low pass filter design of an inverterusing a single inductor and capoacitor

[gedza]

Can you please help me with the formulas to design a simple lc filter inductor and capacitor values .The switching frequency is 20khz and cutoff is 5khz .The out put frequency should be 50khz.

 

[bigdogguru]

Here are a few tutorials covering low pass filters utilizing inductors and capacitors:

LOW PASS FILTERS

LC low pass filter circuit

**broken link removed**

Chebyshev Pi LC Low Pass Filter Calculator

Butterworth Pi LC Low Pass Filter Calculator



These should get you started in the right direction.

 

[LvW]

Can you please help me with the formulas to design a simple lc filter inductor and capacitor values .The switching frequency is 20khz and cutoff is 5khz .The out put frequency should be 50khz.

Before starting the design of a filter, of course, one should know and understand the corresponding requirements (filter specification).
Therefore my question: Do you understand the meaning of the mentioned data (20 kHz, 5 kHz, 50 kHz) ?

 

[FvM]

The specification sounds more reasonable if you put in 50 Hz output frequency.

By saying single L and C, you have already selected a filter topology, the cutoff frequency implicitely sets the product L*C. But to define the actual L and C values you need to know the load and source impedance and intended filter Q, respectively a corresponding filter prototype.

Unfortunately, an inverter has a variable load impedance, so you can at best design the filter based on a typical load case, preferably nominal load.