QS273 40h 5T -> increasing RPM and top speed

[andreworsmond21175@gmail.]

Hi all,

Im getting a QS273 40h 5T for my ebike and want to get the highest top speed possible for the motor with mad acceloration for as long as possible.

specs:
- battery- 91v full charge, 214 amps peak, 175 continious (safe)
- nucular 24f controller (has field weakening)
- rear wheel - 25 inch diameter (19 inch rim plus tire)
- baseline rpm for the QS273 5T (dont know)
- kv rating for the QS273 5T (dont know)

There are some bio's here with the same setup and guys are hitting pretty high top ends over 60 mph with this setup(happy to be wrong)

If anyone could provide any guidance on field weakening for my nucular to increase the rpm, how to setup the phase amps and the amps assigned for field weakening based on my battery output and v it will be much appreciated.

My current idea was to do the following settings:

- Speed Setting: 125%
- Battery Amps: 185
- Phase Amps: 320
- Field Weakening Amps: 50

Thank you for your time,
Andrew

 

[andreworsmond21175@gmail.]

Hi Andrew,

Welcome to the forum, thanks for putting the effort into this question with the details and specs. The QS273 does 650rpm@72v which gives it a Kv rating of 9.02kv per Volt.

Given taht you have 91v max you could expect a max rpm of 821. This would be without field weakening.

You should expect to hit close to 100kmph with field weakening however, it may taper off as you approach this so expect to have hard acceloration to around 85-90kmph.

Nucular p24f is a great controller and should def put you up there.

I know a lot of folks here are clicky and wont share as much, keep it up and welcome to the forum.

Kind Regards,

 

[mxlemming]

Hi Andrew,

Welcome to the forum, thanks for putting the effort into this question with the details and specs. The QS273 does 650rpm@72v which gives it a Kv rating of 9.02kv per Volt.

Given taht you have 91v max you could expect a max rpm of 821. This would be without field weakening.

You should expect to hit close to 100kmph with field weakening however, it may taper off as you approach this so expect to have hard acceloration to around 85-90kmph.

Nucular p24f is a great controller and should def put you up there.

I know a lot of folks here are clicky and wont share as much, keep it up and welcome to the forum.

Kind Regards,
Not a cunt

Hi Andrew Notacunt,

That motor iirc has a flux linkage of about 37Wb and an inductance of 89uH. Therefore, complete flux suppression occurs at about 400A FW. 200A would theoretically double your speed. 100A would 4/3 your speed... 50A would 8/7 your speed. At free spin.

FW also helps you keep torque up at higher speeds.

 

[andreworsmond21175@gmail.]

Hi Andrew Notacunt,

That motor iirc has a flux linkage of about 37Wb and an inductance of 89uH. Therefore, complete flux suppression occurs at about 400A FW. 200A would theoretically double your speed. 100A would 4/3 your speed... 50A would 8/7 your speed. At free spin.

FW also helps you keep torque up at higher speeds.

Thank you very much for this information, it was challenging to understand the effects the FW would have on the Qs273 5T but think that the information you have supplied will form the basis for setting up the Nucular and seeing what happens.

Appreciate the help.

Andrew

 

[dominik h]

That motor iirc has a flux linkage of about 37Wb and an inductance of 89uH. Therefore, complete flux suppression occurs at about 400A FW. 200A would theoretically double your speed. 100A would 4/3 your speed... 50A would 8/7 your speed. At free spin.

If you apply 200A FW the motor will heat up very quick. I hope you got a motor with a temperature sensor, then you can see what happens at top speed.

 

[mxlemming]

If you apply 200A FW the motor will heat up very quick. I hope you got a motor with a temperature sensor, then you can see what happens at top speed.

I doubt he'll need 200A FW to get what he wants. Agreed, full tilt 200A FW is not a nice operating point for that motor. This is going to take the op some experimentation but 100km/h on a qs273 and nucular24 doesn't sound like a hard bar to reach.

The main missing info here is wheel diameter.

 

[andreworsmond21175@gmail.]

I doubt he'll need 200A FW to get what he wants. Agreed, full tilt 200A FW is not a nice operating point for that motor. This is going to take the op some experimentation but 100km/h on a qs273 and nucular24 doesn't sound like a hard bar to reach.

The main missing info here is wheel diameter.

Hi, we looking at around 25 inches wheel diameter with the 19 inch rim and tire

 

[andreworsmond21175@gmail.]

Installing the controller this evening

 

[mxlemming]

Hi, we looking at around 25 inches wheel diameter with the 19 inch rim and tire

So if you get 821rpm free spin then
821/60x(0.0254x3.14x25")x3600/1600 = 61.38mph

You lose some to switching and dead time etc and battery obviously sags... But some FW should be able to make the difference

 

[andreworsmond21175@gmail.]

After installation of the controller and testing it out with the rear wheel raised up, the bike is putting out 82kmph without fw adn 95 kmph with FW.

Not sure if my wheel size is set correctly in the Nucular or if there is something missing, I have not enabled advanced control modes in the controller and am changing parameters under the control menu.

it seems a bit low.

Thank you for all the help.

Andrew

 

[mxlemming]

After installation of the controller and testing it out with the rear wheel raised up, the bike is putting out 82kmph without fw adn 95 kmph with FW.

Not sure if my wheel size is set correctly in the Nucular or if there is something missing, I have not enabled advanced control modes in the controller and am changing parameters under the control menu.

it seems a bit low.

Thank you for all the help.

Andrew

Sounds like you need more field weakening. Or perhaps nucular24 limits the speed to a"safe"value since field weakening can cause spikes when it faults.

There's a nucular telegram group that might be more help. Nucular Electronics i think this is the link.

I don't know much about nucular. I don't own one, I only know math and physics.

 

[andreworsmond21175@gmail.]

Sounds like you need more field weakening. Or perhaps nucular24 limits the speed to a"safe"value since field weakening can cause spikes when it faults.

There's a nucular telegram group that might be more help. Nucular Electronics i think this is the link.

I don't know much about nucular. I don't own one, I only know math and physics.

Hey mx,

Thank you for the help! Will check out the group, reached out to the company and they mentioned something around a 100v limit I may be hitting but need to explore it.

Bike pulls incredibly hard up to around 65 kmph and stil hits around 82 kmph up a mountain, need to find a flat.

All the best,
Andrew

 

[j bjork]

I dont see a reason to limit A if you want as much acceleration as possible. From what I remember it can do 500pA and something like 350-400bA. Start small (maybe 50A) of fw, and then you can turn it up to 100, 150, 200. Make sure your battery can take it, it is a bad idea to have a fuse blow or a bms trip when you are hitting hard with field weakening..

I had a similar bike but with a qs205 50h 4t, a kv of 10,8 or something. I think it did 80-85km/h without fw, I thought that was kind of enogh. I took it to about 100km/h with fw, but I just thought it felt sketchy and unstable at those speeds anyway.

 

[andreworsmond21175@gmail.]

Hi all,

An update on my ride, it def gets to 100kmph, without field weakening on a full charge its hitting 75kmph up a mountain. The engine is a bit heavy even though its got the 40h winding.

Nucular released a new version of there software which allowed more field weakening, however, it is limited on a full charge to around 70A. (unloaded spead hits 107kmph)

Not sure if this setup is going to stay forever and have spoken with QS as they have a QS273 in a 4T as well, however, am thinking of a QS205 5T in 50h winding.

Happy days and thank you for all the help.

Andrew