scholarly journals Increase the Efficiency of an Induction Motor Feed from Inverter for Low Frequencies by Combining Design and Control Improvements

Energies ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 530
Author(s):  
Maria Dems ◽  
Krzysztof Komeza ◽  
Jacek Szulakowski ◽  
Witold Kubiak

Speed-controlled induction motors have the most significant potential for energy savings. The greatest problems with obtaining high efficiency occur in motors with a wide range of rotational speed regulation, as in the motors for driving industrial washing machines under consideration. While for the highest speeds, the dominant phenomenon is at field weakening. The problem is obtaining the optimal size of the magnetic flux for low rotation speed to prevent excessive saturation increasing current, and reduction of efficiency. This problem is usually solved by selecting the appropriate control for an already built machine. The authors propose a combination of activities when designing the motor structure with the selection of proper control, which allows for high efficiency. Since the drive does not require precise speed control or obtaining the required dynamics, it was possible to use an inexpensive control in an open loop, avoiding the cost of transmitters. Furthermore, the number of design parameters that are subject to change is significantly limited by technological factors and the available space in the washing machine. Proper parameter selection was made using a peripheral method assisted by field-circuit simulations. The proposed approach can be used in designing structures and selecting motors controls for other applications.

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2136 ◽  
Author(s):  
Bartosz Gil ◽  
Jacek Kasperski

Theoretical investigations of the ejector refrigeration system using hydrofluoroolefins (HFOs) and hydrochlorofluoroolefin (HCFO) refrigerants are presented and discussed. A comparative study for eight olefins and R134a as the reference fluid was made on the basis of a one-dimensional model. To facilitate and extend the possibility of comparing our results, three different levels of evaporation and condensation temperature were adopted. The generator temperature for each refrigerant was changed in the range from 60 °C to the critical temperature for a given substance. The performed analysis shown that hydrofluoroolefins obtain a high efficiency of the ejector system at low primary vapor temperatures. For the three analyzed sets of evaporation and condensation temperatures (te and tc equal to 0 °C/25 °C, 6 °C/30 °C, and 9 °C/40 °C) the maximum Coefficient of Performance (COP) was 0.35, 0.365, and 0.22, respectively. The best performance was received for HFO-1243zf and HFO-1234ze(E). However, they do not allow operation in a wide range of generator temperatures, and, therefore, it is necessary to correctly select and control the operating parameters of the ejector.


Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 20
Author(s):  
Paul Motzki

The versatility of the form factors of thermal shape memory alloys (SMA) in combination with their unique actuation and sensing abilities allow for the design and construction of innovative multifunctional systems. Despite the considerable number of advantages, such as their exceptional energy density, only a few SMA-based actuator systems are commercially available. One of the main reasons for this is their inefficient thermal activation and the resulting high energy consumption. The efficiency of SMA-based actuator systems can be improved by innovative design and control approaches. In the first part of this paper, the intelligent combination of SMA actuator wires with bi-stable, nonlinear spring elements is described. This combination eliminates the commonly quoted disadvantages of SMAs—slow actuation and energy inefficiency—for a wide range of applications. In particular, two energy-free actuator configurations are realized, which can be applied to any non-proportional actuation tasks. The second approach for the realization of high-speed actuation and energy efficiency is the activation of SMA wires with high voltage pulses, which leads to actuation times in the millisecond range and energy savings of up to 80% in comparison to the suppliers’ recommendations. It is shown that even high AC voltages such as typical mains supplies can be directly used for highly efficient SMA activation.


Author(s):  
Larisa V. Pokhodzey ◽  
Elena A. Rudneva ◽  
Yuriy P. Paltsev ◽  
Nikolay N. Courierov

Introduction. Magnetic resonance imaging (MRI) is one of the most dynamically developing, high-tech diagnostic methods. At the same time, the specific features of the electromagnetic environment and noise exposures at the medical and technical personnel operating and maintaining MRI workplaces are not well understood and are currently not taken into account when conducting a hygienic assessment of working condition in the Russian Federation. The aim of study is scientific substantiation of the need to improve the hygienic assessment of electromagnetic and noise conditions in the workplace of the staff of MRI departments. Materials and methods. An analytical method to evaluate the current domestic and foreign regulatory and methodological documents that determine the hygienic assessment requirements for electromagnetic environment and noise in MRI departments was used. More than 4 thousand measurements of the intensity of electromagnetic fields and noise in 88 rooms in Moscow equipped with different types of MRI (from 0,1 mT to 3 T) and studies of the performing duration various types of work and electromagnetic field and noise exposure on personnel was done. The amplitude-time and frequency parameters of the variables of the electromagnetic field (EMF) and sound pressure detailed studies have been carried out. Results. Significant differences in controlled indicators, acceptable exposure levels, and control methods has revealed by critical analysis of domestic and foreign hygienic regulatory and methodological documents. The studies showed that the medical and technical personnel of MRI departments are exposed with high spatial and temporal gradients static magnetic fields and extreme levels of noise during diagnostic work in the immediate vicinity of the tomograph magnet. The presence of time-varying magnetic fields in a wide range of low frequencies and radio frequencies having a complicated (pulsed) waveform is a feature of the electromagnetic environment in MRI. New standardized control parameters and limit levels for low-frequency ranges magnetic fields for their adequate hygienic assessment are proposed. Conclusion. The studies made it possible to substantiate the proposals the improving of electromagnetic field and noise hygienic assessment at the MRI staff workplaces.


Aerospace ◽  
2006 ◽  
Author(s):  
Julianna Evans ◽  
Diann Brei ◽  
Jonathan Luntz

Nature builds an immense set of materials exhibiting a wide range of behaviors using only a small number of basic compounds. The range of materials comes about through architecture, giving functional structure to the basic materials. Analogously, a new genre of actuators can be derived from existing smart materials through architecture. This paper presents a preliminary experimental study of knitted actuation architectures that yield high strains (up to 73%) with moderate forces (tens of Newtons or more) from basic contracting smart material fibers. By different combinations of the two primary knit loops – purl and knit – a variety of behaviors can be achieved including contraction, rolling, spirals, accordions, arching, and any combination of these across the fabric. This paper catalogs several basic knit stitches and their actuated form: garter, stockinette, seed, rib and I-cord. These knitted architectures provide performance tailorability (force, strain, stiffness, and motion) by manipulation of key design parameters such as the material properties of the wire, the geometric parameters (wire diameter, loop size, and gauge), and architectural parameters (stitch type and orientation). This is demonstrated via a quasi-static force-deflection experimental study with several shape memory alloy garter prototypes with varying geometric parameters. While the basic architecture of a knit is simple, it affords a vast array of architectural combinations and control of geometrical and material parameters that generate a myriad of gross motion capabilities beyond that of current day actuation strategies.


2014 ◽  
Vol 1037 ◽  
pp. 107-110 ◽  
Author(s):  
Xi Yin Lou

Crawler combine harvester walking system is various transmission technology are organic and reasonable matching, foster strengths and circumvent weaknesses, complementary drive system so as to achieve the best overall. Stepless speed walking is particularly suitable for complex condition changes, the demand of drive system for a more comprehensive, more comprehensive, objective stepless speed walking in transmission system innovation or seek better performance, and as a mechanical transmission device of the planetary gear has the advantages of small volume transfer large torque, high efficiency. The combination of both realizes stepless transmission, and has the advantages of low speed and high torque. Hydraulic drive system is mainly to achieve stepless speed regulation, commutation, planetary gear drive mainly reduce speed, increase the torque to. Composite transmission mode that can greatly improve the transmission ability, expand the scope of speed adjustment. In fact, combine the stepless variable speed running and control technology can greatly improve the performance of the product, especially the effect on production efficiency, durability, controllability, environment adaptability, green characteristics were significantly.


1995 ◽  
Vol 117 (B) ◽  
pp. 135-144 ◽  
Author(s):  
A. Baz ◽  
J. Ro

Conventional Passive Constrained Layer Damping (PCLD) treatments with viscoelastic cores are provided with built-in sensing and actuation capabilities to actively control and enhance their vibration damping characteristics. The design parameters and control gains of the resulting Active Constrained Layer Damping (ACLD) treatments are optimally selected, in this paper, for fully-treated beams using rational design procedures. The optimal thickness and shear modulus of the passive visco-elastic core are determined first to maximize the modal damping ratios and minimize the total weight of the damping treatment. The control gains of the ACLD are then selected using optimal control theory to minimize a weighted sum of the vibrational and control energies. The theoretical performance of beams treated with the optimally selected ACLD treatment is determined at different excitation frequencies and operating temperatures. Comparisons are made with the performance of beams treated with optimal PCLD treatments and untreated beams which are controlled only by conventional Active Controllers (AC). The results obtained emphasize the potential of the optimally designed ACLD as an effective means for providing broad-band attenuation capabilities over wide range or operating temperatures as compared to PCLD treatments.


Author(s):  
Orlando Palma ◽  
Carlos Cruz

The continuously variable transmissions (CVT) have been extensively studied, however, few studies of transmissions have been made that can reach the neutral and reverse rotational speeds through the separation distance of a half sided central pulley as a single variable control. This paper proposes a new clutchless transmission model, which operates through orbital pulleys to change velocity ratios for forward and reverse through neutral such that an infinitely variable transmission (OP-IVT) is obtained. The concept is described and explained, and the dynamic model of the system is proposed and shown in open loop. The system is also controlled via a numerical simulation program with PID control showing the dynamic closed loop behaviour of the generated model in trajectory tracking and disturbance rejection, showing the control as the capability to meet a wide range of speeds without losing the known efficiency performance of current continuously variable transmissions.


2018 ◽  
Vol 234 ◽  
pp. 02003 ◽  
Author(s):  
Vasil Dimitrov

This paper presents a methodology of tests of traction asynchronous drives applied in electric vehicles. It is similar to Urban Driving Cycle ECE-15 (UDC). The objective of the research is to verify the developed methodology through tests performed on a laboratory simulator, which consists of energy-saving asynchronous motor controlled by a frequency inverter (converter). Vector Control on the drive is used for smooth speed regulation over a wide range at high values of efficiency and power factor. Contemporary measuring and control devices and special software products are used for capturing the dynamic characteristics when starting, stopping and changing the speed set point of the drive. Some of tests are presented and an experimental verification of the developed methodology is made. An optimal setting of the drive parameters can be made to minimize the electric energy consumption.


2020 ◽  
Vol 71 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Songklod Sriprang ◽  
Babak Nahid-Mobarakeh ◽  
Noureddine Takorabet ◽  
Serge Pierfederici ◽  
Poom Kumam ◽  
...  

AbstractIt is necessary to find the suitable d - and q -axis reference currents to control PMA-SynRM motors with high efficiency. This paper presents the maximum torque per ampere (MTPA) to minimize the copper losses of the system and utilizes the field weakening control to operate above the rated speed of the PMA-SynRM. The copper losses equation and electromagnetic torque are used to optimize the d - and q -axis current references. A small-scale 1 kW prototype PMA-SynRM was designed and manufactured to test and examine the proposed control in the laboratory. The proposed algorithm was digitally carried out using the MicroLab Box dSPACE. The simulation results show that the copper losses of the machine with the MTPA algorithm are lower than those without the MTPA algorithm. The PMA-SynRM operates above the base speed of ~ 70 % in the constant power region by mean of field weakening control.


1997 ◽  
Vol 87 (6) ◽  
pp. 599-605 ◽  
Author(s):  
Kuang-Ren Chung ◽  
Walter Hollin ◽  
Malcolm R. Siegel ◽  
Christopher L. Schardl

Epichloë typhina perennially and systemically infects grass plants, causing choke disease in which maturation of host inflorescences is suppressed. In seedling-inoculation tests, isolate E8 from perennial ryegrass established and maintained infection in this host but not in orchardgrass. In contrast, isolates E469, E2466, and E2467 from orchardgrass varied in infection frequency and stability in orchardgrass, but all were unable to establish stable infections in perennial ryegrass. To investigate the genetics of host specificity, isolate E8 was crossed with each of the isolates from orchardgrass. Seedlings of parental host species were inoculated with F1 progeny, and the frequencies of seedling infection and stability in adult plants were assessed. In the E8 × E2466 cross, the F1 progeny exhibited a wide range of infection frequency and stability in each parental host. In crosses E8 × E469 and E8 × E2467, where the orchardgrass-derived parents infected 5 to 13% of inoculated perennial ryegrass seedlings, the distributions of infection frequencies for the F1 progeny wereskewed toward levels comparable to that of the parent from perennial ryegrass. In all crosses, most progeny had low frequencies of infection in orchardgrass. However, transgression was evident in a cross of E8 with E469, an isolate that infected orchardgrass seedlings at a low frequency (2 to 3%). The E8 × E469 cross had a few F1 progeny that infected orchardgrass at high efficiency (up to 81%). A Spearman rank correlation applied to the E8 × E2466 progeny indicated a significant negative correlation between infection frequencies in perennial ryegrass and orchardgrass. Also, there was a significant correlation of infection frequency and stability in perennial ryegrass but not in orchardgrass. To test whether only a few genes governed infection frequency in perennial ryegrass, an E8 × E2466 F1 progeny (designated E386.04), which had intermediate compatibility with this host, was backcrossed to E8. The progeny of this backcross exhibited a distribution of infection frequencies in perennial ryegrass between that of E386.04 and the backcross parent, suggesting that multiple genes may determine compatibility at the seedling infection stage. The results of these experiments indicated multiple genetic determinants of compatibility or incompatibility with each host, with intermediate or high heritability.


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