A Filippov method based analytical perspective on stability analysis of a DC-AC H-bridge inverter with nonlinear rectifier load

A comprehensive analysis of an inverter with nonlinear rectifier load by Filippov's method and state-space averaged method considering nonidealities have been reported for the first time. A study in comparison with an equivalent linear AC resistance load reveals that even though qualitative behavior remains similar, earlier onset of Hopf bifurcation and delayed onset of period-doubling bifurcation occur. This proves the necessity of modeling the nonlinear load at a switched system level, instead of linearizing it based on the first harmonic approximation which ignores the capacitor after rectifier and reduces the order of the system from four to three. Hopf bifurcation takes place with increase in capacitance after rectifier, along with corresponding decrease in its equivalent series resistance (ESR), limiting the selection of capacitors to lower values. However, ESR compensation solves this problem by preventing the onset of Hopf bifurcation and use of ESR compensated capacitor of higher values result in significant increase, instead of reduction in overall stable domain in parameter spaces. Analytical results have been corroborated by numerical simulation results.