Inverter switching frequency

[gedza]

I understand that the full bridge inverter switching frequency must be above the audible range of 20 khz but what is the optimum switching frequency for dc-ac full bridge inverter with output at 50hz.

 

[Prototyp_V1.0]

The power transistors characteristics will determine this.

Too high frequency will result in dynamic loss and too low frequency may cause the inductor to saturate.

 

[betwixt]

I think you answered your own question, if you want the output to be at 50KHz, then run the inverter at 50KHz.

There is no rule about being above the audible range, it is just that vibration and resonance in some components might cause annoyance to anyone nearby. Electrically, the reasons given by Prototyp_V1.0 are correct.

Brian.

 

[gedza]

Sorrythe inverter is supposed to give a 50hz sine wave after filtering so i was asking the about the optimum H bridge switching frequency before filtering the harmonics.Thanks for the reply.

 

[Nol_]

Switching frequency selection is a complex trade-off mainly between passive component size, resulting switching losses and conduction losses (efficiency impact). You can find many papers on this topic that outline major goals that designers want to achieve and corresponding solutions - just browse ON Semi pages, TI's, Infineon's etc. Just to give you some idea to start with, assuming that you want to design low-power 220 Vac inverter, you can safely select a frequency between 35 kHz and 50 kHz. This is quite popular range, but it seems that frequencies are going higher recently as technology changes and new inverter topologies are being proposed.

 

[gedza]

How do you calculate the dead time required for a mosfet full bridge.