KT motor controllers -- Flexible OpenSource firmware for BMSBattery S/Kunteng KT motor controllers (0.25kW up to 5kW)

atkforever said:
My motor is a MXUS 3K rated at 3000W nominal (90N.M torque and 800RPM at 60V)
There are something wrong with your table :
speed = radius times angular velocity (speed in m/s radius in meter and angular velocity in rad/s)
With your values : 26 inch wheel : speed = 27.4 m/s = 98 km/h !!!
Mechanical power = torque times angular velocity (power in W, torque in N.m and angular velocity in rad/s)
With your values :
Mechanical power = 90 x 800 x 2 x pi /60 = 7500W !!!!

3000W is the electrical power of the motor (if it's correct)
The battery provides 3000/60 = 50 amps for the rated power. it sounds a lot.
In my opinion, I would start with 20 amps. You risk nothing and if everything works well, I would increase gradually.
 
sylvain_wm said:
Only the battery current is limited by the program.
This is not correct. The motor current is limited also. You can detect the motor current limitation by the 7th bit of the motor state.

sdobbie said:
as the rotor position can be sensed with the hall sensors so when power is needed again, the pwm can switch on with correct timing.

Not the rotor position is the problem but the BEMF. You have to start the PWM with the right duty cycle, that's matching the BEMF, otherwise, you'll get magic smoke.

regards
stancecoke
 
sylvain_wm said:
atkforever said:
My motor is a MXUS 3K rated at 3000W nominal (90N.M torque and 800RPM at 60V)
There are something wrong with your table :
speed = radius times angular velocity (speed in m/s radius in meter and angular velocity in rad/s)
With your values : 26 inch wheel : speed = 27.4 m/s = 98 km/h !!!
Mechanical power = torque times angular velocity (power in W, torque in N.m and angular velocity in rad/s)
With your values :
Mechanical power = 90 x 800 x 2 x pi /60 = 7500W !!!!

3000W is the electrical power of the motor (if it's correct)
The battery provides 3000/60 = 50 amps for the rated power. it sounds a lot.
In my opinion, I would start with 20 amps. You risk nothing and if everything works well, I would increase gradually.

You are correct but the RPM is given for no load. 98KPH is obviously unreachable due to the wind resistance (aprox 6000w at this speed), furthermore 3000W is the rated power, it means it can run at 3000W for a long period without getting hot, you can push the motor to 7000W if you use ferrofluid (statorade) or other cooling device.

My motor winding is 3T which means 11.9Kv, here is the simulation out from ebikes.ca, as you can see the top speed (ie crossing point between load and power) is 68kph. Winding is kind of overkill for my bike, I should have orderer a 4T motor instead (I have a 24inch wheel).
154648358_183459626908547_3410358794599631531_n.png
 
atkforever said:
My battery is limited to 50A

I got it.
You can limit you battery current to 50 amps, it's no matter for the 18fet KT.
Each mosfet supports 150 amps and there are 3 mosfets in parallel.
But it could be damaging to your motor.

Regards
 
I think we are getting close. My motor specific angle for the smoothest and most efficient operation is 215. When I changed it to 200, the motor will not start but there is no resistance at all when turning the pedals. Any ideas?
 
sdobbie said:
When I changed it to 200, the motor will not start but there is no resistance at all when turning the pedals.

Hm, are you sure, that the PWM is on? Is the controller drawing current, if you open the throttle?

regards
stancecoke
 
Yeah everything was on. I have to turn the wheel a little to get the motor motor to start but once started it runs fine with no resistance when coasting. I think it may just be the hall angles being a bit off as I did fit the sensors myself. I am not sure how to get the exact angles for the sensors though as in osec app hall angle 5 and 2 are missing
Screenshot_20210222-222108_BluOsec.jpg
 
sdobbie said:
it runs fine with no resistance when coasting
:thumb: Great, nice to hear!

sdobbie said:
I am not sure how to get the exact angles for the sensors
you can print out uint8_t_60deg_pwm_cycles[0] ... uint8_t_60deg_pwm_cycles[5] This are durations between the hall state changes.
Run the motor at a contant speed and look at the values. All values should be nearly the same at constant speed. If certain values are significant different, you can calculate the offset for the angle setting by the ratio of the values. I wonder, why @Xnyle uses an 8-bit variable here, this should only work at high speeds, at lower speeds, there must be overflows :?

by the way, you should not use pure sine, this leads to lower max speeds. I think mid clamp is the SVPWM waveform. I don't know, why @Xnyle implemented this options, they are confusing for newbies (and even for me :wink: ).

regards
stancecoke
 
Hi,
is there a way to use the firmware without a throttle and without a torque sensor?

My torque sensor is the problem of my system. The PAS works well but the torque sensor signal is dead.
I don't want to use a thumb throttle.
I'd like to know if it's possible to use my bike without a thumb throttle : I mean, as soon as I pedal, the motor starts and I can adjust the power assist with my LCD display... like a bafang.

Thanks
 
Awesome, thanks. With the angle setting that gives no resistance the bike runs really well and regen is brilliant, just will not work from standstill. Is pure sine the most efficient option? I would also like to find out how to enable field weakening too so I can really kick the arse out it and go fast if need be. I can't use a higher voltage battery as that would require me to buy a new bms and charger.
 
Hi,
how to activate this driving mode? PAS sensor with torque simulation and reverse step detection
In this mode, I just need a PAS. No Torque sensor, no Thumb Throttle. Am I wrong?
What are the most important parameters in this mode?

Regards
 
sylvain_wm said:
What are the most important parameters in this mode?
Again: read the wiki carefully!!! If you disable the torquesensor mode, the controller runs in "torque simulation mode" automatically. but it expects a duty cycle of the PAS signal different from 0.5 by default.
I don't know, why the ERider T9 / T13 torquesensor always dies on a Kunteng controller. One guy in the german forum wasted three sensors this way. Now he uses a Lishui Controller and everything works well :shock:

sdobbie said:
Is pure sine the most efficient option?
no, the SVPWM has the same efficieny, but you get higher phase voltages with it, so you get higher speeds.

ThirdHarmonics.png


regards
stancecoke
 
Thank you stancecoke for your patience... and for sharing your experience.
stancecoke said:
but it expects a duty cycle of the PAS signal different from 0.5 by default.
I can't change the duty cycle of the PAS signal. Do I have to create an additional circuit?
stancecoke said:
One guy in the german forum wasted three sensors this way.
That's weird. I'm going to put a non-inverter follower circuit between the controller and the torquesensor.

Regards.
 
sylvain_wm said:
I can't change the duty cycle of the PAS signal.
Have you read the wiki??? Or do you think, asking stancecoke is much easier than reading all the stuff? :lol:
You have just to set the right value for PAS threshold.

sylvain_wm said:
I'm going to put a non-inverter follower circuit between the controller and the torquesensor.
Good idea! But I don't know, if the failure is caused by the torque signal line, or by interferences of the power supplies, or whatever... :confused:

regards
stancecoke
 
stancecoke said:
Have you read the wiki??? Or do you think, asking stancecoke is much easier than reading all the stuff?
I have read it for a long time and I don't want to bother you stancecoke.

Thanks a lot.
 
https://www.aliexpress.com/item/10000423707501.html?spm=a2g0o.cart.0.0.43dc3c00UqP2NT&mp=1

Will these KT controllers from Ali work with the opensource firmware ?

Thanks
 
stancecoke said:
I don't know, why the ERider T9 / T13 torquesensor always dies on a Kunteng controller. One guy in the german forum wasted three sensors this way. Now he uses a Lishui Controller and everything works well :shock:
Could it be due to different pull-up voltage on PAS pin? Measured voltage at free floating PAS input on Kuteng od 5,0V while at Lishui is 3,26V ?
 
Im curious I have a ZWL controller but my vendor is saying its sinewave.


KTE-12S5-F is what the board says directly and its a 12 Mosfet im running a DD Hub motor and it does sound pretty silent but I dont have anything for a comparison.

anyone know if it actually is because i want to flash this firmware on it after i upgrade the mosfets
 
atkforever said:
Can you send a picture of the board please?

sure best I can since its all put back together and its late night brightened the images up at least

20210301_232740.jpg20210301_232842.jpg20210301_232951.jpg20210301_233039.jpg
 
This can‘t be a sine type,see the missing phase current sensor right from the green phase wire.

regards
stancecoke
 
stancecoke said:
This can‘t be a sine type,see the missing phase current sensor right from the green phase wire.

regards
stancecoke

thanks is it possible to attach a current sensor or am i SoL

https://opensourceebikefirmware.bitbucket.io/development/Motor_controllers--BMSBattery_S_series--Hardware_mods.html

I have been looking at this and its its a different layout to mine also what sensor would I be using.
the ACS isnt named in the link above for 12 mosfet only 9

I would like to avoid spending £45+ on a controller when I can get similar results with a sensor mod

regards
Izy
 
izy said:
thanks is it possible to attach a current sensor or am i SoL

The footprint on the PCB looks like it could fit an ACS72981 .
You can check the dimension on your PCB. And you have to check, if there is a solder bridge somewhere that shortens the two sensing pads. This has to be removed of course.

regards
stancecoke


ACS72981.JPG
 
stancecoke said:
izy said:
thanks is it possible to attach a current sensor or am i SoL

The footprint on the PCB looks like it could fit an ACS72981 .
You can check the dimension on your PCB. And you have to check, if there is a solder bridge somewhere that shortens the two sensing pads. This has to be removed of course.

regards
stancecoke

thanks finally does the current sensing and sensitivity matter much
theres multiple options
uTg7xJ4.png


also if you know any alternatives it would help due to extortionate seller prices

trying to find a site that sells it without charging an arm and leg for postage in UK seems to be a pain as digikey is only one i see with stock and they want £20 for it including postage the only toher site wants min order £20 before postage

seems lack of stock anywhere else

but if thats the case i may aswell just buy an actual controller https://www.aliexpress.com/item/4001093131407.html?spm=a2g0o.cart.0.0.77163c00rjTr1Y&mp=1

thanks again
izy
 
I was testing a different KT controller today, a 6 fet version without phase sensor and it was working fine until it just suddenly stopped working because it is reading the battery voltage as 0 which means that the throttle won't respond anymore. I am using it with the osec app and when I turn the motor by hand, the hall sensor patterns respond and look fine so it's not like the main chip is dead.
 
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