On 12 January 2012 11:49, Viesturs Lācis <viesturs.la...@gmail.com> wrote:
> Ok, I think that I finally got it - the heatsink is under the board > and only its very black side can be seen... Yes, that was the main change. > How big was that motor? It was a 2HP motor. On reflection, I probably drained the capacitor and then bad things happened. > I am not sure anymore that I do understand, what is inside AC > servo motor. Normal DC brushless motors have permanent magnets, Many "AC servos" are identical in construction to brushless DC motors. There is a class of motor which is a true AC induction servo motor, but they are very rare now. http://en.wikipedia.org/wiki/AC_motor#Two-phase_AC_servo_motors Any AC servo motor you find on eBay will be basically a brushless motor with an encoder. > > What is the rated voltage of Your rectifier bridge? Yesterday I had a > discussion with an electronics guy and he told me, that rectifier > bridge should not get warm at all It didn't, but it had a mounting tab so it was convenient to bolt it to the heatsink too. > BTW did You have something for the current sensing and over-current sense? I think I just put in the minimal components to make it wake up. > I also wanted to ask about GND in the schematics in page 9 of the datasheet: > http://docs-europe.electrocomponents.com/webdocs/0dca/0900766b80dca34c.pdf > > If I understand correctly, then V+ is the place to connect + from > power supply, but I do not see GND connected to that chip anywhere. > Ok, maybe it does not need GND for motor power, but I suspect there > should be something, to which the incoming PWM signals are referenced > to. The gates are AC-coupled through capacitors. So, DC power supply voltage is connected to V+ and the PSU gnd to the three VR(U/V/W) lines. Typically through current-monitoring shunt resistors. Some variants of the IRAMS chips have the shunt resistors built in. Vss is the logic ground. http://en.wikipedia.org/wiki/IC_power_supply_pin I don't think you want to connect the logic and PSU grounds in this case, especially if VR is rectified mains. That might actually be where I went wrong, on reflection. Can I suggest getting advice from someone with half a clue, rather than me? (Freewheel diodes) > Thanks for the explanation, but I do not get, where to look for them? :) Yes, on the datasheet, each of the 6 IGBTs has a diode in parallel with it. -- atp The idea that there is no such thing as objective truth is, quite simply, wrong. ------------------------------------------------------------------------------ RSA(R) Conference 2012 Mar 27 - Feb 2 Save $400 by Jan. 27 Register now! http://p.sf.net/sfu/rsa-sfdev2dev2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
