3 Phase run on 2?

[Jon Slaughter]

Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase converter" to
run a 3 phase motor. It has mofets and a controller which I imagine is used
to create the phases and I'm wondering if one of the fets is "bad"(or weak)
that it could still somehow allow the motor to turn(Even if only very slow).

I'm asking this because I don't want to have to check all the fets(because
they are hard to get to and require desoldering) but I know the motor
"works" at least somewhat(but somewhere there is a problem. i.e., the motor
does spin a little on one of the cycles but when it is suppose to rev up for
the spin-cycle it doesn't and throws and error and the motor speed.

 

[Anthony Fremont]

Jon Slaughter wrote:

Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase
converter" to run a 3 phase motor. It has mofets and a controller
which I imagine is used to create the phases and I'm wondering if one
of the fets is "bad"(or weak) that it could still somehow allow the
motor to turn(Even if only very slow).
I'm asking this because I don't want to have to check all the
fets(because they are hard to get to and require desoldering) but I
know the motor "works" at least somewhat(but somewhere there is a
problem. i.e., the motor does spin a little on one of the cycles but
when it is suppose to rev up for the spin-cycle it doesn't and throws
and error and the motor speed.

Do you really think something is wrong with the motor or its controller?
Does the wash cycle work ok? If so, it sounds to me like there is some kind
of sensor that measures how fast the drum is spinning. It's probably not
generating a pulse train and the computer is shutting it down since it can't
tell how fast it's going. Find and clean the sensor, it's probably optical.
Do you have a scope?

 

[Rick]

"Jon Slaughter" <Jon_Slaughter@Hotmail.com> wrote in message
newsluDk.1090$fD.704@flpi145.ffdc.sbc.com...

Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase converter" to
run a 3 phase motor. It has mofets and a controller which I imagine is used
to create the phases and I'm wondering if one of the fets is "bad"(or weak)
that it could still somehow allow the motor to turn(Even if only very slow).

I'm asking this because I don't want to have to check all the fets(because
they are hard to get to and require desoldering) but I know the motor
"works" at least somewhat(but somewhere there is a problem. i.e., the motor
does spin a little on one of the cycles but when it is suppose to rev up for
the spin-cycle it doesn't and throws and error and the motor speed.

Yes and no...a 3 phase induction motor won't be self starting with one phase missing (it
may rotate slowly). If you spin the shaft manually it will come up to speed.

 

[Tom Biasi]

"Jon Slaughter" <Jon_Slaughter@Hotmail.com> wrote in message
newsluDk.1090$fD.704@flpi145.ffdc.sbc.com...

Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase converter" to
run a 3 phase motor. It has mofets and a controller which I imagine is
used to create the phases and I'm wondering if one of the fets is "bad"(or
weak) that it could still somehow allow the motor to turn(Even if only
very slow).

I'm asking this because I don't want to have to check all the fets(because
they are hard to get to and require desoldering) but I know the motor
"works" at least somewhat(but somewhere there is a problem. i.e., the
motor does spin a little on one of the cycles but when it is suppose to
rev up for the spin-cycle it doesn't and throws and error and the motor
speed.

Three phase motors can run on two phases with a 1/3 reduction in power.
However its not as simple as just leaving off one phase. The motor can be
started using a capacitor start for the missing phase. The are some circuits
online but I don't have time to search now.

Tom

 

[Jon Slaughter]

"Anthony Fremont" <nobody@noplace.net> wrote in message
news:Y8qdnQIWAc9w5EPVnZ2dnUVZ_umdnZ2d@supernews.com...

Jon Slaughter wrote:
Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase
converter" to run a 3 phase motor. It has mofets and a controller
which I imagine is used to create the phases and I'm wondering if one
of the fets is "bad"(or weak) that it could still somehow allow the
motor to turn(Even if only very slow).
I'm asking this because I don't want to have to check all the
fets(because they are hard to get to and require desoldering) but I
know the motor "works" at least somewhat(but somewhere there is a
problem. i.e., the motor does spin a little on one of the cycles but
when it is suppose to rev up for the spin-cycle it doesn't and throws
and error and the motor speed.

Do you really think something is wrong with the motor or its controller?
Does the wash cycle work ok? If so, it sounds to me like there is some
kind of sensor that measures how fast the drum is spinning. It's probably
not generating a pulse train and the computer is shutting it down since it
can't tell how fast it's going. Find and clean the sensor, it's probably
optical. Do you have a scope?

Potentially but I do not think there is any senser on the basket because in
the tech docs it mentions nothing about that. It uses the tachometer on the
motor to sense the speed and gives the error about it either being the
tachometer, mcu or ccu.

Point is, that it's not even starting to spin up on the spin-cycle...
nothing... not even 1/10 of an rpm.

Yet on the drain part it does spin up, at least for 1 second or so for maybe
30 rpms. I think this is always what it did though.

(look at my other post in s.e.d about it)


I'm pretty sure it's the mcu though because on the drain I get a about 100V
across the different phases on the output of the mcu but on the spin-cycle I
get absolutely nothing but some noise from the relays and such. (which might
indicate something wrong wtih the filters or power supply?)

The point is that the mcu works some of the time but not in almost identical
circumstance in other times. (the difference being current and time... yet
it should at least start)

 

[Jon Slaughter]

The problem was a resistor that was blown(was hard to tell) it was the first
resistor in the path of the tach to the uP which basically was part of a
voltage divider into a programmable voltage reference

Tach
|
R1
|
+---- Vref
|
|R2
|
Gnd

R1 was open so my guess is that it was always showing that the motor was
turning as fast as possible(inverted output I think).

I replaced R1 with exactly(by stacking resistors) what it had (470Ohms) and
it works 100% better but every once in a while it still gives the F06 error.

Hence I think it's basically a threshold circuit that does something(not
sure because a pretty large transistor and several small ones are after the
Vref) that might include giving the F06 error.

Hopefully by decreasing R1 I can increase the threshold so it doesn't "trip"
as much... either that or make it worse.

 

[Stephen J. Rush]

On Sat, 27 Sep 2008 12:51:13 -0500, Jon Slaughter wrote:

Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase converter"
to run a 3 phase motor. It has mofets and a controller which I imagine
is used to create the phases and I'm wondering if one of the fets is
"bad"(or weak) that it could still somehow allow the motor to turn(Even
if only very slow).

I'm asking this because I don't want to have to check all the
fets(because they are hard to get to and require desoldering) but I know
the motor "works" at least somewhat(but somewhere there is a problem.
i.e., the motor does spin a little on one of the cycles but when it is
suppose to rev up for the spin-cycle it doesn't and throws and error and
the motor speed.

Have you measured the 3 voltages? A voltmeter can't show the phase
relationships, but if the magnitudes are equal, the fault is probably in
the washing machine.

 

[Jamie]

Jon Slaughter wrote:

"Anthony Fremont" <nobody@noplace.net> wrote in message
news:Y8qdnQIWAc9w5EPVnZ2dnUVZ_umdnZ2d@supernews.com...

Jon Slaughter wrote:

Can a 3 phase motor run on less?

I have a washing machine that uses 1 phase through a "phase
converter" to run a 3 phase motor. It has mofets and a controller
which I imagine is used to create the phases and I'm wondering if one
of the fets is "bad"(or weak) that it could still somehow allow the
motor to turn(Even if only very slow).
I'm asking this because I don't want to have to check all the
fets(because they are hard to get to and require desoldering) but I
know the motor "works" at least somewhat(but somewhere there is a
problem. i.e., the motor does spin a little on one of the cycles but
when it is suppose to rev up for the spin-cycle it doesn't and throws
and error and the motor speed.

Do you really think something is wrong with the motor or its controller?
Does the wash cycle work ok? If so, it sounds to me like there is some
kind of sensor that measures how fast the drum is spinning. It's probably
not generating a pulse train and the computer is shutting it down since it
can't tell how fast it's going. Find and clean the sensor, it's probably
optical. Do you have a scope?



Potentially but I do not think there is any senser on the basket because in
the tech docs it mentions nothing about that. It uses the tachometer on the
motor to sense the speed and gives the error about it either being the
tachometer, mcu or ccu.

Point is, that it's not even starting to spin up on the spin-cycle...
nothing... not even 1/10 of an rpm.

Yet on the drain part it does spin up, at least for 1 second or so for maybe
30 rpms. I think this is always what it did though.

(look at my other post in s.e.d about it)


I'm pretty sure it's the mcu though because on the drain I get a about 100V
across the different phases on the output of the mcu but on the spin-cycle I
get absolutely nothing but some noise from the relays and such. (which might
indicate something wrong wtih the filters or power supply?)

The point is that the mcu works some of the time but not in almost identical
circumstance in other times. (the difference being current and time... yet
it should at least start)

You most likely have shorted FETS on the output, we had a guy bring his

drive board in from a washing machine that employed a driving system
like you are detailing. It was starting up in a slow state or he had to
move the drum a little to get it to start until it finally just started
to blow fuses on the board.

You may also want to check the motor it self. He also had to replace
a motor in his dryer unit which was of the same type and these units
were matching washer and dryer.

I bet you have the same models.

http://webpages.charter.net/jamie_5"