Estimation of Energy Transfer Function Sensitivity using an Energy-Based Heuristic Operator Method

Hard switching (PWM) converters have advantages in high efficiency and simple topologies. However, parameter sensitivity of these topologies needs to be evaluated for any application by carefully selecting the operating mode, as Duty-Cycle-Control, Pulse-Frequnecy Control, DCC or CCM. Moreover, high sensitivity will affect dynamic response in defined operating areas and needs to be evaluated as well as efficiency. An existing approach to power circuit estimation on the base of simple energy-based heuristics is extended for hard-switching PWM converters in this paper [5]. A systematic contructive generation of arbitrary electrical networks with discrete constant elements was compared with electrical transfer functions of empirical heuristic matrice solutions. For very simple networks, a mapping was demonstrable. Applied for hard switching PWM converters, this method shall basically avoid huge computational expense of sensitivity estimation, and shall provide prediction of areas with both, high parameter sensitivity, and low parameter sensitivity, respectively. Applying this method for PWM converters, exact solutions of power transfer functions are compared with fictitious functions using energy-based operators of the heuristic matrice method. As a result, congruence between exact system solutions and heuristic approximation in DCM is achieved for the Buck-Boost converter, the Cuk converter, the ZETA converter, and the SEPIC converter, but not for Buck converter and Boost converter, which indicates its inoperability near Duty-Cycles close to zero (Buck) and Close to one (Boost). Altrough all the other converter types have similar behaviour at DCM operation at the Duty-Cycle of zero and one, they do not show dynamical memory as buck and boost converters do. However, the buck converter, although it provides higher efficiency in some cases than the ZETA converter at same size, and has high senitivity at Duty-Cycle of zero, it has lower sensitivity at CCM than the Buck-Boost and the Boost-Converter. The presented formal method to estimate sensitivity for optimized hard-switching PWM converters will accelerate the design process and yields optimum parameters and an optimal topology for a given application at the first attempt.