Help configurations BLDC 5kW and VEC 500

[Yodidon]

hello, my name is lionel I am from France and I develop small boats with hm 5kw electric motors, I cannot optimize their operation, and I think I will find solutions on this forum.  (I'm not strong in English I use Google Translate hoping that my messages are understandable) thank you
This is the boat

[Yodidon]

I would like to know why I can't run my motors at more than 4000 rpm, I'm trying to find the right controller settings

[Bikemad]

Hi Lionel andto the forum,

According to the dynamometer test data, the 48V and 72V HPM500 motors are rated for 3500 rpm and the 96V motor is rated for 3700 rpm.
Above this rpm, the power and torque output will significantly reduce until the maximum unloaded rpm is reached, where zero torque and/or power is actually produced.

The maximum motor rpm is governed by many factors including battery voltage, motor voltage, battery current and load/gearing etc.
Increasing the maximum motor rpm in the software will not allow a faster rpm than the motor and battery voltage etc. can produce.

As an example, a 48V motor running on 72V should have a 50% higher maximum rpm (i.e. 6,000 rpm instead of 4,000).

If you are unable to increase the battery voltage to increase motor rpm, you would need to add some form of overdrive gearing to drive the propeller/turbine at a higher rpm than the motor to produce more thrust.

Check out this thread for more details on overdrive gearing.

Alan

[Yodidon]

Hi and thx.
my batteries are 57.6v 80ah, I don't have the same software as the one you present, but the parameters are as in the photo.

[Bikemad]

Is there a reason why your Starting phase current is set so high?
I'm pretty sure that the default setting was only 15A, but you have yours set to the same value as your Maximum phase current (170A) 

I think you should be able to increase your Rated/Maximum phase current to ~230A with your Battery draw current limit of 90A, as the default Rated/Maximum phase current is 280A with a Battery draw current limit of 110A.

My only other concern is that your Low voltage triggering current reducing setting of 42V may be a bit on the low side. To increase the lifespan of the pack, I would want the current reducing to begin a bit earlier to ensure the voltage doesn't drop too low.
I would set it at a minimum of 48V for a 16S LiMn pack (3.0V/cell) or 45V for a 18S LiFePO₄ pack (2.5V/cell).

An even higher setting should provide increased notice that the battery is getting low, and hopefully allow more time to return to dry land before the battery's BMS cuts the power completely. 

It could be very inconvenient to suddenly realise that the power was quickly reducing, and then discover that the motor cuts out soon after the power had started to decrease (unless you have another battery to get you back to dry land again).

Alan
 

[Yodidon]

the 170A are the default settings, and I didn't know what I could put without jeopardizing the operation.  I thank you for these valuable tips, I will test it as soon as the weather allows me.

[Yodidon]

hello, another question if you have time, I put a gd engine and a vec 200 on a quad, I have to give it momentum when starting, do you think this is normal?  thanks in advance

[Bikemad]

Hi Lionel,

If the gear ratio between the motor and the Quad's rear axle is too high, the motor may be severely overloaded, causing the stall protection to cut the power before the quad is able to pull away.

If you have simply installed the electric motor in place of the original Gas engine and gearbox unit using the same final drive sprocket ratio, it would require a huge amount of torque to pull away on its own.
Just imagine how hard it would be trying to pull away from a standstill in top gear with the original gas engine. 

If the motor is big enough to cope with this high load it might pull away without any assistance, but a 3kW motor is going to struggle with excessively high gearing.

If the motor and controller are getting very warm in a relatively short time, it could be an indication that the motor is being overloaded too much.

Alan
 

[Yodidon]

Hello, I have a question if you have some time.  I have 2 boats with the same settings.  one with a VEC 200 and a 5KW BDLC and the other with a VEC 500 and a 5kw BDLC.  however the boat with the VEC 200 works much better than the one with the VEC 500. do you have an idea of ??the problem?  thank you in advance for your help.

[Bikemad]

Hi Lionel,

I don't know why the VEC 200 should be better than the VEC 500 with the same settings.

Do you have any rpm or current measurements for both boats under similar loads for comparison?

Alan
 

[Yodidon]

thank you for your answer, with the propeller out of the water I have the same speed on the 2 boats (1980 rpm) however once in the water and the need for force with the vec 500 I am around 30% of  mons that the vec 200. I wonder if there is no connection to be made between the 2 settings

[Bikemad]

Assuming the propellers on both boats have the same pitch and diameter, it looks like it might be something related to the factory "tuning" of the controllers to match specific motors:







It looks like the VEC300 controller is specifically tuned to suit the HPM5000 5kW BLDC motor.

I'm wondering whether the incorrect inductance of the 5kW motor's Phase Windings is causing the noticeable difference in performance between the VEC200 and VEC500 controllers.

Perhaps the 5kW motor is overloading the VEC200 controller and insufficiently loading the VEC500 controller. 

It would be interesting to know what difference the correctly matched VEC300 controller would make.

Alan
 

[Yodidon]

thanks Alan I bought a vec 300 it worked perfectly but it burned out after 2 months…