Re:Making your own VFD
Posted by
Ronald Anderson
on 2001-12-24 09:02:22 UTC
A BIG FYI on this BAD IDEA.
Never hook up Triac's or SCR's to a DC BUS powered by AC, they do not
switch and do not act like switches, once you turn them on the DC will
never shut off, this is why they are used on AC only which reverses
polarity. It is on this reverse polarity that they will shut off.
Triacs must never be used with inductive loads.
If you use the correct transistors for switching if you ever miss on
your timing signals you could have a direct short on the transistor
brdge and smoke it all. Despite your efforts to try and save money,
you will not. It is obvious from your proposal that you do not have
the knowledge to attempt this. It is also doubtful that you will be
able to incorporate any of the safety features and performance
features normally found in commercial VFD's.
Inxpensive VFD's maybe found on EBAY, just do a search for VFD's and
the prices are great.
You will be money and time ahead to buy a VFD, rather than build one.
High power shorts can cause some nasty explosions and flash burns. AC
Power grid level experiments are not for the amateur.
Sincerely,
Ron A.
**********************************************************************
**********************************
Message: 13
Date: Sun, 23 Dec 2001 21:14:00 -0800
From: "Raymond Heckert" <jnr@...>
Subject: Re: Re: VFD for series 1 bridgeport
Does anybody have any plans to make a high-power 3-phase inverter?
I'm
thinking about charging a couple of BIG juicy capacitors through a
full-wave bridge, and use a sinewave synthesizer (3 of them timed
16666
microseconda apart) to feed a husky set of TRIAC's. I want about
15KVA at
230 VAC 3-phase. Any help would be appreciated.
Best Wishes for safe & Happy Holidays!
RayHex at jnr@...
Never hook up Triac's or SCR's to a DC BUS powered by AC, they do not
switch and do not act like switches, once you turn them on the DC will
never shut off, this is why they are used on AC only which reverses
polarity. It is on this reverse polarity that they will shut off.
Triacs must never be used with inductive loads.
If you use the correct transistors for switching if you ever miss on
your timing signals you could have a direct short on the transistor
brdge and smoke it all. Despite your efforts to try and save money,
you will not. It is obvious from your proposal that you do not have
the knowledge to attempt this. It is also doubtful that you will be
able to incorporate any of the safety features and performance
features normally found in commercial VFD's.
Inxpensive VFD's maybe found on EBAY, just do a search for VFD's and
the prices are great.
You will be money and time ahead to buy a VFD, rather than build one.
High power shorts can cause some nasty explosions and flash burns. AC
Power grid level experiments are not for the amateur.
Sincerely,
Ron A.
**********************************************************************
**********************************
Message: 13
Date: Sun, 23 Dec 2001 21:14:00 -0800
From: "Raymond Heckert" <jnr@...>
Subject: Re: Re: VFD for series 1 bridgeport
Does anybody have any plans to make a high-power 3-phase inverter?
I'm
thinking about charging a couple of BIG juicy capacitors through a
full-wave bridge, and use a sinewave synthesizer (3 of them timed
16666
microseconda apart) to feed a husky set of TRIAC's. I want about
15KVA at
230 VAC 3-phase. Any help would be appreciated.
Best Wishes for safe & Happy Holidays!
RayHex at jnr@...