Connection to make motor stall

[abfer]

What happens if i make a connection like this?
U-V-W output of the VFD. X-Y-Z are terminals of a star connected induction machine.

Connection:

U------X
V------Y
|--Z
W

I mean W is free. X and Y terminals are both connected to V. X is connected to U. I think, V leg of the inverter is exposed to more current than a normal connection and motor doesn't rotate. I think this will create an effect like the motor is supplied from a single phase and two of the windings are connected parallel. So motor is an RL load in this case. Is my proposal right?

 

[Marke]

Hello abfer

The motor will not rotate with only two phases connected. You must have all three phases connected in order to develop a rotating torque field in the stator.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[jraef]

The big question is, why would you do this on purpose?


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[abfer]

For testing purposes. With this, motor will be an RL load. (and act as a transformer)And i will try to find rotor phase resistance by measuring voltage and current etc.

 

[Marke]

You will need to change the output pattern in order to make any measurements.
The waveform generator assumes that all phases are connected. If you have two phases only connected, the current will not be equivilent to two phases of a normal supply connected.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[aolalde]

Abfer; you posted:

“X and Y terminals are both connected to V. X is connected to U.”

That is a short circuit!

 

[abfer]

Not a short circuit. Modulation index will be low. And modulation type will be spwm. So when there is 1A at X, Y and Z will have -0.5A. Think like a single phase load is connected to an h-bridge.

 

[coconutalley]

abfer,

Can your drive be configured to drive a single phase motor?
If you do succeed to spin the motor, you would still have the back emf generating so it will be an RL load with bemf voltage.
Why not used a resistor and inductor for RL load instead?
Or take out the rotor and only drive the stator?

 

[abfer]

I think i couldn't explained. The drive is not a commercial one. I'll drive the motor. What i asked is, if i connect like that, does the motor rotate? Actually the connection won't change, only modulation will change in practical. But the same effect will occur. Instead of this connection, i can drive one phase wtih a signal(spwm) and the other phases with the same signal apart 120 degrees from the other signal. I'm trying to verify the validity of my thought before the operation, thanks

 

[Marke]

Hello abfer

If you only drive two phases, the motor will not rotate unless there is some mechnaical spin applied independantly.

The motor needs to have a rotating magnetic field and there needts to be at least two windings driven with a mechnaical displacement and a phase shift in the driving voltage.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[abfer]

Ok, thanks.