Conventional parameter designs of two-stage grid-connected photovoltaic (PV) system relied on its mathematical model of the cascade structure (CS), but the procedure is excessively cumbersome to implement. Besides, for a two-stage converter system, the coupling interaction between the power converters can directly lead to a poor parameter design. To overcome this drawback, this paper uses a simplified structure (SS) of single-phase two-stage grid-connected PV system to better design the parameters of the front-stage dc-dc converter. After establishing the small-signal model for SS and CS in the PV system, the relative eigenvalue sensitivity is used as the criterion for judging the influence of some parameters on the stability of the two structures. The stable boundary of MPPT control parameters is compared and discussed in SS and CS, respectively. In addition, the relationship between the front-stage dc-dc converter and the rear-stage dc-ac inverter is analyzed by the modal participation factor calculated in CS. An experiment is also performed at the end of this paper to further verify the feasibility of using SS to design the parameters of the dc-dc converter in the PV system.
The wireless power transfer (WPT) system based on the parity–time (PT) symmetry can realize stable power transmission with constant efficiency and output power in the PT‐symmetric region. In some applications with long transmission distance requirements, such as medical treatment, it is meaningful to expand the PT‐symmetric region by reducing the critical coupling coefficient. Therefore, a novel WPT system based on PT symmetry with a boost converter in secondary side is proposed in this article to expand the transmission range. The circuit theory is used to analyze the presented system. Then two models with different drive signals of the boost converter are established and simulated respectively to show the effect of the proposed system compared with the original PT‐symmetry‐based WPT system. Finally, the experimental results verify that the proposed system can play a role in extending the stable transmission distance or in suppressing the output power growth of the PT‐symmetric‐based WPT system.
Lifting operating frequency can effectively reduce the size of energy‐storage components and increase the power density of converters, thus the very high frequency (VHF) resonant converters can find wide applications in practice. In order to further study the characteristics of VHF converters, a modeling method is presented for solving the state variables. First, according to the analysis of a typical VHF converter's operating modes, a unified equivalent circuit is established, which contains nonlinear controlled current sources. Then the mathematical model of the equivalent circuit is derived and solved by using the equivalent small parameter (ESP) method. And the approximate analytical solutions of state variables can be finally obtained, which are composed of a DC component and various harmonics. It is shown that the obtained solutions are accurate enough as the results from the proposed method agree well with the simulations and experimental results. Furthermore, the approximate analytical expressions for harmonics of state variables can be used as a guide for circuit design and stability analysis of the converter.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.