36kV/10kW CO2激光器充电电源的研制

为了改善现有CO2激光器工频LC谐振充电时充电电压随激光器工作频率升高而降低、影响激光输出的稳定性和光束质量,不利于装置的小型化和轻量化的问题。采用全桥逆变结构和串联谐振软开关电路,研究了36kV/10kW高频高压充电电源。该电源系统采用三相380V交流电作为供电系统,大功率智能功率模块作为全桥逆变电路。逆变交流信号经串联谐振电路及高频脉冲变压器得到高压脉冲信号,高压脉冲经整流给负载电容充电,电源应用电压电流双闭环控制系统,输出电压、电流经采样及放大后,反馈到电源控制芯片SG3525,芯片SG3525通过判断反馈信号的大小,控制输出脉冲宽度调制驱动信号的占空比。激光器放电频率为25Hz时,电源输出电压为37kV,峰值输出功率为13.05kW,充电效率为0.826。结果表明,该高频高压充电电源适合用作CO2激光器的高压充电电源。     

CO2激光器高压高频充电电源的应用研究

为改善现有CO2激光器工频充电电源体积、重量大、充电精度低等缺点,开展高频高压充电电源的研究,研制一台采用全桥逆变结构和串联谐振软开关电路、输出电压36 kV、输出平均充电功率为10 kJ／s的高频高压充电电源。该电源系统采用三相380 VAC作为供电系统,大功率智能功率模块（IPM）作为全桥逆变电路,逆变交流信号经串联谐振电路及高频脉冲变压器得到高压脉冲信号,高压脉冲经整流给负载电容充电;同时,电源应用电压、电流双闭环控制系统,输出电压、电流经采样及放大反馈到电源控制芯片SG3525,SG3525通过判断反馈信号的大小控制输出PWM驱动信号的占空比。实验结果表明：电源输出电压36 kV,输出平均功率为10.8 kJ／s,充电效率为0.82,电源纹波系数为1％。电源系统保证了激光器稳定工作在30 Hz条件下。     

Optimized transformer design: inclusive of high-frequency effects

Switching circuits, operating at high frequencies, have led to considerable reductions in the size of magnetic components and power supplies. Nonsinusoidal voltage and current waveforms and high-frequency skin and proximity effects contribute to power transformer losses. Traditionally, power transformer design has been based on sinusoidal voltage and current waveforms operating at low frequencies. The physical and electrical properties of the transformer form the basis of a new design methodology while taking full account of the current and voltage waveforms and high-frequency effects. Core selection is based on the optimum throughput of energy with minimum losses. The optimum core is found directly from the following transformer specifications: frequency; power output; and temperature rise. The design methodology is illustrated with a detailed design of a push-pull power converter     

DC-DC converter: four switches V/sub pk/=V/sub in//2, capacitive turn-off snubbing, ZV turn-on

A new four-switch full-bridge dc-dc converter topology is especially well-suited for power converters operating from high input voltage: it imposes only half of the input voltage across each of the four switches. The two legs of a full-bridge converter are connected in series with each other, across the dc input source, instead of the usual topology in which each leg is connected across the dc source. The topology reduces turn-off switching losses by providing capacitive snubbing of the turn-off voltage transient, and eliminates capacitor-discharge turn-on losses by providing zero-voltage turn-on. (Switching losses are especially important in converters operating at high input voltage because turn-on losses are proportional to the square of the input voltage, and turn-off losses are proportional to the input voltage). The topology is suitable for resonant and nonresonant converters. It adds one bypass capacitor and one commutating inductor to the minimum-topology full-bridge converter (that inductor is already present in many present-day converters, to provide zero-voltage turn-on, or is associated with one or two capacitors to provide resonant operation), and contains a dc-blocking capacitor in series with the output transformer, primary winding, and some nonresonant converters (that capacitor is already present in resonant power converters). The paper gives a theoretical analysis, and experimental data on a 1.5-kW example that was built and tested: 600-Vdc input, 60-Vdc output at up to 25A, and 50-kHz switching frequency. The measured performance agreed well with the theoretical predictions. The measured efficiency was 93.6% at full load, and was a maximum of 95.15% at 44.8% load.     

带异形孔的双稳态压电能量采集器研究

针对传统线性压电悬臂梁能量采集器共振频率高、偏离共振频率时输出电压快速下降的问题,该文设计了一种悬臂梁基板上带异形孔的新型双稳态能量采集器。建立该能量采集器的理论模型,并制作了实验样机,研究了该能量采集器在外界不同正弦激振频率下,磁间距对其输出电压和工作频带的影响。结果表明,随着磁极对间距减小,带异形孔结构的双稳态能量采集器的双稳态效应先增强再减弱,由此确定最佳磁极对间距为12 mm,谐振频率为18 Hz,最大输出均方根电压达到12.01 V,采集器有效工作频率为15.5～22.5 Hz,工作带宽达到7 Hz,带异形孔的双稳态能量采集器具有更宽的采集频带,在低频振动环境下具有更高的输出电压响应。     

一种80 MHz隔离式DC-DC变换器

介绍了一种80 MHz隔离式DC-DC变换器,无芯PCB变压器实现了VHF隔离,利用交叉耦合电路和无芯PCB变压器形成持续振荡,采用肖特基二极管作为整流器件,电压反馈环路保证整个系统能够稳定输出。采用FEM和EDA软件实现了无芯PCB变压器的设计和整体电路的仿真。测试结果表明,该变换器能够提供3.3 V隔离电压输出和0.3 W功率输出,效率约为43%。     

Design of a 1-MHz LLC Resonant Converter Based on a DSP-Driven SOI Half-Bridge Power MOS Module

In this paper, the design of a 1-MHz LLC resonant converter prototype is presented. Aiming to provide an integrated solution of the resonant converter, a half-bridge (HB) power metal oxide semiconductor (MOS) module employing silicon-on-insulator technology has been designed. Such a technology, which is suitable for high-voltage and high-frequency applications, allows enabling HB power MOSFET modules operating up to 3MHz with a rated voltage of 400V. The power device integrates the driving stages of the high-side and low-side switch along with a latch circuit used to implement over-voltage/over-current protection. The module has been designed to be driven by a digital signal processor device, which has been adopted to perform frequency modulation of the resonant converter. By this way, output voltage regulation against variations from light- to full-loaded conditions has been achieved. The issues related to the transformer design of the LLC resonant converter are discussed, too. Owing to the high switching frequency experienced by the converter, 3F4 ferrite cores have been selected for their low magnetic power losses between 0.5 and 3 MHz and core temperatures up to 120degC. The resonant converter has been designed to operate in an input voltage range of 300-400V with an output voltage of 12V and a maximum output power of 120W. Within these design specifications, a performance analysis of the LLC converter has been conducted, comparing the results obtained at the switching frequencies of 500kHz and 1MHz. A suitable model of the LLC resonant converter has been developed to aid the prototype design.     

An Analysis of the ZVS Two-Inductor Boost Converter under Variable Frequency Operation

The two-inductor boost converter has been previously presented in a zero-voltage switching (ZVS) form where the transformer leakage inductance and the MOSFET output capacitance can be utilized as part of the resonant elements. In many applications, such as maximum power point tracking (MPPT) in grid interactive photovoltaic systems, the resonant two-inductor boost converter is required to operate with variable input output voltage ratios. This paper studies the variable frequency operation of the ZVS two-inductor boost converter to secure an adjustable output voltage range while maintaining the resonant switching transitions. The design method of the resonant converter is thoroughly investigated and explicit control functions relating the circuit timing factors and the voltage gain for a 200-W converter are established. The converter has an input voltage of 20V and is able to produce a variable output voltage from 169V to 340V while retaining ZVS with a frequency variation of 1MHz to 407kHz. Five sets of theoretical, simulation and experimental waveforms are provided for the selected operating points over the variable load range at the end of the paper and they agree reasonably well. The converter has achieved part load efficiencies above 92% and an efficiency of 89.6% at the maximum power of 200W     

A comparison of UPS for powering hybrid fiber/coaxial networks

Four distinct uninterruptible power supply topologies are presented here for powering hybrid fiber/coaxial (HFC) networks. Topologies based on a low frequency isolation transformer are found to have better efficiency than the topologies with high frequency transformer. However, the latter topologies have much better performance in terms of transient response, quality of the output voltage, input power factor, total harmonic distortion of the input current, size and weight. The series-parallel resonant based UPS topology is found to have best overall performance for the emerging HFC applications     

A contactless power transfer system using a series–series–parallel resonant converter

In this article, a contactless power transfer system using a series–series–parallel resonant converter (SSPRC) is proposed. The proposed converter can improve on or eliminate the disadvantages of the contactless system based on conventional resonant converters, since it independently compensates for a primary side leakage inductance, a secondary side leakage inductance and a magnetising inductance. The proposed converter also reduces the circulating currents and the reactive power by controlling the phase angle difference between the inverter output voltage and the current. In addition, the system design can be simplified, since the voltage gain is determined only by the transformer turns ratio for the overall load range without being affected by the other transformer parameters. The proposed converter is analysed with respect to the gain and current margin. The system design procedure is then described for the proposed circuit based on the circuit analysis. Finally, the experimental results are presented in order to verify the proposed contactless power supply.     

Analysis and design of electronic transformers for electric powerdistribution system

A transformer performs many functions such as voltage transformation, isolation and noise decoupling, and it is an indispensable component in electric power distribution systems. However, at low frequencies (60/50 Hz), it is a bulky and expensive component. In this paper, the concept of electronic transformers is further extended and explored for its suitability in power distribution systems. It should be noted that from the input/output behavior, the electronic transformer and the conventional transformer are identical. Possible topologies employing static converters connected on the primary and secondary sides are explored to realize high-frequency operation of the magnetic core. To assist the commutation process, a four-step switching has been developed which does not require the use of snubbers. Reduced size, losses, higher efficiency, and better voltage regulation are some of the advantages of this approach. A 10 kVA design example along with experiment results are discussed. It is shown that a transformer designed with a conventional grain-oriented silicon-steel core can process three times the power at 1 kHz operating frequency as compared to 60 Hz. The proposed method is scalable in voltage/current with the currently available insulated gate bipolar transistor (IGBT) devices connected in series without special snubbers     

High-power-factor electronic ballast with constant DC-link voltage

This paper presents a high-power-factor (HPF) electronic ballast based on a single power processing stage with constant DC-link voltage. The switching frequency is controlled to maintain the DC-link voltage and the voltage across the switches constant, independently of changes in the AC-input voltage. This control method assures zero-voltage switching (ZVS) for the specified AC-input-voltage range. Besides, with an appropriate design of the fluorescent lamps' drive circuit, the lamps' power can be kept close to the rated value. The power-factor-correction (PFC) stage is formed by a boost power converter operating in the discontinuous conduction mode, which naturally provides HPF to the utility line. The fluorescent lamps are driven by an unmodulated sine-wave current generated from an LC parallel resonant power converter which operates above the resonant frequency to perform ZVS. Theoretical analysis and experimental results are presented for two series-connected 40 W fluorescent lamps operating from 127 V -15% to +10% 60 Hz utility line. The switching frequency is changed from 25 to 45 kHz to maintain the DC-link voltage regulated at 410 V, which leads to a constant output power. The experimental results confirm the high efficiency and HPF of this electronic ballast     

高重复率小型准分子激光开关电源设计

设计了一种用于高重复率准分子激光器的正弦恒流型高压开关电源,逆变主电路采用串联谐振回路,输出电压10kV至15kV,重复率1Hz至300tk。分析了逆变回路工作情况,介绍了变压器的参数计算方法和所采取的抗电磁干扰措施。电源体积小巧,运行稳定。经改进可使重复率提高到600Hz。     

Asymmetrical pulse-width-modulated resonant DC/DC convertertopologies

This paper presents asymmetrical pulse-width-modulated (APWM) DC/DC resonant converter topologies that exhibit near-zero switching losses while operating at constant and very high frequencies. The converters include a bridged chopper to convert the DC input voltage to a high-frequency unidirectional AC voltage, which in turn is fed to a high-frequency transformer through a resonant circuit. The bridged chopper has two switches that alternately conduct. The duty cycles of the conduction of the switches are complementary with one another and are varied to control the output voltage. Three resonant circuit configurations suitable for this type of control are presented. Frequency domain analysis of the converter is given, and performance characteristics are presented. Experimental results for a 48-5 V, 30 W converter show an efficiency of 88% at a constant operating frequency of 1 MHz     

A high voltage resonant inverter for dielectric discharge barrier cell plasma applications

Among the applications of dielectric barrier discharge cells (DBDCs), the generation of cold plasmas for the degradation of toxic organic compounds has received a great deal of attention in recent years. Normally, a DBDC can be energized by means of a high voltage power supply operating at line frequency. In this paper, the analysis, design and construction of a power resonant seriesinverter is presented; this inverter is aimed to operate at high-voltages/high-frequencies, and its suitability to excite a DBDC is investigated. The topological analysis of the inverter is carried out using the fundamental approximation technique, where the DBDC has been modelled as a capacitor whose terminals' voltage is provided by a pulse transformer. Both, the DBDC and the pulse transformer are represented in an RLC equivalent circuit. The resonant inverter is designed to operate in a region where the transfer function is load dependent. The series resonant inverter performance has been experimentally tested in a DBDC application, showing its effectiveness in the generation of the electron discharge by means of a charge/voltage figure of merit.     

Design of LCL-T Resonant Converter Including the Effect of Transformer Winding Capacitance

The transformer winding capacitance, which is significant in high-voltage power supplies, is not gainfully utilized in an LCL-T resonant converter (RC). A simplified analysis presented in this paper predicts the severe degradation of output current regulation of an LCL-T RC due to transformer winding capacitance. The presence of winding capacitance, in fact, changes the third-order LCL-T resonant tank into fourth-order LC-LC topology. Using an AC analysis, it is shown that, under the derived design conditions, LC-LC RC also exhibits constant output current and in-phase source voltage and current, simultaneously at all loading conditions. Thus, the transformer leakage inductance and winding capacitance are gainfully utilized as a part of a resonant network, resulting in improved output characteristics. Closed-form expressions for the converter gain and component stresses are derived. The condition for converter design optimized for the minimum size of the resonant network is obtained. Experimental results on a prototype 100-mA 2-kV DC power supply confirm the observations of analysis.     

小型风力发电系统正弦波逆变器设计

为了提高小型风力发电系统输出电能质量,设计了高效、可靠、低成本的正弦波逆变器。主电路由推挽升压变换器和单相逆变桥组成,采用高频变压器实现电压比调整和电气隔离,降低了噪声,提高了效率、减小了输出电压纹波。逆变器功率开关管采用了RCVD缓冲电路,确保逆变桥安全工作。控制部分采用集成脉宽调制芯片SG3524和正弦函数发生芯片ICL8038实现正弦波脉宽调制(SPWM),简单可靠、易于调试。实验样机体积减小到传统逆变器的1/4,效率达到86%。实验结果表明输出电压波形失真度小于5%,在复杂的工况下实现了220 V/50 Hz的市电输出。     

行波管高压电源中变压器的优化设计

研究了行波管高压电源中变压器的铁芯损耗、绕组损耗(铜损)和工作频率,主要通过理论推导和仿真对磁性元件的设计进行了优化分析,并用PC95材质PQ40/40磁芯设计了一种输出电压10kV、输出功率450 W的行波管高压电源变压器。变压器设计结果满足电源要求,实验结果验证了理论分析。     

Calibration Technique for Maximum Power Harvest of Passive Wireless Microsystems

A calibration technique for maximizing radio-frequency power harvest of passive wireless microsystems with a step-up transformer is proposed. We show that both the impedance and resonant frequency of the step-up transformer matching network can be adjusted by varying the capacitance of a shunt varactor placed at the secondary winding of the transformer to maximize power transfer from the antenna to the transformer and the output voltage of the transformer subsequently the power efficiency of the voltage multiplier. A low-power current-mode tuning technique and a maximum peak amplitude detection technique to allocate the optimal tuning capacitance at which the maximum power harvest exists are introduced. The transformer matching network has been designed in IBM CMRF8SF 130-nm 1.2-V CMOS technology, and its performance is validated using both simulation and on-wafer measurement results.     

LLC谐振半桥变换器的设计

LLC谐振半桥变换器可以在全电压范围内、全负载条件下使得初级端 MOSFET实现ZVS（零电压开关）,次级整流二极管实现ZCS（零电流开关）,减少了开关损耗,大大提高了效率。而且在输入电压和负载范围变化比较大的情况下,其开关频率变化较小,有利于主参数的设计。这种变换器通常应用在高频功率变换领域。文中首先使用 FHA（基波近似原理）进行 LLC谐振半桥变换器的建模,然后分析了如何对变换器中的电气参数进行选择,最后设计了一个工作在70~150 kHz频率下300 W的 LLC谐振变换器。