Lower no-load speed with sine wave controller?

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hias9

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Could it be that I cannot get as much rpm (no-load) with a sinewave contoller (flux weak. disabled) than I could get with a square wave?

I use a MXUS 3k v3 3T with a Sabvoton SVMC72150 and cannot get more than 588rpm @ 54V.
Kv of the 3T is 11.9, so rpm should be around 640.
 
When changing controllers you may need to adjust R shunt value if using a Cycle Analyst to the new controller to get maximum power.
 
bionx 1954 said:
When changing controllers you may need to adjust R shunt value if using a Cycle Analyst to the new controller to get maximum power.
Click to expand...


That shouldn't have anything to do with no-load speeds, as those will be using minimum power.
 
Unfortunately that is not fast enough ;)
By the way, it is a 17'' mc rim.

There is no Cycle Analyst connected. The seller told me that it is normal that the no load rpms are lower with sinewave controllers (flux weak disabled) than with squarewave controllers, but I thought no-load rpm would be the same. And I do not have a square wave controller here for testing.

Do you guys think that is the case or not?
 
It actually depends on the modulation technique used to generate the sinewave. The simpler techniques do result in lower maximum RPM. The higher end controllers may not lose speed. The availability of field weakening can solve the issue, or raising the battery voltage, or using a controller that uses space vector modulation.

https://www.electronicproducts.com/Electromechanical_Components/Motors_and_controls_Space-vector_modulation_vs_sinusoidal_commutation.aspx
 
Thanks a lot for the reply!

So the Sabvoton probably uses a simpler technique.
Are there any controllers that use a more sophisticated technique? (Adaptto?)
Which of them use space vector modulation?
 
hias9 said:
Thanks a lot for the reply!

So the Sabvoton probably uses a simpler technique.
Are there any controllers that use a more sophisticated technique? (Adaptto?)
Which of them use space vector modulation?
Click to expand...

Instead of replacing the controller, why not just just enable the field weakening and set it to get the speed you want?

Avner.
 
I am not going to replace the controller, but I am interested if there are more advanced controllers available. This will probably not be the last ebike that I am building.
Before getting the Sabvoton, I was thinking about the Adaptto MAX-E, but at the moment they are not available and many people seem to have problems with it.

Flux/Field Weakening makes the motor less efficient, so there will be more heat. I only plan to switch it on for top speed runs and plan to leave it disabled for normal riding.
 
Many have reported that it is not all that inefficient at modest levels. Certainly worth testing. If you think of it in terms of "timing advance" then the efficiency loss doesn't seem all that large. Going faster has significant effects on efficiency already, the FW losses may not be the biggest factor at modest levels.
 
The Lebowski controller is pretty advanced, but it's a DIY type. There are PCBs available to simplify it for some versions, but you'd still ahve to build it yourself.

Bunch of threads around for various builds and versions, inlcuding Lebowski's main threads, if you want to learn what it might do for you, and see if it's worth the effort for you.
 
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