A unity power factor resonant AC/DC converter for high-frequencyspace power distribution system

This paper presents analysis and design of a resonant AC/DC converter topology, suitable for use in an advanced single-phase, sine-wave voltage, high-frequency power distribution system of the type that was proposed for a 20 kHz space station primary electrical power distribution system. The converter comprises a transformer, a double-tuned resonant network comprising of series- and parallel-tuned branches, a controlled rectifier, and an output filter. Symmetrical phase control technique that generates fundamental AC current in phase with the input voltage is employed. Steady-state analysis of the converter in continuous current mode of operation is provided, and the performance characteristics presented. The proposed converter has close-to-unity rated power factor (greater than 0.98), a wide range of output voltage control (0%-100%), low total harmonic distortion in input current (less than 8%), and high conversion efficiency. Finally, selected experimental results of a bread-board converter are presented     

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     

Hybrid Full-Bridge Three-Level LLC Resonant Converter—A Novel DC–DC Converter Suitable for Fuel-Cell Power System

This paper proposes a novel hybrid full-bridge (H-FB) three-level (TL) LLC resonant converter. It integrates the advantages of the H-FB TL converter and the LLC resonant converter. It can operate under both three-level mode and two-level mode, so it is very suitable for wide-input-voltage-range applications, such as fuel-cell power systems. Compared with the traditional full-bridge converter, the input current ripple and output filter can be reduced. In addition, all the switches can realize zero-voltage switching from nearly zero to full load, and the switches of the TL leg sustain only half of the input voltage. Moreover, the rectifier diodes can achieve zero-current switching, and the voltage stress across them can be minimized to the output voltage. A prototype of 200-400-V input and 360-V/4-A output is built in our laboratory to verify the operation principle of the proposed converter     

A full-wave rectifier using a current conveyor and current mirrors

The realization of a full-wave rectifier using a current conveyor and current mirrors is presented. The proposed rectifier is composed of a voltage-to-current converter, a current mode full-wave rectifier, and a current-to-voltage converter. A voltage input signal is changed into a current signal by the voltage-to-current converter. The current mode full-wave rectifier rectifies this current signal resulting in the current full-wave output signal that is converted into a voltage full-wave output signal by one grounded-resistor. The theory of operation is described. The simulation and experiment results are used to verify the theoretical prediction. Simulated results show that the proposed rectifier yields the minimum voltage rectification to 94µV. Experimental results demonstrate the performance of the proposed rectifier for 50mV_peak signal rectification.     

Class-E rectifier using thinned-out method

A new control method of a class-E rectifier is presented, which regulates the output voltage or power with elimination of the voltage pulse of the rectifier at a constant rate. When the class-E rectifier controlled by this method is used in a class-E DC/DC power converter, both the inverter and rectifier operate under zero-voltage-switching conditions. Since the rectifier is controlled by a synchronized switch, it achieves the following advantages: (1) power efficiency for low-output voltage is improved; (2) output voltage and power are controllable at a fixed operating frequency; and (3) switching noise can be reduced. Additionally, this method is suitable for applications in which the output voltage or power are changed immediately because the output voltage and power are controlled by means of replacements of pulse patterns. The output characteristics of the rectifier are analyzed under a condition that the amplitude of the input current is constant. Experimental results show good agreement with the theoretical results     

Cascaded Multilevel Inverter With Regeneration Capability and Reduced Number of Switches

Multilevel converters are a very interesting alternative for medium and high power drives. One of the more flexible topologies of this type is the cascaded multicell converter. This paper proposes the use of a single-phase reduced cell suitable for cascaded multilevel converters. This cell uses a reduced single-phase active rectifier at the input and an H-bridge inverter at the output side. This topology presents a very good performance, effectively controlling the waveform of the input current and of the output voltage and allowing operation in the motoring and regenerative mode. The results presented in this paper confirm that this medium voltage inverter effectively eliminates low frequency input current harmonics at the primary side of the transformer and operates without problems in regenerative mode.     

A constant output current three-phase diode bridge rectifier employing a novel "Electronic Smoothing Inductor"

This paper presents an improvement of the well-known conventional three-phase diode bridge rectifier with dc output capacitor. The proposed circuit increases the power factor (PF) at the ac input and reduces the ripple current stress on the smoothing capacitor. The basic concept is the arrangement of an active voltage source between the output of the diode bridge and the smoothing capacitor which is controlled in a way that it emulates an ideal smoothing inductor. With this the input currents of the diode bridge which usually show high peak amplitudes are converted into a 120/spl deg/ rectangular shape which ideally results in a total PF of 0.955. The active voltage source mentioned before is realized by a low-voltage switch-mode converter stage of small power rating as compared to the output power of the rectifier. Starting with a brief discussion of basic three-phase rectifier techniques and of the drawbacks of three-phase diode bridge rectifiers with capacitive smoothing, the concept of the proposed active smoothing is described and the stationary operation is analyzed. Furthermore, control concepts as well as design considerations and analyses of the dynamic systems behavior are given. Finally, measurements taken from a laboratory model are presented.     

A High Efficiency Dual-Mode Buck Converter IC For Portable Applications

This paper presents the design of a novel wide output current range dual-mode dc to dc step-down (Buck) switching regulator/converter. The converter can adaptively switch between pulsewidth modulation (PWM) and pulse-frequency modulation (PFM) both with very high conversion efficiency. Under light load condition the converter enters PFM mode. The function of closing internal idle circuits is implemented to save unnecessary switching losses. The converter can be switched to PWM mode when the load current is greater than 100 mA. Soft start operation is designed to eliminate the excess large current at the start up of the regulator. The chip has been fabricated with a TSMC 2P4M 0.35 mum polycide CMOS process. The range of the operation voltage is from 2.7 to 5 V, which is suitable for single-cell lithium-ion battery supply applications. The maximum conversion efficiency is 95% at 50 mA load current. Above 85 % conversion efficiency can be reached for load current from 3 to 460 mA.     

Three-phase single-stage four-switch PFC buck-boost-type rectifier

This paper proposes a new three-phase single-stage power-factor corrector buck-boost-type rectifier topology. The typical topology uses a bridge configuration with six switches. This new topology only requires four switches, improving the rectifier efficiency as only one reverse-blocking power semiconductor conducts at any time. A vector-based sliding-mode control method for the three-phase input currents is also proposed. This fast and robust technique uses sliding mode to generate /spl alpha//spl beta/ space-vector modulation, which forces the input line currents to track a suitable sinusoidal reference. A near-unity power-factor operation of the rectifier is obtained using a sinusoidal reference in phase with the input source voltages. A proportional-integral controller is adopted to regulate the output voltage of the converter. This external voltage controller modulates the amplitude of the current references. The characteristics of the new rectifier are verified with experimental results.     

A new ZVS semiresonant high power factor rectifier with reducedconduction losses

This paper presents a novel single-phase unity power factor rectifier, which features critical conduction mode and zero-voltage switching. The reduced conduction losses are achieved by the employment of a single converter, instead of the typical configuration composed of a front-end rectifier followed by a boost converter. Theoretical analysis, a design example, and experimental results of a 300 W converter with 127 V_rms input voltage and 400 V_DC output voltage are presented     

Three-Level AC–DC–AC Z-Source Converter Using Reduced Passive Component Count

This paper presents a three-level AC-DC-AC Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can produce the correct volt-second average at its output, while simultaneously achieving inductive voltage boosting by shooting through either an appropriately selected inverter phase-leg or two phase-legs being commanded simultaneously. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence, no increase in switching losses. The proposed converter therefore offers a low-cost alternative to applications that need to ride through frequent input voltage sags. For confirming the converter performance, experimental testing using a constructed laboratory prototype is performed with its captured results presented in a later section of the paper.     

Three-level LLC series resonant DC/DC converter

Paper presents a three-level soft switching LLC series resonant dc/dc converter. Zero-voltage switching (ZVS) is achieved for each main switch without any auxiliary circuit. Voltage stress of each main switch is half of input voltage. Zero-current-switching (ZCS) is achieved for rectifier diodes. Wide input/output range can be achieved under low frequency range because of two-stage resonance. Only one magnetic component is required in this converter. Efficiency is higher in high line input, so this converter is a preferable candidate for power products with the requirement of hold up time. For design convenience, relationship between dc gain and switching frequency, load resistance is deduced. Its open load characteristic and short load characteristic are exposed to provide theory basis for no load operation and over current protection. Design consideration of four dead times is presented to assure that voltage stress for main switches is within half of input voltage and ZVS for each main switch is achieved. Finally the principle of operation and the characteristics of the presented converter are verified on a 500V-700V input 54V/10A output experimental prototype, whose efficiency reaches 94.7% under rating condition.     

Analysis and implementation of a dual-output LLC resonant converter

This article analyses and presents an LLC resonant converter with a high power factor for LCD-TV applications. It integrates the advantages of power factor correction and the LLC resonant converter. It can improve not only power quality but also circuit efficiency. Since the power factor corrector is used in the first stage of the LLC resonant converter, it is suitable for wide input voltage range application. On the basis of the resonant behaviour, zero voltage switching is achieved for the power switches and ZCS is achieved for the rectifier diodes. An experimental prototype of 90–260V _rms input and 12V/10A and ?12V/10A outputs with 92.6% efficiency for 32″ LCD-TV application is built in the laboratory to verify the operation principle of the adopted converter.     

CMOS dual output current mode half-wave rectifier

A CMOS dual output current mode half-wave rectifier is presented. The proposed rectifier is composed of three main components: a dual output V–I converter, two half-wave current rectifiers and two I–V converters. A voltage input signal is changed into two current signals by the V–I converter. The current rectifiers rectify these current signals, resulting in positive and negative half-wave current signals that are converted to positive and negative half-wave voltage signals by the I-Vconverters. The theory of operation is described, and the simulated results obtained from the PSPICE program are used to verify the theoretical prediction. Simulated rectifier performance with a 0.5μm MOSFET model using ±1.2V supply voltage demonstrates good rectifier integrity at operating frequencies up to 100MHz.     

A unity power factor converter using half-bridge boost topology

A single-phase high-efficiency near-unity power-factor (PF) half-bridge boost converter circuit, which has been proposed earlier by other researchers, is presented with detailed analysis. This converter is capable of operating under variable PF. However, the focus of this paper is in achieving unity PF operation only. The efficiency of this circuit is high because there is only one series semiconductor on-state voltage drop at any instant. The existence of an imbalance in the voltages of the two DC-link capacitors, which was noted before, is confirmed here. The cause for the imbalance is analyzed using appropriate models, and a control method to eliminate it is discussed in detail. Analysis and design considerations for the power circuit using the fixed-band hysteresis current control (HCC) technique are provided. The analytical results are verified through simulation using switched and averaged circuit models of the scheme and also through experimental work. At 90-V AC input and 300-W 300-V output, the experimental prototype demonstrates an efficiency of 96.23% and a PF of 0.998. This converter, with its relatively high DC-output voltage, is well suited for the 110-V utility supply system. A circuit modification for universal input voltage range operation is also suggested     

New single-stage PFC regulator using the Sheppard-Taylor topology

This paper describes a new usage of the DC/DC converter developed by D.I. Sheppard and B.E. Taylor in 1983 for achieving high power factor and output regulation. This converter may be viewed as a cascade of a modified boost stage and a buck stage, with the two stages sharing the same active switch. Two possible operation regimes are described. In the first regime, the converter's input part, which is a modified boost converter, operates in discontinuous mode, and the output part, which is a buck converter, operates in continuous mode. In this regime, high power factor is naturally achieved, and the output voltage is regulated by duty-cycle modulation via a simple output feedback. In the second regime, the input part operates in continuous mode, and the output part operates in discontinuous mode, with duty-cycle modulation maintaining a high power factor and frequency modulation regulating the output. Some comparisons between the Sheppard-Taylor converter and conventional boost and buck cascade are given in the paper     

A Three-Level Resonant Single-Stage Power Factor Correction Converter: Analysis, Design, and Implementation

This paper presents a new single-stage power factor correction ac/dc converter based on a three-level half-bridge resonant converter topology. The proposed circuit integrates the operation of the boost power factor preregulator and the three-level resonant dc/dc converter. A variable-frequency asymmetrical pulsewidth modulation controller is proposed for this converter. This control technique is based on two integrated control loops: the output voltage is regulated by controlling the switching frequency of the resonant converter, whereas the dc-bus voltage and input current are regulated by means of duty cycle control of the boost part of the converter. This provides a regulated output voltage and a nearly constant dc-bus voltage regardless of the loading condition; this, in turn, allows using smaller switches and consequently having a lower on resistance helping to reduce conduction losses. Zero-voltage switching is also achieved for a wide range of loading and input voltage. The resulting circuit, therefore, has high conversion efficiency making it suitable for high-power wide-input-voltage-range applications. The effectiveness of this method is verified on a 2.3-kW 48-V converter with input voltage (90–265 Vrms).      

采用倍流整流移相全桥的ZVZCS直流变换器研究

在传统的移相全桥ZVZCS直流变换器中,输出侧多采用全波整流式结构,在大电流输出条件下这种结构将增加输出滤波电感和变压器的体积以及整流管上的电压应力,不利于在低压大电流输出场合的应用。针对这种情况,文章在输出侧采用一种适宜应用在低电压大电流输出场合的倍流整流式结构,使变压器和输出滤波电感的设计得到简化,并且输出整流二极管实现了零电流自然关断,降低了功率器件的应力与开关损耗,适合于大功率场合;文中还简单讨论了软开关的实现范围和参数的设计等问题。最后,在以上分析的基础上,设计了一台输出电压为27V,输出功率为3kW的电源,利用Matlab/Simulink进行了仿真,并给出了相应的仿真结果。     

High Frequency and High Precision CMOS Half-Wave Rectifier

In this paper, a new high frequency and high precision half-wave rectifier circuit which is very suitable for CMOS technology implementation is presented. The system comprises a voltage to current converter, a dual output precision current-mode half-wave rectifier, and two current to voltage converters. An input voltage signal is converted into a current signal by using a current conveyor and a MOS resistor. The current signal is rectified using a dual output class-AB precision rectifier cell and then converted into two output voltages by using grounded MOS resistors. This class-AB current-mode precision rectifier is employed for providing high frequency performance. Simulated rectifier results based-on a 0.5 µm CMOS technology with ±1.2 V supply voltage demonstrates very high operating frequency, very precise rectification and good temperature stability.     

A Variable Frequency Phase-Shift Modulated Three-Level Resonant Single-Stage Power Factor Correction Converter

This paper presents a new single-stage three-level resonant power factor correction ac-dc converter suitable for high power applications (in the order of multiple kilowatts) with a universal input voltage range (90–265 Vrms). The proposed topology integrates the boost input power factor preregulator with a half-bridge three-level resonant dc-dc converter. The converter operation is controlled by means of a combination of phase-shift and variable frequency control. The phase-shift between the switch gate pulses is used to provide the required input current shaping and to regulate the dc-bus voltage to a set reference value for all loading conditions, whereas, variable frequency control is used to tightly regulate the output voltage. An auxiliary circuit is used in order to balance the voltage across the two dc-bus capacitors. Zero voltage switching (ZVS) is also achieved for a wide range of loading and input voltage by having a lagging resonant current in addition to the flowing of the boost inductor current through the body diodes of the upper pair of switches in the free wheeling mode. The resulting circuit, therefore, has high conversion efficiency and lower component stresses making it suitable for high power, wide input voltage range applications. The effectiveness of the proposed converter is verified by analysis, simulation, and experimental results.