pwm inverter decrease inductor size

[franticEB]

Hi, i realized a pwm inverter (full bridge) with these characteristics:

Vbus=245V
Vrms_out=150Vac
Iout=2Arms
Fout=50-200Hz
Fswitching=25KHz
PWM method bipolar

Now the problem is the LC filter... I need a method to design the filter inductor...

I try to follow the powder cores catalog of MAG-INC

https://www.mag-inc.com/design/design-guides/inductor-design-with-magnetics-powder-cores

but i'm not sure the data i use for design are right (for example i don't know what is my DC current and what parameters i have to take into account when i design an inductor for pwm inverter).

Another problem is inductor size... i need a smallest size inductor. :fight:

Could you help me with a guide to design this inductor?

Thanks

 

[BradtheRad]

The inductor smoothes to some degree, and the capacitor does the same.

Choose the inductor value so it starts the rolloff curve, at your load Amperage, about 1.5 to 2x your fundamental frequency.

The inductor causes a phase shift of current in the PWM source. This creates a power factor error. Therefore you need the capacitor to cause a phase shift in the opposite direction. Together they provide power factor correction.

If the inductor is too small, you get insufficient smoothing of the output waveform. If the inductor is too large, it starts to act as a choke which attenuates the output amplitude.