I wonder if the 'Neutral Point' as mentioned in the attached image is correctly labeled or not? Is there any mistake in this 3-phase circuit design?
Also it looks like the 'Neutral point' is electrically at the same potential as DC Bus (+) point. So can we connect the 'Neutral point' with either DC Bus (+) or (-) point? Please correct me if I am wrong.
What condition will turn-off the opto-coupler 'U6'? It looks like it will always be in ON state.
Do we really need diodes D1, D2, D3? If the three resistors R5, R7, R8 are used will they also not give the same result?