驱动回路参数对碳化硅MOSFET开关瞬态过程的影响

在电力电子系统中,碳化硅(Si C)MOSFET的开关特性易受系统杂散参数的影响,表现为电磁能量脉冲形态属性的非理想特性,并进一步影响系统效率和可靠性。针对Si C MOSFET,首先分析控制脉冲、驱动脉冲及电磁能量脉冲三者间形态属性的关系,提取影响Si C MOSFET开关瞬态过程的关键参数,即开关过程中的dv/dt和di/dt。基于Si C MOSFET的开关过程,分析驱动回路参数对dv/dt和di/dt的影响,并通过PSpice仿真及搭建Si C MOSFET双脉冲测试实验平台进行分析和比较。在此基础上,对基于驱动回路参数的瞬态控制方法进行对比分析,为实际应用中对Si C MOSFET的开关特性改善提供重要的理论基础。     

选择供电方案对供电损耗的影响

针对不同的用户提出了几种不同的供电方案.在电压等级的选择上,尽量选用高一级电压,避免低电压损耗.对用户供电设计宜高压引入,若需要增设变电所,应选好位置.低压系统尽可能采用三相四线制,选择合理的供电半径.     

开关电源模块并联供电系统

基于C8051F005单片机设计实现开关电源并联模块供电系统.系统由两块DC-DC模块并联而实现.每个DC-DC模块额定输出功率为16W,系统的额定输出功率达36W.输出电流在0.5～4.4 A范围内变化时,单个DC-DC模块经扩流后输出电流可以达到0.5～3.5 A任意可调,两个DC-DC模块电流按任意指定比例自动分配电流.电流分配方法采用主从均流法,控制精度很高,电路简单,效率高.经过测试,系统效率可达78％,并具有负载短路保护功能.系统DC-DC模块使用雕刻机制板,提高稳定性和抗干扰能力.     

Induction motor drives with minimal power losses

The goal is to synthesize a control system for an induction motor such as to ensure operation with minimal power losses. Standard nonlinearity and losses in the steel of the motor’s stator are taken into account in MatLab simulation. The proposed control system reduces the losses by up to 25% in comparison with classical scalar control.     

电力通信系统1+1交换方案

如何建设一个适应电力系统特点的优质交换网络是值得探讨的话题，文中重点描述了江苏省电力通信网络改造所应用的1 1交换方案实例，提出了网络分层建设的必要性和优势，针对该方案在电力通信网络的使用进行了深入探讨，客观地分析了其对于电力通信系统的优势，并进一步考虑到NGN网络的演进问题，提出建设具备向下一代网络演进的交换网络的建议。     

电缆线圈功率损耗的数值计算

本文建立了由交联聚乙烯（XLPE）电缆绕制成线圈的有限元模型，对线圈在有或无附设钢板时电缆线圈的功率损耗进行了计算，得到了该线圈的交流等效电阻及其与电源频率、钢板特性参数等的关系，为以固体绝缘为基础和电力设备研究打下了基础。     

一种基于UC3842的新型开关稳压电源设计

设计了一种以电流型PWM控制器UC3842芯片为核心的高频单端反激式开关稳压电源.基于信号流程和电路功能模块划分,利用三端稳压器TL431配合新器件UC3842实现了对电源电压的控制和稳压输出.分析了新型开关电源的设计原理、各组成模块的功能以及工作过程.为了满足设计电源的电磁兼容性和安全性要求,设计利用低通滤波扼制了传导干扰,采用光耦器件PC817实现了输入/输出的隔离和反馈,并在电源电路中加入了热敏电阻、压敏电阻以及过压、过流保护等保护措施.实验测试结果表明:所设计的电源具有稳压性能优良,纹波小,电压调整率、负载调整率高等优点.     

Modeling of hysteresis and power losses in transformer laminations

In this paper, a method for the representation of hysteresis and power losses in the laminations of power transformers is proposed. The developed model is based on data supplied from steel manufacturer and able to predict hysteresis and eddy current losses.     

Impacts of material parameters on breakdown voltage and location for power MOSFETs

Journal of Computational Electronics - To improve the electrical performance of power devices, materials used in fabrication need to be analyzed and optimized. By numerical simulations, we reveal...     

Approximating the system losses equation [power systems]

A methodology that develops a quadratic equation to express power system losses based on hourly system loads, transformer no-load loss data, and corona loss data is presented. The data are readily available, often from a utility's Federal Energy Regulatory Commission (FERC) Form 1. Correct application of the equivalent hours loss factor is required by the methodology. A specific utility was selected, data were derived, and an equation developed and verified. This entire procedure is documented here     

3D finite-element determination of stray losses in power transformer

This paper presents a three-dimensional (3D) finite-element (FE) analysis of eddy current losses generated in the tank walls and yoke clamps of a three-phase 40 MV A power transformer. The time harmonic FE model is used to compute the magnetic leakage field in the case of a short circuit condition of the power transformer. Three cases are analyzed to study the impact of modeling tank walls and yoke clamp plates in FE context in estimation of their losses. The load loss test was carried out on an experimental transformer to validate the simulation.     

Switching as means of control in the power system

Many switching operations have been classified as unfavourable from the system point of view. However, an alternative view can also be taken. The effects of switching are described and ways in which these can be used as a means of control are outlined. An approach to modelling the switching operation is presented, including an explanation of the objective, constraints and search techniques involved. Several illustrative examples are presented.     

The compact d.c. electrothermal model of power MOSFETs for SPICE

This paper concerns the problem of modelling of power MOS transistors in SPICE. In the paper the new form of the electrothermal d.c. model (ETM) of the considered class of power devices is proposed. The ETM is based on the modified Shichman–Hodges model, in which the generation current, the breakdown voltage, the sub‐threshold region, the thermally dependent series resistances and self‐heating are included. The device inner temperature calculated from the thermal model is the sum of the ambient temperature and the product of the electrical power dissipated inside the device and its thermal resistance. The presented model has been verified experimentally. The results of calculations and measurements of MTD15N06V (ON Semiconductor) and IRF840 (International Rectifier) transistors are given as well. Copyright © 2009 John Wiley & Sons, Ltd.     

电压调节和无功补偿技术在城市配电网中的降损作用

结合揭阳老市区10kV配电网络的实际，着重阐述电压调节和无功补偿在城市配电网改造中节能降损的重要作用，提出配电网调节和无功补偿的方法，并指出当前城网改造中应大力应用电压调节和无功补偿技术。     

基于电流叠加法的网损分摊算法

提出基于线性电路叠加原理的功率贡献计算方法，用各电源共同作用时的负载电压与单独作用时的负载电流的乘积表示电源对负载的功率贡献，并用这种方法解决电力市场中的网损分摊问题。用电源共同作用时的线路压降和单独作用时的线路电流的乘积计算各个电源在各条支路上引起的网损，计算系统网损在各个电源中的分摊。根据电源对负荷的功率贡献因子计算电源和负荷分别承担网损及它们按比例承担时的系统网损分摊。该方法原理简明、计算量小、方便灵活、合理性强。以IEEE-14节点系统为例进行仿真计算，验证了该方法的合理性。     

Underlying design advantages for GaN MOSFETs compared with GaN HFETs for power applications

This study investigates the underlying reasons and quantifies the advantages the GaN MOSFET has over the GaN HFET for high voltage and power applications. Calibrated simulations with equivalent material model files show that equivalent dimensioned devices are capable of producing similar on-state modes of operation, and achieve similar effective mobility at equivalent larger electric fields. However, during sub-threshold operation, the GaN MOSFET is shown to contain a much lower carrier concentration than the GaN HFET. This prolongs the breakdown avalanche effect in the GaN MOSFET (3500 V) by roughly five times larger than the GaN HFET (600 V) for devices of similar dimensions. Implementing the MOS structure can potentially resolve fundamental constraints for high voltage power applications caused by current device architects.     

高频开关变换器中EMI产生的机理及其抑制方法

开关电源电磁干扰大,影响电子设备的性能。本文从开关电源的电路结构和器件分析产生电磁干扰的原因,并给出了一些抑制措施。     

输电网理论损耗计算的改进方法

电网能量损耗率是电力企业的一项重要综合性技术经济指标,反映了电力网的规划设计、生产技术和运营管理水平,因此理论损耗计算对于生产和管理具有重要的指导意义。目前基于潮流计算的输电网理论损耗计算方法已应用得十分广泛,但实际的操作过程中还存在诸多问题。针对这些问题利用现有的技术手段,就如何提高计算结果的准确性对整个计算过程进行了完整分析,在设备信息的管理方式、原始数据的预处理和计算理论的合理性等几方面提出了改进方法,以期提高输电网理论计算结果的实用性,为实现生产管理的精细化提供可靠的支持。     

输电网理论损耗计算的改进方法

电网能量损耗率是电力企业的一项重要综合性技术经济指标,反映了电力网的规划设计、生产技术和运营管理水平,因此理论损耗计算对于生产和管理具有重要的指导意义.目前基于潮流计算的输电网理论损耗计算方法已应用得十分广泛,但实际的操作过程中还存在诸多问题.针对这些问题利用现有的技术手段,就如何提高计算结果的准确性对整个计算过程进行了完整分析,在设备信息的管理方式、原始数据的预处理和计算理论的合理性等几方面提出了改进方法,以期提高输电网理论计算结果的实用性,为实现生产管理的精细化提供可靠的支持.     

脉宽调制波形励磁磁芯损耗的直流功率测量法

介绍和分析了脉宽调制波形励磁下磁芯高频损耗的新测量方法——直流功率测量法的基本原理、误差构成、定标以及上位机实现,并实际测试对比了正弦波形和脉宽调制波形励磁下磁芯损耗的差异。通过合适的定标方法可以有效消除直流功率测量法的杂散损耗,提高测量精度。提出了定标模型以及定标的具体方法和注意点,结合DSP控制上位机的自动数据处理,得出了定标模型的各个参数。实验验证直流功率测量法及其定标方法有较好的工程应用精度。