A low-profile power converter using printed-circuit board (PCB)power transformer with ferrite polymer composite

A new design of low-cost and low-profile power transformer is presented in this paper. The manufacturing cost of a power transformer can be reduced using the proposed printed-circuit board (PCB) transformer. The transformer windings are etched on the opposite sides of a double-sided PCB. Self-adhesive ferrite polymer composite (FPC) sheets are stuck on the two PCB surfaces to shield the magnetic flux induced from the transformer windings. The PCB transformer does not require manual winding and bobbin. A power converter prototype employing the PCB transformer has been implemented. The technique of choosing the optimum switching frequency of the power converter using the PCB transformer is addressed in this paper. The maximum power delivered from the prototype is 94 W. The maximum efficiency of the power converter is 83.5%     

级联型电力电子变压器控制策略研究

电力电子变压器是一种新型的电能转换工具,它可以利用电力电子转变技术来实现传统变压器的功能.基于此,本文对级联型电力电子变压器进行了简单的研究,并根据其自身特点制定对应的控制策略.     

有源电子式电流互感器高压侧电源的研究

电流互感器是电力系统中的重要设备,介绍一种适用于有源电子式电流互感器的悬浮式直流电源的设计原理。提出一种用补偿线圈和充电电池相结合的方法对母线电流取能方式进行改进的新方案,使电源在更宽的一次侧电流动态范围内满足电子式电流互感器对电源的要求。实验结果表明,该电源能够满足高压侧电子电路的供能要求。该方法是目前解决有源电子电流互感器高压侧电源问题的有效方法之一。     

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     

A novel active power quality compensator topology for electrified railway

To improve the power quality of traction power system, a novel active power quality compensator (APQC) and a new compensating currents detection method are proposed. The APQC consists of a three-phase voltage source converter and a Scott transformer. The Scott transformer, taken as an isolation transformer, not only connects the three-phase converter to the traction power system, but also converts the traction power system to a nearly balanced three-phase power system. Therefore, a general three-phase converter could be used in APQC. Regarding the traction substation as a compensating object, the power quality of a traction substation can be improved integrally. Simulation and prototype experimental results show that the proposed APQC is able to compensate reactive power, harmonic, and negative-sequence currents in two feeders of a traction substation.     

A fully integrated 2.4 GHz CMOS high power amplifier using parallel class A&B power amplifier and power-combining transformer for WiMAX application

A new structure integrated power amplifier with watt-level output power is presented in a standard 0.18 μm CMOS process for WiMAX applications. A parallel cascode class A&B power amplifier with optimized widths is proposed to increase linearity and efficiency simultaneously. A novel interleaved PCT power combiner is proposed for increasing output power that combines output current of two similar class A&B power amplifiers. Proposed interleaved transformer heightens coupling factor compared to typical transformer.     

Big Data-Based Transformer Substation Fault Prediction Method

Transformer substations play a major role in power systems. The fault of a transformer substation will jeopardize the safety and effective operation of the power system. The fault signal of a transformer substation includes the fault status and fault occurrence time. In this paper, we propose a transformer substation fault prediction method based on big data analysis. Thus, a new transformer substation fault prediction method is developed by combining the advantages of decision tree algorithms and grey system theory to predict the fault status and occurrence time with high accuracy. As a case study, the transformer substation fault signals obtained from a region in the southwest of China are analyzed using the proposed method based on big data. The experimental results confirm that the proposed method achieves high-accuracy fault prediction.     

Zero-voltage and zero-current switching full bridge DC-DC converterfor arc welding machines

A new zero voltage and zero current switching (ZVZCS) full bridge DC-DC converter with transformer isolation is proposed for arc welding machines. The proposed DC-DC converter uses an auxiliary transformer to obtain ZCS for the leading leg, which provides load current control capability even under short circuit conditions. The power rating of the auxiliary transformer is ~10% or more of the main transformer. The operation is verified by experiments     

A 21 GHz Complementary Transformer Coupled CMOS VCO

A new topology for low power voltage controlled oscillators (VCOs) using a 0.18-mum CMOS foundry process is presented in this letter. From the measured results, the VCO exhibits a tuning range of 3% at 21.3 GHz. Using complementary topology, the core power consumption and the output power are 9.6 mW and -3 dBm, respectively. With the broadside coupled transformer, the VCO achieves a good phase noise of -106 dBc/Hz at 1 MHz offset and a compact chip size of 350 times 470 mum². It is the first time that the broadside coupled transformer approach is applied to transformer coupled CMOS VCOs.     

径向振动压电变压器的等效电路模型及特性研究

本文使用线性压电方程并结合相关的弹性理论对目前国际上刚刚出现的径向振动压电变压器进行了分析和研究,导出了该压电变压器的等效电路模型,并根据电路模型得出径向振动压电变压器的输入阻抗、输出阻抗、升压比、输出功率及效率等特性的数学表达式.文中通过实验对上述特性加以验证,实验结果与理论计算值基本一致,说明本文给出的径向振动压电变压器等效电路模型及其各种特性的数学表达式是正确的.     

电子电力变压器在光伏发电系统中的运用分析

随着社会经济的不断发展,人们对于电力能源的需求量逐年上涨,传统的化石能源,由于其储量有限,且应用过程中会对环境产生较严重的影响,故应用和开发新能源势在必行.光伏发电是一种用可再生性的清洁能源,通过电子电力变压器接入微电网中,使其具备了一定的事故运行能力,并增强了系统的稳定性和安全性.文章对电子电力变压器在光伏发电系统中的运用进行了分析.     

高保真电子管功放输出变压器的精确设计计算法

hi-end电子管功放音质优美绵厚,影响其音质的关键部件是输出变压器的电声性能,成为系统的喉舌。提出了一个新的方法,改变了以往粗略的估算法,使设计计算更合理﹑更科学﹑更实验化,成功解决了设计制造输出变压器的关键问题。     

Single-stage single-switch PFC converter with low output voltage

A new type of single-stage single-switch converter with low output voltage and power factor correction is proposed. The lower turns ratio for the isolation transformer is the main feature. The proposed converter is suitable for designing high efficiency, high power factor and low cost power supplies for new generation high-speed integrated circuits     

Forward converter regulator using controlled transformer

A new control scheme is proposed for a forward power converter regulator using a controlled transformer. Pulse width modulation (PWM) control is used to reset the control core of the controlled transformer. As a result, a low-cost ferrite core can be used for the controlled transformer to achieve good regulation and high efficiency. Overall efficiency of 82-86% is achieved in a 200 kHz, 500 W, 5 V output regulator. A PWM-controlled transformer regulator is particularly suited for high-output-current and/or high-output-voltage postregulator applications     

非接触式弱电实验供电平台的设计

非接触式弱电实验供电平台是一种新型非接触式电能供应系统,通过电磁感应耦合,实现非接触式能量传输,为负载提供电能。整个系统主要由电能转换、耦合变压器和能量调节三部分组成。电能转换主要完成能量逆变;耦合变压器将逆变后的能量耦合到用户端;能量调节主要为提高耦合到用户端能量的传输能力。该平台克服了传统导线多点接触式电能传输方式的不可靠和不可迁移等缺点,为移动电气设备、易燃易爆环境和水下设备的能量供给提供便捷、安全的解决方案。     

A zero-voltage and zero-current switching full bridge DC-DCconverter with transformer isolation

A new primary-side-assisted zero-voltage and zero-current switching full bridge DC-DC converter with transformer isolation is proposed. The proposed DC-DC converter uses only one auxiliary transformer and two diodes to obtain ZCS for the leading leg. It has a simple and robust structure, and load current control capability even in short circuit conditions, The possibility of magnetic saturation due to asymmetricity of circuits or transient phenomena is greatly reduced, which is a very attractive feature in DC-DC converters with transformer isolation. The power rating of the auxiliary transformer is about 10% of that of the main transformer. Operation of a 12 kW prototype designed for welding application was verified by experiments     

浅谈斗轮机本体控制变、动力变开关控制回路的可靠性

本文将结合枣泉电厂DCS控制就地控制变、动力变开关的案例,分析如何提高斗轮机本体控制变、动力变开关控制回路的可靠性。     

电力变压器油色谱在线监测装置的应用及装置故障分析

电力变压器是电力系统中最关键的设备之一,变压器的正常运行是对电力系统安全、可靠、优质、经济运行的重要保证,应用油色谱在线监测装置,使得电力变压器的持续不间断的油色谱分析得以实现,可早期预测设备内部存在的故障,为电力变压器的安全运行提供了很好的保障。     

Coreless printed circuit board (PCB) transformers with multiplesecondary windings for complementary gate drive circuits

This paper describes the modeling and implementation of a coreless printed circuit board (PCB)-based transformer with “multiple” secondary outputs. This new PCB transformer has been successfully applied in complementary gate drive circuits in a novel low-profile power converter with high-power density and a converter bridge. The PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. The use of the multiple secondary outputs can in principle simplify the complementary gate drive circuits that are often required in many power electronics applications     

Reaching High Power Density in Multikilowatt DC–DC Converters With Galvanic Isolation

In this paper, the possibility of reaching high power densities in multikilowatt dc-dc converters with galvanic isolation is demonstrated and the main design issues are discussed. The issues related to converter topology, transformer design, and thermal management are addressed, and new conceptual solutions are proposed. Implementing zero-voltage-switching quasi-zero-current-switching topology, optimized transformer design with leakage layer, and thermal management based on conduction enhanced by heat pipes at critical places resulted in very high power density and efficiency. The power density reached by the converter prototype is 11.13 kW/L with water cooling and 6.6 kW/L with air cooling. In the same time, the measured efficiency exceeded 97% in a broad load range. The new design concepts are demonstrated on a 50-kW converter prototype that was successfully tested at full-load conditions.