No. You misunderstand, you don't need three phase power, just a three phase motor. The controllers rectify and filter the single phase line current, then generate three phase with a modified H-bridge design. -Denny ----- Original Message ----- From: "Simon Davies" To: Sent: Wednesday, October 15, 2003 4:33 AM Subject: Re: [EE]:Speed control of Synchronous motors > Gentlemen, > > Thank you all for the input, you have certainly given me a lot of food for > thought! > > Denny wrote: > - > > >Ultimately I scrapped the idea, the major stumbling block was the > >motor itself. Single phase synchronous motors have a designed > >frequency (usually 50 -60 hertz). Operating them more than a few > >percent outside this range produces very undesirable results. - gets > >hot - > > Aha, I suspected that something like this might happen... > > >I'm not an expert on the technical details, but as I understand it, > >the inductance and capacitance inside a single phase motor generates a > >second phase that's shifted. When the freq. is off spec, the shifted > >phase is no longer where it needs to be and the motor fights itself. > > OK. > >However, three-phase motors don't have this problem. As I understand > >it, that's because they don't generate the shifted phase(s) > >internally. > > Ok, but I don't have 3ph at my house and it will be cheaper to buy the full > professional controller etc than to get my Dutch electricity supplier to > install 3ph! > > >If you want to "roll your own" head on over to the Fairchild web site > >and read about their "Smart Power Modules" (SPM) some of the > >documentation is inconsistent and calls them "Intelligent Power > >Modules" (IPM). They also have a -bunch- of app notes on the concept > >in general to get you started. > > >BTW, they sent me a couple samples of 1Kw SPMs for free (normally like > >$40 ea) > > Thanks for the references > > >If you want to go DC, look at a treadmill motor from BG Micro. It's > >rated 110V DC and although there's no horsepower spec (or amp draw at > >load) it's like 15 pounds, eight inches long and four inches diamater- > >so I'm guessing it's in the ball park. > > >-Denny > > > > - > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics