which kind of core material, wiring (delat-wye, delta-zigzag, ...) is appropriate for a 3-phase inveter according to the harmonic problems, acoustic noise, neutral overload supplying nonlinear loads, etc?
(I'm looking for a transformer to be connected to an inverter and transmit 3-phase 50Hz 3-wire system to 4-wire with galvanic isolation and increasing voltage level)
Use of delta star connection make output free from harmonics. for better efficiency use high grade silicon steel material.
as per transformer , using D-D connection is better to get the triplen harmonic circulate in the D loop but take in your account that the Voltage and current consideration. also if you have to use star connection it is better to get it with neutral.
high insulation grade with spcl inverter grade insulator for high dv/dt and delta-Y transformer in supply else tertiary winding delta connected in short circuit condition.
Hi, The delta-star connection is convenient to reduce the output harmonics and reduce the effect of unbalanced nonlinear loads. In some cases, for example in UPS systems, the design of the transformer considers the required inductance value in the output filter in order to have a cost reduction. The geometry of the three-phase transformer can be modified tuning the per-phase inductance value.
Dear Salehi,
See, in consumer point of view, it is necessary to have neutral connection besides the phase. so at the end, the load side should be star connection as well. in case of primary side or inverter output side delta is good. it has special characteristics to suppress the harmonics.
D-S
Thank you
Thank you all for your answers,
So, the conclusion might be a delta-star transformer with no special consideration for core material...
At 50 Hz, Silicon Steel, Grade M6 (Best), M19 (medium), or M50 (Low) would all do just fine. The higher the M number, the thicker the lamination and the higher the core loss, but it's all relative at 50 Hz compared to 400 hz. The cost plays a role here with the M6 being more expensive, but you can drive it harder and use fewer turns compared to M19 since M6 can be used at 14.5 kG (1.45T) and M19 only at about 12 kG (1.2T).
May I suggest asking the customer/client/end user what is their main requirement.
If the main requirement is conversion efficiency, then this may narrow down the list of possible trafo core materials.
The customer may need to compromise on some of the other requirements, if they want their main requirement of energy conversion efficiency to be met.
Thank you very much. The first important thing for the customer is galvanic isolation, good performance, efficiency and the occupied space. So, the harmonic loss problem is so important in this system.
Also, based on your answers, no body suggests delta-zig zag transformer and I conclude there is no special advantages for this type of wiring in comparison to delta- star.
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