An input-series output-parallel (ISOP) system, in which multiple converter modules are connected in series at the input sides and parallel at the output side, is very suitable for high input-voltage, low output-voltage, and high output-current applications. Input-voltage sharing (IVS) and output-current sharing of the constituent modules among the ISOP system must be ensured. The existing IVS control strategies have drawbacks of lower reliability and lower modularity. In this paper, we propose a wireless IVS control strategy for ISOP systems based on positive output-voltage gradient method, which can effectively improve the reliability and modularity of ISOP systems. First, the operation principle of the proposed control strategy is introduced, and the IVS performance and output-voltage regulation characteristics of ISOP systems are analyzed. The stability of the proposed control strategy is also explored. A three-module ISOP system prototype is fabricated and tested in the laboratory, and the experimental results verify the effectiveness of the proposed control strategy.Index Terms-Input-series output-parallel (ISOP), inputvoltage sharing (IVS), positive output-voltage gradient method, stability, wireless.
A novel output generalized memory polynomial (OGMP) behavioral model was proposed in this article, which is based on the previous output signal for digital predistortion (DPD) of power amplifiers (PA). Traditional MP or GMP model use polynomials of the previous input signal to characterize memory effect. Although the OGMP model use polynomials of the previous output signal to characterize memory effect. Using the previous output signal to characterize polynomials of the previous input signal, the number of coefficients will decrease. Measurement results show that the proposed OGMP model can achieve the similar effect with less coefficients. In detail, the complexity of OGMP model reduced by about 50% comparing with MP model. Compared with GMP model, the complexity of OGMP model reduced by about 60% with the similar effect.
In this work, Bi[Formula: see text]Na[Formula: see text]Ba2Co2O[Formula: see text] ([Formula: see text][Formula: see text]=[Formula: see text]0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) ceramic samples were prepared by the conventional solid phase method. The influence of Na element doping on the thermoelectric properties of samples was investigated from 300 K to 950 K. Compared with undoped sample, the Seebeck coefficients of Na-doped samples have only a slight decrease. While, the electrical resistivity of the Na-doped samples reduces, for Bi[Formula: see text]Na[Formula: see text]Ba2Co2O[Formula: see text] ceramic samples with [Formula: see text][Formula: see text][Formula: see text][Formula: see text]0.15, the electrical resistivity decreases with increasing Na doping amounts due to the hole-doping effect. In addition, its temperature-dependent resistivity exhibits metallic electrical conductivity behavior. While, the samples with [Formula: see text][Formula: see text][Formula: see text][Formula: see text]0.20 exhibit semiconductor electrical conductivity behavior at the temperature range of 473–823 K, because of the significant reduction of the electrical resistivity and the slight decrease of Seebeck coefficients, the power factors of the doped samples get a significant improvement. For the most suitable doped sample Bi[Formula: see text]Na[Formula: see text]Ba2Co2O[Formula: see text], its ZT value can reach a better value of 0.2 at 873 K.
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