Abstract
In recently published papers, an innovative analytical approach for the design of a class-E resonant dc-dc converter has been first proposed and further extended to many other class-E converter topologies. Its peculiarity is to be dimensionless and based on the exact solution of the system of differential equations regulating the behavior of the circuit, ensuring very high precision and reliability with respect to all methodologies previously proposed by the state-of-the-art and based on the so-called sinusoidal approximation. Here, we review this methodology and improve it in a twofold way. On the one hand, we propose alternative modeling for some devices (in particular the transformer), increasing both flexibility and generality, with the possibility to extend the application to more topologies and more working points. On the other hand, a new normalization is proposed, showing that the actual dimension of the design workspace is 2, and not 3 as assumed in the previous works. This has important consequences. As an example, the solution existence condition can be represented on a simple 2D plot, with the possibility to immediately check whether the optimal class-E condition can be ensured or not. Furthermore, we can completely and conveniently explore the entire design space to investigate properties such as the stress on the switching devices or the root-mean-square currents, allowing further optimization of the converter design.