AC servo motor help !

[rnr107]

You can't run a servo drive from an inverter, as the servo drive load is not constant, which at best would lead to something faulting out/just not working, and at worse blowing something up.
What you could do if you really wanted to use this servo, is build a rotary converter to produce the required 230V 3 phase, and get the phases as balanced as possible. All that's needed is a suitable 3 phase motor, some capacitors, and a couple switches (plus a relay and contactor if you want automatic starting).

Hi m_c,
Your first reply gave me an idea last night...
I opened up the enclosure of the drive and as you said, the AC from the 3 phases goes to 2 bridge rectifiers and a series of big caps.
So, using L and N single phase would use only 1 rectifier (and therefore geting it over worked...

Now, there is nothing in there requiering a phase shift between the 3 phases coming in....all the bridge rectifiers care about is 240V AC...
So, I decided to connect Neutral, Live, Live where the 3 phase were supose to go (L1, L2, L3)... This way the load is spread over the 2 briges as per 3 phase setup.

Tryed that this morning... All good! Motor happy, drive happy... (all stays cool )


These servo motor are really quiete! even at 3000 RPM ! amazing!


Laurent

[Jonathan]

For peace of mind you could increase the size of the capacitors to compensate for single instead of 3 phase.

[rnr107]

For peace of mind you could increase the size of the capacitors to compensate for single instead of 3 phase.

Funny that you mention this... :-) On the PCB there is a foot print for 5 caps but only 4 fitted! Could add an exta one I suppose...

[Colin Barron]

If in doubt as a last resort read the manual provided or if not supplied down load it from the internet or look on the internet to find out how other people have solved the same problem for that particular motor.

[GEOFFREY]

Assuming those caps and the "spare" are all in parallel adding another will increase the capacitance, so should do no harm. G.

[m_c]

grinorfrown?

[rnr107]

If you do add another capacitor, make sure it's a similar spec to the ones already fitted, and that it's capable of a pretty large ripple current i.e. don't go for the cheapest one you can find, as if it can't handle the ripple current it'll overheat and go pop pretty quickly.

Yes... I thought so... There must be a reason why this particular model of cap cost over £30 where you can find some of same value for less than £5.00 ! :-)

All caps are in parallel...

But, anyway I am pretty sure wiring the way I did (N, L, L) gives exactly the same work load to the caps and rectifiers as using 3 phase.