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Kalluf F.J.H.,Embraco | Isfanuti A.S.,Polytechnic University of Timişoara | Tutelea L.N.,Polytechnic University of Timişoara | Moldovan-Popa A.,Polytechnic University of Timişoara | Boldea I.,Polytechnic University of Timişoara
IEEE Transactions on Industry Applications | Year: 2016

An optimal design of internal Ferrite permanent-magnet motor with embedded key finite-element method verification is presented with the scope to increase the efficiency of the small power motors without using expensive rare earth permanent magnets. Two internal flux concentration topologies are analyzed, and the geometric dimensions and performances are presented for three cases, all at 1-kW rated power at 4500 r/min rated speed. The 6/8 poles ferrite-spoke permanent-magnet synchronous motor prototype was built and test results prove an efficiency larger than 88% for a large load range. Two sensorless control methods based on active flux observer are presented, with the key simulation results including acceleration, speed reversal, loading, and unloading speed responses. © 1972-2012 IEEE.


Verardi M.,EMBRACO | Link R.,EMBRACO | Deschamps C.J.,Federal University of Santa Catarina
Institution of Mechanical Engineers - 7th International Conference on Compressors and Their Systems 2011 | Year: 2011

The constant search for performance improvement of reciprocating compressors is usually sought through the analysis of refrigeration systems operating in a steady state condition. Such an approach disregards a set of phenomena related to transient regimes of starting and stalling that also influence the compressor energy performance, noise levels and reliability. This paper brings about a discussion about the relation between the refrigerant charge and the starting pressure of the system, explaining its importance on the transient starting process of the compressor. The study shows that this type of analysis is essential to improve the design of the compressor starting system. © The Authors, 2011.


Link R.,EMBRACO | Deschamps C.J.,Federal University of Santa Catarina
Institution of Mechanical Engineers - 7th International Conference on Compressors and Their Systems 2011 | Year: 2011

Different simulation methods have been proposed in the literature to predict the performance of reciprocating compressors considering valve dynamics. When several design alternatives have to be assessed, the most convenient route is the adoption of simple models based on integral formulation for the compression process inside the cylinder. In these models semi-empirical expressions for effective flow and force areas are used to evaluate the mass flow rate and the dynamics of valves. The occurrence of backflow in valves is a main source of volumetric inefficiency but it is difficult to predict because the expressions for effective areas usually neglect inertial effects of the flow. This paper reports a study of fluid-structure interaction of reed valves allowed by a two-dimensional numerical model of a simplified geometry of discharge valve. Effective flow and force areas are then evaluated taking into account flow inertia so as to better detect backflow. Results for efficiency parameters obtained with a lumped model make it evident the importance of accommodating such transient effects in effective areas. © The Authors, 2011.


Icfanuti A.S.,Polytechnic University of Timişoara | Tutelea L.N.,Polytechnic University of Timişoara | Kalluf F.J.H.,Embraco | Boldea I.,Polytechnic University of Timişoara
2014 International Conference on Optimization of Electrical and Electronic Equipment, OPTIM 2014 | Year: 2014

The present paper introduces a novel two coil 1 phase stator Ferrite PM motor [1]. The main targets are reduced material and fabrication costs in a robust topology at 90% efficiency for a 35W, 1600 rpm case study. Due to complicated flux lines (with tapered airgap for self-starting) and magnetic saturation, direct FEM characterization (preliminary design) was applied. Matlab Simulink modeling for controlled dynamics which made use FEM imposed cogging torque, emf and inductance with rotor position waveforms proved smooth motor starting to rated speed for speed performance, full load in both open loop (V/f) and close loop control. © 2014 IEEE.


Diniz M.C.,Federal University of Santa Catarina | Pereira E.L.L.,Embraco | Deschamps C.J.,Federal University of Santa Catarina
Institution of Mechanical Engineers - 8th International Conference on Compressors and Their Systems | Year: 2013

The volumetric and isentropic efficiencies of scroll compressors are affected by the heat transfer that takes place inside the pockets during suction and compression processes. The present paper details a numerical model developed to predict the conduction heat transfer and temperature distribution of scroll wraps. The model was developed via the finite volume method and coupled to a thermodynamic model of the compression cycle. The results showed that the discharge temperature predicted with the solution of heat conduction through the scroll wraps was slightly lower than that obtained when a linear temperature profile was prescribed. It was also found that the heat transfer taking place in the metallic contact between the scrolls wraps acts to produce a linear temperature variation along their length. © The author(s) and/or their employer(s), 2013.


Diniz M.C.,Federal University of Santa Catarina | Pereira E.L.L.,Embraco | Deschamps C.J.,Federal University of Santa Catarina
International Journal of Refrigeration | Year: 2015

A lumped-parameter thermal model is presented to predict the temperature in different chambers and components inside scroll compressors with particular attention to gas superheating in the suction process. Thermal resistances between the components are based on global heat transfer conductances, whereas conduction heat transfer through the scroll wraps is solved via a one-dimensional finite volume method. The thermal model was coupled to a thermodynamic model of the compression cycle and then applied to simulate the compressor performance under different conditions of speed and pressure ratio. The model was able to correctly predict the compressor temperature for operating conditions within the range of those adopted for its calibration. The results showed a strong coupling between the compressor thermal profile and the temperatures of the motor and lubricating oil. It has also been found that heat conduction through the scroll wraps reduces slightly the discharge temperature. © 2014 Elsevier Ltd and IIR.


Kalluf F.J.H.,Embraco | Tutelea L.N.,Polytechnic University of Timişoara | Boldea I.,Polytechnic University of Timişoara | Espindola A.,Embraco
IEEE Transactions on Industry Applications | Year: 2014

Compressor electric motor drives play a key role in the energy consumption of residential refrigerators. Electrical efficiency, robustness to starting and overloads and speed variation range define the performance of compressor electric motor drives. Between the lowest cost fixed-speed split-phase capacitor grid-connected induction motor, with lower efficiency, and the higherefficiency grid-connected cage permanent-magnet (PM) rotor split-phase capacitor motor and the inverter fed variable speed PM synchronous motor of highest initial costs, we introduce in this paper a 2 speed grid-connected motor drive. The proposed topology uses a separate split-phase winding, cage-PM-4-pole rotor synchronous motor (PMSM) for low speed (4 poles) and a single-phase (main) winding for 2-pole operation. The tentative target is 85% efficiency at 50 W output for 4-poles (low speed) PMSM operation with good starting and about 60% efficiency in 2-pole (high speed) induction motor operation at 100 W, with smooth transients from low to high speed under full torque load. Circuit models for steady state and for transients with dedicated Matlab codes have been developed, with key FEM validation, to substantiate full scale experiments, and an optimal design methodology embedding both operation modes was put forward, as main theoretical contributions. © 1972-2012 IEEE.


Link R.,EMBRACO | Deschamps C.J.,Federal University of Santa Catarina
International Journal of Refrigeration | Year: 2011

Several phenomena that affect energy consumption, noise level and reliability of compressors are associated with transient effects that occur during the compressor startup and shutdown. This paper presents a simulation methodology, experimentally validated, developed to analyze the compressor in such transients. Because the time scale associated with the compressor thermal behavior is much larger than that related to the mechanical physics, a thermal equilibrium condition has been considered herein for convenience. Results for valve displacement, piston motion, pressure in the compression chamber and resistive torques are provided to illustrate the application of the methodology and to assist an understanding of the physical aspects that affect the compressor performance throughout the startup and shutdown. It is observed that the dynamics of suction and discharge valves are greatly affected. Moreover, the model is employed to estimate the minimum voltage required for the compressor startup as a function of the equalized pressure and the auxiliary coil actuation time. © 2011 Elsevier Ltd and IIR. All rights reserved.


Bosco Jr. R.,EMBRACO
American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP | Year: 2010

Designing a compressor to withstand the high pressure inherited from the CO2 transcritical cycle requires special dealing with structural strength and reliability issues mandatory for safety aspects. Moreover, when dealing with high pressure levels, compressor components have their original design adapted to withstand such a high pressures, particularly acoustical mufflers, external housing, and compression mechanism. In order to safety enclose the compression mechanism, the application of a proper design methodology is mandatory to safeguard the structural integrity of both the compressor external housing and the whole refrigerating system. In this application the compressor shall be dealt as a pressure vessel in which there is no analytical way to evaluate the actual stress acting on it unless advanced numerical tool been applied. Looking for acceptable, cost effective safety factors, a simultaneous design approach including advanced structural mechanics techniques, experimentation, safety Codes revision, and Computer Aided Engineering (CAE) tools application is mandatory. The aim of this work is to present an hybrid numerical and experimental approach aiming to optimize the mass keeping the safe aspects in a compressor vessel used in high pressure refrigeration system. Numerical and experimental results will be compared among each other aiming to evaluate some ASME Codes criteria and design procedures. Copyright © 2010 by ASME.


Renaux D.P.B.,Federal University of Technology of Parana | Pottker F.,Federal University of Technology of Parana | Soares C.E.,Embraco | Valerio C.C.,Embraco
Proceedings - 2016 IEEE 19th International Symposium on Real-Time Distributed Computing, ISORC 2016 | Year: 2016

Increasing demands on functional and temporal requirements for the software in electric motor controllers demand for solutions that are efficient in time and space usage while providing the required functionality. Embedded software for electric motor control must deal with the control itself, and with operation, protection, supervision, safety, and user interfaces. Concerning this need, an embedded software multitasking architecture that combines the concept of function queues and of state-based code is proposed and compared to a standard implementation based on an RTOS. In the proposed solution, the queue of function pointers is partitioned into several shorter queues each one active in a given state of the system, thus, reducing queue management overhead. © 2016 IEEE.

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