scholarly journals Simplified approach for simulating hermetic compressor startup regime

2021 ◽  
pp. 13-28
Author(s):  
Eduardo P Falcetti ◽  
Álvaro Gardenghi ◽  
Alvaro B Dietrich ◽  
Luben Cabezas-Gómez
Keyword(s):  
Simple Model ◽  
Angular Velocity ◽  
Electric Motor ◽  
Numerical Technique ◽  
Input Voltage ◽  
Oil Viscosity ◽  
Simplified Approach ◽  
Simulation Procedure ◽  
Transient Data ◽  
Hermetic Compressor

It is presented a hermetic compressor startup simulation procedure considering a simplified approach to obtain the transient data of different compressor parameters. The main numerical technique is a four order Runge-Kutta procedure to numerically integrate the systems of ordinary differential equations, which describe the variables’ variation with time in each part of the compressor. The simulations were performed in the Windali software. The results show how the oil viscosity influences the electrical motor torque, the compressor load and crankshaft angular velocity with time for two electric motor input voltage values. The increase of oil viscosity by a factor of 2, retards the compressor startup for more than one second. The presented simple model could be valuable for studying the geometrical and operational influence on compressor startup.

scholarly journals Is It Possible to Determine Whether a Star is Rotating About a Unique Axis?

1993 ◽  
Vol 137 ◽  
pp. 566-568 ◽  
Author(s):  
D.O. Gough ◽  
A.G. Kosovichev
Keyword(s):  
Simple Model ◽  
Angular Velocity ◽  
Rotation Axis ◽  
The Other ◽  
The Sun ◽  
Natural Question ◽  
Rotating Stars ◽  
The Core ◽  
Axis Of Rotation ◽  
Fixed Axis

Rotating stars are normally presumed to rotate about a unique axis. Would it be possible to determine whether or not that presumption is correct? This is a natural question to raise, particularly after the suggestion by T. Bai & P. Sturrock that the core of the sun rotates about an axis that is inclined to the axis of rotation of the envelope.A variation with radius of the direction of the rotation axis would modify the form of rotational splitting of oscillation eigenfrequencies. But so too does a variation with depth and latitude in the magnitude of the angular velocity. One type of variation can mimic the other, and so frequency information alone cannot differentiate between them. What is different, however, is the structure of the eigenfunctions. Therefore, in principle, one might hope to untangle the two phenomena using information about both the frequencies and the amplitudes of the oscillations.We consider a simple model of a star which is divided into two regions, each of which is rotating about a different fixed axis. We enquire whether there are any circumstances under which it might be possible to determine seismologically the separate orientations of the axes.

A New MEMS Assembly Unit for Hybrid Self Micropositioning and Forced Microclamping of Submilimeter Parts

2010 ◽  
Vol 154-155 ◽  
pp. 1705-1712 ◽  
Author(s):  
Mohsen Hamedi ◽  
Milad Vismeh ◽  
Parisa Salimi
Keyword(s):  
Thin Layer ◽  
Active Material ◽  
Input Voltage ◽  
Rotary Table ◽  
Design Strategies ◽  
Temperature Dependent ◽  
Finite Element Software ◽  
Simulation Procedure ◽  
Shape Structure ◽  
Assembly Unit

In this paper we have presented an assembly unit equipped with electrothermally actuated microclamps (MCs), piezoelectric pad and rotary table to provide an environment for micropositioning and microclamping of submilimeter parts. The structural material of the system is considered to be <100> oriented Si with 20 µm thickness. Activating MCs, two approaches performed in the simulation procedure and results showed that utilizing 140 nm deposited Chromium thin layer on the U-shape structure as active material, reduces the overall input voltage and temperature in comparison with direct applying of potential difference to Si structure. To obtain more realistic results, both of these methods are simulated using finite element software in line with considering temperature-dependent thermophysical properties for structural and active material due to high operating temperatures. Design strategies and other advantages of using thin layer of chromium as active material are highlighted in the text.

scholarly journals STARTING UP AND REGULATING THE ROTATIONAL SPEED OF A POWERFUL ELECTRIC DRIVE USING A MAGNETIC REDUCING GEAR

2020 ◽  
pp. 16-23
Author(s):  
Alexander A. Afanasyev
Keyword(s):  
Electric Motor ◽  
Permanent Magnets ◽  
Frequency Converter ◽  
Input Voltage ◽  
Magnetic Core ◽  
Stator Winding ◽  
State Equations ◽  
Current Frequency ◽  
Reducing Gear ◽  
Load Mode

The article examines a magnetic reducing gear, the stator winding of which receives power in the mode of a valve machine. In the absence of this supply, the electric motor can be started-up in no-load mode. To significantly reduce the power of the magnetic reducing gear frequency converter compared to the power of the adjustable electric motor, it is necessary to make the number of the rotor's pairs of poles with permanent magnets of a magnetic reducing gear large enough. In this case, the design of arranging the magnets in radial grooves is the most adequate, ensuring the concentration of fluxes per pole in the air gaps. The stator winding of such a magnetic reducing gear will be low-pole. When manufacturing a magnetic reducing gear, it is possible to use a stator magnetic core of a serial asynchronous machine together with its regular winding. The electromagnetic moments of the magnetic gearbox rotors are a consequence of the presence of a stator electromagnetic moment. The stator's current frequency is represented by two components, of which the first is defined from the state equations and the second is a constant forming an additional channel of functional influence. The speed of rotation of the gear shafts can be adjusted by changing the specified constant and the input voltage of the frequency converter. The equations of the magnetic reducer state describing its functional modes were solved by means of the Mathcad mathematical program.

scholarly journals Impact of cranks displacement angle on the motion non-uniformity of roller forming unit with energy-balanced drive

2021 ◽  
pp. 141-155
Author(s):  
Viacheslav Loveikin ◽  
Kostiantyn Pochka ◽  
Mykola Prystailo ◽  
Maksym Balaka ◽  
Olha Pochka
Keyword(s):  
Differential Equation ◽  
Angular Velocity ◽  
Electric Motor ◽  
Steady Motion ◽  
Equation Of Motion ◽  
Start Up ◽  
Change Function ◽  
Displacement Angle ◽  
The Impact ◽  
Motion Mode

The impact of the cranks displacement angle on the motion non-uniformity is determined for three forming trolleys of a roller forming unit with an energy-balanced drive mechanism. At the same time, the specified unit is presented by a dynamic model with one freedom degree, where the extended coordinate is taken as the angular coordinate of the crank rotation. For such a model, a differential equation of motion is written, for solved which a numerical method was used. The inertia reduced moment of the whole unit, and the resistance forces moment, reduced to the crank rotation axis, to move of forming trolleys during the formation of products from building mixtures are determined, and also the nominal rated power of the electric motor was calculated, when solved a differential equation of motion. According to these data, asynchronous electric motor with a short-circuited rotor was chosen, for which a mechanical characteristic is constructed by the Kloss formula. Having solved the differential equation of motion with all defined characteristics, we obtain the change function of the crank angular velocity from start-up moment and during steady motion mode. After that, we calculated the time corresponding to the angular velocity value, and obtained the change function of the crank angular acceleration from start-up moment and during steady motion mode. The motion non-uniformity of the roller forming unit has been determined by the motion non-uniformity factor, the motion dynamism factor and the extended factor of motion assessment during steady motion mode. The impact of drive cranks displacement angle on the motion non-uniformity has been traced, as a result, the specified factors have the minimum values at cranks displacement on the angle Δφ=60°. The results may in the future are used to refine and improve the existing engineering methods for estimating the drive mechanisms of roller forming machines, both at design stages and in practical use.

scholarly journals Smart Refrigerators in Return for Energy Efficiency

2018 ◽  
Vol 54 (1) ◽  
Author(s):  
Yurii Baidak ◽  
Iryna Vereitina
Keyword(s):  
Energy Efficiency ◽  
Electric Motor ◽  
Power Efficiency ◽  
Electric Energy ◽  
Smart System ◽  
Domestic Refrigerator ◽  
Smart Systems ◽  
Testing Tools ◽  
Global Trend ◽  
Hermetic Compressor

One of the aspects of the global trend in the development of Smart systems is considered in the paper, namely those solutions of the leading manufacturers of electrical household appliances that relate to the implementation of additional intelligent functions to devices in demand by the society - Smart Diagnosis, Smart Grid-ready, Smart Manager, Smart Access, Smart Adapt. It is emphasized that some tasks related to the energy efficiency of devices, the accuracy of testing tools, which should be used as a basis for the Smart System, remained unresolved. So, the built-in additional sensors and chips of "smart" subsystems require the application of additional measures aimed at reducing the power consumption of the device (preferably twice to restore the balance). On the example of the developed innovative electric motor of domestic refrigerator hermetic compressor drive, the existence of the possibilities for a significant increase in its efficiency has been proved. Since intellectual features of Smart System in its Smart Diagnosis dialog box should be based on monitoring data on power efficiency parameters of the device, a new concept for the development of an electric  energy  counter  is proposed.

scholarly journals Applying the Large Parameter Technique for Solving a Slow Rotary Motion of a Disc about a Fixed Point

2020 ◽  
Vol 2020 ◽  
pp. 1-7 ◽  
Author(s):  
A. I. Ismail
Keyword(s):  
Fixed Point ◽  
Angular Velocity ◽  
Periodic Solutions ◽  
Numerical Solutions ◽  
Initial Conditions ◽  
Numerical Technique ◽  
Equations Of Motion ◽  
First Integral ◽  
The Body ◽  
Large Parameter

In this paper, the motion of a disk about a fixed point under the influence of a Newtonian force field and gravity one is considered. We modify the large parameter technique which is achieved by giving the body a sufficiently small angular velocity component r0 about the fixed z-axis of the disk. The periodic solutions of motion are obtained in the neighborhood r0 tends to 0. This case of study is excluded from the previous works because of the appearance of a singular point in the denominator of the obtained solutions. Euler-Poison equations of motion are obtained with their first integrals. These equations are reduced to a quasilinear autonomous system of two degrees of freedom and one first integral. The periodic solutions for this system are obtained under the new initial conditions. Computerizing the obtained periodic solutions through a numerical technique for validation of results is done. Two types of analytical and numerical solutions in the new domain of the angular velocity are obtained. Geometric interpretations of motion are presented to show the orientation of the body at any instant of time t.

scholarly journals АВТОМАТИЗАЦІЯ КОНТРОЛЮ ПАРАМЕТРІВ ЕЛЕКТРОДВИГУНА

2020 ◽  
pp. 198-206
Author(s):  
Василь Іванович Петренко ◽  
Юлія Миколаївна Толкунова ◽  
Людмила Іванівна Смирнова
Keyword(s):  
Quality Control ◽  
Motor Control ◽  
Angular Velocity ◽  
Power Amplifier ◽  
Electric Motor ◽  
Reference Model ◽  
Output Parameter ◽  
Control Procedure ◽  
Technical Equipment ◽  
Velocity Sensor

The technique of the motor control technical characteristics automation is developed in the article. The control of the technical characteristics is to determine and evaluate information on deviation of the actual values from the specified ones. Quality control occupies a special place at all stages of technical products production. Efficiency of production as a whole depends on perfection of quality control, its technical equipment and organization. Automation of the control procedure allows to prevent the production of products that do not meet the requirements of standards, specifications, approved samples, design and technological documentation, while eliminating errors caused by human factors, reduces time costs, provides high reliability of control and reduces the cost of manufacturing and maintenance. The article offers a diagram of the workplace for the study of the motor technical characteristics and a mathematical model for the motor control process automation. The process of control is to compare the actual parameters of the electric motor with the parameters of its reference model. The reference model is formed on the basis of the input signals and technical parameters of the power amplifier units, the electric motor and the angular velocity sensor corresponding to the design documentation. On the difference signals of the output parameter of the reference model and the controlled sample of the motor, a rejection procedure is performed. The electric motor is represented by the first-order aperiodic link transfer function. The motion of the connection "power amplifier – motor – angular velocity sensor" is modeled by a differential equation in continuous and discrete forms. For the implementation of the reference model, the equation of state is used in a discrete form, as all the control and diagnostic procedures in the test equipment are implemented by digital computing devices. The diagnostic feature of the connection functional state is the deviation of the output parameter of the controlled motor from the output parameter of the reference model. Deviation from the reference value in excess of the tolerance is an indirect diagnostic sign of the presence of destabilizing parameters of motor. The dependence of the deviation of the output parameter on the change of the coefficient of transformation кЕM and the time constant TEM is investigated.

Perfect fluid model with g = 2

2021 ◽  
Vol 34 (2) ◽  
pp. 224-226
Author(s):  
John French
Keyword(s):  
Simple Model ◽  
Angular Velocity ◽  
Special Relativity ◽  
Perfect Fluid ◽  
Fluid Model ◽  
Classical Model ◽  
Model Based ◽  
A Value

A perfect fluid model with a shell of charge is presented which yields g = 2 for low angular velocity. This model is not intended to represent a classical model of the electron but to show that a simple model based on equations consistent with special relativity can yield a value of g = 2.

scholarly journals Two-Stage Control Design of a Buck Converter/DC Motor System without Velocity Measurements via aΣ−Δ-Modulator

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
R. Silva-Ortigoza ◽  
J. R. García-Sánchez ◽  
J. M. Alba-Martínez ◽  
V. M. Hernández-Guzmán ◽  
M. Marcelino-Aranda ◽  
...  
Keyword(s):  
Angular Velocity ◽  
Motor System ◽  
Control Design ◽  
Input Voltage ◽  
Dc Motor ◽  
Power Converter ◽  
Buck Converter ◽  
Two Stage ◽  
Second Stage ◽  
Flatness Property

This paper presents a two-stage control design for the “Buck power converter/DC motor” system, which allows to perform the sensorless angular velocity trajectory tracking task. The differential flatness property of the DC-motor model is exploited in order to propose a first-stage controller, which is designed to achieve the desired angular velocity trajectory. This controller provides the voltage profiles that must be tracked by the Buck converter. Then, a second-stage controller is meant to assure the aforementioned. This controller is based on flatness property of the Buck power converter model, which provides the input voltage to the DC motor. Due to the fact that the two-stage controller proposed uses the average model of the system, as a practical and effective implementation of this controller, aΣ − Δ-modulator is employed. Finally, in order to verify the control performance of this approach, numerical simulations are included.

Sign in / Sign up

Export Citation Format

Share Document