Control Engineering Motors, Drives & Motion Control eNews for February 2003
VOLUME 4, NUMBER 2
| NATIONAL INSTRUMENTS
Motion Assistant Makes It Easy
Market trends: packaging machinery; ac drives
Buyers of new packaging machines want quick changeover capabilities; flexibility; and fast speeds, according to a Jan. 31, 2003, survey by the Packaging Machinery Manufacturers Institute (PMMI, Arlington, VA). Member companies responding to the survey chose those machine attributes as the top three.
It should be no surprise that motion control (along with other technologies) is key to the high performance of packaging machines. Some survey results that center on motion control follow:
Servo controls were included in one out of four machines, according to 40% of survey respondents, while 15% indicate that almost half of their machines apply servo controls. Another 9% report that between half and three-quarters of machine shipped include servo controls, and 14% say at least three out of four of their machines use servo control.
Interesting as well are the two main reasons why servos were not included on some machines sold to customers: ”Equipment does not require an adjustable drive with feedback” (54%) and ”servos would be expensive relative to the sales price of the machine” (36%).
For more information about the survey and PMMI-a trade association of nearly 500 manufacturers of packaging and packaging-related converting machinery in the U.S. and Canada-visit the PMMI Web site .
In a related item, NEMA’s business indexes showed a dip for fourth-quarter 2002. This was not a surprise, given a prolonged, slow recovery in the manufacturing industries.
Specifically, the Primary Industrial Control and Adjustable Speed Drives Index fell 10.5%, as reported Feb. 7, 2003, from data collected by the Industrial Automation Control Products and Systems Section of the National Electrical Manufacturers Association (NEMA, Rosslyn, VA). Actually, the 10.5% decline left a modest gain over the past year; with the index value at 89.5, it is nearly 3% higher than the fourth-quarter 2001 level, according to NEMA.
The PIC&ASD Index is one of NEMA’s Industrial Control Business Indexes issued quarterly. It is quite a new index, started in 2001 by expanding data collection for equipment covered in the Primary Industrial Control (PIC) Index to include adjustable-speed drives. The longer term PIC index covers U.S. shipments of motor starters, contactors, terminal blocks, control circuit devices, motor control centers, sensors, programmable controllers, and other industrial control devices. The PIC Index fell 11% in 4Q2002.
NEMA estimates the U.S. industrial control equipment market at $2.6 billion. The indexes are based on sales data reported by companies that represent more than 90% of the U.S. market.
Software briefs: SolidWorks, Ormec
If you are looking for something new in motion system simulation and analysis, check out CosmosMotion 2003 now available from SolidWorks Corp. (Concord, MA).
This software, previously known as Dynamic Designer Motion Professional for SolidWorks, is promoted as an ”embedded functional virtual prototyping package” that contains all elements needed to verify whether your design will work before it’s built in hardware. Less physical testing, fewer prototypes, and shorter product development times are potential benefits.
Typically, the user creates a system model, after which CosmosMotion simulates the motion of mechanisms and assemblies using the well-known ADAMS (Automatic Dynamic Analysis of Mechanical Systems) simulation engine. Animations and analytical results then lead to a full understanding of the motion system, including sizing of components, checking for interferences, behavior of contacting parts, etc. CosmosMotion also generates operating loads that can be further analyzed to check the design for strength and stress.
|CosmosMotion allows rapid evaluation of more design alternatives to reduce project risk.|
As an aside, here’s an illustration of the highly dynamic world of design software: ADAMS was developed by Mechanical Dynamics Inc. (MDI), which is now part of MSC.Software (Santa Ana, CA). Also Dynamic Designer Motion Professional for SolidWorks was licensed by MDI to Structural Research and Analysis Corp. (SRAC), the 3-D analysis business unit of SolidWorks.
Click here for more on SolidWorks
Another new software tool, MotionObjects ActiveX Control from Ormec (Rochester, NY), promises to speed software development for the company’s ServoWire SM (soft motion) drives, which operate without motion control boards. The software is a kit for developing ServoWire SM applications in Microsoft Visual Basic 6.0, VB.Net, or other programs that act as an ActiveX container. MotionObjects ActiveX for Control consists of object-oriented tools for motion control programming, a soft motion engine, and software connectivity tools for a motion system comprised of a host PC, ServoWire SM drives, and FireWire adapters.
Direct-drive, low-speed PM motors streamline power flow to the load
Help is at hand to simplify your motor-to-load connection. A new line of low-base-speed permanent magnet (PM) ac synchronous motors from ABB (New Berlin, WI) enables direct connection of motor and load-without a gearbox. These motors are the core of a system named DriveITDirect Drive Solution. They work together with low-voltage adjustable-speed ac drives (based on ABB’s ACS 600 or ACS 800 drive) to further simplify the design by eliminating the encoder for speed feedback, in most applications.
|DriveITPM motors offer all options typically associated with standard induction motor frames, including air- and water-cooled versions.|
Neodymium-iron-boron (NdFeB) magnets built into the rotor translate the higher power of this magnet material into as much as double the torque output per frame size compared to induction motors. DriveITPM motors get around the low-speed performance limits of induction motors, for example, torque fluctuation and decreasing efficiency at low operating speeds. This is why a gearbox is often required in the traditional solution.
DriveITPM motors produce a constant flux in the air gap that simplifies traditional synchronous motor construction. Synchronous motor performance is obtained with the robustness of an induction (asynchronous) motor, according to ABB.
The new motors are offered in a size range of 22 to 670 hp (17-500 kW), feature base speeds of 220 to 600 rpm, and run on 380-690 V ac supply. Standard IEC-frame sizes from 280 to 400 are available. DriveITDirect Drive Solution targets pulp and paper, marine propulsion, mine conveyors, rotary kilns (cement and iron ore production), and converting machines, among other applications.
Verifying motor efficiency made easier
U.S. Department of Energy (DOE) has recently classified efficiency verification programs provided by CSA International (CSAI, Charlotte, NC) and Underwriters Laboratories (Northbrook, IL) as ”nationally recognized certification programs in the U.S.”
As a result, electric motor manufacturers can more easily verify that their products comply with DOE’s energy-efficiency mandates through the two programs, namely: CSA International’s ”Electric Motor Energy Efficiency Service Program” or UL’s ”Energy Verification Service Program for Electric Motors.”
Energy efficiency requirements for electric motors stem from the Energy Policy and Conservation Act (EPAct 92) enacted in 1992 and finally made effective in October 1997. The requirements apply to single-speed polyphase induction motors (squirrel-cage type) of 1-200 hp size, classified as continuous-duty operation, open or enclosed, and NEMA design A or B. Electric motor manufacturers must submit a compliance certification to DOE by April 28, 2003, stating that their electric motors meet applicable efficiency requirements.
The final rule of the legislation eases the procedure by providing two options to demonstrate compliance. Besides the self-certification route through an accredited laboratory, motor manufacturers can now use the services of a certifying organization-such as CSAI and UL.
Click here for more information on CSAI.
To learn more about EPAct 92, read Efficient Motors Can Ease Energy Crunch and Efficiency to the Masses-of Electric Motors, that Is on the Control Engineering Web site.
New ac drive inline with trends: Direct Ethernet connectivity, more power
|Random switching frequency modulation reduces motor noise, making Altivar 58 TRX suitable for wider applications.|
The latest adjustable-speed drive from Schneider Electric/Square D (Palatine, IL) reflects ongoing trends in features, such as direct Ethernet connectivity and extended power range up to 500 hp.
At the same time, Altivar 58 TRX ac drive doesn’t skimp on other features, including sensorless vector control, several operator interface options, I/O extension cards, and option cards for Ethernet and other major network protocols. RS-485/Modbus communication comes built-in.
With an Ethernet option card, embedded drive information is reportedly accessible in real-time from anywhere in the world. Many manufacturing facilities can translate availability of this level of drive information into cost-effective production. Powersuite programming software simplifies drive start-up and testing. The software also allows viewing of fault history on a PC or PDA.
Altivar 58 TRX drives carry three rating categories:
1-500 hp for variable torque (or 75 hp constant torque) at 400/460 V ac, three-phase input;
2-50 hp at variable torque (40 hp constant torque) at 208/230 V three-phase input; and
0.5-30 hp for variable torque (7.5 hp constant torque) at 208/230 V single-phase input.
February Control Engineering in print
This is where I usually remind you of other sources of information available in each printed issue of Control Engineering . And the February 2003 issue should be of particular interest to motors, drives, and motion control professionals.
In February News, you can find a brief summary of a user survey on controllers and positioners for servo motion systems. Released in January by IMS Research (Wellingborough, U.K.; Austin, TX), survey results indicate growth for distributed control architectures that employ intelligent field devices, based on purchasing data for 2002 and forecasts for 2005. Click here to read the complete item .
Click here for more on IMS.
”New in Control,” (part of News) discusses the recent launch of a line of NEMA-compliant, energy-saving motors from Siemens Energy & Automation (Alpharetta, GA). These ”NEMA Premium” induction motors offer further choice for users in selecting higher efficiency machines that cut operating costs dramatically. Click here to read the item .
Click here for more information from Siemens E&A .
My article on ”Switched-Reluctance (SR) Technology” updates readers on a simple, rugged type of electric motor that’s been around a long time, yet is being revitalized by the latest in controls. Recent ups and downs of SR technology are examined, along with the advantages and downsides it brings to the market, and prospects for its future. Click here for the complete article .
”Easy to use motion control”-a special supplement in the February 2003 issue produced in collaboration with Design News magazine-highlights several technologies and systems that improve ease of use in motion control. Five articles are included.
”Ease of Use Takes Center Stage” covers the high importance of simplified solutions as customers look to software and drive networking for help. ”When Less Can Be More” looks at distributed control as one way manufacturers reduce complex cables and connectors and gain valuable space. ”Open For Business” examines why many machine tool builders are turning to open systems instead of proprietary machine controls. A special interview with Dr. Jacob Tal, co-founder of Galil Motion Control (Rocklin, CA), provides answers to issues that affect ease of use.
Also part of the special supplement is my article, ”Motion Control Standards Evolve.” It summarizes efforts to bring motion control’s complex dynamics under standard, vendor-independent specifications. These efforts are proving to be tough and long-range ones. Click here to read a longer version of this piece .
The supplement was included in issues sent to qualified readers in this field. Click here to view the supplement.
In February’s Products & Software section, Performance Motion Devices (Lincoln, MA) introduces MC2300 Series motion chips with multiple breakpoint programming that accommodates more complex motion profiles. National Instruments (Austin, TX) offers its PCI-7342 two-axis motion-control board as a low-cost option for servo motor control. Danfoss Drives (Loves Park, IL) likewise stresses cost-effectiveness with a new line of micro ac drives called VLT Micro, intended for motors up to 5-hp rating.
More about these products can be found at the respective companies’ Web sites:
Worth reading: Induction motor control concisely covered
You would think most everything has already been written about the venerable ac induction motor. This is not the case, as new books continue to be published. One notable example is the book with the spartan title of ”Control of Induction Motors” by Andrzej M. Trzynadlowski (ISBN 0-12-701510-8), available through Elsevier Science and Control Engineering Bookstore
Mr. Trzynadlowski takes a streamlined approach to the topic, beginning with the basics and working up to complex control methods. Numerous equations are used throughout the text, including complex matrix equations where appropriate, yet the discussions have a practical flavor. Also, there remain ”white spaces” on most pages for a fresh look that readers should appreciate.
Construction and steady-state workings of induction motors are treated first, followed by simple on-off operation and a review of power electronics associated with motor drives. Separate chapters are then devoted to increasingly sophisticated control methods that regulate speed, torque, and position. These range from scalar control to direct- and indirect-field orientation, direct torque control, flux-vector control, and sensorless control. Numerous diagrams and examples help to clarify the underlying concepts.
These wide ranging subjects are concisely covered in a 228-page book, in 10 chapters plus indexes and a symbols glossary. In keeping with what the author calls the ”three tenets of good teaching philosophy,” each chapter begins with an abstract that tells what is to be covered, then goes on to deliver the content, then ends with a summary of what was covered.
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