Hi everybody,
I am using the DRV8412EVM rev G evaluation board with CC 28035.
- Motor from the kit: Anaheim BDD-38-63
- Motor intended to use: Maxon A-max 22 (110164) + GP 22 (134163) + MR-ENC (201940)
Following the instruction, I can run the Anaheim DC motor from the kit (BUILD LEVEL 3) but as soon as I try with the Maxon motor the current loop can't be tuned right and the PID output goes to limit high/low continuously...
So I began to measure signal and adapt the current sense parts to achieve same condition from both motors (Rmot Anaheim is 1.8 Ohm and Maxon is 21.5 Ohm). This way I get a sensing voltage from 1-100mV (0-6mV without load).
Now that I see the waveforms of the voltage going to ADC input (VR20-23), I can't understand how the feedback is computed to reflect increasing or decreasing current since the Anaheim motor has some kind of carrier frequency.
I saw that the ADC result is trigged at the middle of the low PWM duty cycle so this is synchronized but the mean voltage is moving up/down.
Here is an example of the traces: output OA1 (IC-FB and ID-FB motor from kit)
As the mean value is moving up-down, how is it possible to achieve the regulation without a "proportional" mean value?
Algorithm compute current feedback by subtracting C from D which can give small or bigger delta since the waveforms are symmetrical.
If I can understand the method to compute the current feedback, I think I will be able to understand what is going wrong with another motor.
Thanks for any help.
