煤矿大功率防爆异步电动机软启动技术研究

针对煤矿大功率防爆异步电动机的启动特性需求,提出一种基于数字信号处理器的软启动控制方案,解决起动过程电流过大、能耗高的问题。在分析软启动技术和煤矿大功率防爆异步电动机启动过程上,从软启动器的电气结构出发,设计基于TMS320F2812A的数字式控制系统,实现电动机起动过程端子电压、电流和输出转矩的调节。     

软启动器在轴流螺旋桨式风机上的应用

本文介绍和分析了STRB软启动器在160kW异步电动机上的应用，它能有效限制异步电动机的起动电流，减少对电网、电动机、负载机械设备的冲击。软启动器是传统的星／三角转换、自耦降压、磁控降压等降压起动设备的理想换代产品，是异步电动机起动的新一代技术。     

具有自动稳幅功能的软激励C类大功率射频振荡器

介绍了一种具有自动稳幅功能的软激励C类大功率射频振荡器。大功率射频振荡器已经广泛应用于电力电子、射频电源、低温等离子体、高频感应加热等领域。该大功率射频振荡器能够输出较高的输出电压和输出功率,并且通过对输出电压采样控制MOS管的静态工作点,稳定输出电压;另外,该设计电路起振时工作在AB类状态,稳定工作时在自动稳幅电路的作用下进入C类工作状态,实现了C类射频振荡器的软激励。最后通过仿真和实物电路测试了电路性能,并给出了振荡器输出电压、输出功率与MOS管工作状态关系的经验公式。     

控制交流电源中浪涌电流的电路

采用墙上交流电压工作的大功率电源都要使用大的输入滤波电容。必须限制这些电容的浪涌电流,否则,电源就可能触发交流断路器,或者造成整流器、滤波扼流圈或PCB（印刷电路板）走线的损坏。     

基于锁相放大器的光纤电流互感器研究

为了测试光纤电流互感器中由于Faraday效应引起的旋转量,提出了采用锁相放大器处理信号的方法,改进了传统的将交流成分与直流成分相除的方法。系统将采集信号做单端电压输入测试和差分电压输入测试,并比较了单端输入与差分输入的测试效果,定性分析了输出幅值与被测电流的关系。测试结果表明,锁相放大器输出幅值与被测电流具有线l陛关系,且差分输入较单端输入幅值大、线性度好、对外界干扰抑制性强。其成果为进一步研究基于旋光效应的光纤电流互感器的应用奠定了基础。     

一种宽输入电压范围软开关电流型DC/DC转换器

针对太阳能光伏及燃料电池等领域电源需要较宽输入电压范围的需求,提出一种通用的具有较宽输入电压范围的软开关电流型DC/DC转换器。该转换器采用了固定频率混合调制设计,可以在所有工作条件下实现半导体器件的软开关工作,并采用电流馈电技术以便适用于低电压高电流的电源。相较于传统转换器,该转换器更为通用,能够实现零电压开关和零电流开关,并且能够在输入电压和负载变化出现较大变化时控制输出电压。实验结果显示,在20-60V输入电压范围内且负载出现变化时,该转换器均表现出良好的性能。     

低谐波软启动器的研究

设计一种软启动器,以可控硅做主控元件,单片机控制软启动策略,实现对异步电动机的软启动。STM32系列微控制器通过控制可控硅导通的周期波数,进而改变异步电动机启动电压的平均值,从而减少启动电流对电网的冲击。同时进行相位检测,确定启动电流的过零触发,克服了一般软启动器产生严重谐波污染的问题。     

一种可调LED恒流源设计

系统以DC-DC变压器为核心,通过升压电路对输入电压进行升压,利用由运放、参考电压源,大功率三极管等构成的电流串联负反馈电路实现恒流输出,并使用单片机对系统输出进行测试与控制,以实现限压、报警与脉动模式等功能。     

为什么变频器的输入电流小于电机电流？

答：这些指南适用于工业环境下运行的所有类型的变频器和电气设备。(1)如果电源可能出现电压尖峰，可安装一输入电抗器。电压尖脉冲可能来自于功率因素调节电容器，启动器．DC调速器，电焊机等。电抗器将限制设备上出现这些瞬间能量，且在不良电源条件下，提供此类防护的费用并不高。电抗器还可用来限制系统谐波的产生。     

一种高效低功耗DC2DC升压稳压器的设计

文章设计了一种高效率、低电流、低功耗的DC2DC升压稳压器,通过采用PWM、同步整流、软开关、电流限幅保护等多种技术,使该电路具有较大的输入电压范围、快速瞬态响应、输入欠压/过压保护、输出过流/过压保护和过热保护等功能.最后芯片采用1.5μm的P衬N阱数模混合1P2M BiCMOS工艺流片成功,可用于便携设备显示屏的白光LED背光.     

Voltage and current stress reduction in single-stage power factorcorrection AC/DC converters with bulk capacitor voltage feedback

Single-stage power factor correction (PFC) AC/DC converters integrate a boost-derived input current shaper (ICS) with a flyback or forward DC/DC converter in one single stage. The ICS can be operated in either discontinuous current mode (DCM) or continuous current mode (CCM), while the flyback or forward DC/DC converter is operated in CCM. Almost all single-stage PFC AC/DC converters suffer from high bulk capacitor voltage stress and extra switch current stress. The bulk capacitor voltage feedback with a coupled winding structure is widely used to reduce both the voltage and current stresses in practical single-stage PFC AC/DC converters. This paper presents a detailed analysis of the bulk capacitor voltage feedback, including the relationship between bulk capacitor voltage, input current harmonics, voltage feedback ratio, and load condition. The maximum bulk capacitor voltage appears when the DC/DC converter operates at the boundary between CCM and DCM. This paper also reveals that only the voltage feedback ratio determines the input current harmonics under DCM ICS and CCM DC/DC operation. The theoretical prediction of the bulk capacitor voltage as well as the predicted input harmonic contents is verified experimentally on a 60 W AC/DC converter with universal-line input     

An AC/DC converter with high power factor

The television receiver often employs a capacitor-input-type rectifier. In this case, it is regulated as a class D piece of equipment. This paper presents a novel ringing-choke-converter-type switching regulator, which functions as an active filter. The proposed circuit features a simple circuit configuration and cost effectiveness. It achieves a high power factor of about 0.95 and reduces current harmonics (third, fifth, and seventh) in the AC input current to less than 40% of the limit value for class D. The voltage across the input smoothing capacitor does not show large variations and the components in the conventional ringing-choke converter can be used unmodified. Ripple content of the DC output voltage shows a slight increase and is the subject for future research.     

智能型无功补偿控制器的研究与设计

介绍了以单片机C505L为CPU的智能型无功补偿控制器,该系统采用功率因数设定和实际无功需求相结合作为电容器投切的主判依据,电网电压和电流作为辅助判据,从而实现了电容器自动循环投切并使无功缺额最大限度的得到补偿,彻底消除了投切振荡现象。所设计的无功补偿控制器具有补偿效果好、功能强大、可靠性高、结构简单等特点。     

New zero voltage switching DC converter with flying capacitors

A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at V_in/2. Therefore, power metal–oxide–semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.     

Characteristics of load resonant converters operated in ahigh-power factor mode

The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained     

A novel high-performance voltage regulator for single-phase ACsources

Regulation of load voltage in single-phase applications is becoming an important issue for critical loads. This paper presents a novel high-performance single-phase voltage regulator which has a common arm between the rectifier and inverter, and adopts an appropriate switching strategy. The proposed voltage regulator employs six switches and can be implemented by only one three-phase inverter module. The proposed voltage regulator has the capability of delivering sinusoidal input current with unity power factor, good output voltage regulation, and bidirectional power flow. For these purposes, a fully digital controller is designed and implemented using a TMS320F240 digital signal processor. In addition, a novel low-cost AC capacitor is also presented. This type of capacitor requires two DC capacitors and two diodes, enabling low-cost and compact manufacturing. Consequently, the complete voltage regulator system, which is mainly suitable for an uninterruptible power supply as well as reactive or nonlinear loads, can be constructed compactly and inexpensively. Experimental results are presented to verify the feasibility of the proposed voltage regulator system     

A single-switch AC/DC converter with voltage regulated storage capacitor

A single-stage power-factor-corrected AC/DC converter (SSPFC) usually causes high voltage stress on the intermediate storage capacitor, due to the lack of control of this voltage. The storage capacitor voltage varies largely with line voltage, and load current and is usually higher than the peak line voltage. This paper presents a new single-switch SSPFC based on a flyback topology for which the storage capacitor voltage is loosely regulated by the output voltage. Without using extra power switches to increase the control dimension, the proposed converter uses a flyback converter with dual-output transformer to achieve the control purpose. The range of storage capacitor voltage change against the change of input voltage and load current is significantly reduced. Moreover, the maximum storage capacitor voltage can stay below the peak line voltage at high line condition. Experimental results verifying the operation of the proposed SSPFC are also reported.     

数字控制通讯电源高压防护研究

介绍了一种数字控制通讯电源高压防护电路及其控制方法。数字信号控制器通过检测交流输入电压和PFC输出电压状况做出智能判断,控制高压防护电路中主继电器和辅助继电器的断开和吸合状态,从而对实现通讯电源快速有效的高压防护,提高了通信电源的可靠性。     

Optimal Predictive Control of Three-Phase NPC Multilevel Converter for Power Quality Applications

This paper presents the optimal control of the ac currents, the dc voltage regulation, and the dc capacitor voltage balancing in a three-level three-phase neutral point clamped multilevel converter for use in power quality applications as an active power filter. The ac output currents and the dc capacitor voltages are sampled and predicted for the next sampling time using linearized models and considering all the 27 output voltage vectors. A suitable quadratic weighed cost function is used to choose the voltage vector that minimizes the ac current tracking errors, the dc voltage steady-state error, and the input dc capacitor voltage unbalancing. The obtained experimental results show that the output ac currents track their references showing small ripple, a total harmonic distortion (THD) of less than 1%, harmonic contents that are 46 dB below the fundamental, and almost no steady-state error (0.3%). The capacitor voltages are balanced within 0.05%, and the balancing is assured even when redundant vectors are not chosen. Near-perfect capacitor dc voltage balancing is obtained while reducing current harmonic distortion. Some experimental evidence of robustness concerning a parameter variation was also found, with the optimum controller withstanding parameter deviations from $+$100% to $-$50%. Compared to a robust sliding mode controller, the optimal controller can reduce the THD of the ac currents or reduce the switching frequency at the same THD, being a suitable controller for power quality in medium-voltage applications.      

基于高频高压交流母线多组输出直流电源的研制

本电源是基于高频高压交流母线具有多组输出的直流电源，它具有高达200kHz的开关频率，后级的整流电路由于高频交流母线的存在，使得变压器和电感的设计变得简单，滤波电容的选择也更容易。本电源由PFC电路提供400V的高压直流输入，再由MOSFET组成全桥逆变电路，在固定额率的PWM发生电路和IR2110 MOSFET驱动电路作用下，只加—个谐振电感就可实现开关管的零电压开通，可在大大降低开关损耗和噪声的同时实现直流交流的变换。整流部分采用倍流整流电路以提高原边电压的利用率，可输出低压大电流。由于采用肖特基管，—方面可使得二板管的损耗可以接受，另外—方面还避免了采用同步整流电路所面临的电路结构复杂和驱动困难。