Motor overvoltage and PSU sizing

Hi, I’m new to brushless motors and the ODrive system. I need to use several ODrive D5065 Motors in my new project and I want to use an AC/DC PSU. I need their full torque, so after doing some quick calculations, it seems like I need to cope with quite a substantial load of power. I saw a recommendation to those Astec server power supplies (https://www.ebay.com/itm/Astec-AA23340-341-0092-03-6000W-PSU-Power-Supply-SEE-NOTES/333162633108?epid=663002457&hash=item4d920a5794:g:mcQAAOSwl11dem6P) in a different post. But judging from the label, it can only output at 42 volts. So here is my probably quite stupid question: Can I drive the 32-volt motors with this PSU, by liming current and speed with the ODrive? Or is there a different solution with, for instance, DC-DC converters?

Thanks in advance :slight_smile:

Yes, you can limit the top speed and use a larger voltage without issue.

Thank you very much, for your quick answer! I now decided to go with two 12V Power Supplies in series though.
I received my Odrive and I chose the one with the pre-soldered connectors. Compared to the wire gauges I need, to support the current, they seem pretty small. Are they capable of supporting a constant 100 amps over a long period? Or is there another recommended connector, that fits those bigger holes?

Thanks in advance and kind regards :slight_smile:

No, but neither is the ODrive unless you cool it a lot. If you plan on running the ODrive really hard, I would suggest you solder some thick wires directly to the bigger holes. You can use the bottom side of the board, and then you don’t need to desolder the screw terminals.
You can use a short wire with a large bullet connector so you can easily unplug things still.

Thanks a lot, for your quick support! I am actually planning on running two motors at 50 amps each. So the only connector, that is exposed to 100 amps is the power input one. I just read the post, showing max currents for the corresponding cooling methods and according to that, a simple fan would be enough to keep the ODrive cool.

Just for clearence, I would like to quickly introduce you to my project: I am a young student from Switzerland and I am working on my high school graduation project. My plan is to build a 6DoF robot arm. For axis 2, 3, 4 and 5 I want to use BLDCs with attached planetary gearboxes. Axis 2 and 3 are ODrive D5065 motors and axis 4 and 5 would be 4250-350kv motors. These are attached to Nema 23 and Nema 17 planetary gearboxes. There is actually a YouTube channel, that shows some amazing designs for BLDC and planetary gearbox robot actuators. (It’s called: “Skyentific”)
Once I finished building some working test joints, I’ll definitely post some pictures, etc. in a project topic.

Awesome yeah please post pictures and even work in progress if you want to!

Sure, I’ll see what my time schedule allows. :slight_smile:

You have to remember that you only get 16A from single phase. So 2600W. That Aztec gives you 2900 so you won’t need a 100 Amp connector unless you plan to run 3 phase power supplies.

It’s not because you send 100A total to the motors that the power input will be 100A

Cheers

Carelsbergh Stijn

I switched to HP 1200W PSUs. Two in series for 24V and one for 12V. Every one of those will get it’s own 16 Amp 220V phase.

Yes, it’s 50 Amps per motor, so the only connector exposed to 100 Amps is the input one. But I’ll solder the wire directly to the PCB anyways.

Cheers

Amps don’t work like this with bldc motors but ok, if you solder it, it will be okay.

Cheers

Carelsbergh