Showing papers on "Flyback converter published in 2008"

Pulse-width modulated DC-DC power converters

Abstract: Preface. About the Author. List of Symbols. 1 Introduction. 1.1 Classification of Power Supplies. 1.2 Basic Functions of Voltage Regulators. 1.3 Power Relationships in DC-DC Converters. 1.4 DC Transfer Functions of DC-DC Converters. 1.5 Static Characteristics of DC Voltage Regulators. 1.6 Dynamic Characteristics of DC Voltage Regulators. 1.7 Linear Voltage Regulators. 1.8 Topologies of PWM DC-DC Converters 1.9 Relationships among Current, Voltage, Energy, and Power. 1.10 Electromagnetic Compatibility. 1.11 Summary. 1.12 References. 1.13 Review Questions. 1.14 Problems. 2 BuckPWMDC-DCConverter. 2.1 Introduction. 2.2 DC Analysis of PWM Buck Converter for CCM. 2.3 DC Analysis of PWM Buck Converter for DCM. 2.4 Buck Converter with Input Filter. 2.5 Buck Converter with Synchronous Rectifier. 2.6 Buck Converter with Positive Common Rail. 2.7 Tapped-Inductor Buck Converters. 2.8 Multiphase Buck Converter. 2.9 Summary. 2.10 References. 2.11 Review Questions. 2.12 Problems. 3 Boost PWM DC-DC Converter. 3.1 Introduction. 3.2 DC Analysis of PWM Boost Converter for CCM. 3.3 DC Analysis of PWM Boost Converter for DCM. 3.4 Bidirectional Buck and Boost Converters. 3.5 Tapped-Inductor Boost Converters. 3.6 Duality. 3.7 Power Factor Correction. 3.8 Summary. 3.9 References. 3.10 Review Questions. 3.11 Problems. 4 Buck-Boost PWM DC-DC Converter. 4.1 Introduction. 4.2 DC Analysis of PWM Buck-Boost Converter for CCM. 4.3 DC Analysis of PWM Buck-Boost Converter for DCM. 4.4 Bidirectional Buck-Boost Converter. 4.5 Synthesis of Buck-Boost Converter. 4.6 Synthesis of Boost-Buck (Cuk) Converter. 4.7 Noninverting Buck-Boost Converters. 4.8 Tapped-Inductor Buck-Boost Converters. 4.9 Summary. 4.10 References. 4.11 Review Questions. 4.12 Problems. 5 Flyback PWM DC-DC Converter. 5.1 Introduction. 5.2 Transformers. 5.3 DC Analysis of PWM Flyback Converter for CCM. 5.4 DC Analysis of PWM Flyback Converter for DCM. 5.5 Multiple-Output Flyback Converter. 5.6 Bidirectional Flyback Converter. 5.7 Ringing in Flyback Converter. 5.8 Flyback Converter with Active Clamping. 5.9 Two-Transistor Flyback Converter. 5.10 Summary. 5.11 References. 5.12 Review Questions. 5.13 Problems. 6 Forward PWM DC-DC Converter. 6.1 Introduction. 6.2 DC Analysis of PWM Forward Converter for CCM. 6.3 DC Analysis of PWM Forward Converter for DCM. 6.4 Multiple-Output Forward Converter. 6.5 Forward Converter with Synchronous Rectifier. 6.6 Forward Converters with Active Clamping. 6.7 Two-Switch Forward Converter. 6.8 Summary. 6.9 References. 6.10 Review Questions. 6.11 Problems. 7 Half-Bridge PWM DC-DC Converter. 7.1 Introduction. 7.2 DC Analysis of PWM Half-Bridge Converter for CCM. 7.3 DC Analysis of PWM Half-Bridge Converter for DCM. 7.4 Summary. 7.5 References. 7.6 Review Questions. 7.7 Problems. 8 Full-Bridge PWM DC-DC Converter. 8.1 Introduction. 8.2 DC Analysis of PWM Full-Bridge Converter for CCM. 8.3 DC Analysis of PWM Full-Bridge Converter for DCM. 8.4 Phase-Controlled Full-Bridge Converter. 8.5 Summary. 8.6 References. 8.7 Review Questions. 8.8 Problems. 9 Push-Pull PWM DC-DC Converter. 9.1 Introduction. 9.2 DC Analysis of PWM Push-Pull Converter for CCM. 9.3 DC Analysis of PWM Push-Pull Converter for DCM. 9.4 Comparison of PWM DC-DC Converters. 9.5 Summary. 9.6 References. 9.7 Review Questions. 9.8 Problems. 10 Small-Signal Models of PWM Converters for CCM and DCM. 10.1 Introduction. 10.2 Assumptions. 10.3 Averaged Model of Ideal Switching Network for CCM. 10.4 Averaged Values of Switched Resistances. 10.5 Model Reduction. 10.6 Large-Signal Averaged Model for CCM. 10.7 DC and Small-Signal Circuit Linear Models of Switching Network for CCM. 10.8 Family of PWM Converter Models for CCM. 10.9 PWM Small-Signal Switch Model for CCM. 10.10 Modeling of the Ideal Switching Network for DCM. 10.11 Averaged Parasitic Resistances for DCM. 10.12 Small-Signal Models of PWM Converters for DCM. 10.13 Summary. 10.14 References. 10.15 Review Questions. 10.16 Problems. 11 Open-Loop Small-Signal Characteristics of Boost Converter for CCM. 11.1 Introduction. 11.2 DC Characteristics. 11.3 Open-Loop Control-to-Output Transfer Function. 11.4 Delay in Open-Loop Control-to-Output Transfer Function. 11.5 Open-Loop Audio Susceptibility. 11.6 Open-Loop Input Impedance. 11.7 Open-Loop Output Impedance. 11.8 Open-Loop Step Responses. 11.9 Summary. 11.10 References. 11.11 Review Questions. 11.12 Problems. 12 Voltage-Mode Control of Boost Converter. 12.1 Introduction. 12.2 Circuit of Boost Converter with Voltage-Mode Control. 12.3 Pulse-Width Modulator. 12.4 Transfer Function of Modulator, Boost Converter Power Stage, and Feedback Network. 12.5 Error Amplifier. 12.6 Integral-Single-Lead Controller. 12.7 Integral-Double-Lead Controller. 12.8 Loop Gain. 12.9 Closed-Loop Control-to-Output Voltage Transfer Function. 12.10 Closed-Loop Audio Susceptibility. 12.11 Closed-Loop Input Impedance. 12.12 Closed-Loop Output Impedance. 12.13 Closed-Loop Step Responses. 12.14 Closed-Loop DC Transfer Functions. 12.15 Summary. 12.16 References. 12.17 Review Questions. 12.18 Problems. 13 Current-Mode Control. 13.1 Introduction. 13.2 Principle of Operation of PWM Converters with Peak-Current-Mode Control. 13.3 Relationship between Duty Cycle and Inductor-Current Slopes. 13.4 Instability of Closed-Current Loop. 13.5 Slope Compensation. 13.6 Sample-and-Hold Effect on Current Loop. 13.7 Current Loop in s -Domain. 13.8 Voltage Loop of PWM Converters with Current-Mode Control. 13.9 Feedforward Gains in PWM Converters with Current-Mode Control without Slope Compensation. 13.10 Feedforward Gains in PWM Converters with Current-Mode Control and Slope Compensation. 13.11 Closed-Loop Transfer Functions with Feedforward Gains. 13.12 Slope Compensation by Adding a Ramp to Inductor Current. 13.13 Relationships for Constant-Frequency Current-Mode On-Time Control. 13.14 Summary. 13.15 References. 13.16 Review Questions. 13.17 Problems. 13.18 Appendix: Sample-and-Hold Modeling. 14 Current-Mode Control of Boost Converter. 14.1 Introduction. 14.2 Open-Loop Small-Signal Transfer Functions. 14.3 Open-Loop Step Responses of Inductor Current. 14.5 Closed-Voltage-Loop Transfer Functions. 14.6 Closed-Loop Step Responses. 14.7 Closed-Loop DC Transfer Functions. 14.8 Summary. 14.9 References. 14.10 Review Questions. 14.11 Problems. 15 Silicon and Silicon Carbide Power Diodes. 15.1 Introduction. 15.2 Electronic Power Switches. 15.3 Intrinsic Semiconductors. 15.4 Extrinsic Semiconductors. 15.5 Silicon and Silicon Carbide. 15.6 Physical Structure of Junction Diodes. 15.7 Static I - V Diode Characteristic. 15.8 Breakdown Voltage of Junction Diodes. 15.9 Capacitances of Junction Diodes. 15.10 Reverse Recovery of pn Junction Diodes. 15.11 Schottky Diodes. 15.12 SPICE Model of Diodes. 15.13 Summary. 15.14 References. 15.15 Review Questions. 15.16 Problems. 16 Silicon and Silicon Carbide Power MOSFETs. 16.1 Introduction. 16.2 Physical Structure of Power MOSFETs. 16.3 Principle of Operation of Power MOSFETs. 16.4 Derivation of Power MOSFET Characteristics. 16.5 Power MOSFET Characteristics. 16.6 Mobility of Charge Carriers. 16.7 Short-Channel Effects. 16.8 Aspect Ratio of Power MOSFETs. 16.9 Breakdown Voltage of Power MOSFETs. 16.10 Gate Oxide Breakdown Voltageof Power MOSFETs. 16.11 Resistance of Drift Region. 16.12 Figures-of-Merit. 16.13 On-Resistance of Power MOSFETs. 16.14 Capacitances of Power MOSFETs. 16.15 Switching Waveforms. 16.16 SPICE Model of Power MOSFETs. 16.17 Insulated Gate Bipolar Transistors. 16.18 Heat Sinks. 16.19 Summary. 16.20 References. 16.21 Review Questions. 16.22 Problems. 17 Soft-Switching DC-DC Converters. 17.1 Introduction. 17.2 Zero-Voltage-Switching DC-DC Converters. 17.3 Buck ZVS Quasi-Resonant DC-DC Converter. 17.4 Boost ZVS Quasi-Resonant DC-DC Converter. 17.5 Zero-Current-Switching DC-DC Converters. 17.6 Boost ZCS Quasi-Resonant DC-DC Converter. 17.7 Multiresonant Converters. 17.8 Summary. 17.9 References. 17.10 Review Questions. 17.11 Problems. Appendix A Introduction to SPICE. Appendix B Introduction to MATLAB. Answers to Problems. Index.

Operation, design and control of dual H-bridge-based isolated bidirectional DC-DC converter

Abstract: The operation, design and control of an isolated bidirectional DC - DC converter for hybrid electric vehicle energy management applications are discussed. Different operation modes and boundary conditions are distinguished by phase-shift angle and load conditions. The absolute and relative output voltage ripple was derived. The dead-band effect and safe operational area are further investigated. The relations between output power and leakage inductance and switching frequency are also presented. The proposed converter was simulated and a prototype was built and tested. Experiments on the converter's steady state and transient operations validated the design and simulation.

Design of a Wide Input Range DC–DC Converter With a Robust Power Control Scheme Suitable for Fuel Cell Power Conversion

Abstract: In this paper, an analysis and design of a wide input range dc-dc converter is proposed along with a robust power control scheme. The proposed converter and its control are designed to be compatible with a fuel cell power source, which exhibits 2 : 1 voltage variation as well as a slow transient response. The proposed approach consists of two stages: a three-level boost converter stage cascaded with a current-fed two-inductor boost converter topology, which has a higher voltage gain and provides galvanic isolation from the input source. The function of the front-end boost converter stage is to maintain a constant voltage at the input of the cascaded dc-dc converter to ensure optimal performance characteristics and high efficiency. At the output of the first boost converter, a battery or ultracapacitor energy storage is connected to handle slow transient response of the fuel cell (200 W/min). The robust features of the proposed control system ensure a constant output dc voltage for a variety of load fluctuations, thus limiting the power being delivered by the fuel cell during a load transient. Moreover, the proposed configuration simplifies power management and can interact with the fuel cell controller. Simulation and the experimental results confirm the feasibility of the proposed system.

Method and apparatus for providing wireless power to a load device

Abstract: An apparatus includes a first converter module, a second converter module, and a sensor module. The first converter module converts a wireless power associated with an electromagnetic wave to a first DC voltage. The first converter module can include, for example, a Villiard cascade voltage multiplier, a precision rectifier, or a full-wave bridge rectifier. The sensor module monitors the first DC voltage. The second converter module converts the first DC voltage to a second DC voltage that is larger than the first DC voltage. The second converter module is enabled by the sensor module when the first DC voltage is above a first threshold voltage. The second converter module is disabled by the sensor module when the first DC voltage is below a second threshold voltage that is lower than the first threshold voltage. The second converter module provides power to a load based on the second DC voltage.

A Systematic Topology Evaluation Methodology for High-Density Three-Phase PWM AC-AC Converters

Abstract: This paper presents a systematic evaluation approach of three-phase pulsewidth-modulated (PWM) AC-AC converter topologies for high-density applications. All major components and subsystems in a converter are considered and the interdependence of all the constraints and design parameters is systematically studied. The key design parameters, including switching frequency, modulation scheme, and passive values, are selected by considering their impacts on loss, harmonics, electromagnetic interference (EMI), control dynamics and stability, and protection. The component selection criteria as well as the physical design procedures are developed from the high-density standpoint. The concept of using the same inductor for harmonic suppression and EMI filtering is introduced in the design. With the proposed methodology, four converter topologies, a back-to-back voltage source converter (BTB-VSC), a nonregenerative three-level boost (Vienna-type) rectifier plus voltage source inverter (NTR-VSI), a back-to-back current source converter (BTB-CSC), and a 12-switch matrix converter, are analyzed and compared for high specific power using SiC devices. The evaluation results show that with the conditions specified in this paper, BTB-VSC and NTR-VSI have considerably lower loss, resulting in higher specific power than BTB-CSC and the matrix converter. The proposed methodology can be applied to other topologies with different comparison metrics and can be a useful tool for high-density topology selection.

A Single-Stage AC/DC Converter With High Power Factor, Regulated Bus Voltage, and Output Voltage

Abstract: Unlike existing single-stage AC/DC converters with uncontrolled intermediate bus voltage, a new single-stage AC/DC converter achieving power factor correction (PFC), intermediate bus voltage output regulation, and output voltage regulation is proposed. The converter is formed by integrating a boost PFC converter with a two-switch clamped flyback converter into a single power stage circuit. The current stress of the main power switch is reduced due to separated conduction period of the two source currents flowing through the power switch. A dual-loop current mode controller is proposed to achieve PFC, and ensure independent bus voltage and output voltage regulations. Experimental results on a 24-V/100-W hardware prototype are given to confirm the theoretical analysis and performance of the proposed converter.

Acoustic energy harvesting using an electromechanical Helmholtz resonator.

Abstract: This talk presents the development of an acoustic energy harvester using an electromechanical Helmholtz resonator (EMHR). The EMHR consists of an orifice, cavity, and a piezoelectric diaphragm. When the acoustic wave is incident on the EMHR, a portion of acoustic energy is converted to electrical energy via piezoelectric transduction in the diaphragm of the EMHR. Moreover, the diaphragm is coupled with energy reclamation circuitry to increase the efficiency of the energy conversion. Two power converter topologies are adopted to demonstrate the feasibility of acoustic energy reclamation using an EMHR. The first is comprised of only a rectifier, and the second uses a rectifier connected to a flyback converter to improve load matching. Experimental results indicate that approximately 30 mW of output power is harvested for an incident sound pressure level of 160 dB with a flyback converter. Such power level is sufficient to power a variety of low power electronic devices.

Single-Stage Single-Switch PFC Flyback Converter Using a Synchronous Rectifier

Abstract: A single-stage single-switch power factor correction (PFC) flyback converter with a synchronous rectifier (SR) is proposed for improving power factor and efficiency. Using a variable switching-frequency controller, this converter is continuously operated with a reduced turn-on switching loss at the boundary of the continuous conduction mode and discontinuous conduction mode (DCM). The proposed PFC circuit provides relatively low dc-link voltage in the universal line voltage, and also complies with Standard IEC 61000-3-2 Class D limits. In addition, a new driving circuit as the voltage driven-synchronous rectifier is proposed to achieve high efficiency. In particular, since a driving signal is generated according to the voltage polarity, the SR driving circuit can easily be used in DCM applications. The proposed PFC circuit and SR driving circuit in the flyback converter with the reduced switching loss are analyzed in detail and optimized for high performance. Experimental results for a 19 V/90 W adapter at the variable switching-frequency of 30~70 kHz were obtained to show the performance of the proposed converter.

Advanced Renewable Energy Harvesting

Abstract: The power of DC electrical sources is combined onto a DC buss, such that each source behaves independently from any other source attached to the buss. In one embodiment, a converter module is attached to each of a plurality of solar photovoltaic panels and its output is attached in a parallel manner to a common buss that forms the input to a DC AC inverter. The converter module includes a Maximum Power Point Tracking component that matches the output impedance of the panels to the input impedance of the converter module. The converter also includes a communication component that provides parametric data and identification to a central inverter. Data generated by each converter module is transmitted over the power line or by wireless means and is collected at the inverter and forwarded to a data collection and reporting system.

Integrated Buck-Flyback Converter as a High-Power-Factor Off-Line Power Supply

Abstract: This paper investigates the integrated buck-flyback converter (IBFC) as a good solution for implementing low-cost high-power-factor ac-dc converters with fast output regulation. It will be shown that, when both buck and flyback semistages are operated in discontinuous conduction mode, the voltage across the bulk capacitor, which is used to store energy at low frequency, is independent of the output power. This makes it possible to maintain the bulk capacitor voltage at a low value within the whole line voltage range. The off-line operating modes of the IBFC are also investigated to demonstrate that the control switch of the proposed converter handles lower root-mean-square currents than those in similar integrated converters. The off-line operation of the IBFC is analyzed to obtain the design characteristics of the bulk capacitor voltage. Finally, the design and experimental results of a universal input 48 V-output 100 W ac-dc converter operating at 100 kHz is presented. Experiments show that the IEC-61000-3-2 input current harmonic limits are well satisfied and efficiency can be as high as 82%.

A Full-Bridge DC–DC Converter WithZero-Voltage-Switching Overthe Entire Conversion Range

Abstract: A new topology of full-bridge dc-dc converter is proposed featuring zero-voltage-switching (ZVS) of active switches over the entire conversion range. In contrast to conventional techniques, the stored energy in the auxiliary inductor of the proposed converter is minimal under full-load condition and it progressively increases as the load current decreases. Therefore, the ZVS operation over the entire conversion range is achieved without significantly increasing full-load conduction loss making the converter particularly suitable in applications where the output is required to be adjustable over a wide range and load resistance is fixed (e.g., an electromagnet power supply). The principle of operation is described and the considerations in the design of converter are discussed. Performance of the proposed converter is verified with experimental results on a 500-W, 100-kHz prototype.

Study and Implementation of a Current-Fed Full-Bridge Boost DC–DC Converter With Zero-Current Switching for High-Voltage Applications

Abstract: This paper presents a comprehensive study of a current-fed full-bridge boost dc-dc converter with zero-current switching (ZCS), based on the constant on-time control for high-voltage applications. The current-fed full-bridge boost converter can achieve ZCS by utilizing the leakage inductance and parasitic capacitance as the resonant tank. In order to achieve ZCS under a wide load range and with various input voltages, the turn-on time of the boost converter is kept constant, and the output voltage is regulated via frequency modulation. The steady-state analysis and the ZCS operation conditions under various load and input-voltage conditions are discussed. Finally, a laboratory prototype converter with a 22-27-V input voltage and 1-kV/1-kW output is implemented to verify the performance. The experimental results show that the converter can achieve high output voltage gains, and the highest efficiency of the converter is 92% at full-load condition with an input voltage of 27 V.

Three-Level Converter Topologies With Switch Breakdown Fault-Tolerance Capability

Abstract: This paper presents some modified topologies of the neutral-point-clamped converter. In all of them, the main change consists of adding a fourth leg, which is based on the flying-capacitor converter structure. The aim of this additional leg is to provide the converter with fault tolerance. Furthermore, during normal operation mode, this leg is able to provide a stiff neutral voltage. Consequently, the low-frequency voltage oscillations that appear at the neutral point of the standard three-level topology in some operating conditions no longer exist. As a result, the modulation strategy of the three main legs of the converter does not have to take care of voltage balance, and it can be designed to either achieve optimal output voltage spectra or improve the efficiency of the converter. Simulation and experimental results are presented to show the viability of this approach both under normal operation mode and in the event of faults.

The essence of three-phase AC/AC converter systems

Abstract: In this paper the well-known voltage and current DC-link converter systems, used to implement an AC/AC converter, are initially presented. Using this knowledge and their space vector modulation methods we show their connection to the family of indirect matrix converters and then finally the connection to direct matrix converters. A brief discussion of extended matrix converter circuits is given and a new unidirectional three-level matrix converter topology is proposed. This clearly shows the topological connections of the converter circuits that directly lead to an adaptability of the modulation methods. These allow the reader who is familiar with space vector modulation of voltage and current DC-link converters to simply incorporate and identify new modulation methods. A comparison of the converter concepts, with respect to their fundamental, topology-related characteristics, complexity, control and efficiency, then follows. Furthermore, by taking the example of a converter that covers a typical operation region in the torque-speed plane (incl. holding torque at standstill), the necessary silicon area of the power semiconductors is calculated for a maximum junction temperature. This paper concludes with proposals for subjects of further research in the area of matrix converters.

Photovoltaic-battery powered DC Bus system for common portable electronic devices

Abstract: Renewable energy sources based on photovoltaic along with battery-based energy storage necessitate power conditioning to meet load requirements and/or be connected to the electrical grid. The power conditioning is achieved via a DC-DC converter and a DC-AC inverter stages to produce the desired AC source. This is also the case even when the load is of DC type such as the typical electronic devices which require AC adaptors to be powered from the AC mains. The paper presents a hybrid photovoltaic-battery powered DC bus system that eliminates the DC-AC conversion stage resulting in lower cost and improved efficiency. It is also shown experimentally that the AC adaptors associated with the various commonly used electronic devices can be reused with the proposed system and in some cases offer higher operating efficiencies when powered from a DC bus instead. A novel high-gain modified boost converter is also introduced with several times higher voltage conversion ratio than the conventional boost converter topology. This arrangement results in higher DC bus levels and lower cable conduction losses. Moreover, the voltage stress on the modified boost converter power switch is within half the output voltage. Experimental results taken from a laboratory prototype are presented to confirm the effectiveness of the proposed approach.

A Novel ZCS-PWM Flyback Converter With a Simple ZCS-PWM Commutation Cell

Abstract: This paper proposes a novel zero-current-switching pulsewidth-modulation (ZCS-PWM) flyback dc/dc converter using a simple ZCS-PWM commutation cell. The main switch and auxiliary switch operate at ZCS turn-on and turn-off conditions, and all uncontrolled devices in the proposed converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. In addition, given constant frequency and decreasing commutation losses, the proposed converter has no additional current stress and conduction loss in the main switch compared to the conventional hard switching flyback converter. The averaging approach is used to estimate and examine the steady-state of the proposed converter. The principle of operation, theoretical analysis, and experimental results of the new ZCS-PWM flyback converter, rated 150 W and operating at 80 kHz, are provided in this paper to verify the performance of the proposed converter.

Multistring LED Backlight Driving System for LCD Panels With Color Sequential Display and Area Control

Abstract: In this paper, a multistring light-emitting diode (LED) backlight driving system for liquid crystal display (LCD) panels with color sequential display (CSD) and area control is proposed In large-scale LCD panels, multistring LED backlights are required to provide sufficient back lighting The most popular structure to achieve multistring current regulation is a current mirror However, it cannot be applied to high-power LED (>100 mA) driving, and the number of LEDs in each string is highly limited In the driving system, a multioutput flyback converter associated with a novel control IC is proposed to tightly regulate LED driving currents and to readily achieve CSD and area control The proposed driving system for a 32-in LCD panel has been built, from which experimental measurements have verified that the proposed driving system has the following features: low power consumption, high power conversion efficiency, stable driving currents, and high reliability

A Three-Phase Current-Fed DC/DC Converter With Active Clamp for Low-DC Renewable Energy Sources

Abstract: This paper focuses on a new three-phase high power current-fed DC/DC converter with an active clamp. A three-phase DC/DC converter with high efficiency and voltage boosting capability is designed for use in the interface between a low-voltage fuel-cell source and a high-voltage DC bus for inverters. Zero-voltage switching in all active switches is achieved through using a common active clamp branch, and zero current switching in the rectifier diodes is achieved through discontinuous current conduction in the secondary side. Further, the converter is capable of increased power transfer due to its three-phase power configuration, and it reduces the RMS current per phase, thus reducing conduction losses. Moreover, a delta-delta connection on the three-phase transformer provides parallel current paths and reduces conduction losses in the transformer windings. An efficiency of above 93% is achieved through both improvements in the switching and through reducing conduction losses. A high voltage ratio is achieved by combining inherent voltage boost characteristics of the current-fed converter and the transformer turns ratio. The proposed converter and three-phase PWM strategy is analyzed, simulated, and implemented in hardware. Experimental results are obtained on a 500-W prototype unit, with all of the design verified and analyzed.

The essence of three-phase AC/AC converter systems

Abstract: In this paper the well-known voltage and current DC-link converter systems, used to implement an AC/AC converter, are initially presented. Using this knowledge and their space vector modulation methods we show their connection to the family of indirect matrix converters and then finally the connection to direct matrix converters. A brief discussion of extended matrix converter circuits is given and a new unidirectional three-level matrix converter topology is proposed. This clearly shows the topological connections of the converter circuits that directly lead to an adaptability of the modulation methods. These allow the reader who is familiar with space vector modulation of voltage and current DC-link converters to simply incorporate and identify new modulation methods. A comparison of the converter concepts, with respect to their fundamental, topology-related characteristics, complexity, control and efficiency, then follows. Furthermore, by taking the example of a converter that covers a typical operation region in the torque-speed plane (incl. holding torque at standstill), the necessary silicon area of the power semiconductors is calculated for a maximum junction temperature. This paper concludes with proposals for subjects of further research in the area of matrix converters.

Unity-Power-Factor Operation of Three-Phase AC–DC Soft Switched Converter Based On Boost Active Clamp Topology in Modular Approach

Abstract: In this paper, a three-phase ac-dc converter using three single-phase pulse width modulated active clamped, zero-voltage-switched boost converter in modular approach is presented. The active clamp technique is used for zero-voltage-switching of the main and auxiliary switches. The operating modes, analysis, and design considerations for the proposed converter are explained. To evaluate the performance of the proposed converter, finally simulation and experimental results for a 500-V, 1.5-kW prototype converter are presented. The proposed converter operates at almost unity power factor with reduced output filter size. The output voltage is regulated without affecting zero-voltage-switching, even under unbalanced three-phase input voltages.

Bi-directional DC/DC converters for plug-in hybrid electric vehicle (PHEV) applications

Abstract: Power electronic DC to DC converters in plug-in hybrid and electric automotive applications demand high power bidirectional power flow capability, with wide input voltage range. Output voltage of energy storage devices like ultra capacitor or battery varies with the change in load. The converter needs to provide a successful voltage regulation on the load side for a wide range of input voltage. An isolated half bridge based converter is proposed in this project, with bidirectional power flow and minimum peak current for wide input voltage range through duty cycle, and phase shift control. The proposed converter has competitive total device rating with the conventional isolated bidirectional power converters. The converter uses the transformer leakage inductance as the primary energy transfer element. Proof of concept is realized through a small prototype.

Vector control of three-phase ac-dc front-end converter

Abstract: A vector control scheme is presented for a three-phase AC/DC converter with bi-directional power flow capability. A design procedure for selection of control parameters is discussed. A simple algorithm for unit-vector generation is presented. Starting current transients are studied with particular emphasis on high-power applications, where the line-side inductance is low. A starting procedure is presented to limit the transients. Simulation and experimental results are also presented.

An On-Line UPS System With Power Factor Correction and Electric Isolation Using BIFRED Converter

Abstract: This paper presents the design consideration and performance analysis of an on-line, low-cost, high performance, and single-phase uninterruptible power supply (UPS) system based on a boost integrated flyback rectifier/energy storage dc/dc (BIFRED) converter. The system consists of an isolated ac/dc BIFRED converter, a bidirectional dc/dc converter, and a dc/ac inverter. It provides input power factor correction, electric isolation of the input from the output, low battery voltage, and control simplicity. Unlike conventional UPS topologies, the electrical isolation is provided using a high frequency transformer that results in a smaller size and lower cost. Detailed circuit operation, analysis, as well as simulation and experiment results are presented. A novel digital control technique is also presented for UPS inverter control. This controller follows the reference current and voltage of the inverter with a delay of two and four sampling periods, respectively.

Family of Zero-Current Transition PWM Converters

Abstract: In this paper, a new auxiliary circuit is introduced for applying to buck, buck-boost, zeta, forward, and flyback converters. This auxiliary circuit provides a zero-current switching condition for all switching elements. The proposed zero-current transition (ZCT) pulsewidth-modulated buck converter is briefly described. Also, a ZCT flyback converter is analyzed, and its different operating modes are presented. Design considerations are explained, and a design example along with the experimental results of the ZCT flyback converter is presented.

A Novel Topology for Photovoltaic DC/DC Full-Bridge Converter With Flat Efficiency Under Wide PV Module Voltage and Load Range

Abstract: In this paper, a novel topology for a photovoltaic (PV) dc/dc converter that can dramatically reduce the power rating and increase the efficiency of a PV system by analyzing PV module characteristics is proposed. Based on the analysis, in the proposed topology, only 30.7% power of the total PV system is needed for a dc/dc converter. Furthermore, the dc/dc converter efficiency curve is flat under wide PV module voltage and all load ranges. In particular, the converter efficiency at the lower duty range is dramatically improved. The total PV system is implemented for a 250-kW PV power conditioning system (PCS). This system has only three dc/dc converters with a 25-kW power rating. It is only one-third of the total PV PCS power. The 25-kW prototype PV dc/dc converter is introduced to experimentally verify the proposed topology. In addition, an experimental result shows that the proposed topology exhibits a good performance.

A Single-Stage High-Power-Factor Electronic Ballast Based on Integrated Buck Flyback Converter to Supply Metal Halide Lamps

Abstract: In this paper, a novel single-stage electronic ballast with a high power factor is presented. The ballast circuit is based on the integration of a buck converter to provide the power factor correction, and a flyback converter to control the lamp power and to supply the lamp with a low-frequency square-waveform current. Both converters work in discontinuous conduction mode, which simplifies the control. In spite of being an integrated topology, the circuit does not present additional stress of voltage or current in the main switch, which handles only the flyback or buck current, depending on the operation mode. To supply the lamp with a low-frequency square-wave current to avoid acoustic resonances, the flyback has two secondary windings that operate complementarily at a low frequency. The design procedure of the converters is also detailed. Experimental results from a 35-W metal halide lamp are presented, where the proposed ballast reached a power factor of 0.95, a total harmonic distortion of 30% (complying with IEC 61000-3-2), and an efficiency of 90%.

Zero-Voltage-Switching PWM Hybrid Full-Bridge Three-Level Converter With Secondary-Voltage Clamping Scheme

Abstract: A hybrid full-bridge (H-FB) three-level (TL) converter can realize zero-voltage-switching for switches with the use of resonant inductance (including the leakage inductance of the transformer) and intrinsic capacitors of the switches. As it can operate in three-level and two-level (2L) modes, the secondary rectified voltage is always close to the output voltage over the input-voltage range; thus, the output filter requirement is significantly less. Meanwhile, the voltage stress of the rectifier diodes can also be reduced. Therefore, the H-FB TL converter is very attractive for wide input-voltage-range applications. However, there is a serious voltage oscillation across the rectifier diodes caused by reverse recovery like the Buck-derived converters. In this paper, two clamping diodes are introduced to the H-FB TL converter to eliminate the voltage oscillation across the rectifier diodes. The arrangement of the positions of the resonant inductance and the transformer is discussed. The operation principle of the proposed converter is analyzed in details. A 1.2-kW prototype was built and tested in the laboratory to verify the operation of the proposed converter.

Resonant power factor correction converter

Abstract: An AC-to-DC power converter configured to provide power factor correction and a single isolated low-voltage output. The power converter includes a single-stage resonant power converter including an isolation transformer, a resonant tank, a rectifier, and a bulk storage capacitor coupled to an output of the isolation transformer. In typical applications, at least one non-isolated power converter is coupled to the output of the single-stage isolated power factor correction converter.

Multiple-Output Dual-Polarity DC/DC Converters and Voltage Regulators

Abstract: A multi-output dual polarity inductive boost converter includes an inductor, a first output node, a second output node, and a switching network, the switching network configured to provide the following modes of circuit operation: a first mode where the positive electrode of the inductor is connected to an input voltage and the negative electrode of the inductor is connected to ground; 2) a second mode the negative electrode of the inductor is connected to ground and the positive electrode of the inductor is connected in sequence to one or more of the fourth and fifth output nodes; and 3) a third mode where the positive electrode of the inductor is connected to the input voltage and the negative electrode of the inductor is connected in sequence to one or more of the first, second and third output nodes.

A Family of Isolated Interleaved Boost and Buck Converters With Winding-Cross-Coupled Inductors

Abstract: A boost-type converter is derived by inserting a third winding of the winding-cross-coupled inductors (WCCIs) between the secondary winding and the output diode of the interleaved flyback converter in this paper. A family of isolated interleaved boost or buck DC/DC converters with WCCIs is summarized by employing the four main types of interleaved structures, which is suitable for step-up or step-down isolated distribution power systems. Then, an interleaved flyback-boost converter with WCCIs and an active clamp circuit is analyzed as an example to explore the advantages of the derived converters. The active clamp scheme is adopted to recycle the leakage energy and to suppress the turn-off voltage spikes on MOSFETs. And only one set of active clamp circuit is necessary for the interleaved two phases. Zero voltage transition (ZVT) soft switching performances are achieved for all MOSFETs during the whole switching transition. Furthermore, the output diode turn-off current falling rate is controlled by the inherent leakage inductance of the WCCIs, and the output diode reverse-recovery problem is alleviated. A clear picture is made in this paper of the general law and structure of the isolated interleaved dc/dc converters with WCCIs. At last, a 650 W prototype with 48 V-to-180 V is built and tested to verify the theoretical analysis in this paper.