single to three phase converter (inverter type)

[Electro nS]

any body can help in desiging a single phase to three phase converter for running a 1.5Hp drill press . i want the inverter type that rectifies AC into DC then creates three phase by swithcing IGBTs.

is it a simple or easy circuit to be implemented , or is it not worth the time and should be bought ready , if yes plese advise where to buy online ?

i have first thought of rectifiying the 230v AC into DC using Diodes and capacitor bank . then design a 3 phase inverter (the tricky part) . i have some knowlage in power electronics and microcontrollers , and would be glad to do this design to get the experience .


any help ( schematic , opensource project similar , demonstaration/evaluation board from ti , st , microchip ....) would be great .

cheers

 

[lunatik96]

The simple way to convert single phase to 3 phase is get a single phase motor and a 3 phase motor and connect them via a belt. The pully wheel has to be matched for the necessary RPMs. Connect the single phase motor to the AC line, having the 2 motors mounted and connected by a pully, have a power switch to control power on and off.

Turn it on and the output of the 3 phase motor is 3 phase power. The other way is to make a delay circuit x 3 and calculate the impedances used. This is much more iffy.
YOu can also buy the converters, but I think the 2 motors is the easy (cheapest) way. The other side is ask the power company if you can get 3 phase power to your shop unless it is just 1 device you plan on powering.

 

[lunatik96]

if you rectify and then invert, you incurr a major loss of efficiency. I saw a youtube video that described the quick and dirty circuit.

 

[Electro nS]

it is only 1 machine , so it is not justified to use 3 phase for the whole shop.

secondly the machine is about 1 to 1.5ph consumption , so if i want to use the 2 motor they need to be oversized than this need right ? about 2 - 3 hp ?
what about the voltage and rpm issues ? could it generate higher voltages ??

please provide the link if you still have it for the youtube video and a link to converters online .

 

[menengrone]

The circuit is simple but tIs not easy, see this aplication Note from Microchip - AN-1162, AN-1206.

cheers.

 

[chuckey]

Is the motor wound for 230V delta or 415V for star. If it is a delta connected motor, the easiest way is to feed two windings of the mmains and connect the third terminal to via a capacitor to live or neutral (will reverse the direction of the motor if wrong). the value of the capacitor is about 48MF for 1.5 HP 230V motor. In addition another capacitor may be required on starting for a few seconds until the motor comes up to speed. This is 3 - 5 X the value of the run capacitor.
If the motor is wound for star - 415 V then the above technique can be used BUT you will need a 230V to 415 transformer to get the additional voltages.
Frank

 

[ZASto]

The simplest way is to buy a VFD (Variable Frequency Drive) and to set its output freq. to 50Hz.

HTH

 

[Electro nS]

do you mean this thing that is used to soft start three phase motor like elevator (lift) ??

does the input of such drive single phase and output three phase !! , or both are 3 phase ??

can you suggest any ?

thanks

- - - Updated - - -

Is the motor wound for 230V delta or 415V for star. If it is a delta connected motor, the easiest way is to feed two windings of the mmains and connect the third terminal to via a capacitor to live or neutral (will reverse the direction of the motor if wrong). the value of the capacitor is about 48MF for 1.5 HP 230V motor. In addition another capacitor may be required on starting for a few seconds until the motor comes up to speed. This is 3 - 5 X the value of the run capacitor.
If the motor is wound for star - 415 V then the above technique can be used BUT you will need a 230V to 415 transformer to get the additional voltages.
Frank

i donot know how is the motor wounded , but it is a milling/drilling machine motor and only the thing shown in specs is taht it is 3 phase , no details. how can i know that ?

 

[chuckey]

you still have not said what the voltage rating of the motor is, and if it the same as your single phase supply.
Frank

 

[FlapJack]

You do not know how to figure out what the 3 phase motor voltage is and you want to build a single to 3 phase converter from scratch. That's crazy!

 

[Electro nS]

You do not know how to figure out what the 3 phase motor voltage is and you want to build a single to 3 phase converter from scratch. That's crazy!

did anyone tell you before that you are a smart ass!!
try working with chinese products and catalogs if your are buying online and then tell me how the hell would you know the difference .
the only thing mentioned is that it is 3 phase 1.5HP. and i suppose all products are 220v , none is 110 (the single phase versions) . i guess i have to wait until the machine arrive to know if it is 3phase 230v or 420v . and off course i have 220v 50hz at my place.