stuttering controller

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fractal   1 kW

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stuttering controller

Post by fractal » Jul 05 2012 9:07am

I noticed this morning my controller started stuttering a bit near the end of my commute. It happened when I was accelerating at maybe half or 3/4 throttle. Its the first time it happens and i did not change any settings on the CA or the controller before this. Is there any protection inside the controller to keep it from getting damaged? At lower speeds, it seemed fine, but I was at the end of my commute so I did not test it for a longer period. I have been running it at 100v 40 amps max. It is rated for 72 volts but the caps are good for 100 volts. Any ideas why its doing that? I did not abuse it. It does get hot but I can keep my hands on it no problem.
Norco A-line DH bike with :
«cromotor/hubzilla» from http://www.greyborg.com/
24s 3p Lipo (100v, 15ah)
Methods LVC/HVC cell level protection system http://www.methtek.com
24 fet infineon controller made by Lyen, heavily moded by Methods
8awg harness by Icecube57
17 inch moped rims with Michelin Gazelle tires by John Rob Holmes http://www.holmeshobbies.com
other stuff http://www.ebikes.ca

details
http://www.helicamguide.com

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dogman dan   100 GW

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Location: Las Cruces New Mexico USA

Re: stuttering controller

Post by dogman dan » Jul 05 2012 4:50pm

The common reason for your problem is a wiring issue. Often a connector backing out of the housing, phase or halls wires. Could also be a partialy cut wire, like a phase wire with one strand left.

Look at that sort of thing first, always.

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fractal   1 kW

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Re: stuttering controller

Post by fractal » Jul 06 2012 9:23am

fixed! Well... turns out there is nothing wrong with it! At 100 volts, the throttle is so sensitive that even the slightest variation will cause it to jerk. What we need are better throttles for running 100+ volts. Maybe an Algorithm could be programmed in the firmware to make the throttle response smoother without scarificing fast accelelration. I'm sure somebody has already thought of that.
Norco A-line DH bike with :
«cromotor/hubzilla» from http://www.greyborg.com/
24s 3p Lipo (100v, 15ah)
Methods LVC/HVC cell level protection system http://www.methtek.com
24 fet infineon controller made by Lyen, heavily moded by Methods
8awg harness by Icecube57
17 inch moped rims with Michelin Gazelle tires by John Rob Holmes http://www.holmeshobbies.com
other stuff http://www.ebikes.ca

details
http://www.helicamguide.com

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Jeremy Harris   10 GW

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Location: Salisbury, UK

Re: stuttering controller

Post by Jeremy Harris » Jul 06 2012 9:41am

fractal wrote:fixed! Well... turns out there is nothing wrong with it! At 100 volts, the throttle is so sensitive that even the slightest variation will cause it to jerk. What we need are better throttles for running 100+ volts. Maybe an Algorithm could be programmed in the firmware to make the throttle response smoother without scarificing fast accelelration. I'm sure somebody has already thought of that.
Worth remembering that an ebike speed control isn't a "throttle" and doesn't work like one. The throttle on a motorcycle or car pretty much directly controls the engine torque that's available, by restricting cylinder filling when closed or partially closed. When you open the throttle on a motorcycle the engine responds by producing more torque, so making it accelerate.

On an ebike, the throttle is typically a speed control, the position of the throttle is directly proportional to motor rpm, not motor torque. The reason for this is that it's the easy way to go as far as the controller is concerned, as throttle voltage can be linearly proportional to PWM duty cycle and hence applied motor voltage. The really big downside is that it means that the throttle has little or no direct control of motor torque. If you open the throttle then the controller goes flat out to get the motor up to the demanded speed. If you have a powerful set up this makes the throttle response seem a bit jerky, as you'll get far more torque than you want for an instant, often leading to you sub-conciously backing the throttle of a bit an instant later and then getting less torque than you want.

The real answer is to have a throttle control that is directly proportional to motor torque. This feels a lot better and is a lot smoother, as it stops the big jumps in motor torque as the controller tries to match demanded speed with actual speed. Unfortunately few controllers are able to do this, certainly none of the budget ebike controllers have a torque controlling throttle, AFAIK. It is possible to build an add-on that measures controller current and uses this as feedback to get a throttle that is proportional to power. This is almost as good as a throttle that's proportional to torque, in terms of feel, but doesn't need motor phase current monitoring.
Please ask questions on the forum, rather than by PM, as it helps others and you'll get a better range of answers.

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fractal   1 kW

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Re: stuttering controller

Post by fractal » Jul 06 2012 10:15am

Jeremy Harris wrote:
fractal wrote:fixed! Well... turns out there is nothing wrong with it! At 100 volts, the throttle is so sensitive that even the slightest variation will cause it to jerk. What we need are better throttles for running 100+ volts. Maybe an Algorithm could be programmed in the firmware to make the throttle response smoother without scarificing fast accelelration. I'm sure somebody has already thought of that.
Worth remembering that an ebike speed control isn't a "throttle" and doesn't work like one. The throttle on a motorcycle or car pretty much directly controls the engine torque that's available, by restricting cylinder filling when closed or partially closed. When you open the throttle on a motorcycle the engine responds by producing more torque, so making it accelerate.

On an ebike, the throttle is typically a speed control, the position of the throttle is directly proportional to motor rpm, not motor torque. The reason for this is that it's the easy way to go as far as the controller is concerned, as throttle voltage can be linearly proportional to PWM duty cycle and hence applied motor voltage. The really big downside is that it means that the throttle has little or no direct control of motor torque. If you open the throttle then the controller goes flat out to get the motor up to the demanded speed. If you have a powerful set up this makes the throttle response seem a bit jerky, as you'll get far more torque than you want for an instant, often leading to you sub-conciously backing the throttle of a bit an instant later and then getting less torque than you want.

The real answer is to have a throttle control that is directly proportional to motor torque. This feels a lot better and is a lot smoother, as it stops the big jumps in motor torque as the controller tries to match demanded speed with actual speed. Unfortunately few controllers are able to do this, certainly none of the budget ebike controllers have a torque controlling throttle, AFAIK. It is possible to build an add-on that measures controller current and uses this as feedback to get a throttle that is proportional to power. This is almost as good as a throttle that's proportional to torque, in terms of feel, but doesn't need motor phase current monitoring.
do you mean the add-on current throttle mod on the CA???
Norco A-line DH bike with :
«cromotor/hubzilla» from http://www.greyborg.com/
24s 3p Lipo (100v, 15ah)
Methods LVC/HVC cell level protection system http://www.methtek.com
24 fet infineon controller made by Lyen, heavily moded by Methods
8awg harness by Icecube57
17 inch moped rims with Michelin Gazelle tires by John Rob Holmes http://www.holmeshobbies.com
other stuff http://www.ebikes.ca

details
http://www.helicamguide.com

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Jeremy Harris   10 GW

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Joined: Oct 23 2007 4:15pm
Location: Salisbury, UK

Re: stuttering controller

Post by Jeremy Harris » Jul 06 2012 10:31am

fractal wrote:do you mean the add-on current throttle mod on the CA???
That gives you a throttle that's proportional to power, rather than torque, so is better in some respects than a typical ebike controller that has a throttle that's proportional to speed, but isn't quite as nice a feel (IMHO) as a throttle that is truly proportional to torque.

The difference between a torque controlling throttle and a power controlling throttle is that at low speeds the power control throttle can still demand more torque than you might like. This is due to motor torque being proportional to phase current, not battery current (and the CA current throttle uses battery current). Phase current can exceed battery current significantly, often by a factor of three or more, so you can get maybe double or triple the torque that you might expect for a given battery current under some conditions.

Very few controllers measure phase current though, so there is no signal readily available that can be used to provide feedback to a throttle control circuit, hence the reason that Justin went for the reasonable compromise of building in a power control throttle option for the CA.
Please ask questions on the forum, rather than by PM, as it helps others and you'll get a better range of answers.

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fractal   1 kW

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Joined: May 10 2011 1:26pm

Re: stuttering controller

Post by fractal » Jul 06 2012 12:31pm

Jeremy Harris wrote:
fractal wrote:do you mean the add-on current throttle mod on the CA???
That gives you a throttle that's proportional to power, rather than torque, so is better in some respects than a typical ebike controller that has a throttle that's proportional to speed, but isn't quite as nice a feel (IMHO) as a throttle that is truly proportional to torque.

The difference between a torque controlling throttle and a power controlling throttle is that at low speeds the power control throttle can still demand more torque than you might like. This is due to motor torque being proportional to phase current, not battery current (and the CA current throttle uses battery current). Phase current can exceed battery current significantly, often by a factor of three or more, so you can get maybe double or triple the torque that you might expect for a given battery current under some conditions.

Very few controllers measure phase current though, so there is no signal readily available that can be used to provide feedback to a throttle control circuit, hence the reason that Justin went for the reasonable compromise of building in a power control throttle option for the CA.
The Kelly controllers have what they call «Support torque mode, speed mode, and balanced mode operation. » Is this what you are talking about? They look a bit more complex to wire up though.
Norco A-line DH bike with :
«cromotor/hubzilla» from http://www.greyborg.com/
24s 3p Lipo (100v, 15ah)
Methods LVC/HVC cell level protection system http://www.methtek.com
24 fet infineon controller made by Lyen, heavily moded by Methods
8awg harness by Icecube57
17 inch moped rims with Michelin Gazelle tires by John Rob Holmes http://www.holmeshobbies.com
other stuff http://www.ebikes.ca

details
http://www.helicamguide.com

User avatar
Jeremy Harris   10 GW

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Posts: 4208
Joined: Oct 23 2007 4:15pm
Location: Salisbury, UK

Re: stuttering controller

Post by Jeremy Harris » Jul 06 2012 12:40pm

Yes, some of the Kelly controllers have a torque throttle, not sure how good it is, but it may well be OK. One problem with using a throttle that controls motor current is that you need a fairly good control loop to compare the throttle demand with the actual motor current and then make corrections that are both fast and yet don't allow much overshoot. This isn't that easy to do, as it requires something like a PID control loop to make it work well (Proportional, Integral, Derivative see: http://en.wikipedia.org/wiki/PID_controller). Whether Kelly have a good loop running in their code is something I've never looked at, but Kelly have been known to have a few code quirks in their controllers in the past, so it may not be as great as it sounds.
Please ask questions on the forum, rather than by PM, as it helps others and you'll get a better range of answers.

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dogman dan   100 GW

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Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: stuttering controller

Post by dogman dan » Jul 06 2012 2:32pm

Well, I just think you are wrong. With my race bike, I never felt a hit of stutter. Not starting up, not whacking it back and forth from full on to full off on the track, not riding it slow and easy in the pits. Running 26s at about 90- 109v Same thing with 20s. Silky smooth. The only chatter would be the tire melting itself spinning out or drifting.

I'd still bet on a flaky connection someplace. Halls most likely.

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