Cowardlyduck said:
I have another tuning question:
I think I must be close with my motor tune as I'm getting decent range, however there are a few things that make me think if it's still not right:
1) At full speed on the flat (55kph), I am still seeing max amps draw in Normal mode of 45A. On my other controllers, once top speed is reached, amps should drop off and just be what is required to maintain the speed, but my Mini-E just sits at 45-46A the whole time.
2) Related to the above, riding at full speed results in a lot of heat, but tight twisty single track off-road is ok as I never reach full speed much.
3) Without changing the tuning settings, changing to square wave mode, the motor sounds very rough and is not anywhere near as smooth as my other square wave controllers.
Tuning the controller in Sinewave mode seems much more difficult as I can't hear much change as I adjust things until I adjust them much further than needed. Based on the 3rd issue, I'm wondering if it would be easier to tune the hall angle, and ind timing in square wave mode, then switch back to sinewave. Would this work?
I did try it a bit already, but could not manage to get a smooth result in square wave mode without changing my hall angle to more than -12 degree's which seems way off when my angle for sine wave is around -5 degrees.
Cheers
I noticed this with my motor too (rv100)
first, do you have OVS on? this will make the motor draw a lot more even at no load at max rpm, as field weakening (what OVS controls) essentially uses more current in order to increase the max rpm.
if OVS is off, try setting the max speed to just below the max motor rpm, that should let you hit top speed (or ~1km less than) without the current spiking. The way FOC works means that right at the max rpm of the motor the controller 'runs out of room' in which it can modulate power to the motor (this is putting it VERY crudely).
The best analogy i can think of atm is to imagine driving a car.
the car is the 'motor' in this analogy, and has a max speed of 100km'h.
you are the 'controller' in the analogy, and your goal is to try and maintain a speed of 100km'h, up hills, down hills, on flats, into headwinds, whatever the conditions.
However, the ammount of power the car makes drops off rapidly from about 98km'h to 100km'h.
As you can imagine, this would make maintaining the speed in such conditions right at 100km'h very hard, as you have no power left at 100km'h to compensate for changes in loads such as going up a hill.
In the controllers world, the hills, flats and headwinds change many times per second, so with no headroom in the 'power' department, maintaining 100km'h (or max rpm) becomes very hard, and inefficient, hence the higher currents.
Now if you only needed to maintain 98km'h, then that'd be relatively easy, as the car still has full power available at that speed (same with the controller at just below max motor rpm).
Alternatively, useing FOC (or increasing the OVS in the controller) effectively 'tricks' the car in to thinking that its only running at 80 or 60 or 50% of its max (100km'h) speed, and thus still allows you full power around the 100km'h mark, which would also make maintaining that speed much easier.
Its kind of the same with the motor. The controller has no headroom where it can pump in a little more current in order to keep the phase currents where it wants them, as the back emf is very close to the battery emf. All the controller can do is reduce the current tot he motor, it has no ability to increase it, and as such it does a poor job of controlling it, and wastes a lot of power. Increasing OVS will (or should, haven't tried myself yet) help, as will restricting the speed such that the motor rpm doesn't quite reach its max, just like 'tricking' the car into thinking its not going as fast as it is in the above analogy.
Idk if that makes enough sense, but I hope it gives some idea of why the power use spikes at close to max rpm.
