29 results on '"Ioinovici, Adrian"'
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2. Generalized Structure of Bi-Directional Switched-Capacitor DC/DC Converters.
- Author
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Chung, Henry Shu-hung, Ioinovici, Adrian, and Wai-Leung Cheung
- Subjects
- *
VOLTAGE-frequency converters , *ELECTRIC current converters , *DIRECT current circuits - Abstract
Presents a generalized circuit structure of bi-directional switched-capacitor dc/dc converters that feature voltage step-down, voltage step-up, and bi-directional power flow. Derivation of two structures of single-capacitor bi-directional converter cells; Control scheme applied in the capacitor-charging phase; Formulation of a converter string by cascading a number of converter cells.
- Published
- 2003
- Full Text
- View/download PDF
3. Describing Functions of Power Electronics Circuits Using Progressive Analysis of Circuit Waveforms.
- Author
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Chung, Henry S.-H. and Ioinovici, Adrian
- Subjects
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ALTERNATING currents , *ELECTRIC current converters , *DIRECT currents , *ALGORITHMS - Abstract
Presents a technique for calculating the alternating current line-to-output and control-to-output transfer characteristics of direct current (dc)/dc converters. Algorithm description; Illustrative examples; Conclusion.
- Published
- 2000
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4. High Efficient PWM Zero-Voltage-Transition Boost Converter: AC Small Signal Analysis.
- Author
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Berkovich, Yefim and Ioinovici, Adrian
- Subjects
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DC-to-DC converters , *PULSE width modulation - Abstract
Proposes a direct current (dc)-dc boost converter operating under zero-voltage-transition (ZVT) conditions. Information on ZVT-pulse-width modulation boost converter; DC analysis and time-domain simulation; Discussion on alternating current small signal analysis; What the proposed converter achieves.
- Published
- 2000
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5. Zero-Voltage Transition Converter with High Efficiency Operating at Constant Switching...
- Author
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Wei, Huai and Ioinovici, Adrian
- Subjects
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DC-to-DC converters , *DIODES - Abstract
Focuses on the development of zero-voltage-transition pulsewidth modulation (PWM) dc-dc converter by adding two active switches and three diodes to the structure of a quasi-resonant converter. Description of zero-voltage-transition technique; Analysis of a steady-state cycle and derivation of the dc voltage conversion ratio; Design considerations and practical challenges; Experimental results.
- Published
- 1998
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6. Computer-aided analysis of boost-buck converter in optimal topology.
- Author
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Ioinovici, Adrian
- Subjects
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DC-to-DC converters , *ELECTRIC transients , *ALGORITHMS , *ELECTRIC inductors , *ELECTRIC resistance - Abstract
An exact algorithm for computing the transient response and the steady-state of DC-to-DC converters containing three reactive elements is proposed. The procedure is 'top-down' and automatable; it starts from a general, symbolic formulation and works down to the actual circuit. The method is applied to the analysis of the boost-buck converter operating in both continuous and discontinuous conduction modes. The basic circuit considered for the boost-buck converter contains mutual coupling between the input and output inductors, DC resistances of the inductors and on-resistance of the switching elements, but no load capacitor. The influence of the mutual inductance on the currents ripple is studied. The results are compared with the response, computed using a numerical method, of the boostbuck converter containing a load capacitor. [ABSTRACT FROM AUTHOR]
- Published
- 1988
- Full Text
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7. Design-oriented analysis of common switching DC to DC converters.
- Author
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Ioinovici, Adrian and Shenkman, Arie
- Subjects
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DIRECT current circuits , *ELECTRIC switchgear - Abstract
A general, computer-aided analysis of power electronic circuit dynamics is proposed. An automatic generation of dynamic models from a circuit specification is the starting point for a symbolic, automatable, exact, ‘top-down’ procedure, that contrasts with circuit-specific analyses. The algorithm is suitable for analysing any converter containing two reactive elements, covering the common switching power stages: buck, boost, buck-boost converters. The method is illustrated by application to the computation of the transient response of a boost converter; the computer results are compared with those obtained by applying the ‘state space averaging’ method and with laboratory results. [ABSTRACT FROM AUTHOR]
- Published
- 1987
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8. Optimal design of a switching boost regulator in discontinuous conduction mode.
- Author
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Ioinovici, Adrian
- Subjects
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ELECTRICAL conductors , *CASCADE converters - Abstract
A state-space averaging description of a non-linear boost converter, operating in the discontinuous conduction mode, is used to obtain the ‘equivalent’ duty ratio to output voltage, respectively line voltage to output voltage transfer functions. The coefficients of both of them may vary within some intervals due to the variation of the converter parameter values. Feedback compensators of a switching regulator in which the converter is incorporated are designed such as (a) the start-up transient response lies within imposed specifications despite parameter values and load variation, and (b) the output voltage is kept constant regardless of any variation of input voltage. [ABSTRACT FROM AUTHOR]
- Published
- 1987
- Full Text
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9. Design of a speed regulator electronic system for a DC motor fed from a semi converter supply.
- Author
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Ioinovici, Adrian and Shenkman, Arie
- Subjects
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ELECTRONIC feedback , *ELECTRONIC circuits , *CASCADE converters - Abstract
A feedback system for controlling the speed of a separately excited DC motor supplied from a 3-phase semi-converter circuit is presented. The electronic feedback structure is designed to assure that, in the starting transient state, the motor speed climbs from zero to its steady-state value within specified ‘customer’ bounds. This has to be achieved despite random variations in the characteristics of the supply voltage, of the motor and of the converter, and despite uncertain values of the load, keeping at the same time the starting current peak below a dangerous level. When feedback is applied, the system becomes highly non-linear; but owing to its quantitative approach, the design algorithm uses no small-signal linearizations. [ABSTRACT FROM AUTHOR]
- Published
- 1986
10. PWM convertor with low stresses and zero capacitive turn-on losses.
- Author
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Divakar, B.P. and Ioinovici, Adrian
- Subjects
- *
ELECTRIC current converters - Abstract
Proposes a buck converter operating at constant switching frequency, whose active switches and recovery diode commutate at zero-voltage-switching (ZVS), with zero capacitive turn-on losses. Use of parasitic capacitances of the switches; When the resonant stage takes place.
- Published
- 1997
- Full Text
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11. DC-to-DC converter with no magnetic elements and enhanced regulation.
- Author
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Zhu, Guangyong and Ioinovici, Adrian
- Subjects
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SWITCHED capacitor circuits , *ELECTRONICS - Abstract
Presents an electronics study which proposes a switched-capacitor-based (SC) step-up dc (direct current) converter for the aeronautical industry. Small size and light weight switched-mode power supplies required by the aeronautical industry; Use of two switched-capacitor circuits to control the energy flow from an unregulated voltage source to a regulated output.
- Published
- 1997
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12. Switched-capacitor inverter with high power density and enhanced regulation capability.
- Author
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Ioinovici, Adrian and Mak, On-cheong
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ELECTRIC inverters , *ELECTRIC circuits - Abstract
Presents a study which examined the high power density and regulation capacity of a switch-capacitor inverter as part of an electric circuit. Increase in demand for alternating current power supplies; Principles of the proposed switched-capacitor inverter; Operation of the switched-capacitor circuit.
- Published
- 1998
13. Design of feedback gain vector of two-state basic PWM multifeedback regulators for large-signal...
- Author
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Chung, Henry and Ioinovici, Adrian
- Subjects
- *
ELECTRONIC feedback - Abstract
Presents a method for determining boundaries of the feedback gains in a switching regulator with multiple feedbacks. Outline of model; Example of boost converter with inductor current and output voltage feedback; How large-signal stability of design is checked.
- Published
- 1997
- Full Text
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14. GUEST EDITORIAL.
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Ioinovici, Adrian
- Subjects
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POWER electronics , *SWITCHING circuits , *MINIATURE electronic equipment , *BIFURCATION theory , *ELECTRIC power , *CASCADE converters - Abstract
The article focuses on power electronics. Today high-demanding requests on the switching supplies have to be addressed by researchers: the need of high power density supplies for miniaturization purpose, fast transient response to rapidly changing loads like computers, absorption of clean sinusoidal currents from the electrical network for avoiding its harmonic pollution, supply of low voltages at high currents and steep voltage step-up, as required by telecommunication consumers. Neimark Sacker bifurcation is influenced by interleaving parallel-connected converters.
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- 2004
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15. Generation of the Large DC Gain Step-Up Nonisolated Converters in Conjunction With Renewable Energy Sources Starting From a Proposed Geometric Structure.
- Author
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Li, Kerui, Hu, Yafei, and Ioinovici, Adrian
- Subjects
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ELECTRIC potential , *CASCADE converters , *ELECTRIC current converters , *ELECTRIC currents , *RENEWABLE energy sources - Abstract
A very simple geometric structure whose branches can be filled by inductors, capacitors, diodes, short-circuits, or open-circuits is proposed. It serves for generating large dc gain-purposed switching cells by making different choices of the type of component on each branch. The switching cells are integrated in basic converters. It is shown that almost all the high dc gain nonisolated converters based on switched-capacitor-inductor cells proposed in the last years, regardless of their complexity, can be derived through this method. From the same geometric structure, new high dc gain boosting converters can be derived in a systematic manner. The available and the new converters in each class as defined by the number of reactive components are compared in terms of their performance: dc gain, semiconductor elements count, voltage and current stress on transistors and diodes, character of the input current, easiness of the transistor driving, and easiness of the control as determined by common/uncommon line-load ground, power stage efficiency. This comparison allows us to choose the optimal solution for each specific application in conjunction with the green sources of energy, multisource microgrids, electric vehicles, data and communications systems, and so on. The geometric structure is generalized in different ways, allowing for the development of ultrahigh dc gain converters. One of the proposed generalized ultrahigh dc gain converters is fully analyzed and built in the laboratory, with the experimental results verifying the theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
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16. Phase-Shift Interleaving Control of Variable-Phase Switched-Capacitor Converters.
- Author
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Kiratipongvoot, Sitthisak, Tan, Siew-Chong, and Ioinovici, Adrian
- Subjects
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CONVERTERS (Electronics) , *ELECTRIC power conversion , *CAPACITORS , *CODING theory , *ELECTROMAGNETIC interference - Abstract
This paper proposes a phase-shift interleaving control method for variable-phase switched-capacitor (SC) converters that can perform voltage conversions with little electromagnetic interference over a wide range of operating condition. This is achieved by having multiple units of SC converter connected in parallel and an N-state hysteresis unit selection control scheme which works along the interleaving control to vary the number of converters in operation. By having the capacitors of inactive units connected to the output and the converters operating with output interleaving operation, the output capacitor that is typically required in SC converters for maintaining a small voltage ripple is made redundant in this configuration. A three-unit SC converter of the proposed configuration is described in this paper. Experimental results show that the proposed solution works satisfactorily with good regulation, input and output interleaving operations, and dynamic response for a wide operating range. [ABSTRACT FROM PUBLISHER]
- Published
- 2013
- Full Text
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17. A New Concept of High-Voltage DC–DC Conversion Using Asymmetric Voltage Distribution on the Switch Pairs and Hybrid ZVS–ZCS Scheme.
- Author
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Huai Wang, Chung, Henry Shu-Hung, and Ioinovici, Adrian
- Subjects
- *
HIGH voltages , *DC-to-DC converters , *HYBRID power systems , *METAL oxide semiconductor field-effect transistors , *INSULATED gate bipolar transistors , *ZERO current switching , *ELECTRICAL load - Abstract
A new concept of high-voltage dc-dc power conversion is presented in this paper. Its distinctive feature lies in distributing the high input voltage asymmetrically between two primary-side series-connected switch pairs. This allows using switches of optimal ratings in their respective class: the low-voltage switch pair implemented with MOSFETs only, and the high-voltage switch pair implemented with insulated gate bipolar transistors (IGBTs) only. As the switches in a switch pair are of the same type and voltage rating, they are maximally utilized. With an active snubber on the secondary side of the isolation transformer, a hybrid zero-voltage-switching-zero-current-switching (ZCS) scheme, which is different from the zero-voltage and zero-current-switching technique, is realized and makes all IGBTs be zero-current-switched and all MOSFETs be zero-voltage-switched from very light load to full load condition with minimal circulating energy. The ZCS snubber energy is completely released to the load, leading also to a duty-cycle gain. The operating principles, dc analysis, and design guidelines will be given. A 2-kW, 1500/48-V experimental prototype has been built and evaluated. The measured efficiency of the converter is found to be 92.4% at the rated condition. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
18. A Class of High-Input Low-Output Voltage Single-Step Converters with Low Voltage Stress on the Primary-Side Switches and High Output Current Capacity.
- Author
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Wang, Huai, Chung, Henry Shu-Hung, and Ioinovici, Adrian
- Subjects
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CASCADE converters , *LOW voltage systems , *SWITCHING circuits , *ELECTRIC capacity , *METAL oxide semiconductor field-effect transistors , *ELECTRIC inductors , *DIRECT currents , *ELECTRIC current rectifiers - Abstract
Power conversion from an input voltage of several kilovolts to a low load voltage is of great significance in various applications, but poses serious challenges. In this paper, a new converter, which is able to realize such a large step-down conversion in a single step, is proposed by introducing a novel concept of dc–dc multiphase conversion and n-phase interleaving rectification. The proposed structure is formed by n switch pairs in the primary side, an n-phase isolation transformer with the primary windings connected to dc blocking capacitors, and an n-phase current multiplier in the output side. The switching patterns applied to the switch pairs have a phase difference of 360^\circ \mathord\left/ \vphantom 360^\circ n \right. \kern-\nulldelimiterspace n, and the output inductor currents are interleaved correspondingly, making necessary a smaller output filter. For a V_i input voltage and I_o load current, the converter features V_i/n voltage stress on the primary-side switches, and I_o/n current stress on the secondary-side inductors and diodes. Thus, the magnetic size of the inductors is considerable reduced. The primary-side switches are commutated with zero-voltage-switching (ZVS). Therefore, rather than using insulated-gate bipolar transistors (IGBTs) or MOSFETs with higher voltage ratings, the most available, notable performing 500/600 V MOSFETs can be used in the proposed converter with several kilovolts supply voltage, allowing for a higher operation frequency and lower conduction losses. Compared with an input-series–output-parallel (ISOP) connection of full-bridge (FB) isolated converters, for the same voltage stress on the switches, the proposed converter requires half of the number of transistors and inherently balances the input voltage among the switch pairs. The switching mechanism of a typical switch pair in the kth interval T_s/n of a switching cycle is analyzed. A dc analysis was carried out to determine the dc conversion ratio and the ZVS conditions in an analytical form. It allows for a tradeoff design of the converter, such that to minimize the duty-cycle loss and maximize the ZVS load range. A 1500/48-V, 2-kW prototype with four switch pairs was designed, implemented, and evaluated. The experimental results prove the soft switching of the switches, the low voltage stress across the primary-side switches, and the low current flowing through the rectifier's diodes and inductors. The efficiency measured at nominal power rating was 90.75%. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
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19. Computer-aided analysis of power electronic circuits by stepwise topological identification.
- Author
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Chung, Henry S. H., Tse, K. K., and Ioinovici, Adrian
- Subjects
- *
POWER electronics , *ELECTRONIC circuits , *SIMULATION methods & models , *TOPOLOGY , *ELECTRONICS - Abstract
A new approach for the time-domain simulation of power electronic circuits is developed. The methodology is based on stepwise identification of circuit topology. The simulation process automatically looks for a valid topology in every step. At each simulation instant, the circuit topology is transformed into a resistive network, giving another superior feature of this method: the avoidance of solving complicated s-domain or differential formulas. No small-signal approximation is assumed. Parasitic resistance of the reactive element is included in the circuit model. Several examples illustrating the generality and computational efficiency of this new method are presented. The simulated results are favourably verified with experimental measurements and available literature. © 1997 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]
- Published
- 1997
- Full Text
- View/download PDF
20. A Cascade Boost-Switched-Capacitor-Converter Two Level Inverter With an Optimized Multilevel Output Waveform.
- Author
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Axelrod, Boris, Berkovich, Yefim, and Ioinovici, Adrian
- Subjects
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SWITCHED capacitor circuits , *ELECTRIC inverters , *ELECTRIC current converters , *FOURIER analysis , *MATHEMATICAL analysis , *ELECTRONIC circuits - Abstract
Two structures, a switched-capacitor (SC)-based boost converter and a two-level inverter, are connected in cascade. The de multilevel voltage of the first stage becomes the input voltage of the classical inverter, resulting in a staircase waveform for the inverter output voltage. Such a multilevel waveform is close to a sinusoid; its harmonics content can be reduced by multiplying the stage number of the SC converter. The output low-pass filter, customary after a two-level inverter, becomes obsolete, resulting in a small size of the system, as the SC circuit can be miniaturized. Both stages are operated at a high switching frequency, resulting in a high-frequency inverter output, as required by some industrial applications. A Fourier analysis of the output waveform is performed. The design is optimized with reference to the nominal duty-cycle for obtaining the minimum total harmonic distortion. Simulations and experiments on two prototypes, one with a five-level output and one with a seven-level output, confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
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21. A Family of Zero-Voltage and Zero - Current- S witching (ZVZC S) Three - Level DC-DC Converters With Secondary-Assisted Regenerative Passive Snubber.
- Author
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TingTing Song, Huang, Nianci, and Ioinovici, Adrian
- Subjects
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DC-to-DC converters , *ELECTRIC potential , *TRANSISTORS , *ELECTRIC switchgear , *ELECTRIC current converters , *FORCE & energy - Abstract
A detailed analysis and optimized-oriented design of a family of three-level soft-switching converters is presented. The zero-voltage-switching (ZVS) of the outer switches and zero-cur- rent-switching (ZCS) of the inner switches is realized by employing a pulse-width-modulation (PWM) phase-shift control and a secondary-assisted passive snubber. The switching operation is discussed by comparing the results produced by the use of different passive snubbers (the author's original one and literature-available ones). The voltage on the rectifier diodes is clamped at a reasonable value, specific to each one of the six snubbers taken into consideration. The voltage stress on each transistor is reduced to half of the input voltage. Lower rated transistors and rectifier diodes can be used, thus reducing the conduction losses. Before turning on/off the inner switches, the snubber's capacitor voltage determines the fall of the primary current to zero, thus avoiding wasteful energy circulation and assuring ZCS. The snubber's energy is recuperated to the load. The outcome of these improvements is a high efficiency in energy processing. Soft-switching-oriented constraints on the converter parameters are expressed as implicit equations, whose graphical solution permits the optimized design of the parameters in order to ensure ZVZCS. A comparative analysis of the effective duty cycle and the boost effect of it, due to the use of the secondary snubber, is performed. The influence of the choices of the parameters values on the regulation capability is pointed out. Experimental results prove the expected high performances of the optimized converters. [ABSTRACT FROM AUTHOR]
- Published
- 2005
- Full Text
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22. A ZCS-PWM Voltage-Driven Three-Level Converter With a Secondary-Side Simple Soft-Switching Snubber.
- Author
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Yin, Zhijian, Hu, Jiefeng, Shu-hung Chung, Henry, and Ioinovici, Adrian
- Subjects
- *
PULSE width modulation transformers , *ZERO current switching , *ELECTRIC inductors , *ELECTRIC inductance , *CAPACITORS , *CAPACITOR banks - Abstract
A very simple, low component count snubber is used in order to get ZCS for all the switches of a three-level voltage step-down converter. ZCS allows for the implementation of the switches with insulated-gate bipolar transistor which are able to withstand large input voltages at large power. The snubber is placed in the secondary-side, before the rectifier. The transformer leakage inductance is used in the ZCS-purposed resonant process, eliminating thus the need for an additional resonant inductor. All the resonant circuit energy is recuperated to the load. No voltage stresses appear on the switches, and the current stress is limited in a tradeoff components design. The proposed solution allows for a boost of the effective duty cycle. As a result, the proposed converter operates with a high efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
23. Generation of a Family of Very High DC Gain Power Electronics Circuits Based on Switched-Capacitor-Inductor Cells Starting from a Simple Graph.
- Author
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Chen, Manxin, Li, Kerui, Hu, Jiefeng, and Ioinovici, Adrian
- Subjects
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ELECTRONIC circuits , *CAPACITORS , *SEMICONDUCTORS - Abstract
A simple graph with four nodes and eleven branches is defined. Its branches are filled in different ways with passive elements (capacitors, inductors, diodes) or replaced by shortcircuits in order to get potential voltage step-up switching cells. These cells are inserted in boost converter, obtaining thus non-isolated power electronics circuits with a very high dc gain. Such circuits are necessary today in the green energy systems. The proposed circuits feature a lower voltage stress on its semiconductors (both switch and diodes) than that on the equivalent devices of a boost stage. A state-space-based dc and ac analysis allows for deriving the dc gain, the switches voltage and current stresses, and the frequency characteristics of the obtained converters. The steady-state analysis is performed for both the continuous and discontinuous conduction mode operations. The converters belonging to the new family are compared between them and then compared with available solutions of similar complexity as defined by the component count. Simulation and experimental results confirm the theoretical equations. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
24. On Energy Efficiency of Switched-Capacitor Converters.
- Author
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Cheung, Chun-Kit, Tan, Siew-Chong, Tse, Chi K., and Ioinovici, Adrian
- Subjects
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ENERGY consumption , *SWITCHED capacitor circuits , *CASCADE converters , *METAL oxide semiconductor field-effect transistors , *ELECTRIC discharges , *ELECTRIC resistors , *ENERGY dissipation - Abstract
The energy-efficiency issue of switched-capacitor converters is still a controversial topic that requires a more in-depth discussion. In this paper, we address the issue by dividing the analysis of the entire efficiency problem into two parts. In the first part, the efficiency of a capacitor-charging RC circuit under different aspects (partial charging, full charging, at zero capacitor voltage, at nonzero capacitor voltage, etc.) will be conducted. The efficiency analysis of a capacitor-discharging RC circuit with a resistor, capacitor, and paralleled resistor–capacitor loads will be covered. A complete evaluation of the overall efficiency is then performed in terms of both the charging and discharging efficiencies. Based on the analysis, some design rules useful for developing high-efficiency switched-capacitor converters is suggested. Additionally, it is shown that the belief that quasi-switched-capacitor converters are more lossy than switched-capacitor converters is a common misconception. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
25. Adaptive Mixed On-Time and Switching Frequency Control of a System of Interleaved Switched-Capacitor Converters.
- Author
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Tan, Siew-Chong, Kiratipongvoot, Sitthisak, Bronstein, Svetlana, Ioinovici, Adrian, Lai, Y. M., and Tse, Chi K.
- Subjects
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SWITCHED capacitor circuits , *DC-to-DC converters , *ELECTRIC current converters , *VOLTAGE regulators , *ELECTRICAL load , *ELECTRIC transients , *ELECTROMAGNETIC interference , *ADAPTIVE control systems - Abstract
The switched-capacitor (SC) converters are ideal switching-mode power supplies for consumer portable electronic devices due to their nature of being light weight, small size, and high-power density. However, they suffer from a discontinuous input-current waveform with large di/dt, which leads to significant electromagnetic interference emission. This paper proposes a configuration of SC converters connected in parallel, with their inputs and outputs interleaved and adaptively controlled. The interleaving operation is performed by using an original type of control in which both the capacitors’ charging time TON and switching frequency are adjusted to get the line and load regulation. It is shown that, for a given range of variation of the supply voltage and load, there always exists a solution [TON, TS] that assures both output-voltage regulation and perfect interleaving. Experimental results are provided to validate the feasibility of the proposed scheme. Precise interleaving, and good line and load regulation are maintained for all the designated range, including the transient periods. [ABSTRACT FROM PUBLISHER]
- Published
- 2011
- Full Text
- View/download PDF
26. A ZCS Full-Bridge Converter Without Voltage Overstress on the Switches.
- Author
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Xin Zhang, Henry Shu-hung Chung, Xinbo Ruan, and Ioinovici, Adrian
- Subjects
- *
ELECTRONIC circuit design , *SYNCHRONOUS capacitors , *ELECTRIC circuits , *ELECTRIC switchgear , *SHOCK absorbers - Abstract
A new current-driven soft-switched full-bridge converter is presented in this paper. By connecting a switchedcapacitor snubber in parallel with the primary winding of the coupling transformer, all main switches are zero-current-switched (ZCS) and the switches in the snubber are zero-voltage-switched (ZVS). The proposed converter has the following key features. First, the transformer leakage inductance is utilized as a part of the resonant circuit for the soft-switching actions. Second, the snubber capacitor voltage is adaptively controlled: the capacitor is charged to the minimum necessary energy for switching the main switches at zero current, depending on the actual value of the input/load current. Thus, less resonant energy is circulated. Third, there is no extra voltage stress on the switches and the current through the switches is limited to the value of the input current. Consequently, the conduction losses are kept minimum. The cyclical switching operation and control of the converter are described. A tradeoff design of the snubber circuit is given: the requirement of reducing the duration of the resonant intervals for minimizing the dutycycle loss is superimposed on the requirement of getting ZCS for a very large range of the line voltage and load. A 530-V/15-kV, 5-kW prototype has been built and evaluated. The experimental results confirmed the theoretical predictions. A comparative study on the converter efficiency with and without the proposed snubber circuit is given, showing the superiority of the proposed solution. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
27. A ZCS Current-Fed Full-Bridge PWM Converter With Self-Adaptable Soft-Switching Snubber Energy.
- Author
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Huai Wang, Qian Sun, Henry Shu Hung Chung, Tapuchi, Saad, and Ioinovici, Adrian
- Subjects
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PULSE width modulation , *ELECTRIC current converters , *SWITCHING circuits , *ELECTRONIC circuits , *ELECTRIC circuits , *PULSE modulation , *POWER electronics - Abstract
A new soft-switched, current-driven full-bridge converter is presented. The structure utilizes a simple snubber formed by two unidirectional switches and a capacitor to realize soft-switching operation over a wide line and load range. All primary-side switches are operated with zero-current switching (ZCS) and the snubber switches are operated with zero-voltage switching. The energy used for soft-switching is self-adaptable. For a given input current, the snubber capacitor is charged to the minimum required energy for ZCS of the switches. Thus, less resonant energy is used and the conduction loss can be kept minimal. The cyclical switching operation and control of the converter will be discussed. By compromising the voltage stress on the switches and loss of duty cycle (i.e., the regulation range), an optimized design procedure of the circuit elements is derived. The input voltage range and load variation that ensure both output voltage regulation and soft switching are determined. By studying the small-signal characteristics of the entire system, a current-controlled feedback control circuit has been implemented with a DSP. The experimental results measured on a 5-kW, 530-V/15-kV prototype confirms the advantages of the proposed converter. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
28. Step-Up Switching-Mode Converter With High Voltage Gain Using a Switched-Capacitor Circuit.
- Author
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Abutbul, Oded, Gherlitz, Amir, Berkovich, Yefim, and Ioinovici, Adrian
- Subjects
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SWITCHED capacitor circuits , *ELECTRIC current converters - Abstract
A new circuit is proposed for a steep step-up of the line voltage. It integrates a switched-capacitor (SC) circuit within a boost converter. An SC circuit can achieve any voltage ratio, allowing for a boost of the input voltage to high values. It is unregulated to allow for a very high efficiency. The boost stage has a regulation purpose. It can operate at a relatively low duty cycle, thus avoiding diode-reverse recovery problems. The new circuit is not a cascade interconnection of the two power stages; their operation is integrated. The simplicity and robustness of the solution, the possibility of getting higher voltage ratios than cascading boost converters, without using transformers with all their problems, and the good overall efficiency are the benefits of the proposed converter. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
29. Model predictive control of microgrids – An overview.
- Author
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Hu, Jiefeng, Shan, Yinghao, Guerrero, Josep M., Ioinovici, Adrian, Chan, Ka Wing, and Rodriguez, Jose
- Subjects
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PREDICTION models , *MICROGRIDS , *CASCADE converters - Abstract
The development of microgrids is an advantageous option for integrating rapidly growing renewable energies. However, the stochastic nature of renewable energies and variable power demand have created many challenges like unstable voltage/frequency and complicated power management and interaction with the utility grid. Recently, predictive control with its fast transient response and flexibility to accommodate different constraints has presented huge potentials in microgrid applications. This paper provides a comprehensive review of model predictive control (MPC) in individual and interconnected microgrids, including both converter-level and grid-level control strategies applied to three layers of the hierarchical control architecture. This survey shows that MPC is at the beginning of the application in microgrids and that it emerges as a competitive alternative to conventional methods in voltage regulation, frequency control, power flow management and economic operation optimization. Also, some of the most important trends in MPC development have been highlighted and discussed as future perspectives. • A comprehensive review of model predictive control (MPC) in microgrids, including both converter-level and grid-level control strategies applied to three layers of microgrid hierarchical architecture. • Illustrating MPC is at the beginning of the application to microgrids and it emerges as a competitive alternative to conventional methods. • Some of the most important trends in MPC development have been highlighted and discussed as future perspectives. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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