Inverter schematics
Arao H. Filho
inverter, and want some schematics to see how some problems were
solved.
I only found two schematics on internet, one incomplete and another
with a very low resolution, its unreadable, does anyone have
schematics of VFD's? It can be ABB, Siemens, Omrom, any brand...
This will save me a headache and I'll be very grateful!
Thanks.
--
Arao H. F.
My blog: http://zorktronics.blogspot.com
Dave B
<eletron...@gmail.com> wrote:
> Hi guys, I'm working on a project of a single phase motor VFD
>inverter, and want some schematics to see how some problems were
>solved.
> I only found two schematics on internet, one incomplete and another
>with a very low resolution, its unreadable, does anyone have
>schematics of VFD's? It can be ABB, Siemens, Omrom, any brand...
>
> This will save me a headache and I'll be very grateful!
>
> Thanks.
Yaskawa has lots of prints
db
Joseph Gwinn
<94c8b5db-c128-4314...@l14g2000pre.googlegroups.com>,
"Arao H. Filho" <eletron...@gmail.com> wrote:
> Hi guys, I'm working on a project of a single phase motor VFD
> inverter, and want some schematics to see how some problems were
> solved.
> I only found two schematics on internet, one incomplete and another
> with a very low resolution, its unreadable, does anyone have
> schematics of VFD's? It can be ABB, Siemens, Omrom, any brand...
>
> This will save me a headache and I'll be very grateful!
The best data is often in the patent literature.
Joe Gwinn
Bob Engelhardt
> Hi guys, I'm working on a project of a single phase motor VFD
> inverter, and want some schematics to see how some problems were
I know this isn't an answer to your question, but it might save you a
lot of grief: if you're planning on running a single phase motor, i.e.,
an induction motor, with a variable frequency, it won't work. Single
phase induction motors are designed for a specific frequency and giving
them a frequency much different than a limited range will stall them.
On the other hand, if your project is to generate variable 3 phase from
single phase input, it's been done and is available so cheaply that it
is really not worth your time & material cost.
Bob
Arao H. Filho
Bob, there will be no problem making use of the two windings of the
motor, the inverter will replace the start capacitor and provide the
neccesary phase and magnitude levels as required for the proper
operation.
Using only the two wires of the motor with the internal capacitor,
that's rated for the nominal frequency can't result on the maximum
torque, and on this case the motor will stall on the lower
frequencies.
--
Arao H. F.
Bob Engelhardt
> Bob, there will be no problem making use of the two windings of the
> motor, the inverter will replace the start capacitor and provide the
> neccesary phase and magnitude levels as required for the proper
So, your inverter will generate 2 phases - one for the main winding &
one for the start winding? That's very interesting and clever. Do you
have a link to where this has been done, or are you the first?
Bob
Wild_Bill
although there are already variable speed controllers for PSC motors.. OM
Oriental Motor is one manufacturer of drives for small AC motors, typically
under 1 HP.
Typical VFDs convert the incoming AC to DC, then pulse the DC in positive
and negative pulse trains that approximate the waveform of an AC supply.
The DC pulses are fast rise-time, and can exceed the breakdown limits of
insulation materials of the motor windings.. that's why VFD manufacturers
recommend using motors that are rated for inverter-duty (otherwise, using a
VFD for the motor's lower voltage in the case of 240/440VAC, if the motor is
dual-voltage capable).
The electrical characteristics of Start and Run windings in a typical AC
split-phase motor are considerably different, as the Start winding is only
intended to be powered for very short durations.. in normal use, exceeding
the short duration will burn out the Start winding.
In PSC type motors, the two windings are nearly identical, and intended to
be powered full-time in normal use. The PSC windings are arranged in series,
with three leads.. one at each end, and a center-tap.
--
WB
.........
"Bob Engelhardt" <bobeng...@comcast.net> wrote in message
news:imrc4...@news2.newsguy.com...
azotic
> "Bob Engelhardt" <bobeng...@comcast.net> wrote in message
> news:imrc4...@news2.newsguy.com...
>> Arao H. Filho wrote:
>>> Bob, there will be no problem making use of the two windings of the
>>> motor, the inverter will replace the start capacitor and provide the
>>> neccesary phase and magnitude levels as required for the proper
>>> operation. ...
>>
>> So, your inverter will generate 2 phases - one for the main winding & one
>> for the start winding? That's very interesting and clever. Do you have
>> a link to where this has been done, or are you the first?
>>
>> Bob
>
http://ww1.microchip.com/downloads/en/AppNotes/00967A.pdf
I built a single phase VFD using a TL494 modulated by a XR2206.
Standard H-Bridge configuration, the mod to the motor was to use
a TDR to prevent the start cap coming into the circuit when the RPM
was cranked down low enough to cause the centrifical switch to
switch on. I don't have the schematic finished yet but will have one
in fall, just got to much on my plate right now. I have been testing
the unit since before new year on my drill press. The single phase
motor on my drill press is 110VAC and seems to have no problem
operating using V/F speed control.
Best Regards
Tom.
Wild_Bill
remember who had been working on the circuit, Tom.
Thanks for keeping the RCMers posted.
--
WB
.........
"azotic" <H.B...@network.com> wrote in message
news:imrij9$tc$1...@speranza.aioe.org...
DoN. Nichols
> Hi guys, I'm working on a project of a single phase motor VFD
> inverter, and want some schematics to see how some problems were
> solved.
Do you mean a VFD which runs from a single phase power input, or
which produces only single phase output?
Note that for the latter, most single-phase motors will not
really work well at all on a VFD -- and you can test this by connecting
the motor to only two of the three output wires of a standard
three-phase output VFD. Cap start motors depend on the frequency as
a component in determining the proper value of the capacitor -- so they
are normally designed for either 60 Hz (here) or 50 Hz (U.K. and many
other places). Try to start one at 10 Hz and it almost certainly will
not start. The capacitor value is just too low. Try to start at 110
Hz, and you have similar problems -- except that the cap value is too
high instead.
> I only found two schematics on internet, one incomplete and another
> with a very low resolution, its unreadable, does anyone have
> schematics of VFD's? It can be ABB, Siemens, Omrom, any brand...
I'm surprised that you found *anything*. Manufacturers tend to
sit on their designs and not release the schematics -- except perhaps to
favored repair facilities with a NDA (Non Disclosure Agreement).
Basic principle of them is as follows:
1) Incoming AC is rectified to DC and there is a *big* filter
capacitor. (For single-phase input, you need an even bigger
filter capacitor to minimize ripple.)
2) Each phase output is connected to the positive and negative
ends of that capacitor by a high current switching MOSFET of
some flavor or other.
3) A logic circuit synthesizes the output waveform by putting
out a train of pulses of varying widths to approximate the sine
wave. These pulses go from wherever the voltage is at the moment
to full positive voltage (or full negative voltage) and then
relax back very quickly. These are turned full on or full off,
because the power dissipation in a half-on one would be too high,
and burn out the MOSFET -- and likely its opposite number too.
Perhaps as much as a 10 KHz repetition rate, and the
pulse width corresponds to the part of the output voltage curve
is being simulated. For the negative part of the swing, the
other MOSFET to the negative side is turned on instead.
Note that the logic generating the pulse trains and controlling
a lot of the rest is the real proprietary part. You can get the power
MOSFETs -- often in matched pairs in a single package, or even all three
pairs in a single package. (You'll still need a good heatsink on those
power MOSFETs.
> This will save me a headache and I'll be very grateful!
Depends on what you want to drive with this beastie you are
building. As mentioned above -- if you are planning to drive single
phase motors, things are likely to not be very good. If you are
planning to drive something else, remember that you don't get a real
sine wave out -- but rather a train of full-voltage pulses, which might
damage some things.
Best of luck,
DoN.
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