3-phase inverter using PIC controller problem

[adilmahsan]

Hi

I'm designing a 3-phase inverter using PIC controller

I'm currently using Mosfet drivers but have no qualms with using IGBTs

Let's say i'm using IGBT's and dual supplies (positive and negative) as shown on the 5th page of the attached pdf file

Now, if the gate triggering circuit varies from 0 to 5 volts, then wouldnt the lower transistors be forward biassed at 0 and 5 volts???

Shouldnt they require a triggering signal that varies from -Vdc to -Vdc+5 V

Plz help

Thanx

 

[FvM]

3 phase inverter

-VDC is connect to logic ground in this circuit.