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This paper presents the study of a single-stage, single-phase, unity power factor converter, isolated by a high frequency transformer, based on a Zeta converter operating in discontinuous conduction mode (DCM). The main feature of the proposed converter is its ability to naturally emulate an apparent resistance to the ac input source, without current sensor or current controller. Circuit operation, theoretical analysis and design example are included in this paper, along with experimental results taken from a laboratory prototype rated at 400W, input voltage equal to 127 V, output voltage equal to 200 V, switching frequency of 25 kHz and efficiency of 92 %. In order to reduce the commutation losses and limit the peak voltage across the power semiconductors, a non- dissipative snubber has been included in the laboratory prototype. With the advent of new low losses power semiconductor technologies, such as SiC and GaN, power converters operating in DCM will become very attractive, due to their simplicity and robustness, even for high power applications. This is the main motivation of the study presented hereafter.

This study deals with a reduced sensor configuration of a power factor correction (PFC) based zeta converter for brushless DC (BLDC) motor drive for low power applications. The speed of the BLDC motor is controlled by varying the dc‐link voltage of the voltage source inverter (VSI) feeding BLDC motor drive. A low‐frequency switching of the VSI is used for achieving the electronic commutation of BLDC motor for reduced switching losses. The PFC‐based zeta converter is designed to operate in discontinuous inductor current mode; thus utilising a voltage follower approach which requires a single voltage sensor for dc‐link voltage control and PFC operation. The proposed drive is designed to operate over a wide range of speed control with improved power quality at ac mains. The performance of the proposed drive is validated with experimental results obtained on a developed prototype of PFC converter. [ABSTRACT FROM AUTHOR]

This paper presents a comparative investigation, design and development issues about six different single-stage topologies, applied as electronic ballasts, for electrodeless fluorescent lamps. The ballast is intended to feed a 100 W lamp at 250 kHz, with dimming feature. The proposed topologies use different converters for the power factor correction (PFC) stage: Buck-Boost, SEPIC, Zeta, Cúk, Flyback, and Boost. All of them operate in discontinuous conduction mode. A resonant half-bridge inverter is used as lamp power control (PC) stage. The integration of both stages (PFC and PC) is proposed in this paper. In this way, it is possible to reduce the number of active switches, as well as simplify the required driving and control circuitry. Experimental results demonstrate the feasibility of the proposed dimming technique that achieved around 56% lamp power dimming, from 100 W down to 44 W. The implemented topologies attained high average power factor (>0.98), and low line current average total harmonic distortion (<;15.3%). A comparison among all the proposed topologies in terms of power factor, harmonic distortion, efficiency and number of components is presented. Finally, a comparison between an integrated and a nonintegrated SEPIC half-bridge converter is also performed. [ABSTRACT FROM AUTHOR]

This paper presents a new single phase front-end ac--dc bridgeless power factor correction (PFC) rectifier topology. The proposed converter achieves a high efficiency over a wide range of input and output voltages, a high power factor, low line current harmonics and both step up and step down voltage conversions. This topology is based on a non-inverting buck-boost (Zeta) converter. In this approach, the input diode bridge is removed and a maximum of one diode conducts in a complete switching period. This reduces the conduction losses and the thermal stresses on the switches when compare to existing PFC topologies. Inherent power factor correction is achieved by operating the converter in the discontinuous conduction mode (DCM) which leads to a simplified control circuit. The characteristics of the proposed design, principles of operation, steady state operation analysis, and control structure are described in this paper. An experimental prototype has been built to demonstrate the feasibility of the new converter. Simulation and experimental results are provided to verify the improved power quality at the AC mains and the lower conduction losses of the converter. [ABSTRACT FROM AUTHOR]

In many pulse width modulated DC-DC converter topologies, the controllable switches are operated in switch mode where they are required to turn the entire load current on and off during each switching cycle. Under these conditions, the switches are subjected to high switching stresses and power losses. Recently there is an increased interest in the use of resonant type DC-DC converters due to the advantages of high frequency of operation, high efficiency, small size, light weight, reduced Electro Magnetic Interference (EMI) and low component stresses. A novel PFC (Power Factor Corrected) Converter using Zeta DC-DC converter feeding a PMSM drive using a single voltage sensor is proposed for variable speed applications. A single phase supply followed by an uncontrolled bridge rectifier and a Zeta DC-DC converter is used to control the voltage of a DC link capacitor which is lying between the Zeta converter and a VSI (Voltage Source Inverter). The voltage of a dc-link capacitor of zeta converter is controlled to achieve the speed control of PMSM Drive. The zeta converter is working as a front end converter operating in DICM (Discontinuous Inductor Current Mode) and thus using a voltage follower. A sensor less control of PMSM is used to eliminate the requirement of Hall Effect position sensors. Using MATLAB/Simulink 7.13 environment the model can be simulated to achieve a wide range of speed control with high power factor and the same can be validated by means of hardware. [ABSTRACT FROM AUTHOR]

Digital simulation and implementation of a power factor correction (PFC) zeta converter based adjustable speed controlled voltage source inverter (VSI) fed permanent magnet brushless DC (PMBLDC) motor for mining application is presented in this paper using low cost embedded controller. The main attractive feature of the zeta converter is that it has a naturally isolated structure, which allows a regulated output voltage with only one power processing stage. The VSI is used as an electronic commutator for the motor. This drive ensures high power factor at the input side. The speed control scheme has the concept of DC-link voltage control proportional to the desired speed of the PMBLDC motor. The speed is regulated by a proportional-integral controller. The proposed PFC zeta converter based PMBLDC motor drive is designed, modelled and simulated using MATLAB/Simulink environment. The results of PFC zeta converter system are compared with the results of VSI-fed PMBLDC drive with L-filter and T-filter at the input side. The power factor is found to have improved using zeta converter. The hardware is implemented using reduced cost embedded controller with zeta converter as PFC converter. Merits of the proposed power converter include improved power factor, less harmonic content and simplified control strategy. The experimental results are compared with the simulation results. [ABSTRACT FROM AUTHOR]

In this paper, a dimmable LED current balancing driver is presented, which is based on the current balancing transformer with magnetizing inductance energy recycling considered. Such a driver has the main power stage constructed by one Zeta type converter. Hence, the energy stored in the magnetizing inductance can be released to the energy-transferring capacitor, thereby causing energy recycling to be achieved. In this paper, a detailed illustration of the basic operating principles of the proposed LED driver is first given, and finally some experimental results are provided to demonstrate its effectiveness. [ABSTRACT FROM PUBLISHER]

PWM dc-dc converters operating in Continuous Conduction Mode (CCM) perform similar basic functions despite the topology of which one. The canonical equivalent circuit of small signal & low frequency ac model permits to analyze converter behavior in a general manner, without the need to make reference to a specific topology. For Buck, Boost, Buck-Boost and Cuk topologies the “plug-in” parameters of the canonical model can be easily found just by circuit manipulation using very simple circuit analysis techniques. For the Sepic (Single-Ended Primary Inductor Converter) and Zeta topologies, utilization of the same procedure fails and one cannot arrive to the canonical model. To overcome this barrier, some authors indicate the need to apply circuit synthesis techniques which are not always familiar to many engineers. It will be shown that it is possible to arrive to the canonical model of this two converter topologies by using the well-known two-port network (quadripoles) circuit analysis technique.

SUMMARY This paper presents an interleaved zero voltage switching (ZVS) DC/DC converter with high input voltage applications. In order to reduce the voltage stress of MOSFETs, two half-bridge zeta converters are connected in series at high voltage side. Thus, the voltage stress of MOSFETs can be clamped at one-half of input voltage. Asymmetric pulse-width modulation (APWM) is adopted to control power switches. With the resonant behavior by the leakage inductance of transformer and the output capacitance of MOSFET at the transition interval, MOSFETs can be turned on at ZVS. For each half-bridge zeta converter, two series transformers are connected in series at the primary side and in parallel at the secondary side in order to reduce the current stress of secondary windings for high load current applications. Interleaved PWM scheme is used to control two half-bridge converters in order to reduce the size of output filter inductor and capacitor due to the partial ripple current cancellation. Experimental results, taken from a laboratory prototype rated at 1 kW, are presented to demonstrate the converter performance. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The grid-connected AC module is an alternative solution in photovoltaic (PV) generation systems. It combines a PV panel and a micro-inverter connected to grid. The use of a high step-up converter is essential for the grid-connected micro-inverter because the input voltage is about 15 V to 40 V for a single PV panel. The proposed converter employs a Zeta converter and a coupled inductor, without the extreme duty ratios and high turns ratios generally needed for the coupled inductor to achieve high step-up voltage conversion; the leakage-inductor energy of the coupled inductor is efficiently recycled to the load. These features improve the energy-conversion efficiency. The operating principles and steady-state analyses of continuous and boundary conduction modes, as well as the voltage and current stresses of the active components, are discussed in detail. A 25 V input voltage, 200 V output voltage, and 250 W output power prototype circuit of the proposed converter is implemented to verify the feasibility; the maximum efficiency is up to 97.3%, and full-load efficiency is 94.8%. [ABSTRACT FROM PUBLISHER]

For most actual power applications, power-factor correction (PFC) converters usually operate in the stable continuous conduction mode (CCM), but input current distortion will occur as long as these converters operate in oscillatory condition. This distortion usually manifests itself as a local oscillation within one line cycle. Typically, a Zeta PFC converter under the general pulse-width modulated (GPWM) control possesses high performance, and requires simpler control circuitry with fewer external components. However, due to the large-signal nonlinearity of the GPWM controller, the dynamic analysis and modeling of the input current distortion in its PFC converters remains vacant. In this paper, a large-signal average SPICE model is derived to capture the time-domain waveforms of the input current and output voltage. A power-balance approach for the PFC converter operating in CCM is developed, which can predict the steady-state values of the converters by using the Fourier series expansion. Analysis of the distortion behavior is provided in terms of the proposed model and the unbalanced power transfer mode. Experimental results are presented to verify the proposed method. [ABSTRACT FROM PUBLISHER]

Power converter models are time varying because of the switching action of power electronic devices. To find time-invariant models, this tutorial article presents the applications of the generalized state-space averaging method to the modelling of a zeta converter feeding a resistive load and paralleled buck converters driving a DC motor. Simulations using the proposed models with MATLAB coding agree well with the results of PSIM™ and SimPowerSystem™ of SIMULINK. Beside, simulations using the proposed model reduce the simulation time by 64% as an average in comparison with the available software packages. [ABSTRACT FROM AUTHOR]

This paper demonstrates that one cycle control (OCC) technique cannot be used in conjunction with continuous conduction mode (CCM) operated Zeta converters, as it inherently leads to unstable operation. The approach adopted by the authors to prove this is similar to that used to investigate current-mode controlled converters, except for the fact that the perturbation is applied to the storage capacitor voltage. It is demonstrated that in CCM this perturbation is amplified from one switching cycle to another and thus it results in instability. The theoretical results are verified through computer simulation using the Caspoc package [ABSTRACT FROM AUTHOR]

This brief introduces an isolated two-switch Zeta dc–dc converter, along with the steady-state analysis and experimentation. The high transistor voltage stress due to the ringing caused by the resonance of the transformer leakage inductance and the transistor output capacitance is a major drawback in the conventional isolated Zeta converter. With the incorporation of an additional transistor and two clamping diodes on the primary side of the transformer of the isolated Zeta converter, an isolated two-transistor Zeta converter is proposed. In the proposed converter, the voltage stress of both transistors is reduced to the dc input voltage VI. Experimental results from a 10-V/30-W 100-kHz laboratory prototype is presented to validate the theoretical analysis. [ABSTRACT FROM PUBLISHER]

This paper presents a single-stage AC-DC converter with zeta and flyback topologies to realize the functions of power factor correction, current harmonics reduction and reactive power compensation. The buck-boost topology is adopted in the front stage to reduce the DC bus voltage stress. Thus the low voltage stress of power switches can be used in the converter. Since the buck-boost converter is operated in the discontinuous conduction mode (DCM), the input AC line current is automatically following the utility voltage and the line current is a sinusoidal waveform and in phase with AC mains. The zeta and flyack converters are integrated in the primary side and connected in parallel at the output side to share the power components in the transformer primary side, achieve the partial magnetizing flux reset and share load power. Experimental results, taken from a laboratory prototype rated at 144W, AC source voltage of 110Vrms, output voltage of 24V, and switching frequency of 55kHz, are presented to demonstrate the converter performance. [ABSTRACT FROM AUTHOR]

This paper presents a zeta/flyback hybrid converter with a PV array as its power source for an LED street light or digital signage application. When the PV array is used in a LED lighting system, it needs a battery charger and discharger. In order to increase the areas of application for different PV arrays, a zeta converter has been adopted as the battery charger. In addition, since a flyback converter has a simpler circuit, it is used as the battery discharger. Due to the leakage inductor of the transformer in the flyback converter, an active clamp circuit is used to recover the energy stored in leakage inductance. Zeta and flyback converters use switch integration techniques to form the proposed zeta/flyback hybrid converter. With this approach, the proposed system has less components, a lighter weight, a smaller size, and higher conversion efficiency. Finally, a prototype of the proposed hybrid converter with an output voltage of 12 V and output power of 50 W has been implemented to verify its feasibility. It is suitable for LED lighting system applications. [ABSTRACT FROM AUTHOR]

In this paper, a monitoring method for DC-DC converters in photovoltaic applications is presented. The primary goal is to prevent catastrophic failures by detecting malfunctioning conditions during the operation of the electrical system. The proposed prognostic procedure is based on machine learning techniques and focuses on the variations of passive components with respect to their nominal range. A theoretical study is proposed to choose the best measurements for the prognostic analysis and adapt the monitoring method to a photovoltaic system. In order to facilitate this study, a graphical assessment of testability is presented, and the effects of the variable solar irradiance on the selected measurements are also considered from a graphical point of view. The main technique presented in this paper to identify the malfunction conditions is based on a Multilayer neural network with Multi-Valued Neurons. The performances of this classifier applied on a Zeta converter are compared to those of a Support Vector Machine algorithm. The simulations carried out in the Simulink environment show a classification rate higher than 90%, and this means that the monitoring method allows the identification of problems in the initial phases, thus guaranteeing the possibility to change the work set-up and organize maintenance operations for DC-DC converters. [ABSTRACT FROM AUTHOR]