SPWM Inverter Control

UPDATE #1: The SPWM controller circuit now feeds a totem pole gate driven N-channel MOSFET. The gate voltage is maintained at 10V. Interestingly, while the MOSFET itself is driven by the logic level, apparently for the totem driver, the logic level of the base voltage, must be greater than that of the bias voltage (see zener biasing controller). This somewhat limits the operating regime of the power mosfet especially since the gate voltage must be over 4V. To experimentally tinker around this circuit with applied logic level, I've introduced a SPDT control to changeover the signal to fixed logic level.