Assume that transformer is needed for voltage matching but electrical isolation is not mandatory. It is understood that the line currents on 3-phase will not be balanced, but what is the best compromise method between cost and the magnitude balance ?
Step down to desired voltage, convert to DC and invert to single phase. With modern power electronics this can be done quite efficiently; 15 kW is not an enormous load. It depends on what you mean by acceptable cost.
Step down to desired voltage, convert to DC and invert to single phase. With modern power electronics this can be done quite efficiently; 15 kW is not an enormous load. It depends on what you mean by acceptable cost.
Dear Sujit,
if a two-step conversion is not desired, there still is the chance to build 3-phase in, single-phase out matrix converter to do the trick.
More complex in control but gets you a single-stage conversion with 100% balanced grid currents.
As Daniel already said - it will remain a question on what kind of effort you want to spend, both in money and time to build the solution.
The proposed solution by Daniel Robert Franklin seems to me that is the best and simplest to supply 15Kw. the power electronic components or the industrial converters a more popular for this kind of use.
Daniel's proposal is the best due to use of simple converters and achieving complete balance on 3-phase side. However, considering harmonics current limitation on ac 3-phase side, a PWM rectifier is needed. thus two full capacity converters are needed. Martin's solution uses a single converter, but it is complex & not sure if current harmonics on 3-phase ac side can be controlled.
Nobody willing to suggest solutions involving transformer connections ? As I said earlier, complete balancing is not mandatory.
Der Sujit, as a Transformers will not be able to keep symmetries while reducing three phases to a single phase, it does't Seen to be a promising approach.
You might as well try a Leonard-Converter...
If current balancing is not an issue, for instance if 15 KW is small compared with other loads on that 3-phase supply, then why not just connect a transformer (for whatever voltage matching is necessary) to two of the phases of the 3-phase supply?
I wonder if we could use Open Delta Connection on the secondary. Also, Scott T connected transformer can supply two single phase loads.
Any Number of phases(higher or lower) can be obtained, simply by transformer (zig zag)connections.
A simple three phase diode rectifier feeding a capacitor and a single phase DC AC VSC to control the AC voltage at its nominal value (f,V)
To avoid harmonic contents a passive filter for 5th,7th harmonics
Another solution could be to use a 3 phase VSC as a rectifier on behalf the classical diode rectifier.
Dear Sujith,
The best method for 3 phase to single phase is explained in the following link.
http://www.3phasepower.org/1phaseloadson3phasepower.htm
Indeed an autotransformer starting from L1 and L2 as an input is a good starting point.
With a capacitor between L3 and L1 and an Inductor between L2 and L1, a big part of the asymmetry can be also solved, some 3 times lower current in L and C, but it can be calculated more accurately. Depending on the phase sequence, change L and C..
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