3 phase from func.gen. IC
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From: Kevin Lang on 10 Mar 2010 05:52 What would be the simplest way to derive a simultaneous three phase output from a sine wave produced by a single function generator IC ... that does not change as the frequency is varied? Specifically, two additional sinewaves remaining 120 and 240 degrees out of phase with the original as the frequency is varied between 100Hz and 1KHz. Kevin Lang
From: dcaster on 10 Mar 2010 07:08 On Mar 10, 10:52 am, kevinl...(a)hartley.com (Kevin Lang) wrote: > What would be the simplest way to derive a simultaneous three phase > output from a sine wave produced by a single function generator IC ... > that does not change as the frequency is varied? > > Specifically, two additional sinewaves remaining 120 and 240 degrees > out of phase with the original as the frequency is varied between > 100Hz and 1KHz. > > Kevin Lang I would look at Microchip's application notes. I think they have a PIC that is used for variable frequency drives. Does the whole thing. The function generator with three phase output. Might not be what you want as the sinewave would not be a real sine wave. It would be a pulse width modulated output. Dan
From: John Fields on 10 Mar 2010 08:53 On Wed, 10 Mar 2010 10:52:55 GMT, kevinlang(a)hartley.com (Kevin Lang) wrote: >What would be the simplest way to derive a simultaneous three phase >output from a sine wave produced by a single function generator IC ... >that does not change as the frequency is varied? > >Specifically, two additional sinewaves remaining 120 and 240 degrees >out of phase with the original as the frequency is varied between >100Hz and 1KHz. --- View in Courier: CLK>-+--[COUNT]-+-[LUT000]--[DAC]--[LPF]--> | | +-[LUT120]--[DAC]--[LPF]--> | | +-[LUT240]--[DAC]--[LPF]--> JF
From: pimpom on 10 Mar 2010 11:26 Kevin Lang wrote: > What would be the simplest way to derive a simultaneous three > phase > output from a sine wave produced by a single function generator > IC ... > that does not change as the frequency is varied? > > Specifically, two additional sinewaves remaining 120 and 240 > degrees > out of phase with the original as the frequency is varied > between > 100Hz and 1KHz. > > Kevin Lang How about this: http://www.techbriefs.com/content/view/1839/32/
From: John Larkin on 10 Mar 2010 11:42
On Wed, 10 Mar 2010 10:52:55 GMT, kevinlang(a)hartley.com (Kevin Lang) wrote: >What would be the simplest way to derive a simultaneous three phase >output from a sine wave produced by a single function generator IC ... >that does not change as the frequency is varied? > >Specifically, two additional sinewaves remaining 120 and 240 degrees >out of phase with the original as the frequency is varied between >100Hz and 1KHz. > >Kevin Lang Given a single-phase sine wave as input, you could make an all-pass network that would give two outputs that are 90 degree phase shifted at all frequencies, then do some analog summing to make 120 and 240. There are some allpass phase shifter circuits used in ham-radio type SSB transmitters that aren't too horrible. It could also be done with an integrator to make a 90 degree shift, some sort of AGC to restore the amplitude, and some analog mixing. And a few other terrible ways. But it's probably easier to build a generator that inherently makes quadrature or 3-phase sine waves. John |