Ma Xi-Kui

Generalized synchronization of hyperchaos and chaos using active backstepping design

A novel active backstepping control method is presented for synchronizing two identical Rossler hyperchaotic systems with each other and extended to achieve the generalized synchronization of the Chua chaotic system with the Rossler hyperchaotic system. It is a systematic design approach and consists of a recursive procedure interlacing the choice of a Lyapunov function with the design of active control. In particular, this technique gives flexibility in constructing a control law. Numerical experiments verify the feasibility and effectiveness of the proposed control technique.

Transfer function modeling and analysis of the open-loop Buck converter using the fractional calculus

Based on the fact that the real inductor and the real capacitor are fractional order in nature and the fractional calculus, the transfer function modeling and analysis of the open-loop Buck converter in a continuous conduction mode (CCM) operation are carried out in this paper. The fractional order small signal model and the corresponding equivalent circuit of the open-loop Buck converter in a CCM operation are presented. The transfer functions from the input voltage to the output voltage, from the input voltage to the inductor current, from the duty cycle to the output voltage, from the duty cycle to the inductor current, and the output impedance of the open-loop Buck converter in CCM operation are derived, and their bode diagrams and step responses are calculated, respectively. It is found that all the derived fractional order transfer functions of the system are influenced by the fractional orders of the inductor and the capacitor. Finally, the realization of the fractional order inductor and the fractional order capacitor is designed, and the corresponding PSIM circuit simulation results of the open-loop Buck converter in CCM operation are given to confirm the correctness of the derivations and the theoretical analysis.

Exponential flux-controlled memristor model and its floating emulator*

As commercial memristors are still unavailable in the market, mathematic models and emulators which can imitate the features of the memristor are meaningful for further research. In this paper, based on the analyses of characteristics of the q– curve, an exponential flux-controlled model, which has the quality that its memductance (memristance) will keep monotonically increasing or decreasing unless the voltages polarity reverses (if not approach the boundaries), is constructed. A new approach to designing the floating emulator of the memristor is also proposed. This floating structure can flexibly meet various demands for the current through the memristor (especially the demand for a larger current). The simulations and experiments are presented to confirm the effectiveness of this model and its floating emulator.

Period-doubling bifurcation in two-stage power factor correction converters using the method of incremental harmonic balance and Floquet theory ∗

In this paper, period-doubling bifurcation in a two-stage power factor correction converter is analyzed by using the method of incremental harmonic balance (IHB) and Floquet theory. A two-stage power factor correction converter typically employs a cascade configuration of a pre-regulator boost power factor correction converter with average current mode control to achieve a near unity power factor and a tightly regulated post-regulator DC—DC Buck converter with voltage feedback control to regulate the output voltage. Based on the assumption that the tightly regulated post-regulator DC—DC Buck converter is represented as a constant power sink and some other assumptions, the simplified model of the two-stage power factor correction converter is derived and its approximate periodic solution is calculated by the method of IHB. And then, the stability of the system is investigated by using Floquet theory and the stable boundaries are presented on the selected parameter spaces. Finally, some experimental results are given to confirm the effectiveness of the theoretical analysis.

Effects of switching frequency and leakage inductance on slow-scale stability in a voltage controlled flyback converter

The effects of both the switching frequency and the leakage inductance on the slow-scale stability in a voltage controlled flyback converter are investigated in this paper. Firstly, the system description and its mathematical model are presented. Then, the improved averaged model, which covers both the switching frequency and the leakage inductance, is established, and the effects of these two parameters on the slow-scale stability in the system are analyzed. It is found that the occurrence of Hopf bifurcation in the system is the main reason for losing its slow-scale stability and both the switching frequency and the leakage inductance have an important effect on this slow-scale stability. Finally, the effectiveness of the improved averaged model and that of the corresponding theoretical analysis are confirmed by the simulation results and the experimental results.

Existence of horseshoe maps in voltage-mode controlled buck converters

In this paper, chaos in a voltage-mode controlled buck converter is studied. The existence of chaos is proven theoretically in this system. The proof consists of showing that the dynamics of the system is semiconjugate to that of a one-sided shift map, which implies positive entropy of the system and hence chaotic behaviour. The essential tool is the horseshoe hypotheses proposed by Kennedy and Yorke, which will be reviewed prior to the discussion of the main finding.

Analysis and reduction of conducted EMI from an AC/DC high power converter

This paper discusses how to reduce conducted electromagnetic interference (EMI) from an AC/DC high power converter to agree with EN class A. Herein some passive methods of suppressing conducted EMI noise, such as mixed-mode (MM) EMI filters, snubber circuits, are used based on measurement, the sources of noise are detected with the characteristics analyzed in detail The MM EMI filter is valuable means with which the conducted EMI noise can be efficiently reduced. A simple method of designing EMI filter, combining theoretical calculation with practical modification, is presented. It is easily implemented with only the amplitude of the noise and sinks impedances required. The experiment results prove that the methods adopted are viable and effective.

An approach for analysing the effect of conductor-strip-thickness on quasi-TEM characteristics of printed multiconductor strip lines

The effect of conductor strip thickness on the quasi-transverse electromagnetic (TEM) characteristics of multiconductor striplines is analyzed using the rectangular boundary-division method. This method is similar to the finite-element method (FEM), but has the advantages of simplicity, shorter computation time, higher accuracy, faster convergence, and a closed-form solution in each subregion. >

Characteristic impedance of specific transmission lines with offset inner conductors

The partial charge simulation method is presented to solve the characteristic impedance of the transmission line of specific cross section with an offset inner conductor. This method has a higher accuracy due to the accurate satisfaction of the boundary condition on the outer conductor. The combined method of the Gauss elimination and optimization is used to solve the equation of charge simulation, and it is an effective method for increasing the accuracy and assuring the convergence. The Green’s functions of five transmission lines(i.e. with circular, elliptic, rectangular, trough and slab conductor) are given.

Analysis of the capacitance of rectangular shielded line with offset inner conductor

The partial charge—simulation method is presented for calculating the capacitances of rectangular shielded lines with offset inner conductors. The capacitances calculated by using this method are in good agreement with those of other available methods. This method can improve the accuracy by increasing the term numberN of series.