Very low power available when throttle is initially applied

[R2pittman]

Hello my name is Ronnie Pittman and I am an engineering teacher.  My students are building a solar car and we are using the HPM3000 3kW motor with the VEC200 controller.  The problem we are having is that when taking off we are only getting 2A of current before the motor kicks out.  Any help would be greatly appreciated.

Thanks
Ronnie

[Bikemad]

Hi Ronnie andto the forum.

Is the controller emitting 4 regular flashes/beeps indicating that the Stall Protection has been triggered?

If your gearing is relatively high, try increasing the stall protection time (s) and/or the Starting phase current (A) using the PI-400/VEC programming lead and PI-800 programming software to see if it helps.

Are you able to save the parameters to a file and then attach the saved *.foc file so that I can see what the all of the current settings are?



It might also be helpful to know the following:

• The battery type, capacity, continuous current output and voltage etc.
• The outer tyre diameter (or distance from ground surface to centre of the wheel)
• The total gear reduction ratio (pulley diameters, number of teeth on sprockets or gears etc.)
• Approximate weight of the vehicle with occupants
• The expected top speed
• The maximum gradient it must be able to climb

Alan
 

[R2pittman]

Thank you so much for your reply.  I will check for the flashes today.  As for the specs the car weighs about 450 with driver and the gearing is 6.36:1.  Currently the minimum starting current is set to 15a and the time I is set to 8sec.  I will attach a screen shot of the specs shortly.  We are hoping for a top speed of about 35 mph.  Total wheel diameter is 22".

Thanks again
Ronnie

[R2pittman]

here is the export of our current settings

[R2pittman]

Forgot too mention batteries, they are 4agm 12v batteries in series,

[R2pittman]

I also checked the error code is 3 blinks

[R2pittman]

I tried changing a bunch of settings but nothing has worked so far.  It will get up to aboult 3 amps according to my meter and then cut out with 3 blinks.  Again this is if I am trying to go over a speed bump or something like that.  Any ideas would be greatly appreciated

[Bikemad]

Hi Ronnie,

Sorry for the delayed response but I've been struggling with some major PC problems over the past few days. 

3 blinks indicates an over current fault, but I'm not sure why. 

I have just been looking at your parameters and here are some suggestions which may help:

• Try setting the Number of Pole pairs to 4 instead of 5 (most of GM's HPM Motors have 8 magnets = 4 pole pairs)
• Set the Maximum phase current (A) to 210 (Phase current is usually set a lot higher than the battery current)
• Try setting the Maximum phase current duration (s) to 0.0 (I think 0.0 is the default setting)
• Set the Rated phase current (A) to 210
• Set the Battery drawn current limit (A) to 110 (or the maximum current your batteries can supply if it's lower)
• Set the Acceleration (rpm/s) to 600
• Set the Forword speed ratio (%) to 100
• Set the Default gear(0:HG 1:MG 2LG) to 0 (not sure if this makes any difference with the 3-gears disabled)

You might also want to set the Motor overtemperature protection enable to 1:Enable so it can protect the motor from being overheated.

I hope one of these suggestions will cure the problem.



Alan
 

[R2pittman]

Thank you so much, I will try all of the above on Monday when I get back to school and let you know.

Thanks again
Ronnie

[R2pittman]

Woooohooo, progress!!!!

Ok I am getting more power now, up to 15 amps which I believe is the starting current limit. Unfortunately I did not change 1 thing at a time so I am not sure which setting made the difference. 

I believe it was the poles which brings me to my next question.  Should I change the angle in that setting as well?  I left it at 120 but I am wondering if it should be 90 which makes sense to me.  Not sure though.

Thanks again for all the help.
Ronnie

[Bikemad]

Hi Ronnie and thanks for the update.

As I don't have any first hand experience with the VEC controllers or HPM Motors, it's reassuring to hear that my suggestions have made such a positive difference to your motor's performance.
It would also be nice to know whether the 3 blink error code has now disappeared completely, or whether it has been replaced with an alternative code.

Should I change the angle in that setting as well?  I left it at 120 but I am wondering if it should be 90 which makes sense to me.  Not sure though.

BLDC motors typically use phase angles of either 120° or 60° and I'm pretty sure that the angle on all of the GM BLDC Motors is supposed to be 120°, so it's probably best not to change it. 

Alan