Machines

1668 KiB

Open AccessArticle

Fractional Slot Concentrated Windings: A New Method to Manage the Mutual Inductance between Phases in Three-Phase Electrical Machines and Multi-Star Electrical Machines

by Olivier Barre and Bellemain Napame

Machines 2015, 3(2), 123-137; https://doi.org/10.3390/machines3020123 - 10 Jun 2015

Cited by 9 | Viewed by 10414

Abstract

Mutual inductance is a phenomenon caused by the circulation of the magnetic flux in the core of an electrical machine. It is the result of the effect of the current flowing in one phase on the other phases. In conventional three-phase machines, such an effect has no influence on the electrical behaviour of the device. Although these machines are powered by power inverters, no problem should occur. The result is not the same for multi-star machines. If these machines are using a conventional winding structure, namely distributed windings, and are powered by voltage source converters, current ripples appear in the power supply lines. These current ripples are related to magnetic couplings between the stars. Designers should check these current ripples in order to stay within the limits imposed by the specifications. These electric current disturbances also provide torque ripples. With concentrated windings, a new degree of freedom appears; the configuration—number of slots/number of poles—can have a positive impact. The circulation of the magnetic flux is the initial phenomenon that produces the mutual inductance. The main goal of this discussion is to describe a design method that is able to produce not only a machine with low mutual inductance between phases, but also a multi-star machine where the stars and the phases are magnetically decoupled or less coupled. This discussion only takes into account the machines that use permanent magnets mounted on the rotor surface. This article is part of a study aimed at designing a high efficiency generator using fractional-slot concentrated-windings (FSCW). Full article

(This article belongs to the Special Issue Advances in Machinery for Renewable Power Generation)

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665 KiB

Open AccessArticle

A Non-Photolithography Fabrication for a Microfluidic Chip Based on PMMA Polymer

by Xiaowei Han, Xiaowei Liu, Li Tian, He Zhang and Zhi-Gang Mao

Machines 2015, 3(2), 107-122; https://doi.org/10.3390/machines3020107 - 21 May 2015

Cited by 4 | Viewed by 5775

Abstract

Polymer microchannels can be commonly processed using many non-lithographic methods for reducing the manufacturing cost and steps. In this research, an inexpensive and high-precision thermal engraving technology is developed and achieved to machine polymer microchannels ranging from tens to hundreds of micrometers. This paper presents the design of a thermal engraving device, the processing method and the experimental procedure. Thermal engraving microscribers can fabricate microchannels with a width less than 100 μm. Furthermore, the effects of velocity and temperature on the roughness of polymethyl methacrylate (PMMA) microchannels are also discussed. Finally, a smooth microchannel with these parameters optimally coordinated is achieved. Meanwhile, the contact angle (CA) and the electro-osmotic flow (EOF) of microchannels fabricated by this technology are also measured. The experimental results show that this method of fabrication has the advantages of low cost, high efficiency and small polymer microchannel size compared with several non-lithographic methods. This method of fabrication would be attractive for labs lacking extremely clean rooms and expensive photolithography apparatuses. Full article

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1643 KiB

Open AccessArticle

A Cyber Physical Interface for Automation Systems—Methodology and Examples

by Hung-An Kao, Wenjing Jin, David Siegel and Jay Lee

Machines 2015, 3(2), 93-106; https://doi.org/10.3390/machines3020093 - 14 May 2015

Cited by 46 | Viewed by 15541

Abstract

Cyber physical systems (CPS) in a manufacturing and automation context can be referred to different manufacturing process, including design, simulation, control, and verification. However, for data analytics, the concept of CPS is relatively new, and a standard methodology is lacking on how to incorporate this type of interface for automation applications. This study discusses a modeling methodology for a cyber physical interface and presents the five levels of information for a cyber physical system, that range from the data connection level to the system configuration level. In order to achieve this awareness and health state of the machine and system, a technical approach that uses adaptive health monitoring algorithms is presented. Lastly, an experimental study on a machine tool ball screw is highlighted, in which a predictive model and a cyber physical interface is developed for this application. The outcomes from this study demonstrate that machine health state awareness is feasible, and the core technologies can aim mechanical systems systematically develop its CPS. This can lead to additional product revenue for the manufacturers, and also a potential competitive edge in the market place. Full article

(This article belongs to the Special Issue Advances and Challenges in Manufacturing Automation)

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2682 KiB

Open AccessArticle

Number Determination of Successfully Packaged Dies Per Wafer Based on Machine Vision

by Hsuan-Ting Chang, Ren-Jie Pan and Hsiao-Wei Peng

Machines 2015, 3(2), 72-92; https://doi.org/10.3390/machines3020072 - 9 Apr 2015

Cited by 2 | Viewed by 7644

Abstract

Packaging the integrated circuit (IC) chip is a necessary step in the manufacturing process of IC products. In general, wafers with the same size and process should have a fixed number of packaged dies. However, many factors decrease the number of the actually packaged dies, such as die scratching, die contamination, and die breakage, which are not considered in the existing die-counting methods. Here we propose a robust method that can automatically determine the number of actual packaged dies by using machine vision techniques. During the inspection, the image is taken from the top of the wafer, in which most dies have been removed and packaged. There are five steps in the proposed method: wafer region detection, wafer position calibration, dies region detection, detection of die sawing lines, and die number counting. The abnormal cases of fractional dies in the wafer boundary and dropped dies during the packaging are considered in the proposed method as well. The experimental results show that the precision and recall rates reach 99.83% and 99.84%, respectively, when determining the numbers of actual packaged dies in the 41 test cases. Full article

(This article belongs to the Special Issue Machinery Diagnostics and Prognostics)

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1138 KiB

Open AccessArticle

Initial Work on the Characterization of Additive Manufacturing (3D Printing) Using Software Image Analysis

by Jeremy Straub

Machines 2015, 3(2), 55-71; https://doi.org/10.3390/machines3020055 - 2 Apr 2015

Cited by 126 | Viewed by 18219

Abstract

A current challenge in additive manufacturing (commonly known as 3D printing) is the detection of defects. Detection of defects (or the lack thereof) in bespoke industrial manufacturing may be safety critical and reduce or eliminate the need for testing of printed objects. In consumer and prototype printing, early defect detection may facilitate the printer taking corrective measures (or pausing printing and alerting a user), preventing the need to re-print objects after the compounding of a small error occurs. This paper considers one approach to defect detection. It characterizes the efficacy of using a multi-camera system and image processing software to assess printing progress (thus detecting completion failure defects) and quality. The potential applications and extrapolations of this type of a system are also discussed. Full article

(This article belongs to the Special Issue Machinery Diagnostics and Prognostics)

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Machines, Volume 3, Issue 2 (June 2015) – 5 articles , Pages 55-137

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