Three Phase Output Question

First you rectifiy the 1 faze AC (220 V AC) into an DC signal ( +/- 311 V DC)

Then you buffer this DC signal in a big capacitor or a very huge coil. If the momentairy value of the sinus from the 1 faze current is going through zero, the coil or capacitor must deliver the current.

At last you need 6 transistors (IGBT's). You make three groups of two transistors is serie. These three groups are connected parallel to the DC supply.

At the three serie connection points from the transistors you have the L1, L2, L3 from the 3 phase system.

On the other side you need a timing system that triggers the transistors in the correct way so that the current is flowing from one group of transistor to the other group.

If the trigger system is fast enough and the sequence is correct, the you can change the duty cycle that the transistor or on. (Mostly the call this the carrier frequency +/- 4 till 15 kHz)

If you take the average over one periode, the result is that there is a sinusodial current flowing through your 3 phase consumer (motor, transformer, etc)

I almost understood what you have clarified.Does a VFD and a UPS use a same principle?

Simply put the device, (VFD or UPS), first creates a

DC base and the builds sine waves by switching

and applying it in small increments, (+ or-), to the

legs of the output.

Thanks for the information it was very valuable. Can i still ask you a few more questions if u dont mind ?

No, you have consumed your allotment.

In general it was called Converter-Inverter [Rectifier-AC Supply Generator].

The concept behind the design is:

1. Rectify the what-ever the AC supply is; Single-phase or 3-ph to DC.

2. Generate AC from rectified DC

[by a Rotary-Converter = A motor runs a Generator; single or 3Ph ]

This can be done also by AC-Motor [running on available Mains] driving a genratotor [1 or 3 Ph]

producing different frequency to the Mains [eg 50/60 Hz to 400 Hz for Aviation -Authority]

-- OR --

DC voltage for industrial use. We had this experience during switch-over period from DC to AC.

An example from Pakistan/India/Bungladesh:

Power supplied in late 19th & early 20th century was DC. After the Hydro-electrecity generation

During conversion from DC to AC the puclic had an option for a year or so to remain on DC. The Power Companies installed Rotory-converters [AC to DC] to supply Dc Power to DC consumers.

-- OR --

by an Electronic-circuit [generally called Power-Oscillator];

Fixed-Frequency-Fixed-Voltage [UPS = Unintruptible-Power-Supply] \

-- OR --

Vaiable-Frequency-Variable-Voltage [speed-controllers, VFDs variable-Frequency-Drive]

The Modern Semiconductors & Technology have a vast range of options.