3Phase Inverter from Single Phase Supply

[andreafog]

romanian mc3phac

Hi to all!
I've a question relating this interesting argument.

I would like to use a rectifier bridge (with capacitor) to rectify a AC single phase supply and then use the DC BUS that I've obtained to drive a motor with an inverter. If my suppositions are correct the resulting voltage applied at the motor will be lower than using a DC BUS obtained from a 3-phase rectifier.
How will be the behavior of the motor? It will have a reduced torque, reduced speed or what else?
The inverter that I would like to realize is based on Freescale MC3PHAC.

Thanks in advance.
Ciao

 

[Davood Amerion]

we have 2 config for 3-phase system.
one of them produce 310VDC and other 540V.
in the first case, we dont have significant difference.
in the second, when compare, we have lower voltage in 1-phase system, ( 310/540=1/√3=0.58 ),
and we must get about 50Hz/1.7= 29Hz max for normal motor driving.
if frequency go higher than 29Hz, produced turque decreased.

Regards
Davood

 

[andreafog]

Thank you Davood!

Here's exactly what I would like to know! Before starting the developing of this project I have to be sure that I can realize it physically.

So with my configuration (see attachment), I have to use a max supply frequency of 29Hz to have full torque, but at this frequency the motor cannot run at its full speed. To reach this speed I have to deflux the stator, doing this induces a reduction in th produced torque. Am I right?

Thank you again

 

[Davood Amerion]

in this configuration for all frequency below 29Hz (with 220V) you can get maximum torque. but output power (motor shaft power) proporatinal to [ torque * rotation speed].
in the other word output power proporatinal to frequency (at constant torque).
This means, you can get maximum 58% [29/50] maximum output power of motor.

Added after 14 minutes:

Important note:
If you use 3-phase motor which it's normal voltage is 380V in star connection, you can
use that motor with delta configuration at 380V/1.7=220V at full output power.

 

[andreafog]

Important note:
If you use 3-phase motor which it's normal voltage is 380V in star connection, you can
use that motor with delta configuration at 380V/1.7=220V at full output power.

But in this case to obtain an rms value of 220V at inverter's output I have to use a controlled rectifier bridge? I've forgot almost everything on delta/star connection.

Sorry for bothering you so much !

 

[Davood Amerion]

you can see below link: https://www.windstuffnow.com/main/3_phase_basics.htm
or https://www.eng-tips.com/viewthread.cfm?qid=16137