toolbag
10 mW
- Joined
- Jun 19, 2015
- Messages
- 30
The 'Big Idea' with this DAQ is to get a better picture of what's really happening on the motor side of things when spinning with a load. I've instrumented the DC side on lots of systems, but now that I'm getting more interested in inverter design I thought it'd be good to be able to watch the phase side of things. I started with one big grey box that seemed to fit all the goodies and went from there. If I need more headroom on voltage or current measurements there are equivalent components with different gains.
I haven't built the DC measurement box yet, but when it's all done we'll get:
DC Voltage (0-150Vdc)
DC Current (+-300A)
All three line-to-line RMS phase voltages (0-250Vrms)
Phase Currents (+-300A)
Parts used:
NI-USB 6221 (super easy to use USB DAQ)
HAS 100-S Current Sensors (good for +- 300A, super awesome part)
CRMagnetics Isolated DC Voltage Transducer (new to me)
CRMagnetics Isolated 3Phase RMS Voltage Transducer (also new to me)
Delta 24Vdc Power Supply (universal input, works at down to ~40Vdc in)
Delta +-15Vdc Power Supply (universal input)
It seemed like constraining the controller to be right next to the box was going to be a pain so I put the phase current/voltage probes on a whip that can go wherever within a few feet of the DAQ box. I used cat7 for all the wires out to the 3-phase box. The wire is only rated for 30Vdc and it'll be carrying phase voltage so that's not great, but I think we'll get away with it.
Since this is just a first hack at it I'm not too worried about noise and accuracy (you'll see there are many things that are sub-optimal from a noise standpoint thoughout this setup
). I also didn't get around to doing any analog filtering on the signals. We'll see if aliasing ruins everything later on. I think I will need to do some filtering eventually.
Here's the box mostly assembled! I keep tripping an overly sensitive GFI, but I doubt there's really an isolation issue on the AC supply side.
Testing the DC voltage measurement channel. Had to label the Fluke 715 'This is NOT a multimeter' so people don't pick it up and go blow it up trying to check a voltage more than 30Vdc
.
More tests to come!
I haven't built the DC measurement box yet, but when it's all done we'll get:
DC Voltage (0-150Vdc)
DC Current (+-300A)
All three line-to-line RMS phase voltages (0-250Vrms)
Phase Currents (+-300A)
Parts used:
NI-USB 6221 (super easy to use USB DAQ)
HAS 100-S Current Sensors (good for +- 300A, super awesome part)
CRMagnetics Isolated DC Voltage Transducer (new to me)
CRMagnetics Isolated 3Phase RMS Voltage Transducer (also new to me)
Delta 24Vdc Power Supply (universal input, works at down to ~40Vdc in)
Delta +-15Vdc Power Supply (universal input)
It seemed like constraining the controller to be right next to the box was going to be a pain so I put the phase current/voltage probes on a whip that can go wherever within a few feet of the DAQ box. I used cat7 for all the wires out to the 3-phase box. The wire is only rated for 30Vdc and it'll be carrying phase voltage so that's not great, but I think we'll get away with it.
Since this is just a first hack at it I'm not too worried about noise and accuracy (you'll see there are many things that are sub-optimal from a noise standpoint thoughout this setup
). I also didn't get around to doing any analog filtering on the signals. We'll see if aliasing ruins everything later on. I think I will need to do some filtering eventually.
Here's the box mostly assembled! I keep tripping an overly sensitive GFI, but I doubt there's really an isolation issue on the AC supply side.
Testing the DC voltage measurement channel. Had to label the Fluke 715 'This is NOT a multimeter' so people don't pick it up and go blow it up trying to check a voltage more than 30Vdc
.More tests to come!
