Field/Flux Weakening on Kelly KLS-N Controllers

[ondigio]

Does anyone know how to configure field weakening on Kelly KLS-N controllers? I have a KLS-8435MR running a QS138 90H V3 motor. Screenshot of my settings attached. There is nothing in the manual about the HS_ACQR / HS_ACDR settings. These parameters are also absent from the Android app, only visible on PC, so I'm just assuming they relate to field weakening. I know it's a relatively new feature but surely there must be some documentation somewhere? I'm afraid I'll damage something if I start experimenting with random values.

I'm cross-posting this to the Kelly Controllers Facebook group. Hopefully someone knowledgeable is lurking here or there! I geared my kart assuming I would have 6000+ RPM. Currently it hits 30MPH at about 4000 RPM in a couple seconds and it's stuck there! Haha.

 

[amberwolf]

Have you checked with Fany at Kelly? That's usually the best first place for accurate Kelly info. Unfortunately they don't always know everything about their own controllers and/or communicate very well (language and technical barriers), but I'd still try there first.


Regarding FW vs speed, I'm not sure you can get another 50% speed (2000RPM) out of it, and even if you do there will be a significant efficiency hit while using hte higher RPM (especially if you need the original amount of torque at that RPM) and significant extra heating, so you might require extra cooling for the motor and controller.

Depending on results, you might have to either regear the drivetrain for the necessary RPM or up your system voltage proportionally (assuming your controller can handle it) by changing to a higher voltage battery.

FW will reduce the amount of torque you get, too, so that's another thing to consider.


Also remember that faster speeds will take more than proportionally higher power, unless the vehicle is very aerodynamic--every 5mph increase in speed will require much more power than the previous 5mph. (see the simulator at ebikes.ca to see how this works in general) .

Depending on actual part efficiencies, 6000RPM / 4000RPM x 30MPH = 45mph should take roughly 4kw of battery power to get roughly 3200w of motor power, while the 30mph you're getting now should be taking roughly 1200w of battery power to get roughly 1000w of motor power.

So your system will need to be capable of however much power it really takes to reach your desired speed, including whatever extra amount is needed by field weakening to reach that much higher RPM and vehicle speed.

 

[ondigio]

Thank you so much for the detailed reply! I have not yet reached out to Kelly because I wanted to be sure I'm doing everything correctly with the available documentation before asking for tech support. Is there a way to contact Fany directly? I've seen that name mentioned many times as a good resource.

Based on what you said, it sounds like the best thing to do is up my gearing for higher speed rather than try to make the motor spin faster at the current voltage. Assuming I have the available torque. I'm still new to this stuff and have a lot to learn

I did get a response on the Kelly Controller Facebook group indicating that "Min Excitation" is the parameter to adjust for field weakening. I may experiment with this before changing sprockets. Maybe this post will be helpful to someone searching for this info. I don't understand why Kelly doesn't just put it in the manual!

 

[amberwolf]

Is there a way to contact Fany directly? I've seen that name mentioned many times as a good resource.

Thru the Kelly contact page is probably most certain, but they also post here on ES now and then, so you could try their profile and PM them, or see if they list an email or other messaging app.

Based on what you said, it sounds like the best thing to do is up my gearing for higher speed rather than try to make the motor spin faster at the current voltage. Assuming I have the available torque. I'm still new to this stuff and have a lot to learn

We all learn sometime; it's just easiest if it isn't the hard way. I've been doing this a decade and a half and still learn new things about it every day.

Do you know if your existing torque is excessive, or just sufficient? (a controller that can do FW is an FOC controller, so it almost certainly uses the throttle to modulate torque. That means that if you have to not use full throttle to startup from a stop, or do other maneuvers under high load, the torque is higher than you need). If it's only just sufficient now, the gearing change to get the higher speed will greatly lower the torque, well below what you need.

I don't understand why Kelly doesn't just put it in the manual!

Unfortunatley, most manufacturers of this stuff don't document *anything*, and the few that do never do a complete job of it. Making this worse is that technical stuff is very difficult to translate even when the original documentation is well-written, and that last is not true of most of the documentation that does exist, so you get all sorts of wierd translations like "turn the (insert word here)" for "throttle", or "door lock" for "key switch", etc.

Kelly probably has better documentation than most (maybe any) of the companies that offer parts to DIYers; possibly excluding Grin Tech (ebikes.ca) but Grin develops and makes very few things (and even those are not *fully* documented in every detail, for every update).