I_Bus Current vs Dashboard Current on ODrive GUI

Support ODrive S1 Support
1

I am using an Odrive S1 with a D5312S 330 Kv motor. Odrive is powered by 12V 2200 mAh 120C LiPo Battery with a 2 ohm 50W brake resistor supplied with the Odrive S1. I am using an AMT102V Incremental Encoder. The reason I am using the brake resistor with a battery (the ODrive documentation recommends using a Brake resistor with a PS, which often cannot take any regenerative current) is to help prevent too much current from going back to the battery (the max it can take is 2.2A, but I want it to be 1A for safety reasons).

I am using the O-drive GUI to control the motor, and here are the relevant settings I am currently using (please let me know if there are any other settings that you would like to know).

DC Bus Overvoltage Trip Level: 12.6V
DC Bus Undervoltage Trip Level: 10.5V
DC Max Positive Current: 10A
DC Max negative Current: -200ma
Max_regen_Current: 10ma
Control Mode: Velocity
DC Bus Voltage Feedback = True
DC Bus Voltage Feedback Ramp Start = 14V
DC Bus Voltage Feedback Ramp End = 18V

Brake Resistance: 2 ohm

I am wondering why my I_bus current listed in the Inspector tab of the GUI is significantly different than the Current listed on the Dashboard of the GUI.

0 rev/s to 20 rev/s makes Current on dashboard jump from 0 to around 6.5 A and when going from 20 rev/s to 0 it jumps from 0 to around -6.5. This is a very consistent reading across multiple attempts.

However, when I look at the I_bus on the dashboard, from 0 to 20 rev/s I get readings that change by significant margins (.5A, .9A, 1.75A). I do have my max regen current set to pretty much 0, so going from 20 to 0, the I_bus doesn’t really go negative, and thus I get equally inconsistent current readings on the brake_resistor calculated reading.

On a separate note, my 6.5A jump from going from 0 to 20 rev/s is also a 6.5A jump when doing 0 to 30 rev/s, the same thing occurs from 0 to 40 rev/s. It seems like there is a limit on this value of 6.5A, even though I have a max positive current of 10A.

So to sum up:

What is the difference between the Dashboard Current Listed and the I_bus current listed in the Inspector Tab?

What setting/situation would create that 6.5A “limit” (if there even is a limit)?

Why is the I_bus current so inconsistent when I am braking?

Is there an Inspector current value that I can look at that is the same current listed in the Dashboard?

I truly appreciate your help in this manner, I am using this O-Drive and Motor in my Senior Design Project currently.

2

Ibus is the actual bus current, the current shown on the dashboard is the current through the motor – these are not the same. The equivalent in the inspector would be iq_measured.

You can check the motor’s torque_soft_min/torque_soft_max and current_soft_max to see if there’s any relevant torque/current limit causing that 6.5A number - the GUI gives a 20% torque limit by default, so that sounds about right.

ibus is mostly inconsistent just because the GUI samples the values relatively slowly - even if you’re plotting at 10Hz, an actual deceleration event may only take 100-200ms and thus only have a point or two captured. Making a Python script to run your tests and capture data in real time then plot offline may be better if you want maximum time fidelity.

Dashboard current is iq_measured – you can just plot that in the inspector.