Thermal Modelling and Analysis of A 10HP Induction Machine Using the Lumped Parameter Approach (original) (raw)
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Development and thermal modeling of an induction machine
International Journal of Engineering & Technology
In induction machines, the major concern is the temperature rise since it determines the maximum loading, in an attempt to avoid insula-tion deterioration and eventual loss of motor life. The effect of excessive heat in the motor stator and rotor windings and the stator mag-netic circuit can degrade the developed performance of the machine and also affect the motor loading and life span if not dispensed properly. This research work examines the thermal model for estimating the stator and rotor temperatures in cage induction motor. A state-variable model of the induction is used. The twin-axis stator reference frame is used to model the motor’s electrical behavior, because physical measurements are made in this reference frame. The thermal model is derived by considering the power dissipation, heat transfer and rate of temperature rise in the stator and rotor. The non-linear equations for electrical behavior of the motor and the thermal state equations for the stator and the rotor ar...
An investigation into the thermal modelling of induction motors
1993
Electric motors are the ubiquitous workhorses of the industry, working a in wide range of conditions and applications. Modern motors, designed to exact ratings using new materials improved manufacturing techniques, are now much smaller but have higher loadings. They are being operated much nearer to the point of overload then ever before. To ensure a satisfactory life span for the motor, temperature rise must be limited to safe values. A lumped parameter thermal model has been developed, which allows rapid and accurate estimation of the temperature distribution in a machine. The lumped parameter thermal model depends on the accurate knowledge of the thermal coefficients and more importantly the loss distribution. Hence the temperature time technique was implemented to investigate the iron loss density distribution. Experimental results are discussed and loss density information throughout the volume of the machine was generated. A novel method of determining the thermal coefficients...
Thermal Performance Analysis of Induction Motor
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The aim of this paper is to apply a mathematical model using a lumped parameter thermal method and to conduct experiment test to determine the temperature distribution inside the induction motor to evaluate the thermal stability of the induction motor and to check whether the insulation of the copper windings is sufficient at different operating conditions, and to find out the hottest element which has the main effect on the operation and performance of the motor. We found out from the thermal model analysis that the hottest element in the induction motor is the end winding and rotor bars, this is due to stator copper losses and rotor bars losses which depend on the stator current, the stator current can be increased by increasing the torque or by decreasing the stator frequency, which makes the temperature of each element to increase. The thermal model of the induction motor is validated by comparing the calculated temperatures of each element in the induction motor with the experi...
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Energies
Induction motors have gained a renewed interest due to this new shift from conventional power sources to electric power. These motors are known for their high commencing torque, adequate speed control and reasonable overload capacity. However, induction motors have an innate thermal issue wherein their lifespan and performance are strongly temperature dependent. Hence, it is highly essential to focus on the thermal management aspect of these motors to ensure reliability and enhance performance. Thus, the major purpose of the paper is to comprehensively review various approaches and methods for thermal analysis, including finite element analysis, lumped parameter thermal network and computational fluid dynamics tools. Moreover, it also presents various cooling strategies commonly adopted in induction motors. Furthermore, this study also suggests an integrated approach with two or more cooling strategies to be the need of the hour. These will combine the benefits of the individual sys...
One-dimensional Lumped-Circuit for Transient Thermal Study of an Induction Electric Motor
International Journal of Electrical and Computer Engineering (IJECE), 2017
Electrical machines lifetime and performances could be improved when along the design process both electromagnetic and thermal behaviors are taken into account. Moreover, real time information about the device thermal state is necessary to an appropriate control with minimized losses. Models based on lumped parameter thermal circuits are: generic, rapid, accurate and qualified as a convenient solution for power systems. The purpose of the present paper is to validate a simulation platform intended for the prediction of the thermal state of an induction motor covering all operation regimes. To do so, in steady state, the proposed model is validated using finite element calculation and experimental records. Then, in an overload situation, obtained temperatures are compared to finite element's ones. It has been found that, in both regimes, simulation results are with closed proximity to finite element's ones and experimental records. 1. INTRODUCTION The energy conversion inside an electric machine leads inherently to the heat occurrence, essentially due to different proportions of iron and copper losses. In addition, an overheating of a motor is directly linked to the degradation of its performances [1-3]. Thus, in order to reduce such a limitation and avoid the damage of the device, it is necessary to gather the thermal analysis to the electromagnetic study during design process [3-5]. Indeed, the prediction of the temperature distribution in the different parts of the machine allows us to evaluate if the machine will reach the thermal class for which it is being designed and also to check if the supplied air flow of the cooling system is sufficient to a normal operation at rated conditions. Thereby, a satisfactory life span of the machine gathered to an improvement of its performances could be guaranteed. That explains the existence of several prediction methods of temperatures distribution inside electric motors, like: Computational Fluid Dynamics, Lumped Parameter Thermal Circuits, Finite Elements (FE) …, [6-10]. Thermal models based on lumped parameter were developed since a long time. In such models, each node represents a part of the machine and the thermal circuit, in the steady state, consists of thermal resistances and heat sources connected between motor components. For transient analysis, the heat capacitances are additionally used to take into account the ongoing changes. Despite the accuracy of this method, it needs several improvement. Indeed, in [11], the developed thermal model focused only stator parts. Whereas, when the permanent magnets (PM) are placed in rotor, it is necessary to expand the thermal model and take into account this part. In fact, PMs are very sensitive to the temperature rise and the choice of their polarization is directly related to their thermal behaviour. Moreover, in [12], the temperatures obtained by lumped parameter method were a little higher than the measured ones due to the hypothesis considered to elaborate the thermal model.
Thermal Analysis of an Induction Motor by Hybrid Modeling of a Thermal Equivalent Circuit and CFD
2014
The constant pressure over manufacturers for the production of smaller, more efficient and less expensive motors motivates a thermal analysis simultaneous to an electromagnetic project. In this context, this paper presents a Thermal Network model of a monofasic induction motor with permanent capacitor used in domestic applications. The transient solution and modeling are made with Modelica programing language. The heat transfer convective coefficients are determined by computacional fluid dynamics modeling. Hence, this paper presents a hybrid model which provides fast and accurate results in steady or transient states and for different flow states: turbulent forced convection and natural convection. The model has been validated with experimental data.
IEEE Transactions on Energy Conversion, 2013
This paper presents a practical approach to model thermal effects in directly cooled electric machines. The main focus is put on modeling the heat transfer in the stator winding and to the cooling system, which are the two critical parts of the studied machines from a thermal point of view. A multisegment structure is proposed that divides the stator, winding, and cooling system into a number of angular segments. Thereby, the circumferential temperature variation due to the nonuniform distribution of the coolant in the cooling channels can be predicted. Additionally, partial computational fluid dynamics (CFD) simulations are carried out to model the coolant flow in the cooling channels and also on the outer surface of the end winding bodies. The CFD simulation results are used as input to the analytical models describing the convective heat transfer to the coolant. The modeling approach is attractive due to its simplicity since CFD simulations of the complete machine are avoided. The proposed thermal model is evaluated experimentally on two directly cooled induction machines where the stator winding is impregnated using varnish and epoxy, respectively. A good correspondence between the predicted and measured temperatures under different cooling conditions and loss levels is obtained. Index Terms-Computational fluid dynamics (CFD), conductive heat transfer, convective heat transfer, directly cooled electric machines, induction machines, lumped parameter (LP) thermal models. NOMENCLATURE A Ch Cooling channel cross-sectional area. A EW End winding ring cross-sectional area of one slot in the axial direction. A EW ,Cu Copper cross-sectional area of the end winding ring in the circumferential direction.