Careful of not frying this motor, I'll run it at 48v by changing the top speed setting in the config program to 70%.

Emailed Kelly regarding how exactly does the Controller limit top speed when you change the value of "top speed[1]", response is: Basically you can limit the output voltage to motor, so limit the max speed of motor.

How does one verify if it really is putting out 70%(51v) to the motor?

If this setting works, I don't need to reconfigure my packs, wirings. Have to also limit current to 30A and disable regen.

The bmc is a geared motor that freewheels, so forget about regen - you do need direct drive to achieve regen.
The Kelly does NOT limit voltage, it limits current like most brushless controllers. Steven of Kelly knows his stuff, I would not expect him to make this mistake, is that a verbatim response?
As methods points out, heat from current (amps) is usually a problem with motors, so leave volts as-is and worry about amps. I think there is also a limit to how many watts you can put into a BMC before it generates enough torque to grind the nylon gears into paste; if you limit this with the amp side then your motor runs cooler.
Depending on which Kelly you have, you may be able to limit current, as well as speed. The impact of the %max sliders is best discovered through real-world testing.
The best way to monitor the effects of the changes these settings makes is with a CycleAnalyst.

 

[methods]

The Kelly does NOT limit voltage, it limits current like most brushless controllers. Steven of Kelly knows his stuff, I would not expect him to make this mistake, is that a verbatim response?

He was asking Kelly what the "SPEED" slider did, not what the "CURRENT" slider did.
As we all agree, the kelly limits current, but it can also limit voltage via the "SPEED" slider.

Stevens response was correct in that lowering the %Speed will lower the output voltage by that percentage.
It was the correct answer to the wrong question, hence the confusion.

-methods

 

[oatnet]

The Kelly does NOT limit voltage, it limits current like most brushless controllers. Steven of Kelly knows his stuff, I would not expect him to make this mistake, is that a verbatim response?

He was asking Kelly what the "SPEED" slider did, not what the "CURRENT" slider did.
As we all agree, the kelly limits current, but it can also limit voltage via the "SPEED" slider.

Stevens response was correct in that lowering the %Speed will lower the output voltage by that percentage.
It was the correct answer to the wrong question, hence the confusion.

-methods

Huh. I thought the speed slider set RPMs against the hall inputs and the max poles the processor can handle, but I guess I could be wrong. When I looked at the 'Top Speed' slider in the programmer, I see "1. Configure the Max output speed, this may affect the Max current output." and assumed that they were both modifiying current. I assumed that 'max current' slider limited current across the whole range, and the "max speed" tapered current off as one accellerated, but maybe this is referring to back emf.

In practice, I saw the same watt drain and torque launch and through the band, no matter where I set max speed. However, the lower I set max speed the sooner supply amps would start to taper down. I guess this could just be back EMF from a lower motor-side voltage, I just never thought about it that way.

I am just an amatuer, but voltage regulation seems like a really inefficient control scheme to me. Surely the voltage conversion is lossy; and as you point out, if you achieve the same watts by increasing amps, you add resistance losses and heat. Plus the expense of adding hardware to regulate voltage. Every day I discover I have lots more to learn about this hobby though... I didn't find anything about it on E:S from a search, can you point me to where this was discussed?

Shinyballs, I still would recommend leaving your voltage right where it is, and regulate the number of watts you put into your motor by regulating amps (current slider). I also see from the Kelly manual "(14) current meter to display both drive and regen current. Save shunt" so this might give you a handy tap for a motor-side CA connection. I might try this myself to see what is going on.

-JD

 

[methods]

The way the throttle works is with Pulse width modulation.
50% duty cycle = 50% throttle = 50% voltage
10% duty cycle = 10% voltage
100% duty cycle = WOT

They regulate the voltage with PWM
http://en.wikipedia.org/wiki/Pulse-width_modulation
Pulsing the voltage changes the "apparent" voltage.

So when you slide the SPEED lever all you are doing is setting the maximum PWM duty cycle
100% gives you the full voltage range
50% will limit the voltage to 50% and thereby limit your top speed to 50%

Every controller works like this, both DC and Brushless.

Your advice to limit the power by limiting the current is the correct thing for him to do.

-methods

 

[oatnet]

Pulsing the voltage changes the "apparent" voltage.

Well, there is my ignorance right there. I always thought PWM modulated amps, not volts, so that each peak of the wave it would allow a slice of current through at the supply side voltage, so the more/longer peaks the more amps let through. I guess I inferred that because higher supply side voltage = higher RPM, voltage was the same on supply and motor sides. I'm gonna have to re-invent my whole mental model here, I can't even envision why supply side amps are changing while on the motor side volts are changing.

In addition, when researching brushed controllers, I thought I had read that supply side voltage=motor side voltage. I'm gonna have to hook up a motor-side shunt on the bus and do some learning, you just shook my world.

Like I said earlier, every day in this hobby I discover how much more I have to learn.

-JD

 

[CNCAddict]

If it makes you feel any better...I design motors and they still mystify me. This stuff can be pretty bizarre at times

 

[shinyballs]

Set to 100%
read MPH from Cycle Analyst

Change Kelly to 70%
read MPH from Cycle Analyst

New speed will be 70% of old speed
That is the answer to your question - how to confirm that it works

Thats close but AFAIK the CA only shows the total pack voltage. It doesn't know the max actual voltage(approx 51v) in the the motor at 70%.

EDIT: When they tell you that a motor is "rated for 48V" they are assuming that you are not using current limiting. You can apply whatever voltage you like to the motor so long as you control current.

Hmm... don't think so. For this motor, the dealer assumes you are using a bmc controller as part of the kit, or if a different controller, the current limit should be 35A or less to be covered under their warranty.

The bmc is a geared motor that freewheels, so forget about regen - you do need direct drive to achieve regen.

Wow really?! I can see Russia from my house.

The Kelly does NOT limit voltage, it limits current like most brushless controllers. Steven of Kelly knows his stuff, I would not expect him to make this mistake, is that a verbatim response?

Repeating Steven's email reply -
Basically you can limit the output voltage to motor, so limit the max speed of motor.

Stevens response was correct in that lowering the %Speed will lower the output voltage by that percentage.
It was the correct answer to the wrong question, hence the confusion.
-methods

What's wrong with asking the question about "top speed"?

To monitor what's really going on between the controller & motor, can a volt/amp meter work when wired to the phase wires?

 

[TylerDurden]

I always thought PWM modulated amps, not volts, so that each peak of the wave it would allow a slice of current through at the supply side voltage, so the more/longer peaks the more amps let through. I guess I inferred that because higher supply side voltage = higher RPM, voltage was the same on supply and motor sides. I'm gonna have to re-invent my whole mental model here, I can't even envision why supply side amps are changing while on the motor side volts are changing.

My non-EE mental-model looks like a bigass electronic light dimmer made for inductive loads: the pulsed-power gets smoothed by the caps' & motor's inductance (lowering the average voltage), which also transforms the current because P_in = P_out (less I2R & other losses).

Of course, average motor voltage must be changing; since no-load motor speed changes with variation in throttle/PWM.