H-BRIDGE Large input capacitors functions

[israel7732]

I really want to know the importance of the high uf capacitors across the voltage supply of H bridge inverter.
I have worked with and without them but am unable to find a difference in performance of the two situations.
Please kindly put light on this question.

 

[barry]

The capacitors provide a local source for transient currents. Especially when driving inductive loads, e.g., motors, when the transistors/FETS turn on there is a large current surge. If you don't have those local caps, the current will have to come directly from the power supply, and the PCB trace inductance may have a negative impact on the performance.

 

[israel7732]

Thanks so much for your quick reply.
Any other advantages?

 

[barry]

It might also keep radiated emissions down since you're minimizing the large current spikes flowing through long traces (antennas). Also, minimize noise that might upset nearby circuitry.

 

[israel7732]

that is true. it will act as a filter and noise suppressor. thanks guys.