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Gu Y.,Zhejiang University | Lu Z.,Zhejiang University | Chen S.,Delta Shanghai Design Center
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2010

Buck type converters are widely used, however the power stage transfer function will be changed with the change of input voltage. The stability and dynamic performance are hardly designed to a perfect result simultaneously in wide input voltage range applications. Small signal characteristic of Buck converter is analyzed in detailed, and design considerations are introduced. Input voltage is applied as a compensation signal to change the slope of the sawtooth wave and the effect of input voltage in the power stage is eliminated. The concrete compensation circuits are presented for primary side control application and secondary side control application. The Buck type converter with compensation circuit owns the accordant bode plots of the loop gain and performs the good stability and dynamic under wide range input voltages. This method solves the small signal design issue for Buck type converters under wide range input voltages, and makes Buck type converter more suitable for system integration applications.


Zhang W.,Zhejiang University | Xu D.,Zhejiang University | Li X.,Delta Shanghai Design Center | Xie R.,Zhejiang University | And 4 more authors.
IEEE Transactions on Power Electronics | Year: 2013

Due to the long cold start time and slow dynamics of proton exchange membrane (PEM) fuel cell (FC) stack, operating modes transfer control strategy for fuel cell uninterruptible power supply (FC-UPS) is different from the traditional uninterruptible power supply (UPS) system. In this paper, a seamless transfer control strategy, which is suitable for FC-UPS, is proposed. The power conversion architecture of FC-UPS is presented with the characteristic analysis of PEMFC and the requirements of UPS. Then, the scheme of the seamless transfer control strategy is investigated. The proposed seamless transfer control strategy is not only capable of guaranteeing the uninterruptible load voltage, but also protecting FC against the power demands beyond its allowable bandwidth during the transition for long lifespan and safety. Finally, the control scheme has been verified on a 10-kW FC-UPS prototype. © 1986-2012 IEEE.

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