Subharmonic instability boundary in DC-AC H-bridge inverters with double edge PWM

In this paper a stability condition is obtained for predicting the boundary of subharmonic oscillation in dc-ac H-bridge inverters under double edge modulation. This condition is analytically derived and expressed in terms of the system state-space model matrices. The availability of such analytical expression reveals the effect of all the parameters of the inverter on its dynamical behavior. The derived theoretical condition is validated by numerical simulations using a system-level switched model obtaining a good matching between the results. This work provides a convenient means of predicting subharmonic oscillation boundary in the parameter space hence facilitating the design of dc-ac inverters free from this kind of instability.