Add brake resistor info to hoverboard guide

This commit is contained in:
Paul Guenette
2021-12-22 21:44:06 -05:00
committed by GitHub
parent 16801640ee
commit f411be15df
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@@ -21,6 +21,18 @@ You may wire the motor phases in any order into a motor connector on the ODrive,
Note: In order to be compatible with encoder inputs, the ODrive doesn't have any filtering capacitors on the pins where the hall sensors connect. Therefore to get a reliable hall signal, it is recommended that you add some filter capacitors to these pins. We recommend about 22nF between each signal pin and GND. You can see instructions [here](https://discourse.odriverobotics.com/t/encoder-error-error-illegal-hall-state/1047/7?u=madcowswe).
### ODrive Configuration
There are a few items we need to configure on the ODrive before setting up the motor.
`odrv0.config.enable_brake_resistor`
Set this to `True` if using a brake resistor. You need to save the ODrive configuration and reboot the ODrive for this to take effect.
`odrv0.config.brake_resistance` [Ohm]
This is the resistance of the brake resistor. You can leave this at the default setting if you are not using a brake resistor. Note that there may be some extra resistance in your wiring and in the screw terminals, so if you are getting issues while braking you may want to increase this parameter by around 0.05 ohm.
`odrv0.config.dc_max_negative_current` [Amps]
This is the amount of current allowed to flow back into the power supply. The convention is that it is negative. By default, it is set to a conservative value of 10mA. If you are using a brake resistor and getting `DC_BUS_OVER_REGEN_CURRENT` errors, raise it slightly. If you are not using a brake resistor and you intend to send braking current back to the power supply, set this to a safe level for your power source. Note that in that case, it should be higher than your motor current limit + current limit margin.
### Hoverboard motor configuration
Standard 6.5 inch hoverboard hub motors have 30 permanent magnet poles, and thus 15 pole pairs. If you have a different motor you need to count the magnets or have a reliable datasheet for this information.