Analysis of 3-phase inverter with resistive load

ALTHOUGH GAS-TUBE INVERTERS have had only moderate use in the past, they have potentialities of far wider applications in many fields. Possible applications include use of inverters to supply power to induction and synchronous motors, use of inverters at the receiving end of a d-c transmission line, and use of inverters in electric railway systems to allow power to flow from the d-c system to the a-c supply. Certain polyphase circuits have been designed primarily for operation at a fixed-frequency or over a limited-frequency range. If operation of polyphase inverters can be extended down to zero frequency, inverters may be able to supply variable-frequency power to polyphase induction and synchronous motors, thereby providing continuously variable speed from zero to full speed in either direction. An inverter circuit capable of this type of operation is the 3-phase bridge-type inverter which is commutated by capacitors connected across the output terminals of the inverter, as shown in Figure 1.