Passive power correction - Electronic Circuits Projects Diagrams Free

technogeek · 15th August 2007, 08:35 PM

I have a small circuit that draws 30ma @ 160-170V. I'm currently using a rectifier off mains and a filter cap as an unregulated power supply. I measured the power factor at 0.6..... I've read that there are some tricks to get the PF closer to 1 with just some passive components, but have not read any design notes on how specifically to accomplish this.

Is it as simple as installing an inductor in line between the rectifier and filter cap?

mneary · 15th August 2007, 11:54 PM

Assuming you have a full wave bridge rectifier, installing the correct choke will improve the power factor.

See this article for details. If I understand the process, for 30 mA your choke needs to be about 5 Henries, and your output voltage would become about 105 volts.

technogeek · 16th August 2007, 06:41 AM

5 henries? good lord!

That must be why everyone likes active power factor correction?

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15th August 2007, 08:35 PM	(permalink)
technogeek	Passive power correction I have a small circuit that draws 30ma @ 160-170V. I'm currently using a rectifier off mains and a filter cap as an unregulated power supply. I measured the power factor at 0.6..... I've read that there are some tricks to get the PF closer to 1 with just some passive components, but have not read any design notes on how specifically to accomplish this. Is it as simple as installing an inductor in line between the rectifier and filter cap?

15th August 2007, 11:54 PM	(permalink)
mneary	Assuming you have a full wave bridge rectifier, installing the correct choke will improve the power factor. See this article for details. If I understand the process, for 30 mA your choke needs to be about 5 Henries, and your output voltage would become about 105 volts.

16th August 2007, 06:41 AM	(permalink)
technogeek	5 henries? good lord! That must be why everyone likes active power factor correction?