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In this article, we propose steady-state modeling of dc–dc converters driven by multiple pulsewidth modulation (PWM) signals. The proposed dc–dc converter modeling uses a switched state-space framework, and the switching signal discontinuities are represented by a Fourier series to obtain the average model. The advantage of the proposed modeling is that it is not dependent on the dc–dc converter topology, and the dimension of the state-space model does not increase with the number of storage devices. Additionally, the duty cycle and phase displacements among the driving PWM signals can be arbitrary and systematically modeled. The effectiveness of the proposed modeling is supported by simulation and experimental results. [ABSTRACT FROM AUTHOR]

The circulating current in phase legs is an inherent phenomenon of modular multilevel converters (MMCs). The circulating current affects various aspects of MMC performance, such as power losses, capacitor voltage ripples, and the required current rating of semiconductors. Existing circulating current control methods can improve MMC performance in one aspect, but they may not implement the optimal performance in various aspects. Analytically analyzing how circulating current control affects MMC performance is essential. This paper proposes an improved steady-state analysis method that considers circulating current control. The influence of circulating current control is included by considering the effects of the second-harmonic component on reference voltages. Explicit analytical expressions for various electrical quantities can be derived, and the analytical calculation curves of some MMC performance indexes concerned under varying second-harmonic reference voltages can be obtained. Accordingly, the effects of circulating current control on MMC performance can be concluded, where a theoretical foundation for the accurate design of MMC parameters is provided. In addition, the obtained analytical calculation curves can be used to evaluate different circulating current control targets and find appropriate control targets to comprehensively improve MMC performance. Both simulation and experimental results verify the validity of the proposed steady-state analysis method and the corresponding conclusions. [ABSTRACT FROM PUBLISHER]

This paper presents the steady-state analysis of a fixed-frequency phase-shift LCLC resonant converter with a capacitive output filter which is a very attractive topology for high-voltage applications. A conventional modeling procedure cannot thoroughly describe the converter behavior particularly at the load side. A comprehensive converter analysis is presented, and the obtained analytical expressions precisely describe the converter behavior. This paper shows that the range of zero-voltage-switching operation would extend significantly since the variations of the phase shift can be reduced by this topology. Therefore, high efficiency is achievable for a wide range of operation. This paper also provides some converter practical description for high-voltage implementation. The experimental results obtained from a 1.8-kW prototype verify the theoretical analysis and demonstrate the validity and accuracy of the employed model. [ABSTRACT FROM AUTHOR]

This paper proposes a passivity-based control (PBC) strategy for single-phase pulsewidth-modulated current-source inverters feeding a resistive load. In this strategy, it is required to estimate the load resistance and the inductor-current reference. However, the estimation accuracy depends on the inductance value when the load resistance and the inductor-current reference are estimated using an existing adaptive algorithm. In this paper, it is shown that the inductor-current reference estimation is possible at the expense of a constant reference function for the inductor current. In addition, the design of inductor and the sensitivity of the output voltage to the value of output capacitor used in the controller are studied extensively through the steady-state analysis of the proposed PBC. It is also shown that even very large values of the estimation error do not give rise to significant change in the output-voltage amplitude. Computer simulations and experiments are presented to verify the theoretical considerations. [ABSTRACT FROM AUTHOR]