DC-DC converters have been reported as exhibiting a wide range of bifurcations and chaos under certain conditions. This paper analyzes the bifurcations in current-controlled Luo topology operating in continuous conduction mode using continuous-time model. The stability of the system is analyzed by studying the locus of the complex eigenvalues, and the characteristic multipliers locate the onset of Hopf bifurcation. The 1-periodic orbit loses its stability via Hopf bifurcation, and the resulting attractor is a quasi-periodic orbit. This later bifurcates to chaos via border collision bifurcation. A computer simulation using MATLAB/SIMULINK confirms the predicted bifurcations. It has also been inferred from the experimental results that the margin of system stability decreases as the load decreases.

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Dc-dc converters have been reported as exhibiting a wide range of bifurcations and chaos under certain conditions. In this study, the analysis of bifurcation in a peak current-controlled single-ended primary inductance converter (SEPIC) topology operating in the continuous conduction mode is performed and is compared with the hysteretic current mode control. The stability of the system is analysed by varying the reference current. The locii of the complex eigenvalues and the characteristic multipliers indicate that the one-periodic orbit loses its stability via period-doubling bifurcation. A hysteretic current-controlled SEPIC converter that uses the sum of the two inductor currents as a control variable is discussed. The operation states of the converter are studied based on the theory of sliding mode control. A computer simulation using MATLAB/SIMULINK confirms the predicted bifurcations and the experimental results show that stable periodic operation is obtained for a wide variation in parameter.

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DC-DC converters are widely used in power electronic systems where there is a need for stabilizing a given dc voltage to a desired value. It has been reported that DC-DC converters exhibit different non-linear phenomena including bifurcations, quasi-periodicity and chaos under both voltage mode and current mode control schemes. In this work, current mode controlled SEPIC converter operating in continuous conduction mode is considered and by varying the reference current I ref , the converter exhibits chaos. It has been observed that the system changes from a stable buck-like operation to an unstable boost-like operation by varying I ref . Bifurcation diagram is plotted for control signal and capacitor voltage with I ref as bifurcation parameter. Resonant parametric perturbation control technique has been applied to suppress chaos. Effects of phase shift and frequency mismatch are also analyzed. With phase shift, control power required for suppressing chaos has been reduced. Also intermittent chaotic stages are suppressed with the effect of frequency mismatch at the expense of increasing control power. The stability analysis in SEPIC converter is performed by means of discrete model and is validated through the simulated and experimental results.

A new approach in the PWM technique is proposed through proper choice of active vectors and placement of a shoot through (ST) states for three phase Z source inverter (ZSI). Compared to the existing modulation method, the power conversion interval is maximum in this technique which improves the output voltage at higher modulation indices. Also with the inclusion of ST states, the number of switching is less avoiding the switching losses. The switching is performed at higher operating frequency which reduces the voltage stress and the size of LC components. In each sector, the ST interval is properly selected to improve the bus utilisation thus increases the voltage gain of ZSI. Furthermore, the analysis is performed by deriving the expression for the RMS flux ripple over a sub-cycle and evaluated in terms of switching instants which facilitates immediate comparison for all the presented methods. The proposed method is verified through the simulation and experimental results.

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