Yefim Berkovich - Academia.edu (original) (raw)

Papers by Yefim Berkovich

IEE Proceedings - Electric Power Applications, 2004

A new single switch parallel resonant converter for induction heating is proposed in this work. T... more A new single switch parallel resonant converter for induction heating is proposed in this work. The switch operates in a soft commutation mode with high switching frequency. The switch (MOSFET) is operating at KHz and ZVS is also achieved. Single switch AC-AC converter system is simulated using MATLAB and the results are presented. From the simulation results, it, is observed that the single switch AC-AC converter system produces higher heat when compared to the conventional inverter system and reduced switching losses. The proposed technique can be used for joining of metals, heating and material testing.

2008 11th Workshop on Control and Modeling for Power Electronics, 2008

ABSTRACT A new scheme of a diode-capacitor network, used as a DC voltage multiplier is proposed. ... more ABSTRACT A new scheme of a diode-capacitor network, used as a DC voltage multiplier is proposed. The circuit operates in combination with a high-frequency switch. In contrast to the present similar circuits, during the operational process the capacitors are not shortened by the switch and therefore the large discharge current stresses donpsilat influence the circuit. The circuit provides the multiplication of the input voltage having a smooth (very small ripples) input current and output voltage. The advantages of the proposed circuit make it very appropriate for use with alternative sources of energy. SPICE-simulation and the experimental results confirm the theoretical expectations.

2006 IEEE 24th Convention of Electrical & Electronics Engineers in Israel, 2006

The algebraic representation of idealized DC-DC PWM converters covering various structures and th... more The algebraic representation of idealized DC-DC PWM converters covering various structures and their connection is given. The algebra is constructed on the basis of hyper-complex numbershypernions and allows the analysis of the structures of the converters by using of a symbolical method. The possibility of the calculation of a discontinuous current and soft switching is also considered. Such an abstract description of various schemas allows reducing their variety to several basic structures and formalizes a problem of the synthesis of the converters with the desired parameters. The numerical solution of the algebraic expressions is easily carried out with the help of the standard mathematical programs MATHCAD or MATLAB.

2006 IEEE International Symposium on Circuits and Systems

ABSTRACT Three basic switching structures are defined: one is formed by two capacitors and three ... more ABSTRACT Three basic switching structures are defined: one is formed by two capacitors and three diodes; the other two are formed by two inductors and two diodes. They are inserted in either a Cuk converter, or a Sepic, or a Zeta converter. The SC/SL structures are built in such a way as when the active switch of the converter is on, the two inductors are charged in series or the two capacitors are discharged in parallel. When the active switch is off, the two inductors are discharged in parallel or the two capacitors are charged in series. As a result, the line voltage is reduced more times than in classical Cuk/Sepic/Zeta converters. The steady-state analysis of the new converters, a comparison of the DC voltage gain and of the voltage and current stresses of the new hybrid converters with those of the available quadratic converters, and experimental results are given

2008 10th IEEE International Workshop on Advanced Motion Control, 2008

ABSTRACT A novel four-quadrant bi-directional drive system for a DC motor based on PWM DC-DC conv... more ABSTRACT A novel four-quadrant bi-directional drive system for a DC motor based on PWM DC-DC converter is presented. The converter provides both a positive and negative output voltage, which is supplied to the splitted armature circuit of the DC motor. The converter offers both the motoring and regenerative braking mode of operation. SPICE simulation and the experimental verification of the proposed system prove the ability and the advantages of the new solution.

2002 IEEE International Symposium on Circuits and Systems. Proceedings (Cat. No.02CH37353)

ABSTRACT Following a unitary procedure, a large-signal stability-oriented design is performed for... more ABSTRACT Following a unitary procedure, a large-signal stability-oriented design is performed for basic buck, boost and buck-boost converters. Exact nonlinear equations describing the transient state of these converters are written. Positive-definite Lyapunov functions for each converter are defined. Applying the Lyapunov stability theorem, constraints on the parameters of the feedback circuit are derived for ensuring the negativity of each of derivatives of the Lyapunov functions along the converter's differential equations. Computer simulation and laboratory experiments confirmed that the designs that respected the above constraints were stable even for large-signal perturbations.

2008 IEEE Power Electronics Specialists Conference, 2008

ABSTRACT By replacing the input inductor of the Cuk (respectively Sepic, and Zeta) converter with... more ABSTRACT By replacing the input inductor of the Cuk (respectively Sepic, and Zeta) converter with a cell formed by a coupled inductor and one diode, a new family of converters with high voltage ratio is obtained. The energy accumulated in the leakage inductance is transferred to the load. The voltage stresses across the switching elements are kept at a moderate value. The reverse-recovery problem of the rectifier diode is alleviated. A DC analysis allows for the formulation of the DC gain as a function of the turns ratio and coupling coefficient of the coupled inductor, as well of the load. Experimental results confirm the theoretical expectations.

An equivalent dynamic model of a ZVT boost-converter previously published by the authors is the s... more An equivalent dynamic model of a ZVT boost-converter previously published by the authors is the subject of present paper. The model contains an equivalent current source and an equivalent voltage source whose nonlinear functions take different forms for each switching topology. The model serves for an AC small-signal analysis. The small-signal open-loop and closed-loop transfer functions, including the audio susceptibility are derived. Design-oriented stability criteria are formulated. The theoretical time-domain response and Bode characteristics are checked by experiments or PSPICE simulation

A new version of an AC-AC converter circuit for induction heating has been presented and analyzed... more A new version of an AC-AC converter circuit for induction heating has been presented and analyzed. The basic features of the proposed circuit are as follows: the converter input current is practically sinusoidal and its power factor is close to unity; the output current does not include DC-component and thus it prevents additional losses and eliminates the possibility of the installation of the separating transformer; the circuit topology is very simple and includes only one power switch, which operates in a soft commutation regime; and the converter provides a wide range power control (0.3-1). The computer simulation and the experimental results demonstrate the actual capability and successful performance of the proposed converter.

IET Power Electronics, 2015

In this study a new scheme of a step-up converter with very high voltage gain is proposed. The sc... more In this study a new scheme of a step-up converter with very high voltage gain is proposed. The scheme is based on a natural combination of the switched-coupled-inductor boost converter and the diode-capacitor multiplier. The study proposes a special scheme of their mutual use for attaining very high voltage gain. An important advantage of the proposed circuit is the avoidance of the current spikes through the transistor and diodes because of the leakage inductance of the coupled inductors. The scheme provides soft commutation of the switch and the diodes. The study analyses the modes of operation and obtains the basic fundamental relations in steady state; an expression for voltage stress across the switch is derived. A new method for dynamic analysis is proposed. The corresponding analytical expressions and curves of the transient behaviour are also obtained. Modelling of the proposed structure and the experimental results are in full agreement regarding the expected efficiency and correctness of the theoretical analysis. A 100 W laboratory prototype was built and verified.

SPEEDAM 2010, 2010

ABSTRACT By replacing the input input inductor of buck converter with a cell formed by a coupled ... more ABSTRACT By replacing the input input inductor of buck converter with a cell formed by a coupled inductor and one diode, a new converter with low voltage ratio is obtained. The energy accumulated in the leakage inductance is transferred in a non-oscillatory manner to the load, thus avoiding a voltage overstress across the transistor. The DC gain expression and experimental results show its dependency on the coupling coefficient of the coupled inductor k, the turns ratio n, and the load.

2003 IEEE Bologna Power Tech Conference Proceedings,

ABSTRACT This paper presents a transformerless ac-dc and or dc-dc converter with a high output vo... more ABSTRACT This paper presents a transformerless ac-dc and or dc-dc converter with a high output voltage multiplicity, which contains only one switch. The converter consists of the inverter and diode-capacitor multiplier (DCM), which provides the voltage gain equal to the double number of the multiplier steps. In the case of the ac-dc conversion the proposed converter offers practically unit power factor and provides a sine wave input current. The analysis of the steady state as well as the transient behavior of the DCM is given and a simplified equivalent circuit is proposed. The prototype of the DCM has been built and tested to show the validity of the proposed converter. The theoretical analysis, the computer simulation results and the experimental testing results are in good agreement.

2005 IEEE International Symposium on Circuits and Systems

ABSTRACT The energy-transfer-capacitor in basic Cuk, Zeta and Sepic converters is split into two ... more ABSTRACT The energy-transfer-capacitor in basic Cuk, Zeta and Sepic converters is split into two capacitors. The rectifier diode is replaced by two diodes that form with the two capacitors a switched-capacitor circuit, which appears connected between the input and output inductances of the original converter. As a result, hybrid circuits, presenting a higher DC voltage ratio than the classical Cuk, Zeta and Sepic converters, are obtained. Even if the new hybrid structures do not reach the DC gain of quadratic converters, they present a higher efficiency in processing the energy: unlike the cascaded converters whose efficiency is a product of the efficiencies of each block, the hybrid converters do not require an additional level of energy processing. A DC analysis, simulation and experimental results concerning the proposed circuits are presented.

IET Power Electronics, 2015

The study provides improved modifications of the positive output super-lift Luo converter that al... more The study provides improved modifications of the positive output super-lift Luo converter that allows significantly increase the voltage transfer gain by the modest means. In the simplest case this increase is provided by replacing the inductor by the switched-inductor structure consisting of two inductors and three diodes. This allows getting practically double increase in the line-to-output voltage ratio at the high values of duty cycle. Analysis of steady-state and transient conditions shows that the zeros of the transfer function for the converter, as well as for the conventional boost converter, are positive. The study indicates possible ways to further increase the output voltage ratio without additional switchesby the use of magnetically coupled inductors and diode-capacitor voltage multipliers. Simulation and experimental results confirm the theoretical analysis and the advantages of the proposed converters.

Journal of Circuits, Systems and Computers, 2004

A method of using hypercomplex numbers for the analysis of linear electric circuits with nonsinus... more A method of using hypercomplex numbers for the analysis of linear electric circuits with nonsinusoidal voltages and currents has been proposed. Similar to the complex number method for circuits with sinusoidal voltages and currents, the proposed method reduces the analysis of nonsinusoidal circuits to the analysis of direct-current circuits. A special system of hypercomplex numbers, called hypernions, has been created in order to obtain a new efficient method for analyzing nonsinusoidal networks. This system is interesting in that it expands the concept of numbers and attaches meaning to equations and transformations involving discontinuous functions and makes it possible to describe various non-Euclidean spaces. It is shown that the proposed method of analysis of linear nonsinusoidal electric networks makes it possible to carry out numerical calculations for complex circuits by using standard software.

IET Power Electronics, 2008

New single-switch structures of single-and three-phase transformerless controlled rectifiers are ... more New single-switch structures of single-and three-phase transformerless controlled rectifiers are proposed and analysed. These structures consist of a common rectifier, an input inductor filter, a high-frequency operated switch and a diode-capacitor ladder network. The latter, in its known application as a multiplier, is used for increasing the input voltage. A new scheme of a diode-capacitor network, which can be used as a divider to reduce the input voltage, is also proposed. The detailed analysis of the steady-state mode is performed and simple formulas for the calculation of step-up and step-down rates of the voltage are derived. Transient analysis of the proposed circuits, by solving the recurrent equations and by using the z-transform, is also performed. Since the proposed schemes do not consist of any transformers and/or any inverters, their operation is very efficient; no high harmonics and/or a DC component are produced, and so the input current and voltage waveform are close to the sinusoid. The power factor of such structures reaches unity and their weight is low, compared with those having a transformer. A laboratory model of one of the proposed structures has been built and tested. The experimental results confirm the converters efficiency and the correctness of the theoretical analysis.

IEE Proceedings - Electric Power Applications, 2004

In this paper the dynamic analysis of the open-and closed-loop systems of a new singleswitch AC-A... more In this paper the dynamic analysis of the open-and closed-loop systems of a new singleswitch AC-AC frequency converter is presented. The main advantages of the proposed converter are that it provides a sine wave input current and a close to unit power factor. The converter circuit dynamic analysis is performed in small-signal quantities. The analytical expressions of the transfer function of the open and closed-loop systems with the integrator regulator are obtained. The results of the theoretical analysis were checked on the PSPICE-model and on the laboratory prototype and they are in good agreement with the experiments.

IEE Proceedings - Electric Power Applications, 2001

A new single-switch parallel resonant converter for induction heating is introduced. The circuit ... more A new single-switch parallel resonant converter for induction heating is introduced. The circuit consists of an input LC filter, bridge rectifier and one controlled power switch. The switch operates in a soft commutation mode and serves as a high-frequency generator. Output power is controlled via a switching frequency. Steady-state analysis of the converter operation is presented. Theoretical analysis, computer simulation and experimental results are in good agreement.

IEE Proceedings - Electric Power Applications, 2006

ABSTRACT A novel pulse-current converter topology for induction heating is introduced. The possib... more ABSTRACT A novel pulse-current converter topology for induction heating is introduced. The possibility and expediency of the pulse current for induction heating have been demonstrated. The converter comprises the input filter, input reactor, bridge rectifier, two power switches, two coils mutually coupled with the input reactor and the heating inductor (load), where the output power is controlled by a switching frequency. The steady-state analysis of the converter operation, its computer simulation and the experimental verifications on the converter model have been performed. The simulation on the computer and the experimental results are shown to be in good agreement with the theoretical results. The following two goals have been achieved: (a) the analysis of the heating process with the pulse current has been performed; and (b) the appropriate scheme of the pulse-current supply has been developed. The proposed scheme fulfills the requirements of modern power supplies: sine form of the input current, unity power factor, soft commutation and a wide range of output power. The proposed configuration can be used for heating, annealing, melting and hardening in the power range of 250-300 kW

IEE Proceedings - Electric Power Applications, 2002

ABSTRACT An invariant control system of PWM (pulse-width modulation) converters is discussed. Suc... more ABSTRACT An invariant control system of PWM (pulse-width modulation) converters is discussed. Such a system ensures the stabilisation of the output quantities (such as voltage, current or a certain time interval) even in open control systems. This control system is obtained by using the carrier voltage with a more complicated form than a simple linear (triangular) form that is usually used in common PWM systems. In the systems discussed here, the carrier voltage follows the form or characteristic of the output quantity, having a mathematical expression, which is similar to those of the output quantity. For this reason the authors call this kind of regulation a mathematical similarity. The general approach of creation of such a carrier voltage and its application in such invariant regulation systems is formulated. Examples of specific invariant PWM systems for a control rectifier, a DC DC converter in continuous and discontinuous operating mode, the power factor corrector and the resonant inverter are given.

IEE Proceedings - Electric Power Applications, 2004

A new single switch parallel resonant converter for induction heating is proposed in this work. T... more A new single switch parallel resonant converter for induction heating is proposed in this work. The switch operates in a soft commutation mode with high switching frequency. The switch (MOSFET) is operating at KHz and ZVS is also achieved. Single switch AC-AC converter system is simulated using MATLAB and the results are presented. From the simulation results, it, is observed that the single switch AC-AC converter system produces higher heat when compared to the conventional inverter system and reduced switching losses. The proposed technique can be used for joining of metals, heating and material testing.

2008 11th Workshop on Control and Modeling for Power Electronics, 2008

ABSTRACT A new scheme of a diode-capacitor network, used as a DC voltage multiplier is proposed. ... more ABSTRACT A new scheme of a diode-capacitor network, used as a DC voltage multiplier is proposed. The circuit operates in combination with a high-frequency switch. In contrast to the present similar circuits, during the operational process the capacitors are not shortened by the switch and therefore the large discharge current stresses donpsilat influence the circuit. The circuit provides the multiplication of the input voltage having a smooth (very small ripples) input current and output voltage. The advantages of the proposed circuit make it very appropriate for use with alternative sources of energy. SPICE-simulation and the experimental results confirm the theoretical expectations.

2006 IEEE 24th Convention of Electrical & Electronics Engineers in Israel, 2006

The algebraic representation of idealized DC-DC PWM converters covering various structures and th... more The algebraic representation of idealized DC-DC PWM converters covering various structures and their connection is given. The algebra is constructed on the basis of hyper-complex numbershypernions and allows the analysis of the structures of the converters by using of a symbolical method. The possibility of the calculation of a discontinuous current and soft switching is also considered. Such an abstract description of various schemas allows reducing their variety to several basic structures and formalizes a problem of the synthesis of the converters with the desired parameters. The numerical solution of the algebraic expressions is easily carried out with the help of the standard mathematical programs MATHCAD or MATLAB.

2006 IEEE International Symposium on Circuits and Systems

ABSTRACT Three basic switching structures are defined: one is formed by two capacitors and three ... more ABSTRACT Three basic switching structures are defined: one is formed by two capacitors and three diodes; the other two are formed by two inductors and two diodes. They are inserted in either a Cuk converter, or a Sepic, or a Zeta converter. The SC/SL structures are built in such a way as when the active switch of the converter is on, the two inductors are charged in series or the two capacitors are discharged in parallel. When the active switch is off, the two inductors are discharged in parallel or the two capacitors are charged in series. As a result, the line voltage is reduced more times than in classical Cuk/Sepic/Zeta converters. The steady-state analysis of the new converters, a comparison of the DC voltage gain and of the voltage and current stresses of the new hybrid converters with those of the available quadratic converters, and experimental results are given

2008 10th IEEE International Workshop on Advanced Motion Control, 2008

ABSTRACT A novel four-quadrant bi-directional drive system for a DC motor based on PWM DC-DC conv... more ABSTRACT A novel four-quadrant bi-directional drive system for a DC motor based on PWM DC-DC converter is presented. The converter provides both a positive and negative output voltage, which is supplied to the splitted armature circuit of the DC motor. The converter offers both the motoring and regenerative braking mode of operation. SPICE simulation and the experimental verification of the proposed system prove the ability and the advantages of the new solution.

2002 IEEE International Symposium on Circuits and Systems. Proceedings (Cat. No.02CH37353)

ABSTRACT Following a unitary procedure, a large-signal stability-oriented design is performed for... more ABSTRACT Following a unitary procedure, a large-signal stability-oriented design is performed for basic buck, boost and buck-boost converters. Exact nonlinear equations describing the transient state of these converters are written. Positive-definite Lyapunov functions for each converter are defined. Applying the Lyapunov stability theorem, constraints on the parameters of the feedback circuit are derived for ensuring the negativity of each of derivatives of the Lyapunov functions along the converter's differential equations. Computer simulation and laboratory experiments confirmed that the designs that respected the above constraints were stable even for large-signal perturbations.

2008 IEEE Power Electronics Specialists Conference, 2008

ABSTRACT By replacing the input inductor of the Cuk (respectively Sepic, and Zeta) converter with... more ABSTRACT By replacing the input inductor of the Cuk (respectively Sepic, and Zeta) converter with a cell formed by a coupled inductor and one diode, a new family of converters with high voltage ratio is obtained. The energy accumulated in the leakage inductance is transferred to the load. The voltage stresses across the switching elements are kept at a moderate value. The reverse-recovery problem of the rectifier diode is alleviated. A DC analysis allows for the formulation of the DC gain as a function of the turns ratio and coupling coefficient of the coupled inductor, as well of the load. Experimental results confirm the theoretical expectations.

An equivalent dynamic model of a ZVT boost-converter previously published by the authors is the s... more An equivalent dynamic model of a ZVT boost-converter previously published by the authors is the subject of present paper. The model contains an equivalent current source and an equivalent voltage source whose nonlinear functions take different forms for each switching topology. The model serves for an AC small-signal analysis. The small-signal open-loop and closed-loop transfer functions, including the audio susceptibility are derived. Design-oriented stability criteria are formulated. The theoretical time-domain response and Bode characteristics are checked by experiments or PSPICE simulation

A new version of an AC-AC converter circuit for induction heating has been presented and analyzed... more A new version of an AC-AC converter circuit for induction heating has been presented and analyzed. The basic features of the proposed circuit are as follows: the converter input current is practically sinusoidal and its power factor is close to unity; the output current does not include DC-component and thus it prevents additional losses and eliminates the possibility of the installation of the separating transformer; the circuit topology is very simple and includes only one power switch, which operates in a soft commutation regime; and the converter provides a wide range power control (0.3-1). The computer simulation and the experimental results demonstrate the actual capability and successful performance of the proposed converter.

IET Power Electronics, 2015

In this study a new scheme of a step-up converter with very high voltage gain is proposed. The sc... more In this study a new scheme of a step-up converter with very high voltage gain is proposed. The scheme is based on a natural combination of the switched-coupled-inductor boost converter and the diode-capacitor multiplier. The study proposes a special scheme of their mutual use for attaining very high voltage gain. An important advantage of the proposed circuit is the avoidance of the current spikes through the transistor and diodes because of the leakage inductance of the coupled inductors. The scheme provides soft commutation of the switch and the diodes. The study analyses the modes of operation and obtains the basic fundamental relations in steady state; an expression for voltage stress across the switch is derived. A new method for dynamic analysis is proposed. The corresponding analytical expressions and curves of the transient behaviour are also obtained. Modelling of the proposed structure and the experimental results are in full agreement regarding the expected efficiency and correctness of the theoretical analysis. A 100 W laboratory prototype was built and verified.

SPEEDAM 2010, 2010

ABSTRACT By replacing the input input inductor of buck converter with a cell formed by a coupled ... more ABSTRACT By replacing the input input inductor of buck converter with a cell formed by a coupled inductor and one diode, a new converter with low voltage ratio is obtained. The energy accumulated in the leakage inductance is transferred in a non-oscillatory manner to the load, thus avoiding a voltage overstress across the transistor. The DC gain expression and experimental results show its dependency on the coupling coefficient of the coupled inductor k, the turns ratio n, and the load.

2003 IEEE Bologna Power Tech Conference Proceedings,

ABSTRACT This paper presents a transformerless ac-dc and or dc-dc converter with a high output vo... more ABSTRACT This paper presents a transformerless ac-dc and or dc-dc converter with a high output voltage multiplicity, which contains only one switch. The converter consists of the inverter and diode-capacitor multiplier (DCM), which provides the voltage gain equal to the double number of the multiplier steps. In the case of the ac-dc conversion the proposed converter offers practically unit power factor and provides a sine wave input current. The analysis of the steady state as well as the transient behavior of the DCM is given and a simplified equivalent circuit is proposed. The prototype of the DCM has been built and tested to show the validity of the proposed converter. The theoretical analysis, the computer simulation results and the experimental testing results are in good agreement.

2005 IEEE International Symposium on Circuits and Systems

ABSTRACT The energy-transfer-capacitor in basic Cuk, Zeta and Sepic converters is split into two ... more ABSTRACT The energy-transfer-capacitor in basic Cuk, Zeta and Sepic converters is split into two capacitors. The rectifier diode is replaced by two diodes that form with the two capacitors a switched-capacitor circuit, which appears connected between the input and output inductances of the original converter. As a result, hybrid circuits, presenting a higher DC voltage ratio than the classical Cuk, Zeta and Sepic converters, are obtained. Even if the new hybrid structures do not reach the DC gain of quadratic converters, they present a higher efficiency in processing the energy: unlike the cascaded converters whose efficiency is a product of the efficiencies of each block, the hybrid converters do not require an additional level of energy processing. A DC analysis, simulation and experimental results concerning the proposed circuits are presented.

IET Power Electronics, 2015

The study provides improved modifications of the positive output super-lift Luo converter that al... more The study provides improved modifications of the positive output super-lift Luo converter that allows significantly increase the voltage transfer gain by the modest means. In the simplest case this increase is provided by replacing the inductor by the switched-inductor structure consisting of two inductors and three diodes. This allows getting practically double increase in the line-to-output voltage ratio at the high values of duty cycle. Analysis of steady-state and transient conditions shows that the zeros of the transfer function for the converter, as well as for the conventional boost converter, are positive. The study indicates possible ways to further increase the output voltage ratio without additional switchesby the use of magnetically coupled inductors and diode-capacitor voltage multipliers. Simulation and experimental results confirm the theoretical analysis and the advantages of the proposed converters.

Journal of Circuits, Systems and Computers, 2004

A method of using hypercomplex numbers for the analysis of linear electric circuits with nonsinus... more A method of using hypercomplex numbers for the analysis of linear electric circuits with nonsinusoidal voltages and currents has been proposed. Similar to the complex number method for circuits with sinusoidal voltages and currents, the proposed method reduces the analysis of nonsinusoidal circuits to the analysis of direct-current circuits. A special system of hypercomplex numbers, called hypernions, has been created in order to obtain a new efficient method for analyzing nonsinusoidal networks. This system is interesting in that it expands the concept of numbers and attaches meaning to equations and transformations involving discontinuous functions and makes it possible to describe various non-Euclidean spaces. It is shown that the proposed method of analysis of linear nonsinusoidal electric networks makes it possible to carry out numerical calculations for complex circuits by using standard software.

IET Power Electronics, 2008

New single-switch structures of single-and three-phase transformerless controlled rectifiers are ... more New single-switch structures of single-and three-phase transformerless controlled rectifiers are proposed and analysed. These structures consist of a common rectifier, an input inductor filter, a high-frequency operated switch and a diode-capacitor ladder network. The latter, in its known application as a multiplier, is used for increasing the input voltage. A new scheme of a diode-capacitor network, which can be used as a divider to reduce the input voltage, is also proposed. The detailed analysis of the steady-state mode is performed and simple formulas for the calculation of step-up and step-down rates of the voltage are derived. Transient analysis of the proposed circuits, by solving the recurrent equations and by using the z-transform, is also performed. Since the proposed schemes do not consist of any transformers and/or any inverters, their operation is very efficient; no high harmonics and/or a DC component are produced, and so the input current and voltage waveform are close to the sinusoid. The power factor of such structures reaches unity and their weight is low, compared with those having a transformer. A laboratory model of one of the proposed structures has been built and tested. The experimental results confirm the converters efficiency and the correctness of the theoretical analysis.

IEE Proceedings - Electric Power Applications, 2004

In this paper the dynamic analysis of the open-and closed-loop systems of a new singleswitch AC-A... more In this paper the dynamic analysis of the open-and closed-loop systems of a new singleswitch AC-AC frequency converter is presented. The main advantages of the proposed converter are that it provides a sine wave input current and a close to unit power factor. The converter circuit dynamic analysis is performed in small-signal quantities. The analytical expressions of the transfer function of the open and closed-loop systems with the integrator regulator are obtained. The results of the theoretical analysis were checked on the PSPICE-model and on the laboratory prototype and they are in good agreement with the experiments.

IEE Proceedings - Electric Power Applications, 2001

A new single-switch parallel resonant converter for induction heating is introduced. The circuit ... more A new single-switch parallel resonant converter for induction heating is introduced. The circuit consists of an input LC filter, bridge rectifier and one controlled power switch. The switch operates in a soft commutation mode and serves as a high-frequency generator. Output power is controlled via a switching frequency. Steady-state analysis of the converter operation is presented. Theoretical analysis, computer simulation and experimental results are in good agreement.

IEE Proceedings - Electric Power Applications, 2006

ABSTRACT A novel pulse-current converter topology for induction heating is introduced. The possib... more ABSTRACT A novel pulse-current converter topology for induction heating is introduced. The possibility and expediency of the pulse current for induction heating have been demonstrated. The converter comprises the input filter, input reactor, bridge rectifier, two power switches, two coils mutually coupled with the input reactor and the heating inductor (load), where the output power is controlled by a switching frequency. The steady-state analysis of the converter operation, its computer simulation and the experimental verifications on the converter model have been performed. The simulation on the computer and the experimental results are shown to be in good agreement with the theoretical results. The following two goals have been achieved: (a) the analysis of the heating process with the pulse current has been performed; and (b) the appropriate scheme of the pulse-current supply has been developed. The proposed scheme fulfills the requirements of modern power supplies: sine form of the input current, unity power factor, soft commutation and a wide range of output power. The proposed configuration can be used for heating, annealing, melting and hardening in the power range of 250-300 kW

IEE Proceedings - Electric Power Applications, 2002

ABSTRACT An invariant control system of PWM (pulse-width modulation) converters is discussed. Suc... more ABSTRACT An invariant control system of PWM (pulse-width modulation) converters is discussed. Such a system ensures the stabilisation of the output quantities (such as voltage, current or a certain time interval) even in open control systems. This control system is obtained by using the carrier voltage with a more complicated form than a simple linear (triangular) form that is usually used in common PWM systems. In the systems discussed here, the carrier voltage follows the form or characteristic of the output quantity, having a mathematical expression, which is similar to those of the output quantity. For this reason the authors call this kind of regulation a mathematical similarity. The general approach of creation of such a carrier voltage and its application in such invariant regulation systems is formulated. Examples of specific invariant PWM systems for a control rectifier, a DC DC converter in continuous and discontinuous operating mode, the power factor corrector and the resonant inverter are given.