Approximate method for modeling and control of a two-stage power converter

In this paper, it is presented a procedure to simplify the well-known average model as well as to approximate the controller design for a Pulse-Width-Modulation (PWM) based power converter that transforms energy from some DC source (such as batteries or fuel cells) into an AC voltage source. The power converter studied is formed by two stages: a DC-DC bidirectional converter (boost) and a DC-AC H-bridge converter (inverter). It is demonstrated that second-order average models of those power converters can be simplified to obtain first-order approximate models, which in turn are used with frequency analysis to design approximate controllers that perform well compared to the complete design procedure, as it is observed in the simulation tests. As a result, parameters of the controllers for the power converter are calculated directly from the specifications of the power stages and control loop constraints. Hence, this method can be used to implement adaptive controllers as well.