Passive Input Current Harmonics Filter - Design & Calcuations
Passive Input Current Harmonics Filter - Design & Calcuations
(OP)
Application: SCR-controlled Battery Charger.
Input power: 440 VAC, 60 Hz, 3 ph, 3-wire, 10 KW.
Output power: 42.3 VDC, 200 Amps.
Input Transformer: 440V pri. Δ, 44V sec. Y, 18-pulse (9-phase).
Links shows sketch of application and transformer winding configuration.
Link
I thought the 18-pulse transformer would eliminate most of the unwanted input current harmonics...
However, I'm still seeing harmonics, 5th, 11th, 17th, and 19th are all above 3% (5th and 17th being the highest, at 6%).
I would like suggestions on how to attenuate these harmonics to below 3% using a passive (RLC) AC filter on the 440V primary side.
Design papers, calculations, or rules of thumb are welcome.
Looking for a solution that is robust (allowable ~5-10% tolerance on selected RLC components).
Thanks.
Input power: 440 VAC, 60 Hz, 3 ph, 3-wire, 10 KW.
Output power: 42.3 VDC, 200 Amps.
Input Transformer: 440V pri. Δ, 44V sec. Y, 18-pulse (9-phase).
Links shows sketch of application and transformer winding configuration.
Link
I thought the 18-pulse transformer would eliminate most of the unwanted input current harmonics...
However, I'm still seeing harmonics, 5th, 11th, 17th, and 19th are all above 3% (5th and 17th being the highest, at 6%).
I would like suggestions on how to attenuate these harmonics to below 3% using a passive (RLC) AC filter on the 440V primary side.
Design papers, calculations, or rules of thumb are welcome.
Looking for a solution that is robust (allowable ~5-10% tolerance on selected RLC components).
Thanks.






RE: Passive Input Current Harmonics Filter - Design & Calcuations
RE: Passive Input Current Harmonics Filter - Design & Calcuations
RE: Passive Input Current Harmonics Filter - Design & Calcuations
They are measured values using a power analyzer, phase-locked to the input voltage supply.
Active solution cannot be considered, sorry.
RE: Passive Input Current Harmonics Filter - Design & Calcuations
FWIW, 10kW is within the reach of a big switchmode supply, which would give you the option of an active front end with a near-perfect input waveform.
RE: Passive Input Current Harmonics Filter - Design & Calcuations
The other possibility is the incoming voltage. Is it a nice clean waveform and balance well across the three phases?
RE: Passive Input Current Harmonics Filter - Design & Calcuations
Probably not totally unbiased, but indicates some possible limitations to 18 pulse drives. As ScottyUK stated, it is unusual to see 18-pulse configuration on a drive this small.