The post explains an interesting single phase AC to 3 phase AC circuit. The idea was requested by Mr. Sachin Sinalkar.
The Circuit Request
Hi dear sir,
is there any way by which we can convert single phase 230V supply into three phase. i had try to ask question on your web site but couldn't succeed.
i know that you can do it.i got one diagram from internet the name written on diagram that 230v ac to 400v dc power supply.
i had try according to ckt diagram but it make 700v ac supply only at one time but after next it won't worked. at next time my electricity board burn.
Actually it is not for any purpose just one thought came in my mind and i think if it possible it will be really helpful for all of us since in village there is so much of load shading problem.
But one think good in few villages that at night for homes single phase supply available of farmer's crop wasted since they couldn't supply water to there crop if this happen it will be miracle.
The Circuit Design
I am not very sure regarding the working feasibility of the presented design, I hope it would function as expected from it.
The circuit is basically a voltage amplifier which is able to amplify a source input voltage to the level that's applied across the mosfets.
Three identical circuits need to be built for implementing the proposed single phase to three phase converter circuit design idea.
Making an accurate three phase input source was difficult to design and implement therefore I thought of a rather unusual method of generating the required three phase input pattern.
Since normally the load at the output of the proposed design would be a three phase motor so initially this motor could be rotated manually such that it behaves like a three phase alternator generating the required initial sample three phase voltage for the amplifier input.
As shown in the circuit diagram, we need three such identical circuits connected with the three wires of the motor integrated with their outputs.
We can see that a feedback link from the mosfet output been applied to the input of the amplifier.
With the given conditions if the connected three phase motor is rotated at the specified frequency, a sample equivalent voltage/frequency would be fed back at the input.
This input would then get amplified and returned at the required high potential AC voltage to the motor, locking its rotation in that particular frequency, once this takes place the manual rotation could be stopped and hopefully the latching would sustain the influence as long as the 330V DC continues to exist across the mosfets.
The manual rotation of the connected three phase motor could be done through an external single phase motor coupled with the three phase motor using gears which could be detached by some suitable mechanism as soon the system gets latched.
Of course this is just an idea from my part, if there's any feasibility in this idea it can enhanced or improved through suitable modifications.
The left hand side driver section requires 12V DC which can be acquired via a standard AC/DC adapter while the mosfet supply can be obtained from a bridge rectifier network directly connected with the existing 220 or 120V single phase source.
Devices required for the above single phase to three phase converter circuit.
Q1, Q2 = BC557,
Q3 = BD140
Q4, Q5 = BD139
Mosfets = 600V 1 amp, or approximate equivalent