三相异步电动机单相电容制动性能分析及参数计算

本文根据三相异步电动机单相电容制动的等值电路,通过计算和实验验证,分析了不同阻容参数对电机在制动过程中机械特性的影响,从而提出获得单相电容制动最佳效果之阻容参数的工程选择方法。     

异步电动机定子两相短接制动瞬态过程仿真研究

采用三相异步电动机在αβo坐标系下的数学模型,根据具体定子绕组接线的不对称情况,推导出电机定子端电压的约束条件。编写了一个适合于异步电动机对称和定子不对称运行情况的实用仿真计算程序,通过实例对定子Y形接法三相异步电动机的两相短接制动、倒拉反接制动和能耗制动运行过程进行仿真计算,并对仿真结果进行比较分析,得出了一些有用的结论。     

异步电动机定子绕组短接制动瞬态过程仿真研究

采用三相异步电动机在αβ30坐标系下的数学模型，根据具体定子绕组接线的不对称情况，推导出电机定子端电压的约束条件，编写了一个适合于异步电动机定子对称和不对称运行情况的实用仿真计算程序，通过实例对定子Y形接法三相异步电动机的单相短接制动、两相短接制动和三相短接制动运行过程进行仿真计算，并对仿真结果进行比较分析，得出了一些有用的结论。     

异步电动机定子两相短接制动瞬态过程仿真研究

采用三相异步电动机在αβo坐标系下的数学模型，根据具体定子绕组接线的不对称情况，推导出电机定子端电压的约束条件，编写了一个适合于异步电动机对称和定子不对称运行情况的实用仿真计算程序，通过实例对定子Y形接法三相异步电动机的两相短接制动，倒拉反接制动和能耗制动运行过程进行仿真计算，并对仿真结果进行比较分析，得出了一些有用的结论。     

逆变器供电下异步电动机定子断相故障运行过程仿真

根据三相异步电动机在αβo坐标系下的数学模型和电压型逆变器的数学模型,用MATLAB语言编写仿真程序。通过实例对三相异步电动机定子断相故障的运行过程进行仿真计算,并对仿真结果进行分析。     

逆变器供电下下异步电动机定子断相故障运行过程仿真

根据三相异步电动机在αβο坐标系下的数学模型和电压型逆变器的数学模型，用MTLAB语言编写仿真程序，通过实例对三相异步电动机定子断相故障的运行过程进行仿真计算，并对仿真结果进行分析。     

三相异步电动机电容制动机械特性的计算

本文提出了一种三相异步电动机电容制动时机械特性的理论计算方法。计算公式是根据定子侧接上一个阻容并联负载的异步电机等值电路而导出的。制动过程中,由于感应电势的幅值与频率随电机速度变化,计算中必须考虑磁路饱和程度的变化。通过实例计算和实验验证,本文最后得出了一种获得最佳制动效果的制动电阻的合理选择方法、     

异步电动机定子串不对称电抗起动的瞬态分析

对三相笼型异步电动机定子串不对称电抗的起动过程进行瞬态分析。为了得到起动特性，根据三相异步电动机在相坐标系下的瞬态数学模型，编写计算机仿真程序，通过实例对三相笼型异步电动机的定子电路一相串联电抗时的起动过程进行仿真计算；用对称分量法分析定子电路一相串联电抗时的不对称系统，确定起动电抗的数值。对仿真结果进行比较分析。     

六相异步电动机能耗制动瞬态仿真研究

对六相异步电动机能耗制动的瞬态过程进行仿真分析。为了得到瞬态特性,建立了六相异步电动机在静止d-q-0坐标系下的混合磁链瞬态数学模型。编写计算机仿真程序,通过实例对六相异步电动机的能耗制动的瞬态过程进行仿真计算。仿真结果表明六相异步电动机可以在两套绕组中通入较小的直流电流获得较强的恒定磁场,从而产生较大的制动转矩。     

六相异步电动机能耗制动瞬态仿真研究

对六相异步电动机能耗制动的瞬态过程进行仿真分析。为了得到瞬态特性,建立了六相异步电动机在静止d-q-0坐标系下的混合磁链瞬态数学模型。编写计算机仿真程序,通过实例对六相异步电动机的能耗制动的瞬态过程进行仿真计算。仿真结果表明六相异步电动机可以在两套绕组中通入较小的直流电流获得较强的恒定磁场,从而产生较大的制动转矩。     

六相感应电动机电源反接制动瞬态仿真研究

对六相感应电动机电源反接制动的瞬态过程进行了仿真分析。为了得到瞬态特性,建立了六相感应电动机在静止dq0坐标系下的混合磁链瞬态数学模型。编写计算机仿真程序,通过实例对六相感应电动机的电源反接制动的瞬态过程进行仿真计算,对仿真结果进行分析,得出了一些有用的结论。     

Capacitor braking of double-cage induction motors

Capacitor braking relies on the self-excitation process and represents a well-established technique of braking of single-cage induction machines. However, there appear to be no papers on the capacitor braking of double-cage induction motors. Since the self-excitation process constitutes the basis of capacitor braking, a correct representation must include the effects of main flux saturation in the induction machine model used. The paper first summarises the mathematical model of a saturated double-cage induction machine and then presents experimental results together with results of a comprehensive simulation study. Both symmetrical three-phase and asymmetrical single-phase capacitor braking techniques are considered. The results are shown for two different double-cage induction machines. The experimental and simulation results are found to be in good agreement.     

Dynamic behavior of a single-phase self-excited induction generator using a three-phase machine feeding single-phase dynamic load

This paper is motivated to analyze the transient behavior of a single-phase self-excited induction generator (SEIG) using a three-phase machine due to switching of single-phase dynamic load like induction motors. The generator consists of a three-phase star connected induction machine excited with three-capacitors and a single-phase induction motor (IM) load. The developed dynamic models of the SEIG and the motor are based on stationary reference frame d–q axes theory incorporating the effect of cross-saturation in the magnetic circuit of the machine and the equations of excitation capacitors are described by three-phase abc model. The system suffers from heavy transients during switching of induction motor and becomes unstable. These problems may be due to resonance caused by series capacitors and the inductive motor load. The use of damping resistors across one series capacitor is proposed to damp out the starting transients for the stable operation. The motor can be started up successfully using the damping resistor. The variation of the damping resistance with the increase in load on the motor after successful starting to maintain constant terminal voltage has been presented. The eigenvalue technique is also employed to examine the transient conditions in the studied SEIG-IM system. The simulated and experimental results are presented for both the unsuccessful and successful starting of the motor. These results are in close agreement with each other, which show the effectiveness of the approach.     

Braking Scheme for Vector-Controlled Induction Motor Drives Equipped With Diode Rectifier Without Braking Resistor

This paper deals with sensorless vector control of pulsewidth-modulated inverter-fed induction motor drives equipped with a three-phase diode rectifier. An electronically controlled braking resistor across the dc link is not used. Instead, the power regenerated during braking is dissipated in the motor while a dc-link overvoltage controller limits the braking torque. Losses in the motor are increased by an optimum flux-braking controller, maximizing either the stator voltage or the stator current depending on the speed. Below the rated speed, the braking times are comparable to those achieved using a braking resistor. The proposed braking scheme is very simple and causes no additional torque ripple. Experimental results obtained using a 2.2-kW induction motor drive show that the proposed scheme works well.     

Rebuilding of three-phase load voltage during single-phase auto reclosing in medium voltage distribution lines

Most faults in medium voltage (MV) distribution lines are temporary single line to ground (LG) faults. Single-phase auto reclosing (SPAR) may be used to remove the LG fault producing highly unbalanced and low voltage across the load during the reclosure dead time. The negative sequence voltage produced may cause severe over heating in three-phase induction motors. It is proposed to connect a zigzag winding grounding transformer at the remotest load bus to rebuild the three-phase voltage during the SPAR dead time. The zigzag transformer neutral should remain disconnected from the ground during normal operation.     

三相感应电动机瞬间断电重新投入电网时的瞬态

首先列出三相感应电动机起动、断电和重新投入电网时的运动方程,然后着重研究了定子断电后转子电流初值的确定和转子电流、转速、转角的解答,以及最不利的重合时间。最后实例计算了一台三相感应电动机在1／3额定负载和额定负载两种工况下运行时,瞬间断电和重合后电磁转矩和定子电流的冲击峰值,得到了一些有用的结论。     

基于出厂数据的电动机仿真模型参数计算方法

提出基于感应电动机的出厂数据(如额定功率、额定功率因数、最大转矩倍数和转子转速等)估算适用于电力系统机电暂态仿真的电动机单笼模型参数的方法。该算法充分考虑了电动机的转矩–滑差物理机制特性,其收敛特性好、鲁棒性强。通过计算15台实际电动机的单笼模型参数,分析它们的电磁转矩–滑差特性,并与其出厂数据值进行对比,结果表明,根据算法计算的模型参数用于模拟电动机的机电暂态特性具有较高的精度,证明了算法的有效性。最后通过动模实验与数值仿真对比,进一步验证了所提算法的有效性和适用性。