Losses In Induction Motors Research Articles

Operational electricity cost reduction using real-time simulators

Ensuring the safe and cost-effective electricity transmission to consumers, along with the efficient and sustainable operation of power systems, has long been a primary objective for power system managers and operators. However, achieving optimal performance in a modern power system requires timely planning and operational optimal routines to be run within the realm of real-time simulation programs, and sometimes, the divergence becomes a problem with these developed routines. Despite extensive research aimed at advancing these objectives, the growing complexity of networks and their constraints has often led to the oversight of simultaneously considering both technical and economic aspects during operation. In this paper, an innovative real-time framework is introduced to reduce the operational costs of a power system swiftly. This framework addresses various nonlinear constraints, such as transmission losses, generation-consumption balance, power device limitations, and transient stability constraints, across various operational scenarios within a real-time simulator. This novel approach leverages scattered search and intentional contingencies within the network to pinpoint the optimal operating point, taking into account various network dynamics, including Automatic Voltage Regulators (AVR), governors, and tap of the transformers. The proposed method offers a fast and robust approach to identifying the most effective operating conditions for a power system. It incorporates considerations for sudden contingencies and extends capabilities through parallel simulations. It not only facilitates pre-determined preventive actions but also enables the adjustment of control parameters during post-contingency periods, such as fine-tuning of the active and reactive power generation of generators and adjusting the tap settings of transformers within power networks. Since the network simulation can be executed on distributed computers, referred to as ’Global,’ it is possible to achieve global network optimization. This approach allows for the consideration of grid networks, including renewable energy sources with models distributed through PCs. Also, it accounts for the induction motor losses within all factories involved in the global simulation. The results obtained from simulating the proposed method on a commercial real-time simulator demonstrate the superior effectiveness of the proposed framework compared to the existing methodologies, highlighting its potential to enhance the operational efficiency and economic viability of power systems.

An effective higher order finite element computation method for analyzing the eddy current losses in induction motors using subparametric transformations

An enhanced sub-parametric finite element method is presented for analyzing the eddy current losses in induction motors using higher order sub-parametric transformations. The purpose of this study is to construct a very efficient, simple, and exact higher order sub-parametric approach employing a 2D automated mesh generator implemented in JuliaFEM. Alternating current motors are employed in a wide range of industrial and household applications on a frequent basis such as in fans, water heaters, ovens, pumps and many more. High efficiency of the motors is one of the most desirable parameters of these motors. Eddy current losses are predominant in these motors which are responsible for a decline in the efficiency. Consequently, the use of eddy current analysis is vital in evaluating the behaviour of electric devices under various loads. This paper proposes a novel finite element method approach to minimize the 2D eddy current phenomenon by taking the diffusion equation into account. Eddy currents are the primary source of torque in various types of equipment, such as induction motors. In other cases, it is important to analyse the eddy currents to estimate the losses, reactance, and resistance.

General Online Current-Harmonic Generation for Increased Torque Capability With Minimum Stator Copper Loss in Fault-Tolerant Multiphase Induction Motor Drives

This paper proposes a current-reference generation method including current harmonic injection (CHI) for enhancing the torque capability of multiphase induction machines (IMs) with negligible space-harmonic effects, which is useful, e.g., during transient overload in electric vehicles. The admissible torque is increased because the harmonics reduce the phase-current peaks, so that the instantaneous peak-current constraint of the drive, usually associated with the converter ratings, is respected. The harmonics are injected in the so-called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x-y</i> subspaces of the IM, which do not produce torque, so that no torque ripple is introduced. The optimum harmonics are found online for each load, making it possible to minimize the stator copper loss (SCL) per torque in the entire torque range, ensuring full-range minimum loss (FRML). The method is suitable for healthy operation or open-phase faults, and for multiphase machines of any phase number and with either symmetrical or asymmetrical windings. Compared with FRML methods without CHI, higher torque is achieved. Although some techniques were available for increasing the torque capability by CHI, FRML was not attained, laborious offline optimization was needed, or they were only suitable for specific drives or for healthy conditions, unlike the proposal. Experimental results with a symmetrical six-phase IM are provided.

Experimental and statistical analysis of the effects of punching and laser cutting methods on induction motor efficiency and total magnetic losses in silicon lamination sheets

In this study, M400-50A electrical steel laminations (ESLs) used in electrical machines were cut with punching and laser methods and the effect of these cutting methods on the efficiency and total losses of induction motors was investigated. ESLs were prepared by laser and punching cutting methods concerning an induction motor with a power of 5.5 kW. After the stator and rotor packages were created, processes such as winding, varnishing, and mechanical assembly were performed on the motors. It is prepared for motor efficiency (MEfficiency) and total magnetic losses (TLosses) tests according to the direct measurement method specified in the IEC 60034-2-1-1A standard. Four different frequencies (f: 50, 75, 100 and 125 Hz) and five different motor loading rates (MLoad: 25, 50, 75, 100 and 125%) were defined as independent variables in the tests. MEfficiency and TLosses values were measured as dependent variables. Plastic deformation and edge rounding were observed on the edges cut with punching and edge rounding and angled edge formation on the edges cut with the laser. The average surface roughness of the laser-cut edges was determined to be higher than the ESLs cut by punching. It was observed that TLosses increased while MEfficiency decreased with increasing frequency and MLoad value in motor tests. It was determined that the training, testing, and experimental data are quite compatible with each other and the R2 values are close to 1 in the statistical analyzes performed with ANN (Artificial neural network). In addition, it was specified that RMSE (Root mean square error) and MAPE (Mean absolute percentage error) values vary between 0.007 and 13.310% for each cutting method and mathematical models can be used to predict MEfficiency and TLosses with ANN.

Method of calculation of electromagnetic torque and energy losses of three-phase induction motors when powered by a regulated single-phase voltage

Introduction. Single-phase power supply of induction motors is used in public utilities, in microclimate control systems for remote agricultural consumers, in water supply and pipeline transport systems, etc. In practice, there is the use of induction motors with three-phase stator winding in the conditions of single-phase power supply. Starting and operating capacitors are used to enable their operation when powered by a single-phase network. Problem. There are many fairly accurate methods for calculating the characteristics of an induction motor in asymmetric, including single-phase, modes of operation, but they are based on differential equations, which does not allow to obtain analytical expressions for preliminary analysis and synthesis of such systems. Goal. The purpose of this article is to develop the analytical method of definition of electromagnetic torque and energy losses of voltage-regulated three-phase induction motors working according to the scheme of single-phase inclusion with the phase-shifting capacitor. Methodology. The method is based on the theory of symmetric components and analysis of replacement schemes of induction machine in motor and generator modes. Results. The analysis of the obtained data shows that at a constant value of the phase-shifting capacitor capacity induction motor working according to the scheme of single-phase inclusion has a minimum of losses at one value of slip at different values of supply voltage. Therefore, if you keep this slip constant when the load changes, you can achieve a mode of minimizing losses at a constant value of the capacity, optimal for this slip. This shows that the thyristor voltage regulator can be used as an energy-saving element under variable load, while the capacitance of the phase-shifting capacitor can remain constant when changing the load in a wide range provided that this slip is stabilized. Originality. The developed method allows to obtain analytical expressions for comparative analysis of electromagnetic torque and energy losses of three-phase induction motors powered by a single-phase network at different values of the capacity of the phase-shifting capacitor, supply voltage for different variants of schemes for including three-phase induction motors in a single-phase network. Practical value. Based on the developed analytical method, the optimal parameters of phase-shifting capacitors and rational schemes for including three-phase induction motors in a single-phase network can be determined.

Experimental study on the influence of high frequency PWM harmonics on the losses of induction motor

For the purpose of studying the influence of high frequency PWM harmonics on the losses of induction motor, this paper first introduces the latest international standard IEC/TS 60034-2-3 for the separation of the losses and the measurement of the efficiency of induction motor under PWM power supply. Then, considering that the skin effect of windings in induction motors under the condition of PWM power supply more apparent, this paper uses the stator AC resistance to replace the stator DC resistance in the IEC/TS 60034-2-3 standard to obtain more accurate separation results. On this basis, an improved method of loss separation for converter-fed induction motor is proposed by using the accurate time-step finite element method to calculate the rotor copper loss under no-load condition which cannot be considered in IEC/TS 60034-2-3 standard. Finally, this method is used to measure and separate the losses of a 5.5 kW converter-fed motor under different operating conditions. The results show that the loss of induction motor which is driven by PWM converter is obviously greater than that of sinusoidal drive, especially under light load or no load condition. The whole no-load losses of the motor driven by PWM converter increases by more than 20.0% compared with that of the sinusoidal driving condition.

FAULT LEVEL DETECTION OF A THREE PHASE INDUCTION MOTOR USING MATLAB SIMULINK

This paper present a MATLAB based fault level detection of a three phase induction motor. Because of their simple and durable structure, as well as low production costs, three phase induction motors are employed in a wide range of applications. When it is in use, it is vulnerable to damage due to the defects that may occur. Overcurrent, unbalanced, overvoltage, undervoltage, single phasing, are examples of faults. Induction motors are employed in a wide range of industrial applications. THD (Total harmonic distortion) is also a problem for electrical engineers as it leads to heavy power loss in AC induction motors. These losses in AC induction motors leads to excessive heating, which happens because of additional copper losses and iron losses (eddy current and hysteresis losses) in the stator winding, rotor circuit, and rotor laminations. This causes lots of electrical equipment failure in the plants. The proposed scheme is simulated using MATLAB Simulink. MATLAB simulation results show that the well trained protest scheme is able to detect all types of internal faults and THD at different location. Keywords: three phase induction motor, fault classification, Proteus environment, THD.

Cage Losses in Induction Motors Considering Harmonics: A New Finite Element Procedure and Comparison With the Time-Domain Approach

The cage losses in induction machines due to spatial or time harmonics in the air-gap field are a crucial parameter for a precise estimation of the machine efficiency. Using finite element, the common approach to consider the overall cage losses, by performing complete time-domain analyses. Alternatively, a rough estimation is achieved introducing equivalent parameters in the circuital model. In this article, a methodology for cage losses computation due to air-gap spatial field harmonics is described. The proposed finite element procedure is faster than the time-domain analysis since it is based on magneto-static and linear time-harmonic simulations to carefully consider the iron saturation and compute the induced currents in a specific working point. In the article, a detailed procedure description and comparison with respect to the time-domain approach is reported.

The determination of induction motor losses in steel taking into account its saturation

PurposeThis paper aims to work out a method for calculating losses in induction motor steel taking into account its saturation.Design/methodology/approachThe theory of electric machines is applied during the analysis of induction motor equivalent circuits. The theory of Fourier series is used to determine the harmonic components of voltage, current and power. Instantaneous power theory and trigonometric transformations are used to solve algebraic and differential equations and their systems. The methods of approximation and interpolation are applied to obtain analytical expressions from the experimental data. Experimental research was carried out to verify the reliability of theoretical provisions and research results.FindingsA method for assessing an induction machine steel as a function of the generalized electromotive force has been proposed. It allows taking into account higher harmonics of the current, which are caused by the presence of nonlinearity of an induction motor magnetic circuit.Practical implicationsThe obtained results can be used in calculating the energy characteristics and operating modes of an induction motor, as well as in the construction of control systems.Originality/valueA method for determining the losses in the stator steel of an induction motor, using a generalized electromotive force, has been proposed for the first time. It enables taking into account the currents flowing both in the stator circuit and in the rotor circuit.

Collective Losses of Low Power Cage Induction Motors—A New Approach

Energy efficiency of systems of water pumping is a complex problem since efficiency of two distinct interacting systems needs to be combined: water and power supply. This paper introduces a non-intrusive method of calculating the so-called “collective losses” of a cage induction motor. The term “collective losses”, which the authors define, allows for accurate estimation of motor efficiency. Control system of a pump determines operating point of a pumping station, and thus its efficiency. General estimated performance characteristics of a motor, components of a control system, are assumed to serve selection of a range of pumping speed variations. Rotational speed has a direct effect on motor load torque, pump power and head, and thus on motor performance. Hellwig’s statistical method was used to specify characteristics of estimated collective losses on the basis of experimental studies of 21 motors rated at up to 2.2 kW. The results of simulations and experiments are used to verify validity and efficiency of the suggested method. The method is non-intrusive, simple to use, and requires minimum data.

Stray Load Loss Calculation for Induction Motor by Combination of General Airgap Field Modulation Theory and 2D FEA

The accurate calculation of stray load loss has an important contribution to increasing motor efficiency. The stray load loss can be regarded as the difference of the total iron losses and harmonic rotor cage losses between the no load and load conditions. A method combining the general airgap field modulation theory (GAFMT) and 2D finite element analysis (FEA) is proposed for calculating the stray load loss of the squirrel cage induction motor (SCIM). Firstly, the amplitudes and rotation speeds of the main space harmonics of the airgap magnetic flux density are calculated based on the GAFMT. And the relationships between these space harmonics and stray load loss are analyzed. Secondly, these space harmonics are synthesized by the equivalent current layers in the airgap and then are substituted into the 2D FEA models to calculate the losses. At last, the stray load loss calculated by the proposed method is compared with that obtained by practical motor tests.

The Performance of a Three-Phase Induction Motor under and over Unbalance Voltage

Voltage unbalance is an adverse global phenomenon impacting three-phase induction motor output. Three-phase source voltage may become imbalanced in a variety of respects, while a balanced system preserves stable voltage magnitude and angles in three phases, but a completely balanced state is difficult to get. Imbalanced cases may differ in multiple ranges which may practically affect the motor. So, this work is an effort to analyze the operations with appropriate propositions. The output of a three-phase induction motor working with an imbalanced supply grid, MATLAB/SIMULINK is further used for simulation purposes and programming based on the asymmetrical component approach is adopted. A new design for system rerating is being proposed. As a case study, a 10 HP three-phase induction motor was used. The findings of the study show that to determine the output of the induction motor, positive voltage series must be respected under the voltage unbalance factor (VUF) or proportion voltage unbalance index with six various voltage magnitude imbalance conditions, the copper losses of three-phase induction motors were calculated under full load conditions by simulation. So, the qualified percentage change in total copper losses for the motor operating under imbalanced and balanced voltages was determined.

Analytical Evaluation of Core Losses, Thermal Modelling and Insulation Lifespan Prediction for Induction Motor in Presence of Harmonic and Voltage Unbalance

Electrical motor are the ubiquitous workhorses of the industry, working over wide range of conditions and applications. Modern motors, designed to exact ratings using new materials and improved manufacturing techniques, are now much smaller but have higher loadings. They are being operated much closer to the point of overload than ever before. To ensure a satisfactory lifespan for the motor, temperature rise must be limited to the safe values. This paper proposes an analytical approach to estimate core losses of induction motor supplied by either harmonic content or voltage unbalance source. A model based on the thermal lumped parameters is introduced and used to predict the insulation lifespan of induction motors. Lumped parameters network of the motor is developed based on dimensions of the motor, thermal resistances, thermal capacitances, and loss sources. Then, the model is used to estimate the temperature in different parts of the machine and its insulation lifespan. Finally, the predicted results are verified by experiments.

Variable Frequency Drive Source Based Efficiency Measurement of an Induction Motor

Induction motor loss separation and efficiency measurement needs loading dynamometers and other tools as like variable voltage sinusoidal power supply. These are costly and not always usable except though a loading tool is usable. Variable frequency drives are also commonly utilized for running induction machinery and are readily accessible and low cost. Nevertheless, their usage in lieu of a constant frequency sinusoidal power supply to calculate system performance precisely is interesting, but potentially difficult because of the PWM output voltage. This paper provides few studies into the usage of variable frequency drives. The usage of the machine, the measurement criterion and the protocols shall be reported and addressed. The output presented describes the possibility of the suggested idea of calculating machine effectiveness with a PWM power source.

FIELD WEAKENING CONTROL FOR INDUCTION MOTORS BASED ON COPPER AND IRON LOSSES MINIMIZATION

This paper is concerned with the analysis of losses in induction motors. The most significant have been chose for minimization. These are in particular the losses in the windings and in the magnetic circuit due to eddy currents and hysteresis. Equations for the rotor flux linkage and orthogonal components of the stator current in the rotor reference frame dq in the induction motor’s vector control system based on the condition of minimizing the total losses in copper and motor steel in the steady state. Here, effects of steel saturation are not taken into account. The limit values of the torque and speed are determined, where the rotor flux linkage con-trol can improve the energy characteristics of the drive outside the magnetic saturation. It is shown that the main difficulty in imple-menting energy-optimal control is that the rotor flux linkage operates not only energy parameters, but also speed regulation in the field-weakening region.A block diagram of the implementation of energy-optimal control with field weakening mode is proposed. The idea is to switch the control algorithms of the magnetic field of the motor in such a way that in the start-brake modes the rotor flux linkage changes in the speed reference function, and when operating at a steady speed, in the function of the torque. A co mpara-tive analysis for a typical and developed drive systems in field-weakening mode by the simulation is carried out.It is shown that with the same transients of the torque and speed in a typical system, the efficiency in steady-state decreases with a decrease of torque load torque, whereas the proposed system it remains unchanged. The change in efficiency in dynamic conditions occurs when the rotor flux linkage changes. With energy-optimal control, there is a slight increase in the stator current peaks when the torque load changes abruptly, but at low torque load an additional field-weakening leads to a decrease in the stator voltage, which carry on a decrease in electricity consumption.

Fast Solution of Rotor Losses in Inverter-Fed Cage Induction Motors With Skewed Slots

The conventional calculation of rotor losses in cage induction motors by the time-stepping finite element method requires the full slip waves of the rotor flux densities and currents. The calculations of the full slip waves are extremely expensive in CPU time, memory, and hard disk space for the induction motors with skewed slots and pulsewidth modulated supply. This article proposes a technique that reproduces those full slip waves by utilizing both the time varying and the spatial information of the rotor electromagnetic quantities and, hence, significantly saves the calculation cost. The more rotor bars per pair of poles the induction motor has, the more calculation cost this technique saves. The calculation costs of the proposed and conventional methods are compared for the rotor losses of a 5.5-kW inverter-fed skewed induction motor under load condition, and the calculated losses are validated by tests.

Derating of Induction Motors Due to Power Quality Issues Considering the Motor Efficiency Class

Heating and losses of induction motor (IM) grow with the supply voltage unbalance and harmonic distortion. To avoid thermal overload, the IEEE 141-1993, the IEEE 3004.8, NEMA MG1-2014, and the IEC 60034-26 standards establish derating factors for IMs operating under those conditions. In this article, we show that while the derating factors proposed by these standards adequately protect standard-efficiency IMs, they are only marginally adequate to protect modern higher-efficiency IMs. To this end, we compare the derating factors provided by the standards with the derating factors required to maintain the losses at rated values in a standard-efficiency IM, in a premium-efficiency IM, and in a super-premium-efficiency IM. To extrapolate the results from these IM, we compared the nameplate data of 548 IMs of different efficiency classes and found that higher efficiency classes correlate to higher IM starting currents and lower impedances to the negative sequence and harmonic voltages. These lower impedances in turn may lead to higher losses for unbalanced and harmonic voltages conditions.

A Comparative Performance Analysis of Indirect Vector Controlled Induction Motor Drive Using Optimized AI Techniques

This paper exhibits a point by point comparison between Neuro Fuzzy and Genetic Algorithm GA based control systems of Induction Motor drive, underlining favorable circumstances and drawbacks. Industries are advancing and upgrading generation line to enhance efficiency and quality. Induction machines are considered by nonlinear, time varying dynamics, inaccessibility of few states and thus can be considered as a challenging issue. In this paper, a novel method using modified GA is presented to limit electric losses of Induction Motor and it is compared with Neuro Fuzzy Controller. GA is a subordinate of AI, whose principle relies upon Darwin’s theory—struggle for existence and the survival of the fittest. The technique for deciding the gain parameters of PI controller utilizing GA whose output is utilized to control the torque applied to the Induction Motor in this way controlling its speed. The gains of PI controller are improved with the assistance of GA to upgrade the performance of IM drive. The results are simulated in MATLAB Simulink and are related with the conventional PI controller and Adaptive Neuro Fuzzy controller (NFC). NFC is less complicated and gives great speed precision yet GA based PI controller produces significantly reduced torque and speed ripples compared with other controllers, in this way limiting losses in IM drives.

In-Vehicle System Identification of an Induction Motor Loss Model

The influence of induction motor model parameter deviations on field-oriented control performance has been widely investigated. Various methods have been introduced to track variations of magnetic and resistive parameters of the so called T-equivalent circuit model. Online methods on embedded systems exist and are successfully used in modern motor controls. For the use in vehicle motion control and particularly supervisory controls, however, state-of-the-art identification methods may not be applied directly, due to restricted communication interfaces or a limited amount of available measurements at sampling frequencies above the required rates. To cope with these limitations, a moddeling approach is introduced which is based on the equivalent flat system representation of the induction motor, stationary operation conditions, and the incorporation of the vehicle specific field-oriented control strategy. The inclusion of the control strategy allows for derivation of least-square error formulations which are used to identify a selection of induction motor model parameters from low frequency vehicle measurements. An experimental study demonstrates the accuracy of the proposed method and shows how effectively the introduced model can reproduce the measurment of the rms phase current and electric power.

Investigation of high frequency loss in electrical machine lamination considering skin effect and hysteresis

Reducing induction motor losses is very important because of the fulfilment of increasingly stringent requirements set by international regulations for reducing electricity consumption. Since core losses begin to dominate in motors operating at higher frequencies the exact calculation becomes more and more important. The common view is that losses due to higher harmonics caused by stator and rotor slotting constitute an important part of losses in the motor core. Proper calculation of the core losses requires inclusion both hysteresis and eddy current phenomena. For the hysteresis simulation, method included in package Opera 3D has been used. Using that model it was possible to investigate flux behavior at high frequency like as for higher harmonics field. Next part is focused on practical determining of proper method for higher harmonics losses limitation.