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Old 01-02-2012, 04:36 PM   #42 (permalink)
thingstodo
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More DC to AC inverter tests

Quote:
Originally Posted by thingstodo View Post
On the agenda for tomorrow - power the inverters from separate 12V batteries, verify that the inverters can be connected in series to get about 280 VDC, and connect this voltage up to a test VFD to ensure that it powers up as it should.
More progress. I recycled some parts and a portion of a circuit. There is a self-resetting 5A fuse, a switch, a pre-charge resistor with a minibreaker that can short out the resistor, and a terminal block mounted on a piece of lumber.

The 2 DC to AC inverters are connected in series, that gives me 281.4 VDC. I connect this through the small alligator clips (which will likely melt before I get to 5A) to my lumber-mounted switch and on to my VFD.

The VFD powers up normally. I bypass the pre-charge resistor, then start the VFD outputting 0.9 Hz. All is fine.

I shut it all down and wire the VFD to a small three-phase 240VAC motor, modify the motor wiring to allow my clamp-on meter to show the current for one phase, then power it back up.

The VFD is powered up, the speed setpoint is set to 10 Hz, and the motor is started from the keypad. The clamp-on meter shows 2.5 amps. The DC from the batteries into the inverters shows about 7 amps - not excessive.

The VFD has issues - it's current sensor reads full scale all of the time. This means that it has very little protection, since the current is already at maximum, and that it will only run a motor for 30 seconds before shutting it down and displaying an overload fault.

So I would say this test is a success.

I'm trying out a small video camera - the Kodak touch. I'll try to post some pictures and a schematic. The video is quite disappointing.
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