A novel single-phase ZCS-PWM high-power-factor boost rectifier

This paper presents a novel single-phase high-power-factor (HPF) pulsewidth-modulated (PWM) boost rectifier featuring soft commutation of the active switches at zero current (ZC). It incorporates the most desirable properties of conventional PWM and soft-switching resonant techniques. The input current shaping is achieved with average current mode control and continuous inductor current mode. This new PWM power converter provides ZC turn on and turn off of the active switches, and it is suitable for high-power applications employing insulated gate bipolar transistors (IGBTs). The principle of operation, the theoretical analysis, a design example and experimental results from a laboratory prototype rated at 1600 W with 400 VDC output voltage are presented. The measured efficiency and the power factor were 96.2% and 0.99%, respectively, with an input current total harmonic distortion (THD) equal to 3.94%, for an input voltage with THD equal to 3.8%, at rated load     

Smart Internet of Things (IOT) System for Performance Improvement of Dual Bridge LLC Resonant Converter by Using Sophisticated Distribution Control Method (SDC)

A resonant converter is a kind of electric power converter that contains a system of inductors and capacitors called a resonant tank, tuned to resonate at a particular frequency in this work recommends a better-quality dual bridge LLC resonant converter with a novel controller technique. The resonant converters include the serial or parallel connections of inductors and capacitors to activate the switch to realize the Zero Current Switching (ZCS) and Zero Volt Switching (ZVS) under resonance conditions. The resonant effects are switching sufferers, turning strain and electromagnetic interference problems the switching resonant converter controls the output voltage through changing frequency and generally can be sub classified in ZCS converter and ZVS converter. This scheme had combined wireless monitoring for dual bridge LLC resonant converter for dc distribution applications based on sophisticated distribution controller (SDC) through the internet of things and embedded structure access and other mechanisms. The consequence of our exhibition demonstrates that the framework can monitor and store the manipulate data from the converter. Thus, the wireless monitoring functions are realized in real-time. This converter permits both forward and reverses power exchange between the source and the load, to keep up the output voltage consistent, regardless of load and line unsettling influences, it is important to work the converter as a closed loop system. The proposed SDC based dual bridge resonant converter has validated through simulation in Matlab Simulink environment. A hardware setup is also developed to validate the simulation. General 97% effectiveness accomplished at full load condition in light of the dual bridge resonant converter.     

Analysis and design of a modified series resonant converter

A modified series resonant converter (SRC) (also referred to as the LCL-type SRC) which overcomes the problems of the standard series resonant converter is presented. A state-space approach is used for the analysis. Analysis shows that the converter enters into three different modes. Converter gain and other component stresses are plotted with variation in the load current. Detailed experimental results obtained from a 500 W MOSFET converter are presented to verify the theory. With a proper selection of inductor ratio, only a narrow variation in switching frequency is required to regulate the output voltage for wide variation in the load current. It is shown that, by placing the parallel inductor on the secondary side, the parasitics of the high-frequency transformer can be used profitably     

Constant-frequency control of quasi-resonant converters

An additional independent control needed to eliminate the undesirable variable switching frequency of quasi-resonant (QR) converters is obtained by replacing the output rectifier by an active switch. The concept is applicable to all classes of converters. Compared to QR converters with conventional switch realization, constant-frequency quasi-resonant (CF-QR) converters exhibit the same type of switching transitions and similar switch voltage and current stresses. Advantages of CF-QR converters are not restricted to the constant-frequency control. In all classes, operation at zero load is possible, so that the available load range is unlimited. The range of attainable, conversion ratios is significantly extended in the classes of zero-voltage quasi-square-wave (CF-ZV-QSW) and zero-voltage multiresonant (CF-ZV-MR) topologies. A practical design example of a 25 W CF-ZV-MR buck converter is constructed and evaluated. The converter operates at 2 MHz from zero load to full load, with a full-load efficiency of 83%. Simple duty ratio control is used to maintain the output voltage constant for all loads. The circuit is inherently immune to the short-circuit condition at the output. Disadvantages of CF-QR converters are the increased gate-drive losses and increased complexity of the power stage and the control circuitry     

Operation of the LCC-type parallel resonant converter as a lowharmonic rectifier

A single-phase high-frequency transformer isolated single-stage AC-to-DC controlled rectifier with low line current harmonic distortion using a variable-frequency controlled LCC-type (or series-parallel) resonant power converter (SPRC) is presented. A simple analysis and design procedure is used for designing the converter for low line current harmonic distortion and high power factor operation. The converter performance characteristics have been verified with SPICE3 simulations (without active control) and experimental prototype SPRC (rated at 150 W, with and without active control) for variation in load as well as line voltage. When operated with active current shaping, this converter operates in zero-voltage-switching mode for the complete range, maintaining power factor close to unity with low line current distortion and low peak current compared to the parallel resonant converter     

A Soft-Switched Full-Bridge Single-Stage AC-to-DC Converter With Low-Line-Current Harmonic Distortion

A single-phase high-frequency transformer-isolated soft-switching single-stage ac-to-dc converter with low-line-current distortion is presented. The circuit configuration is obtained by integrating two discontinuous current mode (DCM) boost converters with a DCM full-bridge buck converter. The zero-voltage switching for the top switches is achieved automatically, whereas bottom switches are aided by zero-voltage transition circuits. The output voltage is regulated by duty-cycle control at constant switching frequency. The intervals of operation and steady-state analysis are presented. A systematic design procedure is presented with a 1-kW converter design example. PSPICE simulation and experimental results obtained from a 1-kW laboratory prototype are presented for a wide variation in line and load conditions.     

Novel Current-Mode AC/AC Converters With High-Frequency AC Link

A novel circuit-topology family of the current-mode AC/AC converter with high-frequency AC link, based on a Flyback converter, is proposed. These circuit topologies, which can transfer one unregulated sinusoidal voltage with high total harmonic distortion (THD) into another regulated constant-frequency sinusoidal voltage with low THD, are composed of input cycloconverter, high-frequency storage transformer, and output cycloconverter. The circuit-topology family includes single four-quadrant power switch mode, push-pull mode, half-bridge mode, and full-bridge mode circuits. The single four-quadrant power switch mode and push-pull mode converters are suitable for low input voltage fields, but the half-bridge mode and full-bridge mode converters are suitable for high input voltage fields. The operational mode, steady principle, and transient voltage feedback control strategy of the kind of converter are investigated. The output characteristic curve, its relation to internal resistance, and the design criteria for the key circuit parameters are given. The theoretical analysis and the test result of the 500 VA 220 V 15% 50 HzAC/220 V 50 HzAC prototype have shown that the converters have advantages such as high-frequency galvanic isolation, simple topology, two-stage power conversion [low frequency alternating current (LFAC)/high frequency alternating current (HFAC)/LFAC], bidirectional power flow, high efficiency, high power density, low THD of the output voltage, strong adaptability to various loads, higher line power factor, low audio noise, etc.     

Design and Implementation of an Accurately Regulated Multiple Output ZVS DC–DC Converter

An accurately regulated multiple-output zero-voltage switching (ZVS) DC-DC converter is proposed. The converter is composed of three outputs altogether. The first and second outputs are regulated through the duty cycle control of two asymmetrical half bridge converters, while the third output is regulated through the phase shift of the two asymmetrical half bridge converters. The characteristic of this multiple-output dc-dc converter is analyzed and design process is investigated. ZVS is realized for all the main switches. Therefore this multiple-output dc-dc converter can operate with higher efficiency at higher switching frequency. The operation stages, ZVS condition and control detail are also presented. A 400 V input, 48 V/10 A, 5 V/20 A, 12 V/5 A outputs prototype is built to verify the design. The efficiency at rated input voltage full load is 93.36%.     

Buck converter small-signal models and dynamics: comparison ofquasi-resonant and pulsewidth modulated switches

The generalized canonical model obtained from extended state-space averaging is used as a design tool for the evaluation of the buck converter dynamics in different switching schemes. Designs are given at a specified constant conversion ratio and load for the pulse width modulated, zero current, zero voltage, and nonlinear resonant switch full- and half-wave converters. The small signal equivalent circuit model is discussed, and the feedback effects introduced by resonant switching on line and control transfer functions are evaluated. The small signal transfer functions of half-wave converters are heavily load-current dependent, and exhibit significant damping at light loads, which can result in two real poles in the converter response instead of a complex conjugate pair. This damping effect is evaluated over the entire normalized load current range for the linear and nonlinear zero-current switching converters. Simple approximate expressions are given for the real poles. Experimental verification of the half-wave analysis is presented, and the effects of converter efficiency on model accuracy are discussed     

Low-power variable frequency PFC converters

Based on the SinoMOS 1 μm 40 V CMOS process, a novel power factor corrention (PFC) converter with a low-power variable frequency function is presented. The circuit introduces a multi-vector error amplifier and a pro-grammable oscillator to achieve frequency modulation, which provides a rapid dynamic response and precise output voltage clamping with low power in the entire load. According to the external load variation, the system can modulate the circuit operating frequency linearly, thereby ensuring that the PFC converter can work in frequency conversion-mode. Measured results show that the normal operating frequency of the PFC converter is 5-6 kHz, the start-up current is 36 μA, the stable operating current is only 2.43 mA, the efficiency is 97.3%, the power factor (PF) is 0.988, THD is 3.8%, the load adjust rate is 3%, and the linear adjust rate is less than 1%. Both theoretical and practical results reveal that the power consumption of the whole supply system is reduced efficiently, especially when the load varies. The active die area of the PFC converter chip is 1.61×1.52 mm~2.     

An improved family of ZVS-PWM active-clamping DC-to-DC converters

A new family of DC-to-DC converters featuring clamping action, PWM modulation and soft-switching (ZVS) in both active and passive switches, is proposed to overcome the limitations of clamped mode DC-to-DC converters. The new family of converters is generated and the new circuits are presented. As the resonant circuits absorb all parasitic reactances, including transistor output capacitance and diode junction capacitance, these converters are suitable for high-frequency operation. Principle of operation of the boost converter, theoretical analysis, simulation and experimental results are presented, taken from a laboratory prototype rated at 1600 W, input voltage of 300 V, output voltage of 400 V, and operating at 100 kHz. The measured efficiency at full load was 98%     

Analysis and design of LCL-type series resonant converter

A series resonant converter modified by adding an inductor in parallel with the transformer primary (or secondary) is presented. This configuration is referred to as an “LCL-type series resonant converter”. A simplified steady-state analysis using complex AC circuit analysis is presented. Based on the analysis, a simple design procedure is given. Detailed experimental results obtained from a MOSFET-based 640 W converter are presented to verify the analysis. A narrow variation in switching frequency is required to regulate the output voltage for a very wide change in load, and the converter has load short-circuit capability. It is shown that by placing the parallel inductor on the secondary side, the parasitics of the high-frequency transformer can be used profitably     

A simple input current wave-shaping technique for three-phase diode and SCR converters

Three-phase converters using diode or silicon-controlled rectifier (SCR) are widely employed to convert the commercial AC supply to DC. Such converters inject harmonics into the power supply system and thereby distort supply system voltage waveform. A simple input current wave-shape improvement technique using a shunt-connected harmonic current compensator is presented in this work, intended to reduce the total harmonic distortion (THD) of input current of three-phase diode and SCR phase-controlled rectifiers operating with inductive loads, by matching them to the specific converter as a combined package. The compensator proposed here comprises of a three-limb voltage source converter using insulated-gate bipolar transistor, working on instantaneous current and voltage measurements of the compensator only and not of the load. The technique uses a simple feedforward control for AC source current harmonic compensation of rectifiers without monitoring the AC line currents, i.e. use of online computation. The proposed system is simulated and tested on a laboratory prototype. The measured input current THD values without additional line filters are found to be below 8.3%, which is within acceptable limits, proving that the new technique is capable of compensating predetermined current harmonics of diode or SCRs.     

Fixed-frequency phase-controlled full-bridge resonant converterwith a series load

A fixed-frequency phase-controlled full-bridge parallel resonant converter (PCPRC) that consists of a phase-controlled parallel resonant inverter (PCPRI) and an input-inductor rectifier is analyzed. The input impedances of the resonant circuits represent inductive loads for both switching legs at f/f₀>1.24 and therefore zero-voltage-switching turn-on can be achieved for all the transistors. The fundamental frequency approximation is used to derive expressions for the voltage transfer function and the efficiency of the PCPRI. The behavior and performance characteristics of the PCPRI are then studied. Three types of input-inductor rectifiers are considered and a design procedure is developed. A 30 W PCPRC is designed and tested. The theoretical calculations were in good agreement with experimental results. The converter exhibits an excellent efficiency. The measured efficiency was 92% at full load. The converter is capable of regulating the DC output voltage from full load to no load and over a wide line voltage range     

A generalized steady-state analysis of resonant converters usingtwo-port model and Fourier-series approach

A generalized steady-state analysis of resonant converters using a two-port model and Fourier-series approach is presented. Analysis is presented for both voltage-source (VS) and current-source (CS)-type loads. Analysis can also be used either for variable-frequency (half- or full-bridge) or fixed-frequency (phase-shift control for full-bridge) operation. Steady-state solutions have been obtained. Particular cases are considered to show the method of application in analyzing different schemes. A simple design procedure is given for two particular cases to illustrate the use of analysis in obtaining design curves and in designing the converters. Experimental results obtained from a MOSFET-based 500-W fixed-frequency LCL-type resonant converter are presented to verify the analysis     

Characteristics of load resonant converters operated in ahigh-power factor mode

The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained     

PWM-controlled SRC with inductive output filter at constantswitching frequency

By using the PWM control scheme in the series resonant power converter (SRC) with inductive output filter, the converter can be operated at a constant frequency. This converter has lower switching loss than the PWM converter and better control characteristics than the ordinary SRC. Since the peak current in the present converter equals the load current, it has the lowest possible peak current stress among converters. The analysis and the performance characteristics of the converter operating at a constant switching frequency are presented. Experimental results are given to confirm the analytical work     

Soft switching resonant converter with duty-cycle control in DC micro-grid system

Resonant converter has been widely used for the benefits of low switching losses and high circuit efficiency. However, the wide frequency variation is the main drawback of resonant converter. This paper studies a new modular resonant converter with duty-cycle control to overcome this problem and realise the advantages of low switching losses, no reverse recovery current loss, balance input split voltages and constant frequency operation for medium voltage direct currentgrid or system network. Series full-bridge (FB) converters are used in the studied circuit in order to reduce the voltage stresses and power rating on power semiconductors. Flying capacitor is used between two FB converters to balance input split voltages. Two circuit modules are paralleled on the secondary side to lessen the current rating of rectifier diodes and the size of magnetic components. The resonant tank is operated at inductive load circuit to help power switches to be turned on at zero voltage with wide load range. The pulse-width modulation scheme is used to regulate output voltage. Experimental verifications are provided to show the performance of the proposed circuit.     

Class-E DC/DC converters with a capacitive impedance inverter

Analysis and design rules are presented for three class-E switching-mode DC/DC power converters, each with a capacitive impedance inverter. Experimental results are given for one of the converters. A zero-voltage switching technique is achieved for both class-E inverters and rectifiers. Therefore, the efficiency of the converters is very high at switching frequencies in the megahertz range. By applying a capacitive impedance inverter, lossless operation of the class-E inverter can be obtained for a wide range of converter load resistance, from full load to infinity. Experimental results are in excellent agreement with the theoretical calculations. Only a 12% relative bandwidth of the switching frequency is required to maintain a constant DC output voltage for the load resistance from full load to infinity at about 1 MHz with 15-W output     

An improved ZCS-PWM commutation cell for IGBT's application

An improved zero-current-switching pulsewidth-modulation (ZCS-PWM) commutation cell is proposed, which is suitable for high-power applications using insulated gate bipolar transistors (IGBTs) as the power switches. It provides ZCS operation for active switches with low-current stress without voltage stress and PWM operating at constant frequency. The main advantage of this cell is a substantial reduction of the resonant current peak through the main switch during the commutation process. Therefore, the RMS current through it is very close to that observed in the hard-switching PWM converters. Also, small ratings auxiliary components can be used. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost converter. Operating principles, theoretical analysis, design guidelines and a design example are described and verified by experimental results obtained from a prototype operating at 40 kHz, with an input voltage rated at 155 V and 1 kW output power. The measured efficiency of the improved ZCS-PWM boost converter is presented and compared with that of hard-switching boost converter and with some ZCS-PWM boost converters presented in the literature. Finally, this paper presents the application of the proposed soft-switching technique in DC-DC nonisolated power converters