I am working on VFD for single phase induction motor. I am rectifying AC 220V directly to DC link capacitor. There is no LC filter from AC mains. There are harmonics in the AC mains. Can you suggest me a good way to design AC main filter or recommend me a filter that I can attach directly to my VFD to remove the harmonics?

enter image description here I have used the LC filter and LCL filter to check the response of the applied filter.
Value of the components are C= 56uF (AC capacitor) L= 2mH ( yellow iron powerder core)

I am want to know which type of core must be used, what will be the cut off frequency for this AC main filter.

The components that are appeared with my filter are given below.

  • \$\begingroup\$ Can you provide more details about the harmonics you have? Do you have a measurement? \$\endgroup\$
    – Jeroen3
    Nov 11, 2018 at 19:43

1 Answer 1


It will be impossible to remove the harmonics and difficult to reduce the harmonic content to a negligible level. You should determine what level is acceptable. Putting an AC reactor in the AC line or a DC reactor after the bridge may be sufficient. Many low-power VFDs on the market have very little built-in harmonic current mitigation. A VFD for a single-phase induction motor would be considered low-power.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.