Steady-state analysis of an AC-AC Z-Source inverter including discontinuous power flow

Z-Source inverters, consisting of both inductors and capacitors as DC link components, provide unique boost capability in contrast to conventional inverters. The simple structure needs no additional switching elements and only small step-up chokes. Due to the oscillatory arrangement of both inductors and capacitors in the DC link, voltages and currents exhibit characteristical dynamic behaviour especially if using the Z-source inverter with an AC supply. The consequences are discontinuous power flow and distortion of the output voltage. The authors derive analytic equations describing the steady-state behaviour of the Z-source inverter for all relevant variables with special regard to AC supply without additional high-performance measures, resulting in a discontinuous power flow. The significance of the approach is verified by practical tests.