Parallellism of power converters for automatic power factorcorrection

The modular development of a single-stage 3-phase AC-DC power converter is described. The converter offers several advantageous features     

Implementation of a three-level rectifier for power factorcorrection

In this paper, a new single-phase switching mode rectifier (SMR) for three-level pulse width modulation (PWM) is proposed to achieve high input power factor, low current harmonics, low total harmonic distortion (THD) and simple control scheme. The mains circuit of the proposed SMR consists of six power switches, one boost inductor, and two DC capacitors. The control algorithm is based on a look-up table. There are five control signals in the input of the look-up table. These control signals are used to control the power flow of the adopted rectifier, compensate the capacitor voltages for the balance problem, draw a sinusoidal line current with nearly unity power factor, and generate a three-level PWM pattern on the AC side of adopted rectifier. The advantages of using three-level PWM scheme compared with two-level PWM scheme are using low voltage stress of power switches, decreasing input current harmonics, and reducing the conduction losses. The performances of the proposed multilevel SMR are measured and shown in this paper. The high power factor and low harmonic currents at the input of the rectifier are verified by software simulations and experimental results from a laboratory prototype     

A high-performance single-phase rectifier with input power factorcorrection

In this paper, a high-performance single-phase AC-to-DC rectifier with input power factor correction is proposed. The proposed approach has many advantages, including fewer semiconductor components, simplified control, and high-performance features, and satisfies IEC 555 harmonic current standards. Simulation and experimental results obtained on a laboratory prototype are discussed. A hybrid power module of the proposed approach is also shown     

Performance evaluation of a Schottky SiC power diode in a boost PFC application

The performance of a 600 V, 4 A silicon carbide (SiC) Schottky diode (Infineon SDP04S60) is experimentally evaluated. A 300 W boost power factor corrector (PFC) with average current mode control is considered as a key application. Measurements of overall efficiency, switch and diode losses, and conducted electromagnetic interference (EMI) are performed both with the SiC diode and with two ultra-fast, soft-recovery, silicon power diodes, namely the RURD460 and the presented STTH5R06D. The paper compares the results to quantify the impact of the recovery current reduction provided by SiC diode on these key aspects of the converter behavior. Based on the experimental results, the paper shows that the use of SiC diodes in PFC designs may only be justified in high switching frequency applications.     

A power boost for copper

The capabilities of today's digital subscriber line (DSL) technology are being stretched to the limit. Residential and business subscribers need more and more bandwidth, especially for applications such as interactive personalised TV, high definition TV (HDTV) and video-on-demand, which are growing in popularity. Ultimately the answer may lie in running fibre out to the building, or at least to the kerb, to deliver virtually unlimited bandwidth. In the meantime, most operators must look for new cost-effective ways of exploiting their existing copper infrastructure to deliver the speeds that subscribers need. The very high bitrate DSL 2 standard (VDSL2) offers looks set to fill the gap neatly     

Novel current transducer in a single-phase active power factorcorrection system

In line-fed converters implementing power factor correction, the current shaping process requires input current sensing, commonly obtained using dedicated power components as shunts or current transformers. This work presents a current sensing circuit applied to active power factor correction with boost topology, which does not use the previous components. The sensing element is an inductor placed in the input filter, needed to comply with electromagnetic emission standards. The operating principle of the proposed sensing circuit is then extensively discussed, and analytical formulation of the frequency response is given for real conditions. The influence of transducer error on the performance of the power factor correction (PFC) system is also analyzed. Theoretical analysis shows that a system with a low total harmonic distortion (THD) can be achieved, and this is confirmed by experiments on a laboratory prototype     

Reduced conduction loss zero-voltage-transition power factorcorrection converter with low cost

A new low conduction loss low-cost zero-voltage-transition (ZVT) power factor correction converter (PFC) is presented. The conventional PFC, which consists of a bridge diode rectifier and a boost converter (one active switch), always has three semiconductor conduction drops. The two-switch-type PFC, which was presented recently, reduces conduction loss by reducing one conduction drop, but the cost is increased because of one additional switch. The proposed PFC reduces conduction loss with one switch. Conduction loss reduction is a little bit less than that of the two-switch type, but it is achieved with low cost. Operation, features, and characteristics are comparatively illustrated and verified by the experimental results from a 2.5-kW 100-kHz laboratory prototype     

A novel chopper for the power control of DC loads

When AC lines are used to supply DC loads, conventionally a rectifier and a DC chopper or a controlled rectifier are used. In many cases, a transformer is available for isolation purposes and also for matching the maximum DC load voltage requirements. When the conventional methods are used for the power control, line power factor deteriorates. A new chopper to improve the line power factor and which is free from commutation problems is developed and is presented in this paper. Experimental verification of the basic principles involved are carried out.     

Optimal operation of single-stage three-phase power factorcorrection circuit using modular PWM DC-to-DC converters

A critical conduction parameter K_3Φ is derived for the three-phase modular system. This parameter optimises the output filter to achieve the highest power factor of the system. The voltage conversion ratio required to achieve a high power factor to fulfil the harmonic requirements is also derived. Both simulations and experimental results from a 1.5 kW prototype using full-bridge converters have confirmed the analysis     

ZVT-PWM boost converter for unity power factor applications

A new single-phase ZVT-PWM boost converter with an active snubber is proposed to achieve unity power factor operations for a wide load range. The unique location of the resonant inductor and capacitor ensures that low switching stress and commutation losses are obtained in the converter. The proposed converter is suitable for high power factor correctors     

激光二极管驱动电源的设计

设计实现了分布式光纤测温系统(DTS)中的激光二极管驱动电源。首先研究激光二极管对驱动电源的要求及技术指标,比较目前几种设计方法的优缺点,分析雪崩三极管的工作原理和参数选择因素,并选择雪崩三极管ZTX415,最后由同步触发信号产生电路、预雪崩电路、雪崩电路三部分设计实现了激光二极管的驱动电源。其中预雪崩电路采用开关三极管获得纳秒级脉冲并进行功率放大,降低了对雪崩三极管的参数要求。实验结果表明,设计合理,参数正确,并已成功应用于光纤测温系统中。     

Negative-resistance diode power amplification

An analysis is presented for the nonlinear behavior of power amplifiers utilizing negative-resistance diodes in a reflection circuit. The analysis applies to both stable and locked-oscillator modes of operation. Special emphasis is given to a simple model involving a cubic nonlinearity in theI-Vrelationship, and to the idealized LSA device in an amplification mode.     

Current balancing control for an interleaved boost power converter

The interleaved boost power converter has the advantages of ripple cancellation and better efficiency. The major problem of the interleaved boost power converter is the current balancing among different phases of the boost power converters. In this paper, a current balancing control method for equalizing the currents of two-phase interleaved boost power converter is proposed. The output current can effectively detect the mismatch between the boost power converters for the interleaved boost power converter. The output current is used to perform both the current balance and the current-mode control. The salient feature is that only one current sensor is used in the proposed current balancing control method. A hardware prototype is developed, and the experimental results verify the performance of the proposed current balancing control method is as expected.     

大功率半导体激光器驱动电源的设计

高能激光系统通常需要多种输出模式的驱动电源,现有电源存在输出模式单一的问题。采用能量压缩技术和电流串联负反馈技术实现了多输出模式半导体激光器驱动电源。分析了特殊设计高输入阻抗差分运算电路作为负反馈网络的工作原理,推导出了精确的参考电压与输出电流的关系式。最后,将所研制的驱动电源应用于国内首台400W工业级光纤激光器系统中,驱动电源实现了0~26A连续可调、稳定度优于0.15‰的连续电流和准连续电流输出。测试结果验证了设计思路的可行性,实现了半导体激光器驱动电源的多输出模式和高电流稳定度。     

Buck or boost tracking power converter

A cascade of buck and boost converter is presented here. The control operates in a manner that the converter is either in buck or boost (BOB) mode on a cycle by cycle basis. It transitions between the modes seamlessly to provide a tracking power conversion function for modulating the power supply of a variable envelope radio frequency (RF) power amplifier. The control algorithm and its implementation using switched capacitor circuits is described. Simulation and measured experimental results including converter efficiency, tracking accuracy, and spectrum at the output of the RF power amplifier are provided. This control technique allows seamless transition between the buck and boost modes while tracking RF envelopes with bandwidth greater than 100 kHz, and maintaining extreme accuracy and extremely low ripple. The efficiency of this converter operating at 1.68 MHz is close to 90% over a wide range of conversion ratios. The area of the power converter is extremely small allowing this to be integrated into a cellular telephone. The controller was integrated as part of a larger power management IC as well as a discrete IC.     

Calculation of power diode reverse-recovery time for SPICEsimulations

A new model for the calculation of power diode reverse-recovery time is described. The model takes into account the effect of emitter recombination and is easily incorporated into the PSPICE simulator. Comparisons between the proposed model and numerical simulation results are presented     

Composite avalanche diode structures for increased power capability

The possibility of operating several avalanche oscillator wafers in parallel to obtain higher power and/or higher efficiency CW operation is explored analytically and experimentally. Experiments show that over a wide range the efficiency is roughly proportional to the power density in the semiconductor. The power densities required for good efficiency are very high and cannot be achieved in large area junctions without an excessive temperature rise caused by the thermal spreading resistance of the heat-sink material. The scheme delineated herein considers small area wafers spaced sufficiently close electrically that they operate as a single avalanche oscillator whereas their physical separation permits essentially independent heat sinking. It has been found that, as expected, the efficiency for CW operation improves approximately inversely with the diode diameter whereas the power capability for a given size wafer increases directly with the number of such wafers employed. The relative merits of mounting diodes on copper and on diamond are discussed. Experimental work indicates that the present approach is capable of producing 10 to 15 watts CW at 14 GHz in a single oscillator with available silicon diodes.     

Using power diode models for circuit simulations-a comprehensivereview

In recent years, a number of new models for the power diode have been proposed. The objectives of this paper are to provide the power electronics community with a comprehensive review and summary of recent power diode models. The models have been categorized systematically according to their modeling concepts with objective comparison of their status pertaining to the various modeling issues. A summary table has been created to aid power circuit design engineers and power rectifier device engineers in selecting appropriate models for their applications     

High power diode laser arrays

Recent progress in the development of high-power diode laser arrays for solid-state laser pumping is detailed. Advances in available wavelength, efficiency, temperature of operation, duty cycle of operation, and peak and average power levels or densities are described. A packaging architecture capable of addressing the broadest range of pump applications and designs in an economic manner is defined, and a range of such package designs is presented