pwm sequence for synchronous 3 phase motor

I am designing driver for 3 phase synchronous ac motor using IGBT inverter...6 Igbt and thier corresponding driver...pwm sequence for each pair..
However, I have read that synchronous motor must be given proper sequence inorder to maintain 120 degree phase shift between each phase...

how to give this kind of pulse sequences using controller...
Let take 1kHz frequency. so my total time is 1mSec. now in this duration , how to determine the pattern ??

I have attached my driver circuit...(overview)

Why start a new thread on the same subject. It was also pointed out you need 6 outputs not 3

tcmtech said:

full control of three phase requires six independant outputs. One fror each IGBT driver input not three. Theres your only real solution.

Click to expand...

blueroomelectronics said:

Why start a new thread on the same subject. It was also pointed out you need 6 outputs not 3

Click to expand...

I have taken 6 inputs for each 6 IGBT gate...now for 3 pairs of IGBT...input of high side and low side of each igbt must be opposite and either one high or low igbt must be turn on at a instant....

to run 3 phase motor I have to give proper sequence of pulses, I heard about 120 degree phase difference....
now Let say my 6 input would be A,A', B,B' ,C,C'...see the figure attached...i have taken a case in which f=50hz, Ttotal=20ms and Ton=10ms... is it correct???
I saw a negative cycle also at output in some design ...but my pulses are +5v only and Vbus=240V ...so how it would go in negative....

I am confused...

sorry, my figure is this..