One Phase to three Phase conversion

[rikilshah]

I am planning to build an one phase to 3 phase converter which will drive very small,low power 3 phase motor.Now my doubt is I have two ways to accomplish the task.
(1)Use TRIAC or SCR and directly convert AC to AC
(2)Use MOSFET and First Convert AC- DC and than Again to AC

My inclination is towards second option due to:
(1)MOSFETs are easy to control using micocontroller as compared to TRIAC
(2)I can have advantage of variable frequency for speed control of motor.

I need your help for justifying the right way to do the same.Thanks in advance.

 

[MrAl]

Hello,

Many commercial units use MOSFETs. The input is converted to DC, then back to AC only 3 phase.
The input filter depends on how much power output you need.

 

[MikeMl]

I have some of these. Read the manual. It will take input from 120V to 240V Single Phase, and it will speed control a three-phase motor up to ~2HP.

 

[rikilshah]

@MrAl So I guess there shouldn't be any problem with that topology.

@MikeMI Excellent product but I am a student and I have to make it on my own as part of my internship at a company.

 

[RichTheDude]

I have seen old engineers accomplish this by capacitors for a small Wye wound motor for a pillar drill. It definately works, it phase lags the single phase to generate the other 2 missing phases. Not ideal (it took a lot of mains rated capacitors) but its easy to do.

If its a delta wound motor, I dont think it can be done. Buying a converter is probably the best option.

 

[rikilshah]

@RichTheDude Yeah it is so obsolete and kind of not recommended for industrial operation because we need compactness and good efficiency!

 

[RichTheDude]

Yes it is a bad trick for industrial . Seen it done in hobby environents though.

I would probably go for AC to DC then DC to AC to be honest. Maybe be better ways (I dabble in analogue, but I am a digital engineer by trade).

 

[tcmtech]

Here is what I have been using for many years. It works with both delta and Wye wound motors and given the size of modern AC capacitors the converter box is as small as a VFD unit for a similar size of motor but far cheaper to build. Also the converter box does not have to be directly on the motor itself. It can be remotely located away form the motor if space is needed. Its just a thought.

https://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

 

[RichTheDude]

Thanks I will keep that in mind if an old 3 Phase miller comes up for sale