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The Energy Transfer Mode (ETM) in a Boost dc-dc converter is classified into two types, i.e., the Complete Inductor Supply Mode (CISM) and the Incomplete Inductor Supply Mode (IISM). The critical inductance and boundary condition of CISM and IISM are derived in the paper. Based on the classification, three operating modes are defined, and they are CISM, IISM in Continuous Conduction Mode (IISM-CCM) and IISM in Discontinuous Conduction Mode (IISM-DCM). Output voltage ripple (OVR) in three modes is analyzed, respectively. As for a Boost converter with certain load, output capacitance and switching frequency, the OVR in CISM is the lowest and independent of the inductance and OVR in IISM is higher and increases with the decrease of the inductance. It is concluded that the minimal inductance to guarantee the Maximum OVR (MOVR) to be the lowest is actually the critical inductance of CISM and IISM under the condition of the lowest input voltage and minimum load resistance. In addition, the lowest MOVR is independent of the inductance. The design method to find the minimal inductance is proposed in the paper. Experiment results are in positive to the analysis showing the feasibility of the proposed methods. [ABSTRACT FROM AUTHOR]

A dual-output dc-dc converter based on the complementary pulsewidth modulation is proposed to overcome the cross-regulation problem between the outputs. Using a special-connected two transformers cell, one operational period is divided into two complementary parts. One output branch gets the pulsewidth and is regulated by the duty cycle; the other output branch gets the complementary pulsewidth and is regulated by the PFM. Only one full bridge and several passive components are needed, but both the two outputs have the fully regulated abilities even in the no-load situation. Moreover, a full zero-voltage-switching (ZVS) range is achieved in all the switches without auxiliary circuits. Therefore, the proposed topology has compact structure, high switching frequency, high-power density, and high efficiency. The operation principle, ZVS conditions, and design considerations are presented in the paper. The analysis is verified by a 300 V input, and 24 V/10A and 48 V/5 A outputs prototype. [ABSTRACT FROM AUTHOR]

Fuel cell systems have not significantly penetrated the low-power (< 50 W) portable energy source market, largely due to complexity of control and the balance-of-plant systems required. Even though the fuel cell and fuel container may scale down well, the pumps, blowers, and power converters required may dominate the system mass. This paper focuses on the tradeoff between efficiency and converter mass, and achieving the design objective of minimum mass of both converter and fuel. The effect of desired run-time, or mission duration, on the optimal dc-dc converter design was explored in detail. The effort focused on boost converters; however, the methodology can be applied to any converter topology. In an example case, at a mission length of 100 h, the optimized converter saved 91 g of system mass when compared to an off-the-shelf dc-dc converter. [ABSTRACT FROM AUTHOR]

Single-ended and two-ended bidirectional capacitor multipliers for providing on-chip compensation, soft-start, and fast transient mechanisms are proposed in this paper. The bidirectional current mode capacitor multiplier technique can effectively move the crossover frequency toward to the origin in the start-up period for a smoothly rising of the output voltage. Besides, the small time constant is set by the fast transient control circuit in order to get a higher crossover frequency. Thus, the output voltage can be regulated to its stable value as fast as it can when large load current changes. A test chip fabricated by the Taiwan Semiconductor Manufacturing Corporation (TSMC) 0.35-μm process verifies the correctness of the bidirectional current mode capacitor multiplier technique. Experimental results demonstrate the transient speed by our proposed technique is faster than that by conventional control by about 2 times, and there is only about 76% dropout voltage of the conventional design with off-chip compensation. The proposed circuits consume more quiescent current about 10 μA in single-ended capacitor multiplier and 20 μA in two-ended capacitor multiplier. With the proposed bidirectional current mode capacitor multiplier technique, the performance of dc-dc converters is improved significantly and the external pins and footprint area are minimized. [ABSTRACT FROM AUTHOR]

This paper presents the theoretical analysis of the three-phase zero voltage switching pulsewidth modulation dc-dc converter associated with a double Wye connected rectifier, delta primary, using a special switching scheme in order to maintain equilibrium among the currents through the output filters. The operating stages are described and the simulation and experimental results of a 6-kW prototype are presented. [ABSTRACT FROM AUTHOR]

In this paper, an averaged model for a recently pro- posed novel three-phase transformer-isolated phase-shift dc-dc converter is derived. Fuel cell static and dynamic characteristics are used for the converter power stage design consideration. The controller is then designed based upon the power stage parameters and system dynamic requirements. The entire system has been designed, fabricated, and tested using a commercial 1.2-kW proton exchange membrane fuel cell. The experimental results match the simulation results fairly well on both fuel cell source dynamic and step load transient responses. [ABSTRACT FROM AUTHOR]