Is the VEC300 speed or torque controlled?

[KevinD]

Hello,

We have a VEC300 inverter and was wondering if it is speed or torque controlled, or if the option is configurable. We know that Golden Motor says it is torque controlled, but when we set it up on a test rig, applied a load and gave it the same throttle voltage as when it was unloaded, we made the following observations:

1) The current drawn from the battery was much larger than what was drawn with no load at the same throttle setting, which implies that torque is not constant either.
2) The speed of the motor ramped up very quickly, so much that we had to stop applying power at just a bit over 0.5V throttle setting (the motor was spinning much slower at the same throttle setting with no load)

We double checked our throttle parameters and confirmed that the range was set to 0.5 to 4V (the maximum range), so we know that is not the problem. What could be causing the throttle to be so sensitive when a load is applied, and why is the current not staying somewhat constant at the same throttle setting?

Any help is greatly appreciated. Thanks!

-Kevin

[Bikemad]

It sounds like the motor may be producing too much power, the load on the motor is not enough, or the test load does not proportionally increase with motor speed like it normally does on most vehicles.

See what happens if you increase the load on the motor and/or decrease the battery & phase current to reduce the power.

The "Maximum rated phase current(A)" should be approx. 1.3 times more than the "Battery Main current", so make sure you adjust both settings when you adjust the current to reduce the power.

You may also need to reduce the "Acceleration (rpm/s)" setting if the motor speed is ramping up too quickly.

Alan
 

[KevinD]

Thanks Alan, we'll take your advice and will play around with the current and acceleration settings.

Would you have any idea why the current is changing in the first place under different loads at the same throttle setting though? If the inverter is torque controlled, shouldn't the current stay somewhat constant at the same throttle setting? And when a load is applied wouldn't the speed be expected to decrease rather than increase like what we were observing?

-Kevin

[KevinD]

Actually, please disregard my last post. We did some more testing and found something interesting.

We have two VEC300 controllers, one connected to an unloaded motor (let's call it controller 1) and one that was on our test rig with a loaded motor (controller 2).

When controller 1 was used with the throttle to power the unloaded motor, the speed seemed to increase proportionally with the throttle input, and so did the current, up a maximum of 3.6A. This is very alike to the characteristics of a speed-based controller.

However, when controller 2 was used on the same unloaded motor with all the same parameters as controller 1, it showed the same behavior as it did on the test rig and ramped up to a very high speed as soon as the 0.5V throttle threshold was passed. Normally we would consider this to be torque controlled, except that at that same throttle setting, we're measuring ~3A on the test rig and ~6A on the unloaded motor.

So now the question is, why would the controllers behave differently with the same set parameters? Are both described behaviors valid or should we expect one of our controllers to be defective?

Thank you,
Kevin

[Bikemad]

Are the two motors the same, and are they both GM motors?

I am wondering whether the controllers are slightly different versions or have different firmware loaded that causes the throttle to work differently.

Unfortunately, I don't know whether you have a controller problem or whether they are both working OK, albeit differently. 

I suggest you send an email to Andy at GM China and see if he can clarify the situation, his email address is andyzhang@goldenmotor.com.

Alan
 

[KevinD]

Both the motors are from GM, I believe the exact model is HPM3000, rated at 48V and 3kW.

Thanks for proving us with Andy's email. We'll try emailing him next.

-Kevin