Sabvoton Throttle Sensitivity

I am using an unlocked Sabvoton SVMC72150 with a MXUS 3k 3T. I guess the throttle is controlling the phase amps.
I am using 350amps max. phase amps. When near top speed with flux weakening disabled (around 55mph) only about 1/8 of the throttle is usable (15% throttle has the same effect as full throttle), because the motor can only pull around 50 battery amps (and maybe around 60 phase amps).
I dont think there is a way to change this, is there?

I am using 3V and 170amps as medium throttle values.

Another problem is when riding offroad in a low speed section or steep uphill, the throttle should be much less sensitive.
Is there anyway to add something like a low speed mode to the throttle (so throttle voltage seen by the controller would be for example 1.2-1.6V instead of 1.2-5.0V in this mode)
The low speed mode of the Sabvoton I think only limits rpm, but does not limit phase amps.

Hi Hias9,

I think the first step would be to calibrate your throttle. By verifying actual output from the hall sensor under your program system status. Then from the throttles tab set Throttle Min Voltage ~.4 vdc above absolute minimum. (absolute off is usually close to .8 vdc so min would be ~1.2) Do the same with setting Throttle Max Volt just under (~.4vdc) WOT.
See Throttle Mid Voltage and Current settings below...

hias9 said:

I am using 350amps max. phase amps. When near top speed with flux weakening disabled (around 55mph) only about 1/8 of the throttle is usable (15% throttle has the same effect as full throttle), because the motor can only pull around 50 battery amps (and maybe around 60 phase amps).
I dont think there is a way to change this, is there?

I am using 3V and 170amps as medium throttle values.

Click to expand...

This is what I would try... Since your drawing 50 amps continuous current.(you have set your Basic Tab settings?) I would set Max Phase Amps at 100. A bit conservative as most are set 2 to 2.5 times the battery draw but let's get the throttle reigned in first...
So having got those to actual real values, go back again to the throttle settings and set Throttle Mid Voltage to the actual mid voltage output of your throttle or at least within the value range provided of 2 to 2.5 vdc.
Then set the Throttle Mid Current to half of the phase amperage or 50. You can increase this later up to 66% for more torque off the line if desired. This should get the throttle working in a more full and linear manner.

hias9 said:

Another problem is when riding offroad in a low speed section or steep uphill, the throttle should be much less sensitive.
Is there anyway to add something like a low speed mode to the throttle (so throttle voltage seen by the controller would be for example 1.2-1.6V instead of 1.2-5.0V in this mode)
The low speed mode of the Sabvoton I think only limits rpm, but does not limit phase amps.

Click to expand...

I would try the the Low Speed (or three speed) feature of the controller first after you get the throttle response sorted. Just programming and jumping wires... and see if that would meet your requirements.
But if your looking at possible hall sensor throttle mods and what they can do... Check out This Thread...

Regards,
T.C.

Thanks a lot for the reply.
100 max phase amps would be very boring. It is running at 150/350 amps, sometimes 200/450 for testing. I set the mid throttle voltage to 3V. If I set this to about 2V or less, the front will lift already only with little throttle applied.
So using 3V and 170amps as throttle medium values give quite linear torque at low speeds.
By the way, the values for rated battery and rated phase current do not change anything I think.
At high speeds the motor cannot pull these high phase amps any more. 100% throttle = 350amps, 50% throttle = 170amps, so at high speeds about 20% throttle will have the same effect as 100% throttle. This does not feel perfect, but it is not a big problem. Of course this would be much better when setting max phase amps to 100, but I need the high phase amps for the lower speeds

Sorry I must have misunderstood you. What are your batteries/BMS full constant current capabilities and voltage? And what is your target amperage that you want to run your 3K motor at?

Lipos 22S (92.4V fully charged), 320amps continous and 640amps maximum. No BMS. I constantly monitor battery voltage.
However I never managed to draw more than 190amps from the battery (Controller was set to 200/450amps).
The battery is not the limiting factor. Limiting factor for acceleration is front wheel lift for low speeds and the amount of current the MXUS can draw for high speeds.

I just did some little tests.
My throttle voltage range is 1.17V-5.00V
Using a 464ohm in series with the red cable will make the voltage range 1.11V-3.06V
Using 2x 464ohm in series (928ohm) gives a range of 1.07-1.96V.
When using a resistance around 1.6kohm, it did not work at all.

So my idea is to use a switch or 1kohm potentiometer on the handlebar to adjust throttle sensitivity (while limiting phase current) while riding.

I follow you.

Have you tried the motor simulator to try and smooth out the torque curve?

https://www.ebikes.ca/tools/simulator.html

The motor simulator is a very nice tool, but unfortunately it does not support field/flux weakening.
By the way, when using a custom controller in the simulator, I need to set a value for effective resistance. How do I measure this for the Sabvoton?

I have used a bunch of cheaper controllers with horrible throttle. The only fix I found was to go to ASI with a calibrated domino throttle, using torque request mode and minimum ramp time. The throttle on that setup is heavenly. INSTANT response but totally controllable. I don't have any of the problems you reported.

It's good that Sabo has torque control mode but it doesn't sound like it's implemented very well at all.

I plan to use an ASI controller for my next project. Which motor are you using together with the ASI controller?

In the Sabvoton software you can set 4 values regarding throttle: min throttle voltage, max throttle voltage, middle throttle voltage and middle throttle phase amps.

hias9 said:

By the way, when using a custom controller in the simulator, I need to set a value for effective resistance. How do I measure this for the Sabvoton?

Click to expand...

Effective Resistance Ω: This is the combined resistance of both the mosfets and the phase leads going from the controller to the hub motor. It can be estimated from the resistance of 2 mosfets (one high side, one low side) plus the controller->motor lead resistance based on the wire gauge. For instance, a controller with 10mΩ mosfets and a 6 foot 14g motor lead wire would have a resistance of (2*10mΩ + 2*6 feet* 2.52Ω/foot) = 50 mΩ, or 0.05Ω.

I like the idea of the pot throttle as it would provide a wider operational range and has worked for some to provide more linear response.

Thanks. Do you know the resistance of the Sabvoton SVMC72150 mosfets?

Are there any waterproof 1kohm potentiometers? (which I would mount on the handlebar)
Another option would be to mount a switch on the handlebar and the potentiometer hidden.

hias9 said:

Another option would be to mount a switch on the handlebar and the potentiometer hidden.

Click to expand...

Personally, this looks like the most reliable longterm solution, pot. on handlebar is to risky for my taste :wink:

I remember I had little scooter with three speeds, as they call it. It had 1.6kw trapolized controller. At first speed at full throttle it would output all amps before reaching certain rpms, the same with second speed and third one. The same way are designed are all controllers including Sabvoton.
ASI has real torque, sounds good, but twice the price, but if fault rate is low and more power than why not.

Have you manged to install potentiometer on handlebar? Have a pic? Is it comfortable to adjust it on the go? Particularly I'm interested how does it feel running ~60km/h and giving ~20% throotle. Still getting full phase amps dumped to windings or lowering voltage with variable resistors solved jerkiness?

Hias9, How you keep mxus 45H 3T temperature within limits with settings 150/350 amps? I tested mxus with ~70A / 180A (72v nominal) and after few good starts motor is hot. By chasing torque with these high amps have you considered loosing some top speed (maybe increase voltage) and getting hub with more resistance, like 9kv? Would get the same or better initial torque with lower amps. From what you wrote it seems opposite, ie you seek lowering resistance and pushing as much amps through it; you even wrote about if someone rewind a hub, for more copper; people did rewind themselves, but it is very tedious thing to do. You might win few additional strands or not. Maybe worth considering qs205 (3.5T 13.28Kv 33x3.5 most copper) for next project, as you plan for ASI anyway.