Quote by Karl Hammar: "There are several drawback useing the old transformer + rectifier design. Of main consern is the current spikes seen on the power grid when the diodes starts to conduct. Your power supplier don't like them and that is why we have PFC to make the unit behave more like a resistor to the power grid."
If PFC stands for Power Factor Correction, using a switching power supply doesn't free one from using rectification of the mains to power the switching transistors. The rectifier diodes will also have current spikes and we are essentially back to square one. With 3 phase power rectification the current spikes can be greatly reduced as the rectified voltage output from the rectifier without a smoothing capacitor never goes below ~85% of peak. If voltage rectification was such a problem, all devices/appliances that have to use a DC voltage source would be at blame, which is clearly not the case. Power Factor Correction enters the equation when loads having a substantial inductive component exist. This is the case when certain types of motors are used. Three phase motors do not produce a significant inductive load if they are well designed. This is also true of transformers given their primaries are well designed to keep the magnetising currents at a minimum. For voltage rectification Power Factor Correction (PFC) is not an issue. If this is a new issue that older text books about electricity/electronics did not discuss, please direct me to your sources of information. _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
