Showing 5 results for Equivalent Circuit
A. Darabi, T. Ghanbari, M. Rafiei, H. Lesani, M. Sanati-Moghadam,
Volume 4, Issue 4 (12-2008)
Abstract
Hysteresis motors are self starting brushless synchronous motors which are
being used widely due to their interesting features. Accurate modeling of the motors is
crucial to successful investigating the dynamic performance of them. The hysteresis loops
of the material used in the rotor and their influences on the parameters of the equivalent
circuit are necessary to be taken into consideration adequately. It is demonstrated that some
of the equivalent circuit parameters vary significantly with input voltage variation and other
operating conditions. In this paper, a comprehensive analysis of a hysteresis motor in the
start up and steady state regimes are carried out based on a developed d-q model of the
motor with time-varying parameters being updated during the simulation time. The
equivalent circuit of the motor is presented taking into account the major impact of the
input voltage. Simulation results performed in Matlab-Simulink environment prove that the
existing simple models with constant parameters can not predict the motor performance
accurately in particular for variable speed applications. Swings of torque, hunting
phenomenon, improvement of power factor by temporarily increasing the stator voltage and
start up behavior of the hysteresis machine are some important issues which can accurately
be analyzed by the proposed modeling approach.
H. Rajabalipanah, M. Fallah, A. Abdolali,
Volume 15, Issue 2 (6-2019)
Abstract
An intelligent design method of double screen frequency selective surfaces (FSSs) is addressed in this paper. The employed unit cell is composed of two metallic screens, which are printed on both sides of a substrate. The presented non-trial-and-error approach is investigated based on the separate design of each screen. With the help of some physical intuition and an equivalent circuit model, it is shown that the conventional use of complement geometries restricts the final desired filtering response. Therefore, unlike the previous studies, the metallic screens are not geometrically complementary in this paper. An excellent agreement between the full-wave simulations and corresponding equivalent circuit models has been observed. Using standard lumped elements, a highly selective miniaturized FSS (0.06λ0 ~ 0.08λ0) with two closely-spaced pass bands is designed, for GSM and WLAN frequencies. Simulation results show a dual-polarized characteristic with a good angular stability performance for the proposed structure.
F. Rezaee-Alam, B. Rezaeealam, S. M. M. Moosavi,
Volume 17, Issue 3 (9-2021)
Abstract
Poor modeling of air-gap is the main defect of conventional magnetic equivalent circuit (CMEC) model for performance analysis of electric machines. This paper presents an improved magnetic equivalent circuit (IMEC) which considers all components of air-gap permeance such as the mutual permeances between stator and rotor teeth, and the leakage permeances between adjacent stator teeth and adjacent rotor teeth in the air-gap. Since the conformal mapping (CM) method can accurately take into account the air-gap region, IMEC gets help from the CM method for calculating the air-gap permeance components. Therefore, the obtained model is a hybrid analytical model, which can accurately take into account the magnetic saturation in iron parts by using the CMEC, and the real paths of fringing flux, leakage flux, and the main flux in the air-gap by using the CM method. For a typical wound rotor induction motor, the accuracy of the results obtained by IMEC is verified by comparing them with the corresponding results determined through CMEC, improved conformal mapping (ICM), finite element method (FEM), and the experiment results.
V. Naeini, M. Moomeni,
Volume 19, Issue 1 (3-2023)
Abstract
This paper introduces the modeling and fault diagnosis of rotor eccentricities of permanent magnetic synchronous machine (PMSM). The modeling of machine in healthy and fault condition have been proposed based on magnetic equivalent circuit (MEC). Nevertheless, the research methods of diagnosis and modeling are common, this paper tends to provide a fast computation and more detailed model with reasonable degree of accuracy. Firstly, the MEC modeling of PMSM in the electric and magnetic fields are introduced and next, the different fault conditions are carried out. Also to consider the eccentricity fault of an interior mounted PMSM, a methodology based on MEC is proposed. The accuracy of this model will be verified by comparing with identical results obtained by finite element method (FEM).
Nabiollah Ramezani, Mohsen Shahnazdoost Kilvaei,
Volume 21, Issue 1 (3-2025)
Abstract
In this paper, a novel method is presented that can accurately estimate the Thevenin equivalent circuit parameters of an external power system by RTUs. The presented method is based on the simultaneous measurements of the desired points in the boundary system, which includes the bus voltage amplitude, the current amplitude of the boundary transmission lines, as well as active and reactive power, and is continuously active until the Thevenin equivalent circuit model would be available online. The practical application of the proposed method is related to online monitoring and control of wide-area power systems as well as their development design. Also, the innovation of the method is the accurate estimation of the Thevenin equivalent circuit model from part of the power network where information is not available. In the proposed method, an additional measurement and the least squares method are used to eliminate measurement errors in order to accurately estimate the parameters of the equivalent circuit model. In order to avoid providing the wrong equivalent circuit model due to external system changes, a method is presented that can track the correct system changes to continuously monitor the disturbances. The proposed method performance has been implemented and validated by DigSILENT software.
