Three-phase Asynchronous Machine Research Articles

Bearing Faults Diagnosis by Current Envelope Analysis under Direct Torque Control Based on Neural Networks and Fuzzy Logic—A Comparative Study

Diagnosing bearing defects (BFs) in squirrel cage induction machines (SCIMs) is essential to ensure their proper functioning and avoid costly breakdowns. This paper presents an innovative approach that combines intelligent direct torque control (DTC) with the use of Hilbert transform (HT) to detect and classify these BFs. The intelligent DTC allows precise control of the electromagnetic torque of the asynchronous machine, thus providing a quick response to BFs. Using HT, stator current is analyzed to extract important features related to BFs. The HT provides the analytical signal of the current, thus facilitating the detection of anomalies associated with BFs. The approach presented incorporates an intelligent DTC that adapts to stator current variations and characteristics extracted via the HT. This intelligent control uses advanced algorithms such as neural networks (ANN-DTCs) and fuzzy logic (FL-DTCs). In this paper, a comparison between these two algorithms was performed in the MATLAB/Simulink environment for a three-phase asynchronous machine to evaluate their effectiveness under the proposed approach. The results obtained demonstrated a high ability to detect and classify BFs, confirming the effectiveness of each algorithm. In addition, this comparison highlighted the specific advantages and disadvantages of each approach. This information is valuable in choosing the most suitable algorithm according to the constraints and specific needs of the application.

Simulation Model of an Asynchronous Machine with Wound Rotor in Matlab Simulink

The article presents a three-phase mathematical model of asynchronous machine with wound rotor based on differential equations. The equations are resolved with respect to the derivatives of flux linkages. The description of the computer program in the Matlab Simulink that implements the model and allows to simulate transients of the asynchronous motor is present. A simulation model of a three-phase asynchronous machine with wound rotor, which allows to investigate static and dynamic operating ranges when power converters are connected to the rotor circuit has been obtained. The results of approbation of the obtained simulation model in the Matlab Simulink environment and experimental research of asynchronous engine with wound rotor, driving into the asynchronous-valve cascade, are presented. The results of experimental studies of the asynchronous machine under sinusoidal voltage using a stand based on the asynchronous-valve cascade, and comparison of the oscillograms obtained with simulation results of the proposed model are presented. The comparison of experimental and calculated oscillograms of the current of the investigated asynchronous motor can be concluded on satisfactory accuracy of the proposed model and the possibility of its application for modeling and analysis of asynchronous electric drives.

Power Conditioning With Intelligent Control Using a Novel Recursive Stochastic Optimization

This paper presents a novel smart-grid power-conditioning system with intelligent control for solving a critical issue affecting the performance and life of three-phase asynchronous machines that are highly sensitive to voltage and phase drifts power disturbances of the electric grid. The present work of controlling the power supply of an electric-grid is based on an original power conditioning control algorithm; named recursive stochastic optimization (RSO) algorithm. An asynchronous machine steady-state model is derived based on symmetrical components analysis, permitting the evaluation of the effect of both voltage and phase unbalance using voltage and current unbalance factors. The three-phase power supply is conveyed through a power conditioning and intelligent control system, driven by a digital signal processor (DSP) controller, which measures the input currents, estimates the unbalance factors, and searches for voltage levels that minimize the electric-grid unbalance using the RSO, in order to act on a feedback power-electronics stage. The RSO algorithm shows excellent results along with very fast response time of the order of 20 ms allowing real-time control. Results obtained are validated with a Simulink dynamic model. The intelligent control system architecture based on TMS320C6748 DSP board with signal acquisition and control microcontroller is proposed.

Design of an off-grid model of micro-smart grid connection of an asynchronous motor fed with LUO converter

This paper proposes a model for a photovoltaic (PV)-based micro-smart grid system connection with asynchronous motor driving via LUO converters. LUO converter is a kind of DC–DC converter developed by Fang Lin Luo. It occupies less space than many other converters owing to a small number of electronics elements. In this model, a method was developed for forecasting the total power output under particular conditions of Ankara city (Capital of Turkey). PV cell parameters are determined firstly, and then PV array is formed including cells designed in order to calculate cumulative effect. It has tried to catch an approximation of necessary energy for systems that use the three-phase asynchronous machine using actual irradiation and temperature values. Then PV array output voltage, which is 12 V, has been converted 325 V thanks to LUO converter. Finally, space vector PWM has used for PWM production that supplies 325 V DC to 220 V AC via LUO converter for driving asynchronous motor. Instead of taking energy from the grid, energy saving is achieved by producing necessary energy from the solar panels. Thus, industrial consumption causing disruptive effects at grid can be decreased. The capability of system is demonstrated using MATLAB/Simulink simulation models.

The mathematical model for analysis and evaluation of the transient process of the three-phase asynchronous machine performance

This paper describes an adopted method which could be used in transient process modelling of three-phase asynchronous machines on the computer. Converter asynchronous electric machine feeding requires a detailed research of the transient process influence and the dynamic states of energy exchange between the electrical circuit feeding and the machine itself. A mathematical model has been formulated in order to solve the transient process of the three-phase asynchronous electric machine referring to the two asynchronous machines and containing two matrix models defined by Park?s d - q components. In the system of symmetrical components the state and the operation of the first machine was defined based on relations and operation conditions of a direct sequence system and of other machines based on relations and operation conditions of an inverse sequence system. The new method has been derived from the existing psbpwm MATLAB package. The new model simulates the state and operation of a single machine with identical parameters through the state and operation of the two machines with identical parameters: the first in a direct sequence system and the others in an inverse sequence system. Operation analysis of the three-phase induction machine is limited to a transient process occurring in the right angled shape of voltage feeding. The new presented model can, with certain limitations, be applied not only to a three-phase asynchronous machine model but to other alternating current machines which have a stator and a rotor. The experiment has been performed following an example of asymmetrical feeding followed by inverse component phenomena of electrical and mechanical values in the machine.

VHDL Design and FPGA Implementation of the SVPWM of a Three-phase Asynchronous Machine Powered by a Voltage Inverter

In this paper, we will focus on the VHDL design and the FPGA implementation In the Loop (HIL) of the space-vector Pulse with modulation technique (SVPWM) applied to the three-phase inverter ensuring the speed variation of an asynchronous machine .We will adopt a modular approach, by dividing the global entity into a set of elementary blocks designed and implemented separately. The obtained performances of the proposed architecture of the SVPWM are 1185 LUTs of complexity and 2 latency clock cycles. We have also realized a platform based on the Matlab / Simulink and DSP Builder co-simulation of the speed variation of an asynchronous machine using our architecture, the results obtained enable us to validate our SVPWM circuit.

Experimental prototype of an electric elevator

The main objective is to achieve an elevator prototype powered by a three-phase voltage system via a bidirectional static power converter ac-ac with regenerating capability. In order to diminish the power size of the electric motor up to 1/3 of rated power, the elevator contains two carriages of the same weight, one serving as the payload, and the other as counterweight. Before proper operation of the static power converter, the capacitor must be charged at rated voltage via a precharge circuit. At the moment of stabilizing the DC voltage at nominal value, the AC-AC power converter can operates in the proper limits. The functions of the control structure are: the load control task, speed and torque controls. System includes transducers for current measuring, voltage sensors and encoder. As reserve power sources the hybrid battery-photovoltaic panels are used. The control voltage is modulated by implementing four types of pulse width modulations: sinusoidal, with reduced commutation, third order harmonic insertion, and the space vector modulation. Therefore, the prototype could operates with an increased efficiency, in spite of the existing ones. The experimental results confirm the well design of the chosen solution. The control solution assures bidirectional power flow control, precharge control, and load control and it is implemented on a digital signal processor. The elevator capacity is between 300-450 kg, and it is driven by using a 1.5 kW three-phase asynchronous machine.

Chaotification and fuzzy PI control of three-phase induction machine using synchronization approach

In this manuscript, a three-phase asynchronous machine is forced to behave chaotically. The rotor speed becomes chaotic and thereafter is forced to follow a constant speed using a fuzzy controller. The approach is useful to attain an optimum trajectory planning. This will be achieved in two stages of; chaotification and control. Primarily outputs of the three-phase induction motor in terms of currents, voltages and speed become chaotic. The chaotification is achieved in a synchronization framework, considering a fifth-order nonlinear dynamics. In this approach, Lorenz chaotic system (as master) is applied as an input to the system when (speed of) the motor as a slave will be synchronized. The achieved synchronization error enters a fuzzy PI controller where an inverter provides required correspondent three phase voltages. According to this strategy, the voltage source inverter works as an actuator to provide a sinusoidal three-phase voltage with required frequency in a V/f constant ratio mechanism. In the second step, the chaos is stabilized at a constant value when the Lorenz master system is arbitrarily controlled. In this regard, the chaos in the motor speed is controlled and stabilized in response to a constant command. Two simulations of HWIL (Hardware in the Loop) approach and software implementation are carried out. Simulation results show that the proposed scheme can effectively make the motor outputs chaotic where another cascade control tunes the speed. Practical HWIL realization ultimately confirms the achievement.

The Effect Fault of Inverter Multi Levels on Asynchronous Machine

The voltage source inverter has a diversity known in many industrial applications, such as the variation speed in electrical training. But the characteristic inverter recognized grace of the power electronic development can presented a structural faults, however the closed fault of semiconductors, that can provoke a serious problem for the protection of the system. T his article presented the diagnostic of the inverters multi levels associates with the three-phase asynchronous squirrel-cage machines witch show the faults of the switches for each inverter multi levels and their influence on the answers of speed and torque.

Transient model of the three-phase cage asynchronous machine with saturation and space harmonics effects

Three-phase induction machines are excessively used and their control has been widely developed. The machine model often used in the control system is the linear 2-axes d-q machine equations. There is a need for improved methods of analysing the dynamic behaviour to check the validity of the control system. We propose a real three-phase model including space harmonics effects by Fourier analysis of the air-gap induction and taking into account simultaneously the non-linearity of the ferromagnetic parts by using a complete permeance network.

Losses in three-phase induction machines fed by PWM converter

The paper deals with the analysis and evaluation of test results of PWM converter-fed induction motors. The test results presented point out the dependency of the harmonic losses on the pulse frequency. The measured values were obtained by means of a novel high precision power-analyzer capable of measuring the harmonics of voltage, current and power. Following a detailed investigation regarding the sources of the harmonic losses the paper describes new methods for determining the harmonic losses by both calculation and measurement. The calculation is based on a new equivalent circuit comprising specific impedances for imaging the eddy-current circuits within the iron core derived from the fundamental equations of the three-phase asynchronous machine. These impedances permit the calculation of the harmonic iron losses under the influence of the eddy-currents in all sections of the magnetic circuit caused by the harmonics. Measured and calculated losses were found to correspond satisfactorily for the various voltage harmonics.

Detection of an End-Ring Fault in Asynchronous Machines by Spectrum Analysis of the Observed Electromagnetic Torque

For asynchronous machines, 20% of the failures are due to the rotor [1] and particularly the end-ring fault of cage motors. Studies [2, 4] have shown that a rotor fault generates flux harmonics which induce in term of harmonics in the stator currents. So, the analysis of the torque which is the product of these two quantities, must give a better information on the faults. In this paper a new technique is presented allowing the diagnostic of an end-ring fault of a cage threephase asynchronous machine. Previous researches by the authors [5] have given the expression of the instantaneous electromagnetic torque with these defects influence. It has been observed actually that the ruptures influence greatly this quadratic quantity. The torque was calculated from the line currents and the e.m.f across flux sensors placed in the stator windings. In this method, the flux sensors are not essential to determine the electromagnetic torque. The rotor flux can be directly estimated by using an observer. This study presents how a model of the asynchronous machine is used to build the observer.