modulation strategy based on levels for an asymmetric cascaded multilevel inverter

Hi everybody, im new at this forum, sorry for my english, ive been trying to find information about how to generate the patters to commutate a asymmetric cascaded 7 level inverter exponent two and implement it in the PSIM software with modulation strategy based on carriers and a reference, since the inverter has to generate 7 levels it need 6 carriers, thats true for a simmetric cascaded multilevel inverter, for an ACMLI do i need six carriers too?...i don´t understan exactly the relationship between switching states and the reference signal compared with the carriers based on levels....

weel, how can i simulate an asymmetric cascaded 7 level inverter in PSIM software?? has someone simulated that configuration?

again sorry for my english...jejej

thanks a lot...