上变频器原理与应用

本文对卫星广播电视地球站现使用的上变频器工作原理、设备组成、技术指标、实际使用和维护测试进行了全面的介绍,为本设备的日常运行维护提供了参考。     

电气传动中的变频器技术分析

阐述电气传动中变频器的使用功能与常见故障的特点。随着矢量控制技术的延伸,变频器的工作特性得到很大改善。探讨变频器的实际应用和发展趋势,电气传动中变频器的维护措施,包括监控温度环境、屏蔽干扰源、降低噪声、发挥变频器优点。     

变频器在神东集团各选煤厂的应用及问题

随着工业自动化程度的不断提高,变频器得到了非常广泛的应用。选煤厂应用了大量的变频器,主要控制皮带、泵类、风机类负载。变频器有很多种品牌,每个品牌都有很多种系列,因此在选型时对技术性能和经济指标进行综合考虑,合理的选择相应的变频器规格容量变得尤为重要。同时变频器及其附属设备的调试、日常维护及维修工作量较大,给选煤厂日常维护造成一定难度。本文针对变频器的以上问题,对现有变频器各品牌分析利弊,选择合理的变频器类型;又对现场的实际应用情况进行分析,从变频原理、应用环境、电网质量、使用维护等方面,对选煤厂变频器的常见问题分析并提出合理解决方法,最大限度的提高设备使用效率。     

浅谈煤气化装置K1301机组中压变频器的使用与维护

本文通过对中石化安庆分公司煤气化装置K1301激冷气压缩机组先后使用的西门子6SE80 MV中压变频器和罗克韦尔A-B PowerFlex7000中压变频器运行使用维护情况的比较,总结安装调试及检维修过程中的心得和经验,分析了中压变频器在使用过程中出现过的问题,并结合现场实际采取相应的解决措施。     

ABB-ACS800系列变频器实际应用问题研究

ACS800系列变频器是ABB公司新一代全数字高端交流变频器。本文未深究其理论和控制方法,而是通过祥实的实例和近似、简化的计算,浅显易懂地介绍了该系列变频器的四个主要特点,使现场维护、使用人员对该系列变频器有一个全面而直观的认识。     

变频器在纺织行业粗纱机电气控制系统应用分析

本文阐述了在纺织生产中粗纱机采用变频器进行变频调速的必要性，详细介绍了采用变频器的控制方法和实际工艺要求，给出了变频器在粗纱机自动控制系统的合理使用和维修维护中需注意的一些问题，对明电变频器在粗纱机电气控制系统中的应用情况做出了较为具体的分析。     

高压变频器日常维护

针对高压变频器在实际工业生产应用中的广泛应用,本论文对高压变频器的日常维护进行了深入探讨,首先简单分析介绍了高压变频器的内部结构组成和基本工作原理,在此基础上分析了高压变频器常见的故障及其原因,有针对性的分析了高压变频器在运行期间、停机期间的维护建议,并从日常维护和故障检修措施角度给出了具体的高压变频器的维护建议与执行措施,对于进一步提高高压变频器的日常维护和故障处理应用水平具有很好的指导借鉴意义。     

一种通用的变频器数据采集系统的设计

为了变频器生产调试和日常维护的需要,设计了一套适应现场复杂环境的数据采集系统。该系统数据采样周期短,数据采集量大,在实际应用中运行稳定可靠,数据记录准确详细,为生产调试和故障分析提供了大量极具价值的数据,成为变频器维护的。     

浅议高压变频器的日常维护技术

高压变频器在工厂生产实际中的应用非常广泛,本文在对高压变频器内部组成结构和工作原理进行论述的基础之上,分析了高压变频器常见故障的产生原因,并在此基础上对高压变频器运行以及停机期间的维护工作进行了总结,结合日常维护和故障检修两方面给出高压变频器的维护建议。     

变频器常见故障的处理及日常维护

本文介绍了变频器在使用过程中几种常见故障产生的原因和处理方法以及变频器的日常维护。     

LCL-T Resonant Converter With Clamp Diodes: A Novel Constant-Current Power Supply With Inherent Constant-Voltage Limit

The LCL-T resonant converter behaves as a constant-current (CC) source when operated at the resonant frequency. The output voltage of a CC power supply increases linearly with the load resistance. Therefore, a constant-voltage (CV) limit must be incorporated in the converter for its use in practical applications wherein the open-load condition is commonly experienced by a CC power supply, such as in an arc welding power supply. A novel LCL-T resonant converter with clamp diodes is proposed in this paper, which has built-in CC-CV characteristics. Since the CC-CV characteristics are inherent to the converter, and complex feedback control is not required, the proposed converter is rugged and reliable. The principle of operation of the converter is explained. Experimental results on a 500-W prototype are presented to demonstrate the inherent CC-CV behavior of the converter. Simple extensions of the topology featuring variable CV limits are described     

A 1-MHz Zero-Voltage-Switching Asymmetrical Half-Bridge DC/DC Converter: Analysis and Design

The asymmetrical half-bridge (AHB) topology discussed in this paper is one of the complementary driven pulse-width modulated converter topologies, which presents an inherent zero-voltage switching (ZVS) capability. In the previous work, the ideal operation of the converter and the ZVS realization process have been analyzed. However, the influence of the circuit parasitics on the output voltage drop and the design constraints of the circuit parameters to ensure the ZVS operation have not been investigated. The minimum load needed to ensure the ZVS operation is also not readily available. This paper presents a detailed and practical design for a 1-MHz AHB converter. A revised voltage transfer ratio of the converter is derived considering the influence of circuit parasitics and the ZVS transition. Two circuit parameters responsible for maintaining the ZVS operation are the transformer leakage inductance and the interlock delay time between the gate signals of two switches. A design method of the two parameters is proposed, which can ensure the ZVS transition. The possible ZVS range of the load variation is also investigated. A 50-W AHB converter with 1-MHz switching frequency was constructed, and a maximum efficiency of 91% was achieved.     

A high-power high-frequency ZCS-ZVS-PWM buck converter using afeedback resonant circuit

This paper presents a buck DC-to-DC power converter using a novel lossless commutation cell for high switching frequency and high power operation. The proposed cell consists of a main and auxiliary switches, with ZVS and ZCS switching characteristics, respectively. The power converter control using this cell is realized by the PWM technique, with constant switching frequency operation. The complete operation principles, theoretical analysis, relevant equations, state-space phase, simulation and experimental results for the buck converter are presented     

Resonant Contactless Energy Transfer With Improved Efficiency

This paper describes the theoretical and experimental results achieved in optimizing the application of the series loaded series resonant converter for contactless energy transfer. The main goal of this work is to define the power stage operation mode that guarantees the highest possible efficiency. The results suggest a method to select the physical parameters (operation frequency, characteristic impedance, transformer ratio, etc.) to achieve that efficiency improvement. The research clarifies also the effects of the physical separation between both halves of the ferromagnetic core on the characteristics of the transformer. It is shown that for practical values of the separation distance, the leakage inductance, being part of the resonant inductor, remains almost unchanged. Nevertheless, the current distribution between the primary and the secondary windings changes significantly due to the large variation of the magnetizing inductance. An approximation in the circuit analysis permits to obtain more rapidly the changing values of the converter parameters. The analysis results in a set of equations which solutions are presented graphically. The graphics show a shift of the best efficiency operation zone, compared to the converter with an ideally coupled transformer. Experimental results are presented confirming that expected tendency.     

A Monolithically Integrated 12V/5V Switch-Capacitor DC-DC Converter

A monolithically integrated 12V/SV switch capacitor DC-DC converter with structure-simplified main circuit and control circuit is presented. Its topological circuit and basic operating principle are discussed in detail. It is shown that elevated operating frequency, increased capacitance and reduced turn-on voltage of the diodes can make the converter's output characteristics improved. Reducing resistance of the equivalent resistors and other parasitic parameters can make the operation frequency higher. As a feasible efficient method to fabricate monolithically integrated converter with high frequency and high output power, several basic circuits are parallelly combined where the serial-parallel capacitance is optimized for the maximum output power. The device selection and its fabrication method are presented. A feasible integration process and its corresponding layout are designed. All active devices including switching transistors and diodes are integrated together with all passive cells including capacitors and resistor on a single chip based on BiMOS process,as has been verified to be correct and practical by simulation and chip test.     

Design-oriented analysis of boost zero-voltage-switching resonantDC/DC converter

Analysis and design procedures are presented for a high-efficiency, high-frequency, boost zero-voltage-switching resonant DC/DC power converter. Equations describing converter operation are derived. The basic performance parameters of the circuit are analyzed as functions of the normalized load resistance and switching frequency. These equations are then used to determine conditions for lossless converter operation and design equations that yield the required component values     

变频器故障诊断技术研究

随着社会的不断发展和完善,变频器的应用越来越广泛。传统的设备调速方法效率比较低,并且损耗相对比较大,应用变频器可以有效解决这些问题。但是在对变频器实际应用的过程当中,经常有故障出现,从而对变频器的使用效率产生比较严重的影响,所以需要解决这些问题。文章对此展开分析。     

A Monolithically Integrated 12V/5V Switch-Capacitor DC-DC Converter

Motivated by the battery-operated applications that demand compact,lightweight andefficient DC-DC converters,many kinds of converter circuits have been published.Amongthem,resonantconverters and the soft-switching convertershave greatl...     

Analysis and design of a saturable reactor assisted soft-switchingfull-bridge DC-DC converter

Analysis and design considerations for a saturable reactor assisted soft-switching full-bridge DC-DC converter are presented. The converter has advantages such as low switching losses with no substantial increase in conduction losses, wide load range, and constant frequency operation. To show how to utilize the analysis results, a 350 W, 500 kHz converter is chosen as a design example. The results are verified experimentally on a prototype converter     

The ZVS-PWM commutation cell applied to the DC-AC converter

This paper presents the analysis of a DC-AC power converter using a zero-voltage-switching (ZVS) commutation cell. First, the authors show the cell applied to the buck power converter. The stages of operation are presented along with the main current and voltage equations. Next, they adapt the power converter to the regenerative-operation mode. Hence, the full-bridge power converter at low-frequency operation is connected in the DC-DC output stage (at high frequency). The main switches commute at zero voltage. The power converter operated at constant frequency with pulse-width modulation (PWM), and neither overvoltage nor additional current stress was observed by digital simulation. A design example and experimental results obtained by prototype, rated at 275 V and 1 kW, are also presented