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The article compares the centrifugal pumping units electric drive dynamic characteristics at different rotational speeds of the main magnetic field. The tooth harmonics order is determined by the number of stator slots, which depends on the main magnetic field rotation frequency. Proposed mathematical model takes into account the tooth harmonics of the electric motor and the hydraulic parameters of...
It is well-known that in multiphase drives the spatial harmonics of the air-gap magnetic field can be controlled independently of each other. In this paper it is shown how the third-order spatial harmonic of the magnetic field can be used to estimate the rotor speed without the need of a mechanical sensor. Experimental results confirm the feasibility of the developed sensorless speed observer.
In recent years, the diagnosis of electric motors appealed increasingly to signal processing methods. To develop these methods, it is necessary to have a reliable mathematical model of the physical signal to be processed, in our case the signal is the stator current. Unfortunately, often this stator current can only be obtained from an expensive measurement bench, or from a complex modelling of the...
Lately, a new diagnostic mean has been introduced for reliable fault diagnosis in delta-connected induction motors. This diagnostic mean is the zero-sequence current frequency spectrum. It will be shown in this paper that, the zero-sequence current waveform can be reliably used for identifying the induction motor's iron core saturation level. So in this work, simulations with the Finite Element Method...
Based on rotor slot harmonics theory in the Georgia Institute of Technology, this paper proposed to develop a sensor-less temperature estimation method for electrical submersible motor(ESM). This work can realize the demand for the real-time temperature monitoring of ESM worked in the underground 2km deep. To obtain the effective message of slot harmonics, the stator current has been analyzed and...
This paper presents an electric drive consisting of a multiphase induction motor fed by a multiphase inverter. The control system is similar to that of a traditional field-oriented control for three-phase motors, but the machine speed is estimated by a novel sensorless observer. Since multiphase motors with M phases (M is supposed odd) have the capability of controlling the odd spatial harmonics of...
Sawmill loads are disturbing loads. When connected to a power system, they constitute sources of harmonics, voltage fluctuations and flicker. In this paper, measurements of power quality parameters carried out in a case study of MERENSKY Northern Timbers Sawmill Ltd at Tzaneen, Limpopo Province of South Africa are reported. The report indicates that, due to some mitigation measures implemented by...
In an inverter, the number of legs can be increased to any number. So, any number of phase voltages can be generated with proper firing pulses. In this work, a five phase machine is modeled and simulated in MATLAB / Simulink. The space vector modulation (SVM) technique is applied to the proposed model for its torque control. The torque control characteristic obtained using SVM based DTC is compared...
The contribution deals with steady state estimation of a electromagnetic torque ripples and a current waveform of a two-phase induction motor, which is supplied by an three-leg IGBT bridge connected inverter. The inverter's output voltage is controlled by a modified sinusoidal SPWM of the input DC voltage. The complex Fourier series analysis of the inverter's output voltage was made, to obtain a spectrum...
The paper deals with the of AC fractional windings design by the new method. The new method is based on the local density of conductors. The local density of conductor describes distribution of conductors of the whole winding in the slots. By the new method, it is simple to analyze and design any fractional winding. On example of simple fractional winding, it is shown using of this new method for...
Condition monitoring units are employed in industries to monitor the health of the machines continuously. Air gap eccentricity fault is one of the asymmetrical faults which can result in the machine failure. Motor Current Signature Analysis and Vibration Analysis are the two most popular methods used for eccentricity fault detection in the induction motor. In this paper, a study conducted on an induction...
The current filaments (CFM) and the finite elements (FEM) models for analyzing Tubular Linear Induction Motor (TLIM) performances are presented. The governing equations of CFM model can be reduced to the ordinary differential equations that can be solved by numerical method and it is easy to program. A 2D time harmonic finite elements analysis of the motor is used to validate the current filaments...
This paper deals with the resistive losses in the deep-bar induction motor fed by a PWM inverter. The effect of harmonics from the inverter on the resistive losses of the induction motor is investigated by varying the amplitude or phase of the harmonics. The investigation is performed on 45 kW and 1250 kW induction motors. The equivalent circuit of the deep-bar induction motor is presented and used...
This paper presents a 2-D nonlinear time-harmonic finite element model of induction motor for use in the accurate dynamic simulation. In the proposed model, it is not necessary to rotate the rotor, the resistivity of the rotor material is modified in terms of the specified load condition. The nonlinear properties are represented by using the effective magnetization curve. The field-coupled circuit...
A fast calculation method for parametric survey is needed when designing motors. We propose a new method for analyzing the harmonic components of air-gap flux density distribution in three-phase wound rotor induction motors. The proposed method is based on analytical equations for permeance and magnetomotive force distribution, considering the influence of the circumference slot arrangement and winding...
The synchronous reference frame is widely used in DFIG modeling. It is usually assumed that slip control is in place at the rotor-side converters to make sure that the injected rotor voltage at slip frequency gives a nominal stator frequency (60 Hz or 50 Hz). In the analysis, the injected rotor voltages are directly expressed in the synchronous reference frame. In the cases where slip control is not...
This paper deals with modeling of induction machines and in particular of its slotting effects. It is a further improvement of former papers dealing with dynamic modelling of the induction machine including stator and rotor slotting effects. Starting from a previously developed space-vector dynamic model of the induction machine including rotor slotting effects, this work improves the analysis developing...
The model of the squirrel cage AC Motor is based on multiple coupled circuits and takes into account the geometry and winding layout of the machine. All inductances are derived by means of the winding function approach and are integrated with the decomposition into their Fourier series. An important issue in such effort is the modeling of the induction motor including rotor slot harmonics (RSH) under...
As the effects of power systempsilas frequency fluctuation and harmonics, errors are unavoidable when using the FFT to analyze the induction motor current signal. In order to saving the problem of frequency leakage and error of the FFT, the polynomial approximation method is employed to obtain simple formulas for frequency correction. This paper is aimed at using the frequency correction to estimate...
This paper is devoted to the development of a mathematical model of the induction motor operating under stator inter-turns short-circuits. The model is based on the multiplied coupled circuit approach. The inductances calculation is performed thanks to an extension in 2-D of the modified winding function approach (eMWFA), which is able to take into account the space harmonics in addition to the effects...
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