Analysis and design of an LCL-T resonant converter as a constant-current power supply

An LCL-T resonant converter (LCL-T RC) is shown to behave as a current source when operated at resonant frequency. A detailed analysis of the LCL-T RC for this property is presented. Closed-form expressions for converter gain, component stresses, and the condition for converter design optimized for minimum size of resonant network is derived. A design procedure is illustrated with a prototype 200-W 20-A current-source power supply and experimental results are presented. The LCL-T RC as a current source offers many advantages such as easy parallel operation and low circulating currents at light load. Additionally, with appropriate phase shift in paralleled modules, the peak-peak ripple in output current is reduced and the ripple frequency is increased, reducing filtering requirements. The leakage inductance of a transformer can be advantageously integrated into the resonant network. These merits make the topology applicable in various applications such as magnet power supply, capacitor charging power supply, laser diode drivers, etc.     

High static gain single-phase PFC based on a hybrid boost converter

In this paper, a single-phase unity power factor rectifier, based on a hybrid boost converter, resulting from the integration of a conventional dc–dc boost converter and a switched-capacitor voltage doubler is proposed, analysed, designed and tested. The high-power rectifier is controlled by two feedback loops with the same control strategy employed in the conventional boost-based rectifier. The main feature of the proposed rectifier is its ability to output a dc voltage larger than the double of the peak value of the input line voltage, while subjecting the power switches to half of the dc-link voltage, which contributes to reducing the cost and increasing the efficiency. Experimental data were obtained from a laboratory prototype with an input voltage of 220 Vrms, line frequency of 60 Hz, output voltage of 800 Vdc, load power of 1000 W and switching frequency of 50 kHz. The efficiency of the prototype, measured in the laboratory, was 96.5% for full load and 97% for half load.     

智能野战万用电源变换器

介绍一种基于单片机的智能野战万用电源转换器的原理.该电源转换器能适应多种环境电源的输入,而输出稳定可靠的交流220V电压.     

A capacitor charging power supply utilizing a Ward converter

A prototype capacitor-charging power supply (CCPS) that utilizes a Ward converter is presented. This converter is a member of the family of resonant converters and is capable of zero-current switching. It is applicable to capacitor charging because of its inherent short-circuit protection and its insensitivity to the value of the load capacitance. The converter is controlled using a constant on-time constant frequency scheme that allows the utilization of zero-current switching techniques. The prototype CCPS is capable of charging various values of load capacitors up to 1000 V DC. Waveforms that show single- and repetitive-charge operation of the CCPS are presented     

Three-phase AC-to-AC series-resonant power converter with a reducednumber of thyristors

Power pulse modulation with internal frequencies of tens of kHz and suited for multikilowatt power levels is applied to a series-resonant converter (SRC) system for generating synthesized multiphase bipolar waveforms with reversible power flow and low distortion. The high pulse frequency allows the application of the principle of modulation and demodulation for fast system response. The use of an SRC for power transfer and control obtains natural current commutation of the thyristors and the prevention of excessive stresses on components. Switches with bidirectional current conduction and voltage blocking ability are required. The conventional series-resonant AC-AC converter applies a total for 24 antiparallel thyristors. An alternative circuit configuration for the series-resonant AC-AC converter with only 12 thyristors is presented. Use of the converter results in a higher efficiency and lower costs     

Phase-staggering control of a series-resonant DC-DC converter withparalleled power modules

A method of decreasing the ripple on the output voltage of high-power AC-DC or DC-DC series-resonant converters without increasing the internal converter frequency or the capacity of the energy storage elements is discussed. This improvement is accomplished by subdividing the converter into two or more series-resonant power modules operated with a constant relative phase shift (phase-staggering control). The method of eliminating the harmonic components in the input and output currents of the conversion system, without increasing the internal pulse frequency, is justified by Fourier analysis of the current waveforms. The frequency spectra of the source and output waveforms for the continuous and discontinuous resonant current mode are shifted to higher frequency ranges, as computations show for both one single module and multiple paralleled modules. Inadequacies in the phase-staggering control method applied to series-resonant converters are indicated in relation to the dominant harmonic component, in particular for two modules and supported by experimentally acquired waveforms. High-frequency current components to the source and to the load are reduced. Resulting in smaller input and output filters. This improves the resolution of the control of the flow of energy from the source to the load, resulting in a faster system response     

Comment, with reply, on `Analysis of a static power converter underunbalance: a novel approach' by P. N. Enjeti and P.D. Ziogas

The commenter argues that the expressions obtained in the above-named work (see ibid., vol.37, no.1, pp.91-93, Feb. 1990) by P.N. Enjeti and P. D. Ziogas for the harmonics of the output voltage are in error. Certain modifications of the formulas presented by Enjeti and Ziogas are suggested. An authors' reply is presented     

A compact DC-to-DC power converter for distributed power processing

The authors present a compact (55-W/in³), efficient (86% power train), 1-MHz switch-mode, DC-to-DC power converter contained in a 2-in by 2-in by 0.25-in, 1-in³ package. They describe the interleaved forward topology, steady-state analysis, switch transitions, capacitor substrate, planar printed-wiring-board transformer, packaging, electrical performance, power loss analysis, thermal analysis, reliability, and efficiency and power density improvements     

Fuel cell power system and high power DC-DC converter

This paper discusses the principle and electrical characteristics of the fuel cell, designs an innovative hybrid power system, and proposes a new DC/DC converter scheme to combine the fuel cell with the storage system. An effective converter scheme for the fuel cell is obtained by analyzing the high efficient topology as well as the phase shifted pulse-width modulation. Through comparing several different control modes of converters, a 75-kW prototype system is constructed, moreover, which steady-state operating characteristics are illustrated and discussed in detail. At last, experimental results are also shown to verify the proposed scheme.     

New high power, high performance power converter systems

A new, high performance, low cost power converter system architecture is proposed. The system consists of a main converter and a multifunctional load conditioner. The main converter deals with most of the power flow running at a low switching frequency. The load conditioner is designed at a much lower power level running at a high-switching frequency. The load conditioner can (1) act like a current source and inject harmonic currents required by the load; (2) act like an active resistor to provide damping to the main converter; and (3) for three-phase inverters, decouple the coupling sources in the main inverter model in the rotating coordinates to make the control loop design for the main inverter much easier. The concept has been proved by simulation and experimental results on a 150 kW high performance three-phase utility power supply prototype. The proposed system configuration can be used in high power DC-DC converters, inverters, PFC and UPS applications     

模块化多电平静止无功补偿器控制策略研究

随着多电平逆变器在电力系统无功功率补偿领域的广泛应用,提出了一种基于模块化多电平( MMC)技术的新型静止无功补偿器( STATCOM)的拓扑结构。该拓扑结构具有模块化程度高、可靠性好、便于维护及容量拓展等特点,是一种极具发展潜力的拓扑结构。首先对MMC-STATCOM的工作原理和数学模型进行了分析,提出了无功功率解耦控制策略以及提出了一种新的控制子模块电容电压平衡的控制算法。仿真和测试结果均表明MMC-STATCOM具有补偿效果好,动态响应速度快等优点,是一种具有工程应用价值的大容量STATCOM主电路拓扑。     

大屏幕LCD背光照明的控制方案

近来,CTV产品中的LCD屏幕尺寸越来越大,已经超过40英寸。由于屏幕尺寸的增大,CCFL的数目及其驱动电路也有所增加。目前有很多种方法将CCFL置于大型LCD屏幕的背面,以便为整个屏幕提供背光照明。     

A high-efficiency regulation technique for a zero-voltagezero-current power switching converter

This paper describes the application of a new regulation technique to a resonant converter that features zero-voltage (ZV) and zero-current (ZC) switching and works at constant frequency and duty cycle. The regulator utilizes the concept of regulating only a percentage of the total power in a bidirectional manner, thus allowing the converter to be optimized for both mass and efficiency. The proposed regulation technique has a wide range of applicability to almost all types of power converters or inverters that utilize a transformer to produce an isolated output. By using the concept of addition or subtraction of AC voltages, a fully regulated output voltage is achieved. The resultant effect of this regulation technique is that the main transformer of the converter or inverter appears to have a variable turns ratio. This turns ratio can be changed dynamically and in almost a lossless way to maintain the converter (or inverter) regulation. This technique can be used most effectively when input-voltage variation is limited to a reasonable tolerance range (e.g., + or -25%)     

An adaptive digital controller for a unity power factor converter

This paper describes an adaptive digital controller for a unity power factor AC-DC power converter. The controller is based on a linear large-signal model of the boost power converter. A hardware design is presented and analyzed, followed by the software implementation of the control algorithm. Issues in digital control of power converters, such as quantization effects and fixed-point representation of system parameters, are examined in the context of this system. Experimental results are presented and compared with simulations     

User-friendly dedicated power electronic converter simulator

A user-friendly power electronic simulator for the design and analysis of power electronic circuits is presented. A graphic input interface module called ATOSECG has been developed for the dedicated power electronic converter system simulator ATOSEC5. ATOSECG has tremendously facilitated the interaction of the user with the simulator. Examples of application of the ATOSEC5 simulator for the analysis of a complex multiconverter system are given     

Three-phase step-down reversible AC-DC power converter

Bidirectional DC current flow is not a natural feature of the buck (step-down) switch-mode rectifier, which leaves it at a disadvantage to boost (step-up) designs. A circuit topology is presented that allows bidirectional flow and which, by dual use of components, uses fewer devices than anti-parallel bridges. Sinusoidal current, controlled displacement factor, and variable voltage transfer ratio are demonstrated in a 1.5 kVA prototype. Dynamic performance is investigated through simulation and experiment. A PI plus velocity controller is shown to be adequate provided care is taken over changing between rectification and inversion     

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.     

有助于无线探头测量感应式电源的低功耗电压-频率转换器

为执行长期监视任务的便携式遥测系统供电．向人们提出了有趣的设计挑战。电池不适合于某些关键性应用，且在这些环境中，设计人员一般用无线感应链路来传输功率与数据。感应链路由一个驱动固定初级线圈的射频发射器与一个为便携式装置提供电源的松耦合次级线圈组成。对设计工程师来说．测量发射功率相当重要．因为它会限制设计人员可包含至便携式装置中的电路数量。但不幸的是，传统测试设备不适合执行该任务．     

Steady-state analysis of a series-resonant DC-DC converter with abipolar power flow

A time-domain analysis for the steady-state model of a series-resonant power interface for both step-up and step-down modes is presented. The exchange of electrical energy between a source and the resonant circuit in order to stabilize the stored electrical energy is defined. The characteristics of a series-resonant converter with bilateral power flow are presented in normalized form, described by the output characteristics. The results obtained in a four-quadrant motor drive illustrate the characteristics of a high-frequency power interface