What is the relation between the inverter frequency and the load of a motor? Does it increase? and how come. Is there a formula or something like that for this?
I think you mean a Frequency Inverter ckt? not 'Inverter Frequency'... Anyway, the basic function of a Freq Inverter/Converter is to convert normal power supply to another frequency.
I think that the frequency of the load would depend on the input, and many ckts are designed to have variable output frequencies.
if you'd like to learn more, this might help: