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Oskar Weigl
2018-08-10 23:16:40 -07:00
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@@ -163,7 +163,7 @@ In the previous step we started `odrivetool`. In there, you can assign variables
For instance, to set the current limit of M0 to 10A you would type: `odrv0.axis0.motor.config.current_lim = 10` <kbd>Enter</kbd>
</div></details>
* The current limit: `odrv0.axis0.motor.config.current_lim` [A]. The default current limit, for safety reasons, is set to 10A. This is quite weak, and good for making sure the drive is stable. Once you have tuned the drive, you can increase this to 75A to get some performance. Note that above 75A, you must change the current amplifier gains by requesting a different current range. i.e. for 90A on M0 'odrv0.axis0.motor.config.requested_current_range = 90' [A], then save the configeration and reboot as the gains are written out to the DRV (MOSFET driver) only during startup.
* The current limit: `odrv0.axis0.motor.config.current_lim` [A]. The default current limit, for safety reasons, is set to 10A. This is quite weak, and good for making sure the drive is stable. Once you have tuned the drive, you can increase this to 75A to get some performance. Note that above 75A, you must change the current amplifier gains. You do this by requesting a different current range. i.e. for 90A on M0: 'odrv0.axis0.motor.config.requested_current_range = 90' [A], then save the configeration and reboot as the gains are written out to the DRV (MOSFET driver) only during startup.
* Note: The motor current and the current drawn from the power supply is not the same in general. You should not look at the power supply current to see what is going on with the motor current.
<details><summary markdown="span">Ok so tell me how it actually works then...</summary><div markdown="block">
The current in the motor is only connected to the current in the power supply _sometimes_ and other times it just cycles out of one phase and back in the other. This is what the modulation magnitude is (sometimes people call this duty cycle, but that's a bit confusing because we use SVM not straight PWM). When the modulation magnitude is 0, the average voltage seen across the motor phases is 0, and the motor current is never connected to the power supply. When the magnitude is 100%, it is always connected, and at 50% it's connected half the time, and cycled in just the motor half the time.