新型三相电容式电机在变频调速系统下的性能研究

为了提高三相电容式电机的效率和功率因数,有效地消减电机的谐波磁势,对新型三相电容式电机在变频调速系统下的性能进行了详尽的分析,并通过实验研究对新型三相电容式电机与普通三相异步电机在不同频率下的转矩特性、电流特性及功率因数等进行了对比性研究。实验数据表明,该新型电机具有一定的应用优越性和可推广性。     

三相电容式电机的理论分析和性能计算

从单相电机的观点出发,推导了三相电容式电机的性能方程,列出对称运行状态时电机的匝比和最佳电容值必须满足的条件,并以一台Y802-4型电机改绕成三相电容式电机为例作具体计算,其计算实例与样机实验结果吻合较好。     

三相电容式电机的理论分析和性能计算

从单相电机的观点出发，推导了三相电容式电机的性能方程，列出对称运行状态时电机的匝比和最佳电容值必须满足的条件，并以一台Ｙ８０２－４型电机改绕成三相电容器电机为例作具体计算，其计算实例与样机实验结果吻合较好。     

三相电容式电机的绕组型式对性能的影响

三相电容式电机通过在空间互差90.电角度的主、副绕组相互作用,能有效地削弱电机的谐波磁势,提高电机的效率和功率因数.本文就生产的两台样机进行实验,测定其工作性能和起动性能,指出应通过选择合适的绕组重绕形式,才能最大限度削弱电机谐波磁势、改善电机性能.并同时提出增加电机起动转矩的方法.     

三相电容式异步发电机在风力发电系统中的应用

分析了风力发电系统中异步发电机的应用情况,提出一种新型的三相电容式异步发电机,它克服了原有的异步发电机功率因数过低的缺点,同时也可使电机性能得到极大的改善.通过两台样机进行实验对比,实验数据表明三相电容式异步发电机在风电系统中有很高的应用推广价值.     

三相电容式异步发电机的研究

分析了风力发电系统中异步发电机的应用情况,提出了一种新型的三相电容式异步发电机。该发电机克服了原有异步发电机功率因数过低的缺点,同时还可针对电机的不同运行点配置相应的电容,由此改善电机性能。这是普通异步发电机端部并联电容无功补偿所不能达到的。对两台样机进行试验对比,结果表明三相电容式异步发电机在风电系统中具有很高的应用推广价值。     

三相电容式异步发电机的研究

分析了风力发电系统中异步发电机的应用情况,提出了一种新型的三相电容式异步发电机。该发电机克服了原有异步发电机功率因数过低的缺点,同时还可针对电机的不同运行点配置相应的电容,由此改善电机性能。这是普通异步发电机端部并联电容无功补偿所不能达到的。对两台样机进行试验对比,结果表明三相电容式异步发电机在风电系统中具有很高的应用推广价值。     

12/10极绕组变结构双模式开关磁阻电机系统运行性能研究

采用多相系统可以提高开关磁阻电机功率密度、降低电机转矩脉动,但功率器件开关频率和损耗也随之提升,影响电机高速运行性能。采用少相系统更适合开关磁阻电机高速运行,但其低速效率较低、转矩脉动较大。针对单一运行方式难以同时满足电机低速和中高速运行需求的问题,提出一种既可以六相运行也可以三相运行的12/10极绕组变结构双模式开关磁阻电机。基于线性模型从电路角度推导电机三种不同绕组连接方式的转矩关系,利用有限元法对比分析电机六相和三相运行的静态电磁特性和稳态运行性能,通过六相/三相运行模式切换系统仿真模型,对电机变转速工况下模式间切换进行系统运行性能分析,最后搭建样机实验平台,验证理论推导和系统模型的正确性以及六相和三相运行模式间切换的可行性。仿真和实验结果表明,通过切换运行模式可以提高电机整体性能和利用率。     

整马力单相电容式电动机的特点

一、引言单相电容式电动机的最大优点是有良好的起动性能,即起动转矩大,起动电流小。而且也与三相电动机一样,便于正反转。因此,随着科学技术的发展和人民生活水平的提高,对于单相电容式电机的需要,无论在数量上,还是容量上都有很大的发展。例如目前大量生产的400毫米电容式风扇电机容量     

三相电容电机无功补偿分析

三相电容电机是一种新型节能电机,与传统的三相异步电动机相比,其效率和功率因数有明显提高。详细分析了异步电动机无功补偿的原理和意义,并将三相异步电动机与传统异步电动机定子出线端并接电容提高功率因数的方法进行对比,同时进行自激分析。从实验和理论的数据可见,在提高功率因数方面,三相电容电机选择较小的电容器就能达到与普通三相异步电动机相同的效果,不会出现自激现象,无功补偿具有更好的效果。     

Novel configuration for three-phase hybrid power filter

A novel configuration for the power converter of a three-phase hybrid power filter is proposed in this paper. This power converter uses only a two-arm bridge structure and a DC capacitor. The hybrid power filter is configured by the proposed power converter serially connected with a passive power filter set. The salient feature of this hybrid power filter is that it permits one of the power lines of the utility connected directly to the negative terminal of the DC capacitor located in the DC side of the power converter through the passive power filter set. Consequently, the power converter uses less number of power electronic switches to reduce the manufacturing cost. A three-phase prototype is developed and tested to verify the performance of the hybrid power filter using the proposed power converter. The experimental results show that the hybrid power filter using the proposed power converter can reach the expected performance.     

Determination of Autotransformer-Capacitor Phase Converter Parameters

An analytical approach is described for determining the parameters for an autotransformer-capacitor phase converter that allows matching of the converter to a specific motor for a given load. Equations are developed for the capacitor size and autotransformer turns ratio that will give balanced operation of a three-phase motor. Predicted values are compared with the experimental results.     

Three-phase induction motor operating from single-phase supply with an electronically controlled capacitor

In this paper the performance of a three-phase induction motor operating from single-phase supply with a new electronically controlled capacitor using an electronic switch in series with a fixed capacitor to achieve a minimum unbalance of the motor phase voltages at all loading conditions is proposed. No mechanical or centrifugal switch is used here. Basic system operation, theoretical analysis, simulated and experimental results in comparison with conventional operation using one and two fixed capacitors are presented in this paper. The optimum effective capacitor value can be on-line adjusted at any operating speed by periodically changing the duty cycle of the controlled switch to achieve minimum unbalance in phase voltages to improve the motor performance at different speeds.     

一种新颖的矩阵式三相/单相变换器的设计与实现

提出了一种新颖的矩阵式三相/单相变换器,变换器由三相整流桥和单相逆变桥组成,其最大特点是开关管只需要采用单极性开关管并且无需直流母线支撑电容。三相整流桥采用基于扇区判断的同步整流控制策略,得到六脉波直流母线电压,并经过单相逆变桥得到频率和幅值可调的单相交流电。设计并制作了一台1.5kVA的样机,PSIM仿真结果和样机实验结果的吻合验证了本文所提出变换器的可行性。     

混合型有源电力补偿技术与实验研究

分析了混合型有源电力补偿技术的原理，提出了混合型有源补偿与常规并联有源滤波器在直流侧电容电压、装置容量等方面进行比较的分析方法。分析表明，混合型有源补偿具有直流侧电容电压低、在补偿同等容量负荷条件下其逆变器容量远小于常规有源滤波逆变器容量的突出优点。对两者所进行的计算机仿真结果与理论计算值相吻合。最后，文中给出了50kVA样机的实验结果，验证了混合型有源电力补偿技术具有良好的补偿特性。     

TRANSIENT ANALYSIS OF CAPACITOR SWITCHING IN UNBALANCED DISTRIBUTION SYSTEM WITH HARMONIC DISTORTION

ABSTRACT

The wide application of shunt capacitor banks in distribution systems for economic reasons, have raised concern about over-voltage transients and harmonic magnification in unbalanced distribution systems. This paper introduces a new method for transient analysis during capacitor switching. Presence of harmonic sources, unbalance in feeder configuration, and combinations of single-and three-phase loads are accounted for. The new method is a frequency domain-based approach using a three-phase Z-Bus algorithm. The paper reviews the concepts of the building algorithm of a three-phase Z-bus matrix in the complex frequency domain. Untransposed feeders and different types of loads are considered. Finally, the boundary conditions for different capacitor switching cases and the results with harmonic distortion are reported.     

Transient analysis of an advanced static var compensator using quad-series voltage-source PAM inverters

This paper deals with an advanced static Var compensator (ASVC) using quad-series voltage-source PAM inverters. The ASVC consists of four three-phase voltage-source inverters with a common dc capacitor and four three-phase transformers, each primary winding of which is connected in series with each other. Each inverter outputs a square-wave voltage, while the synthesized output voltage of the ASVC has a 24-step wave shape. This results not only in a great reduction of harmonic currents and dc voltage ripples but also in fewer switching and snubbing losses. In this paper, transient analysis is performed with the focus on the response of reactive power and the resonance between the dc capacitor and ac reactors. Experimental results obtained from a small-rated laboratory model of 10 kVA are also shown to verify analytical results based on the p-q transformation. The analytical results help in the design of system parameters such as the capacity of the dc capacitor and feedback gains.     

四开关空间矢量脉宽调制控制算法及母线电容电压不平衡问题的研究

三相四开关逆变器采用"五段式"空间矢量脉宽调制(SVPWM)方案可有效减小电机的转矩脉动,而四开关逆变器的母线电容电压不平衡将直接影响SVPWM的效果,导致电机三相电流不平衡,使电机的转矩脉动加剧。在深入分析四开关逆变器SVPWM原理的前提下,分析了直流母线电压不平衡对电机运行的影响,提出了一种有效的补偿办法。仿真结果表明,补偿后的异步电机VVVF系统具有较好的性能。     

基于单星MMC的新型STATCOM及其控制策略

通过分析基于级联半桥子模块双星形结构的模块化多电平变换器(MMC)拓扑,提出了一种基于单星形MMC的静止同步补偿器(STATCOM)拓扑结构,并与级联H桥STATCOM等拓扑进行了比较。该拓扑只采用双星MMC的一半,比级联H桥星形STATCOM节省13.4%的绝缘栅双极型晶体管(IGBT)。采用电流直接控制策略,给出了单星MMC-STATCOM的电容电压多层次控制方案及一种相间电容电压平衡控制改进方案,该方案不需要对零序电压注入量进行复杂计算。此外,还搭建了10kVA实验样机。仿真和实验结果表明,所提的单星MMC-STATCOM具有优良的动静态特性,验证了所提控制方案的可行性和有效性。