倍频同步的高频链变换器锯齿形载波发生电路

对高频链矩阵式变换器进行PWM控制且实现软开关工作时,常需要高频变压器一次侧及二次侧的功率变换环节能同步工作,从而要求能为二次侧矩阵变换器提供具有倍频且同步特征的载波信号.基于此研发了一种适用于高频链变换器的具备倍频同步功能的锯齿形载波发生电路,该电路没有直接使用倍频环节,而是通过方波三角波转换后采用双向开关使能选通的...     

有源电力滤波器锁相倍频电路的参数优化

通过对锁相倍频电路的研究,针对锁相环电路参数不易确定的特点,运用自动控制原理相关理论,分析了锁相倍频电路的原理及稳定性、环路滤波器的衰减特性,并建立了环路数学模型.提出一种锁相环电路参数的优化方法,实验结果表明,运用该方法设计的锁相倍频电路能够准确稳定地倍频出所需要的触发信号.较好地实现了同步采样、等间隔采样,以及整周期电压的均匀细分,同时降低了设计难度.具有很强工程适用性.     

一种新的鉴相倍频电路

介绍一种新的鉴相倍频电路ＰＤＣ９３０１，用它替代以前利用阻容件实现的鉴相倍频电路，使用效果良好。     

基于网侧功率前馈的二倍频功率有源解耦控制

在单相脉宽调制(PWM)变流器中输入功率存在二倍频波动,会导致直流侧电压二倍频纹波含量较高,需要大容量电容进行滤波.设计了H桥结构的有源功率解耦电路来吸收二倍频功率波动,通过网侧电压电流可计算输入的二倍频功率波动,进而获得二倍频有源功率解耦电路中电感电流或电容电压指令,并利用单电感电流控制环或电容电压外环电感电流内环的双闭环控制方式实现二倍频功率的有源解耦控制.分析对比了有源功率解耦电路采用电感电流单闭环控制方式和电容电压双闭环控制方式的优缺点,指出双闭环控制方式具有稳定性强、响应速度快等优点,并通过Matlab/Simulink仿真和Typhoon HIL602实验平台验证了该控制策略的有效性.     

倍频式IGBT高频感应加热电源的研究

倍频式感应加热电源负载输出频率为功率开关管工作频率的二倍，且功率开关器件工作时具有软开关特性，在需要高频应用的场合很有意义。文中以IGBT来实现倍频式高频感应加热电源，比较了不同频率比下的电路工作状态，得出电路工作在断态下更适合电路功率调节的结论。详细分析了断态下电路工作状况，得出直流等效电阻与交流负载等效电阻的关系，并给出了选取电路参数的经典方法。根据该方法设计了一台样机，通过实验验证了理论分析及参数选取方法的正确性。     

链式STATCOM单极倍频载波移相技术的研究

调制技术是链式STATCOM控制系统的核心部分,为了实现装置的高性能控制,采用单极倍频和载波移相相结合的调制技术。论文介绍了链式STATCOM的主电路结构,研究了单极倍频载波移相调制技术在链式STATCOM中的应用,通过详细的数学分析论证了其特性;最后,搭建了仿真模型,仿真结果表明链式STATCOM采用单极倍频载波移相调制技术可以将等效开关频率提高2N倍(N指每相级联单元数),从而有效地降低了输出谐波含量。     

基于FPGA的交流采样同步倍频算法及实现计

为了保证电能质量监测系统中电力参数的准确性,需要对其进行交流采样[1]。而在交流采样中,需要进行同步倍频。传统的由锁相环CD4046做成的频率跟踪电路来进行倍频,很难进行倍频倍数的改变。本文利用verilog HDL语言,针对传统倍频电路的限制,通过计数分频的方式实现了抖动信号源、任意低频、任意高倍的倍频算法。最后通过matlab仿真,以及提供的FPGA器件搭建硬件电路后,用示波器测试,都证实了算法的正确性可用性。     

倍频式高频感应加热电源工作模式

提出一种使用自关断器件IGBT作为功率开关,利用倍频技术实现感应加热电源高频化的控制方法,分析比较了不同频率比值条件下的电路工作状态,通过改变内外槽路频率差的大小来实现功率的调节和负载阻抗的匹配,得出了电路最适合工作在断续模式的结论.同时详细分析了断态模式下电路工作状况,推导出直流等效电阻的关系.仿真和实验研究验证了该方法的正确性以及技术的可行性.     

基于中心抽头变压器的倍频感应加热电源

针对高频大功率应用场合,提出了一种基于中心抽头变压器的倍频式感应加热电源。采用结构对称的两个半桥、共用谐振电容、抽头变压器耦合的方式,使得负载工作频率为功率开关管工作频率的两倍,达到倍频的目的。功率开关管具有软开关特性,且导通时间为其开关周期的25%,相对于传统的桥式逆变器来说,明显降低了开关管的功耗。详细分析了8个不同的工作模式及相应的系统参数关系,给出了电路参数的设计方法。最后以IGBT为功率开关管,设计了一台小型样机,通过实验验证了所提出的电源拓扑、理论分析及参数选取方法的正确性。     

基于CPLD的光电编码器四倍频电路的设计

在工业测控系统中,光电编码器用于测量电机的角位移。由于现场的干扰以及光电编码器的高分辨率的特点,常运用四倍频电路来提高被控电机的测量精度和控制精度。设计基于可编程逻辑器件CPLD,利用CPLD的可重构性,在系统可编程以及能够实现复杂逻辑功能的特点,设计了光电编码器信号的四倍频电路。测试结果表明,这种方法实用有效,实现了四倍频、鉴相和计数功能,具有成本低、设计灵活的优点,提高了电机的控制精度。     

基于高阶谱与支持向量机的电力电子电路故障诊断技术

针对现有电力电子电路故障诊断方法存在的不足，研究了采用高阶谱分析和支持向量机(support vector machine，简称SVM)的电力电子电路故障诊断和定位方法。首先利用高阶谱中的双谱技术分析、处理和提取电路状态的故障信息特征；然后设计和采用多类层次支持向量机分类器作为故障模式的训练和识别器，其中，分类器的结构利用模糊C-均值算法(fuzzy C-means，简称FCM)进行了优化；最后采用一个实际的Buck功率电路进行了建模、仿真和验证。结果表明，采用该方法对电力电子电路故障的诊断和定位率可达99%以上，达到了较为理想的诊断精度。     

微型数控铣床开发平台运动控制卡的设计

根据开放式系统的设计理念,开发了微型数控铣床的运动控制卡系统。首先,对运动控制卡的功能及硬件结构进行详细设计;然后,根据功能需求将控制卡分成DSP系统、主轴电动机控制系统、XYZ轴步进控制系统及双端口RAM通讯系统进行详细设计;最后,根据设计原理完成控制卡的PCB图和电路板的设计加工调试工作。该运动控制卡已在微型数控铣床开发平台上实验成功,其设计方法对今后运动控制系统的设计具有较高的参考价值。     

Power quality considerations for CNC machines: grounding

Computer numerical control (CNC) machines are used to shape metal parts by milling, boring, cutting, drilling, and grinding. A CNC machine generally consists of a computer-controlled servo-amplifier, servo-motors, spindle motor, and various tooling. The machine can be programmed to shape a part by use of a front control panel. More sophisticated models allow a computer-aided design drawing to be uploaded to the machine. The electronic components within a CNC machine are particularly sensitive to the grounding techniques used in the electrical supply to the machine. Malfunction, degradation, and damage to the electronics can often be traced to supplemental ground rods and lightning strikes to earth. Production downtime, product loss, and expensive repair bills result. With the wide-spread use of CNC machines across the world, these problems have become a significant financial concern to many CNC machine users and their electric utility companies. This paper begins with a brief explanation of the fundamentals of service and equipment grounding. The basic design of CNC machines is also explained. Based on a survey of several CNC machine representatives, the paper will explore the common grounding techniques recommended by many CNC machine tool builders with particular emphasis on the ground-rod problem. In addition, several actual case studies that support the ground-rod problem are described. Finally, a recommended powering and grounding practice is presented to help eliminate power quality related operating problems with CNC machines while maintaining the safety requirements of electrical codes     

Microcomputer-based testing and repairing system using digitalsignature mapping

A new approach known as digital signature mapping (DSM) is proposed for testing and repairing loaded printed circuit boards (LPCBs). This method uses standard state-of-the-art measurement equipment to record the response of a well-known LPCB during its operation, on a microcomputer, and uses the recorded references to compare the board under test output response in what is known as signature testing. In such a test, no test generation is required. The method can be used to perform real-time measurement for LPCBs under test with a focus on computer numerical control (CNC) controller boards. The DSM employs an MC6809 and uses well-known test tools. Therefore, the proposed system is not very expensive. It is very useful in testing and repairing small quantities of LPCBs. In addition, the software required, which is generated from mapping the signature of test points of a good LPCB, makes it suitable for a factory that uses a variety of CNC machines     

数控铣床视觉在位测量路径规划方法

以提高加工精度和效率为目标,针对数控铣床开发了一种视觉在位测量系统,根据视觉测量技术的特性,重点研究了该系统中的测量路径规划问题,包括采样策略规划和测量路径规划算法。首先,基于工件CAD模型,依据提出的采样策略,自动生成采样点坐标;然后,根据设计的测量路径规划算法,生成一条依次通过各采样点的优化的测量路径。实验表明,所提出的采样策略和测量路径规划算法适用于工件的视觉在位测量。     

岭澳核电站1150MW发电机转轴加工工艺

介绍了岭澳1150MW核能发电机转轴结构特点、制造难点以及采用双托架-万向节车削加工和在d260数控镗床上利用直角头盘铣刀铣槽加工工艺创新点。     

钕铁硼磁路的结构系数设计方法

基于轴径向基本ＶＣＭ磁路,提出了钕铁硼磁路磁体结构系统设计方法。与传统方法不同,它将工作点和磁全结构系数结合起来,考虑磁路性能和成本最优,并使磁体径向尺寸减小,所导出的工作点一般不在磁能积最大点处,磁体结构系数ｋ值一般大于ｋｍａｘ。最后给出了在直线伺服电机中的设计应用实例并进行了性能比较,说明了本方法的实用性,该直线直接驱动伺服单元已经用于凸变椭圆活塞数控车床 。     

混合励磁爪极同步电机磁路结构及其调磁性能

在分析轴向/径向磁路混合励磁同步电机磁路与性能优缺点的基础上,提出了四种新结构轴向/径向磁路混合励磁爪极同步电机。详细分析了这四种电机的拓扑结构及磁路,给出相应的磁路图。采用三维有限元技术计算了不同励磁电流时电机气隙磁通。分析与计算结果表明,所提出的四种结构的混合励磁爪极同步电机,均具有较好的调磁性能,其中非对称交错永磁电机的弱磁和增磁性能最好,可满足宽调速同步电动机的需要。     

Parameter estimation for induction machines based on sensitivityanalysis

Induction machine parameters supplied by manufacturers are usually sufficient for short-circuit analysis only. System studies that involve transient simulation of machines require additional parameters that are not readily available, but nonetheless are essential for an accurate modeling of the machines. A mathematical method for estimating the equivalent circuit parameters of induction machines from the most readily available performance characteristics is presented. In this method, machine equations are used to estimate the parameters and sensitivity analyses are then performed with respect to the circuit parameters to match the given performance characteristics. An example is included to illustrate how well the performance of the estimated model matches that of the actual machine. The example is a three-phase, 1000 HP, 4.16 kV, 60 Hz induction motor. The example indicates that, with a restricted set of input data, it is possible to find the elements of a machine model that duplicates the given performance to a high degree of accuracy. Without sensitivity analysis, accuracies on the order of 10% are obtained, but after sensitivity analysis an accuracy of 0.1% or better can be achieved     

PERFORMANCE CALCULATIONS FOR INDUCTION MACHINES WITH A SOLID STEEL ROTOR

ABSTRACT

A method of calculating the performance characteristics for induction machines having solid steel rotors is presented. An equivalent circuit is derived in which the expressions for the circuit elements include the effects of rotor steel saturation, the finite length of the rotor, and the effect of induced rotor currents on the air gap flux density distribution. The analysis may be applied, with equal facility, to machines operating under conditions of constant voltage supply, or constant current supply. The accuracy of the method is demonstrated by comparison of torque/slip, power factor/slip, and current/slip curves that have been obtained by calculation and from practical tests. Results for three solid rotor machines of different rating, and pole number, are presented.