Reducing harmonics in output voltage of a single phase voltage source inverter.
you need to determine the range of frequency to be removed first and as well the switching frequency of the inverter, and at most more than one set of LC arrangement have to be used in parallel in get rid of large range of harmonic frequencies.
Without filter find the output harmonic spectrum. Find the RMS voltage and the frequency of harmonic whose frequency is nearest to required fundamental frequency. This is lowest order harmonic( LOH). If the required output voltage frequency is less than the unwanted LOH frequency, then design a low pass filter hose cutoff frequency is 10 times less than the LOH frequency. If the frequencies of LOH and required frequency is close, then try PWM inverter and push LOH frequency away from fundamental frequency, or use a notch filter to remove LOH frequency followed with low pass filter.
My favourite paper (a bit old):
Dahono P.A., Purwadi A., Qamaruzzaman: An LC filter design method for single-phase PWM inverters. International Conference on Power Electronics and Drive System 21 - 24 February 1995, vol. 2, pp. 571 - 576.
And many others
This depend on the order of harmonics, each filter is characterized by its cutoff frequency
The design of the inverter output filter has it own rules depending on standards.
The properties of the output filter of the voltage source inverter can be characterized by IEEE-519 and IEC 62040-3 American and European standards. The harmonic with the frequency equal or very close to the switching frequency has the highest amplitude . And this harmonic should be efficiently damped. It gives the product LC value. The next step is calculation of L/C value using a kind of the cost function (having previously calculated product LC value). Using the idea of P.A. Dahono (and other authors as J. Kim, B. Ryu) of creating the cost function of absolute values of the reactive powers in the filter inductor and capacitor I have calculated the required values of them for various types of inverters. The disadvantage of these calculations are relatively high values of the inductance what can cause the high THD for the standard (IEC 62040-3) nonlinear rectifier load (PF=0.7).
Rymarski, Z.: ‘The discrete model of power stage of the voltage source inverter for UPS’, International Journal of Electronics, vol.98, No 10, October 2011, pp. 1291-1304
First we have to determine the harmonics present .Depending their strength higher order LC filter in cascade form is to connected in the output stage of inverter.
If you know the fundamental frequency of operation , you can use tuned class C amplifier for harmonic reduction.
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