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1

A novel in-phase disposition SPWM pulse allocation strategy for cascaded H-bridge inverter

Zhang Y., Xiong J., Kong L., Wang X.

Archives of Electrical Engineering

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2018

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Vol. 67, nr 2

361–-375

EN

A novel in-phase disposition (IPD) SPWM pulse allocation strategy applied to a cascaded H-bridge (CHB) converter is presented in this paper. The reason causing the power of the CHB converter imbalance is analyzed according to the traditional structure, the conception of power imbalance degree is introduced and the principle of the novel in-phase disposition SPWM allocation strategy is deduced in detail. The new pulse allocation scheme can ensure the power balance in 3/4 cycles through interchanging the PWM pulse sequence of the different CHB cell, meanwhile it makes the full advantage of the IPD control strategy, lower the total harmonic distortion (THD) of line voltage compared to a carrier phase shifted (CPS) control strategy, which is verified by theoretical derivation. A seven-level cascaded inverter composed by three H-bridge cells is taken as the example. The simulation and experiment is performed. The results indicate the validity of the analysis and verify the effectiveness of the proposed SPWM allocation strategy.

2

Generation of chirped microwave signal with any central frequency based on a nonuniformly spaced finite impulse response filter

Chen D., Wang R., Pu T., Xiang P., Fang T., Zheng J., Xiong J.

Optica Applicata

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2016

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Vol. 46, nr 3

399--408

EN

A novel optical approach to generating a chirped microwave signal by using a nonuniformly spaced finite impulse response filter is proposed and demonstrated. In this scheme, a narrowband Gaussian pulse is used as the original chirped-free signal, which is easy to be acquired. To eliminate the need of a wideband chirped-free signal, a mixer and a radio frequency signal are used to up-convert the spectrum of the original Gaussian signal. Therefore, the required frequency response can be calculated and reconstructed by a finite impulse response filter with nonuniformly spaced taps. Besides, a dual drive Mach–Zehnder modulator is used to realize single sideband modulation of the chirpedfree signal. Thus, the transfer function induced by the fiber dispersion is eliminated and the chirped microwave signal with any central frequency can be generated. In this paper, a design example of a filter with a central frequency of 10GHz is provided, and generation of the target chirped microwave signal is also demonstrated by numerical simulations.

3

Measuring power system harmonics and interharmonics by envelope spectrum analysis

Xiong J., Wang B.

Przegląd Elektrotechniczny

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2010

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R. 86, nr 12

319-324

EN

An envelope spectrum analysis-based algorithm for harmonics and interharmonics estimation is proposed. First the envelope is extracted with narrow band Hilbert transform. Then the spectrum of the envelope and the harmonic components are calculated with windowing and interpolation method. Finally the interharmonic parameters are restored according to amplitude modulation equation. The proposed method has two distinguish features, first, it is able to confirm if the calculated interharmonic components do exist, and second, it is not affected by the spectral leakage caused from the harmonics. Several simulation examples are given to demonstrate the precision, effectiveness, and feasibility.

PL

Zaproponowano algorytm analizy widmowej umożliwiający określanie składowych harmonicznych. Najpierw wydzielana jest obwiednia przy wykorzystaniu wąskopasmowej transformaty Hilberta. Następnie obliczane jest widomo obwiedni i składowych harmonicznych metodami interpolacyjnymi. Wreszcie parametry interharmonicznych są odtwarzane na podstawie równania modulacji amplitudowej. Zaproponowana metoda ma dwie istotne zalety – umożliwia obliczanie składowych interharmonicznych i nie jest obciążona wpływem przecieku od harmonicznych. Zaprezentowano kilka przykładów symulacji potwierdzających skuteczność metody.