This paper deals with an integrated magnetic design for the boost PFC and flyback converters with single magnetic core. A phase-shifted PWM technique is proposed to reduce the maximum flux density of the shared magnetic paths of the core. The proposed technique provides the advantage of minimizing the cross sectional area of the shared core limbs required to avoid the flux saturation, which results in the size reduction and cost down of the magnetic core. The principle and operation of the IM design and proposed PWM technique are presented for the boost PFC and flyback converters with single magnetic core. The simulation and experimental results are provided to verify the effectiveness of the proposed method.I.

In this paper, in order to design an optimal power conditioning system (PCS) for fuel cell (FC) application, nonlinear and dynamic characteristics of fuel cell are modeled. And design considerations, such as power semiconductor switches, capacitor and inductor, for optimal design of FC-PCS are deduced form comparative analysis of ideal de source and fuel cell characteristic model. And co-simulation of FC-PCS is then performed by using developed model with input condition of PCS. Through analysis and co-simulation results, optimal design methodology of PCS for fuel cell is provided. II. FUEL CELL SIMULATION MODEL A. Fuel cell modeling [7]The chemical energy deciding the fuel cell output is explained by Gibbs free energy and the theoretical maximum voltage is 1.229V, called by open circuit voltage (OVC), if the reaction of the reactant is reversible. The theoretical fuel cell voltage at the irreversibility is determined by temperature and partial pressure of hydrogen, oxygen, and water. And this can be calculated by the Nernst equation as in (1). where, EO reversible cell voltage, R gas constant (8.3144 llmol K), T temperature in Kelvin scale (K), F Faraday's constant (96,485 C/mol), P partial pressure.A practical fuel cell voltage is always lower than OCV due to irreversible voltage losses which are activation, ohmic, and concentration as expressed by (2) to (4). Therefore, about half of OCV appears at rated load condition.where, a transfer coefficient, n number of electrons per reacting ion or molecule, i.,exchange current density, i current density. R r is ri+re+rc, r, is ionic resistance, r e is electronic resistance, r c is contact resistance, and i L is limit current density.The exchange current density, which is one out of important factors of the efficiency of the fuel cell, is proportional to the catalyst, catalyst area, electrode area, the partial pressure of the reactant, temperature and activity energy. It can be derived as (5).

-This paper describes a Cross-regulation characteristics of a multi-output LLC resonant converter widely used in consumer electronics. The output characteristics of the multi-output LLC converter is derived from the assumption that the current and voltage in the resonant network is sinusoidal and the duty loss exists. The simulation and experimental results are provided to verify the theoretic results.