Controller vec300 48v: problem with current erogation

[Giorda]

Hello everybody
I've set up a lightweight quadricycle with:
-vec300 48v controller,
5kw BLDC motor
two Lifepo4 48v-60Ah batteries in parallel configuration.
I'm having problems with the initial power erogation, because if I start moving the vehicle on a flat and leveled surface the current erogation is ok, it climbs steadily to over 60 A as I push on the throttle, but if I start the vehicle with a little obstacle in front of the wheels, let'say a 5 cm step, the max current erogation is 18 A and the vehicle is not able to overcome the obstacle and move.
I've tried different configurations of the controller but can't fix the problem.
Is there anyone having experienced this and help me please?
many thanks
Giovanni

[Bikemad]

Hi Giovanni andto the forum.

I don't know what parameters you have already tried, or what programmable options are actually available with the VEC300 controller, but it sounds like you may need to increase the Starting phase current (A) and/or the stall protection time (s) to allow more current to be supplied to the motor during the initial acceleration stage.


What is the diameter of the driven wheel and what is the overall gear ratio?
 
It would also be helpful if you could post screenshots showing all of the available settings and what their values are currently set to. 

Alan
 

[Giorda]

hello Alan,
thank you for you suggestions,
we tried to increase the starting current and the stall time (max allowed 4 secs) but nothing changed.
the wheel diameter is 13" and the gear ratio is 1:8.
I have attached the screenshot of the controller configuration used for the last test.
many thanks
Giovanni
 

[Bikemad]

Hi Giovanni and thanks for adding the screenshots of the controller settings.

I am surprised that it is not able to pull away over a small obstacle with such low gearing. If the 13" measurement relates to the outer tyre diameter, it will have a top speed of less than 17 mph @ 85% of 4000 rpm!

According to the dynamometer figures for the 5kW motor, it should produce ~1.4Nm of torque @ 18A, which would be multiplied by the 8:1 gear reduction to ~11.2Nm at the wheel. This would produce a driving force of less than 6.92kg (15.22lbs) acting upon the vehicle after mechanical losses, which might explain why it can't climb a 50mm step from a standing start.

Here are some suggestions/observations based on your posted settings:

• Rated motor speed (rpm) could be set higher (4500 rpm)
• I would expect the Low voltage protection exit value (V) to be slightly higher than the 42V Low voltage protection value (V)
  (Something like 43V would make more sense)
• Maximum phase current (A) should be 300A according to the controller guide
• I would set the Maximum phase current duration (s) to 5 seconds
• Rated phase current (A) should be 120A according to the controller guide
• Motor temperature protection exit value should be 135
• Throttle voltage range protection enable should be 1:Enable to prevent full throttle being instantly applied in the event of a poor or broken connection on the throttle ground wire
• Acceleration (rpm/s) could be increased if faster acceleration is required (0-17 mph should currently take ~8 seconds)
• Forword speed ratio (%) could be increased to 100% for maximum forward speed
• Backword speed ratio (%) could be reduced to prevent it from going too fast in reverse (25% should allow a maximum of ~5 mph)

Suggestion 3 and 4 above will hopefully improve the initial current draw, which should produce more torque.


Alan