Motors & Drives Information

Mountain View, Calif.--1997 will be the year in which digital signal processors (DSPs) push microcontrollers and other discrete devices into the background as the semiconductor platform of choice for emerging and traditional embedded markets--including motor control applications and disk drives, according to industry observers involved in both segments.

As the pace of integration of peripherals onto DSPs picks up steam, DSPs will play a vital role in combination wireless devices, digital versatile disc (DVD) and set-top box markets as well as in the development of the Internet.

In addition, where once DSPs were confined almost exclusively to the telecommunications and wireless markets, in 1997 there will be no limits. DSPs will be integrated into systems that were once reserved almost exclusively for microcontrollers including automotive applications, vending machines, electric meters, washing machines, refrigerators, dishwashers, disk drives and many other consumer products that demand fast time-to-market with digital functionality--areas where DSPs in the past have had limited or no presence at all.

"DSPs are going to be in everything. They are becoming the new microcontroller," asserted Edgar A. Sack, chairman and CEO for Zilog. For several years, Mr. Sack has been predicting that DSPs will be the platform of choice for a host of emerging systems applications--an interesting stance for the leader of the company that, although heavily involved in DSPs today, also invented the ubiquitous Z8 microcontroller architecture.

"When we think back and see 8-bit microcontrollers in everything, I see the same thing happening for DSPs. Five years ago when it was talked about to engineers, they were scared of the technology. Now they shrug their shoulders and go right to the design. I really think it is going to be the (key) part of 1,000 applications."

Mr. Sack said he sees DSPs in WebTVs, web browsers for TVs, bit-map graphics, process video and audio as well as appliances. The automotive and wave table markets--normally areas heavily dominated by microcontrollers--will be areas where DSPs will proliferate in 1997.

"I would imagine we will see more architectures for the DSP than we do in the microcontroller industry," commented Mr. Sack. "I don't see every DSP vendor using the same standard DSP for every function. It will be more of a horses-for-courses kind of a thing."

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Under terms of the agreement, Reliance(TM) industrial, commercial and marine motors and generators will incorporate SuperPower's groundbreaking ceramic-based Second Generation (2G) coated conductor technology. SuperPower is developing a 2G HTS wire that demonstrates superior performance over commonly used "first generation" wire. The enhanced current carrying performance at higher operating temperatures makes SuperPower's 2G wire an essential component for more energy efficient and cost effective industrial motors and generators.

Since 1987, Rockwell Automation engineers have been pioneering new technologies to make superconductivity a viable energy-saving solution. In 2001, Rockwell Automation demonstrated a 1600 horsepower superconducting motor using first generation wire. The use of the more cost effective 2G wire will help further the development of lightweight, highly-efficient generators and motors, ideal for a multitude of industrial applications that place a high premium on energy efficiency, weight and size. The combination of benefits will provide lowest life cycle cost solutions to commercial, industrial and marine customers. The development of HTS motors also offers new access in markets like marine propulsion.

"The results of our future efforts under this joint agreement will make a significant impact on the successful commercialization of second-generation HTS rotating machinery leading to cost-effective electric motors and generators that are ultra-efficient, lighter, and substantially more power dense than those that are available today," said Joseph D. Swann, president, Rockwell Automation Power Systems. "This is a significant step forward in the continued development of the world's first commercial HTS motor and generator. We are all extremely excited about the potential of this vital energy-saving technology, as well as the total cost of ownership benefits it could provide to our customers."

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Electric motors perform a variety of functions that were formerly consigned to cranks, gears and levers. All systems such as intelligent brake-control, throttle-by-wire and steer-by-wire require a sensor, a control unit and an electric motor. Electric motors are found in anything that has an electrical movement or solenoid function - such as window-lifts, fuel pumps, mirror and headlamp adjusters, anti-lock brake systems, clutches, automatic manual transmissions, parking brakes and electric steering. This second edition report reviews the key market drivers for automotive electric motors and looks at the main product applications for electric motors, highlighting some recent innovations as well as providing product forecasts. Chapter two reviews a range of automotive applications, providing product forecasts by value and volume in Japan, Europe and North America through 2007 and estimates and forecasts the volume and value of electric motors in those regions. Chapter three provides profiles of the major electric motor manufacturers: ArvinMeritor, Bosch, Continental Temic, Denso, Globe Motors, Jideco, Johnson Electric, SAIA Burgess, Siemens VDO & Valeo

Extract from the report - Power surge

The importance of electrical motors in the automotive industry is growing. Besides standard brushed DC motors, mainly found in body and convenience areas, multiphase unipolar BLDC motors, typically used in open loop pump drives and HVAC applications, are becoming popular. Manufacturers of brushless DC motors are pushing to develop smaller motors yet maintain power and speed. The driving force behind market growth is motorists' insatiable demand for enhanced safety, comfort, fuel economy and improved emission performance.

Although electric motors have long since been used in wiper systems and to power engine-cooling fans, these markets have matured. There are, however, some promising applications to improve comfort and convenience in the mid-range car segments, such as power windows and anti-lock brake systems. Electric steering is also becoming a common feature in small cars while electric parking brakes show great promise.

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ANDOVER, Mass. -- I-Logix Inc. kicked-off 2005 on a high note following record sales growth momentum in 2004. Q1 2005 posted a 50% increase in new sales and bookings over Q1 2004, with total sales up over 30% from the same quarter in 2004. I-Logix Q1 successes demonstrates that diversified industries are embracing I-Logix's Statemate and Rhapsody design and development environments into their development processes to improve product quality while compressing time-to-market cycles. In Q1, aerospace, transportation, consumer and medical were growth areas for the company while telecom, a segment that has been historically hard-hit in past years, grew aggressively as well.

"We challenged ourselves to launch new state-of-the-art embedded systems products in early 2005, and aggressively geared up to capitalize on the competitive advantage that the latest versions of Rhapsody and Statemate offer to our market. I-Logix's continued growth and healthy cash positive position reflects the strength of this strategy, and we are focused to get the most out of the overwhelming interest in our new products for a strong 2005," Gene Robinson, CEO I-Logix Inc, said.

In Q1 major telecom companies such as Alcatel Sel AG, Novatel, Nokia Corporation, Motorola, and Lucent Technologies purchased I-Logix products and services. In the aerospace defense market, I-Logix continued to win new business from General Dynamics, Lockheed Martin, NASA, Northrup Grumman, Raytheon, and Thales Electronics. Medical customers Cameron Health, Sane Software, Siemens AG Medical coupled with transportation leaders Bombardier, General Motors Corporation, ITT Industries, Renault and Siemens AG and consumer products innovators like Texas Instruments and Hewlett-Packard rounded out sales successes to post a profitable and cash-positive close for the first quarter of 2005.

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SOUTH PORTLAND, Maine -- Fairchild's SPM portfolio is the industry's most comprehensive line-up of power modules--50 W to 3 kW--for inverter motors

Fairchild Semiconductor's (NYSE:FCS) Motion-Smart Power Modules (SPM(TM)) offer a highly integrated solution for low-power (below 100 W), brushless dc (BLDC) motor applications. The Motion-SPM devices integrate multiple functions in a single compact package, offering a simplified motor drive solution to speed engineering design, reduce PC board space and enable energy-efficient and reliable designs in home appliances. Motion-SPM multi-chip modules combine six fast recovery MOSFETs (FRFET(TM)) and three half-bridge high-voltage ICs (HVIC) in one thermally efficient, ultra-compact (29 mm x 12 mm) Tiny-DIP package designed for BLDC motors with built-in control.

"The low-power appliance market is selecting high-voltage brushless dc (BLDC) motors over single-phase AC induction motors, due to their increased efficiency (from 50 to 90%), decreased acoustic noise and vibration, and higher power density per volume and weight. Fairchild's Motion-SPMs make it possible to build the motor control into the BLDC assembly," said Taehoon Kim, vice president of Fairchild's High-Power product line. "By integrating power analog and power discrete IC functionality into a single package, the SPM represents how Fairchild understands--and meets--the thermal efficiency, reliability and board space demands of the home appliance market. In addition to offering advantages over non-integrated solutions, the new Motion-SPM series makes Fairchild's SPM portfolio the industry's most comprehensive line-up of power modules covering inverter motors used in a full range of 50 W to 3 kW appliances."

Each Motion-SPM uses advanced FRFET and HVIC devices to ensure the performance and long-term reliability of the end product, while simplifying motor inverter designs. The Motion-SPMs' FRFETs optimize system efficiency by lowering switching and conduction losses during low-current conditions. For ruggedness, they provide a wider reverse bias safe operating area (RBSOA) than IGBTs of similar ratings. By using the MOSFETs' body diodes as freewheeling diodes, Motion-SPMs eliminate the need for additional components, improving the efficiency and noise immunity. The gate-driver ICs increase reliability through high-isolation, 5 V CMOS/TTL interface and under-voltage lockout (UVLO) protection features.

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SOUTH PORTLAND, Maine -- The FCAS50SN60 Offers 40% Space-Saving, Excellent Thermal Performance and Reliability over Discrete Solutions

Fairchild Semiconductor (NYSE:FCS), the leading global supplier of products that optimize system power, introduces the world's first Smart Power Module (SPM(TM)) designed especially for driving single-phase switched reluctance motors (SRM) for vacuum cleaners. Fairchild's new 50 A-rated FCAS50SN60 Smart Power Module integrates a high-voltage IC (HVIC) and low-voltage IC (LVIC), IGBTs, fast recovery diodes and a thermistor in an ultra-compact (44mm x 26.8mm) Mini-DIP package. This package features Direct Bonded Copper (DBC) technology that significantly increases thermal performance. Compared to typical discrete solutions, Fairchild's FCAS50SN60 reduces power circuit space by up to 40%, enabling designers to incorporate the controller into the SRM assembly. This compact solution greatly reduces overall system size while simultaneously enhancing reliability.

"Fairchild's one-of-a-kind Smart Power Module, the FCAS50SN60, enables very compact and high-performance SRM drives in vacuum cleaner designs," said Taehoon Kim, vice president of Fairchild's high power product line. "This Smart Power Module is an example of Fairchild's expertise in understanding when to integrate different technologies and streamline existing ICs with advanced packaging technologies to meet the needs of the rapidly growing consumer appliances market."

The UL-certified FCAS50SN60, with its built-in HVIC, provides an optocoupler-less, single-supply IGBT gate driving capability that further reduces overall system size, and its integrated under-voltage lock-out (UVLO) and short-circuit (SC) protection ensures excellent reliability. The FCAS50SN60's optimized switching speed meets electromagnetic interference (EMI) requirements.

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NORMAL, Ill. -- Company Promotes 33-Year Industry and Operations Veteran as Fourth-Generation Eclipse is Readied for Dealer Showrooms

Mitsubishi Motors North America (MMNA) today named Jerry Berwanger Executive Vice President and Chief Operating Officer, Manufacturing Division, promoting him to run the company's lone North American assembly plant located in Normal, Ill. Berwanger, who most recently was senior vice president of Quality and Operations at the facility, takes over leadership of the plant from Rich Gilligan, who in January was appointed President and CEO of MMNA.

Berwanger, 56, is a 33-year automotive industry veteran. He was hired by Gilligan in March 1999 as MMNA Manufacturing Vice President of Quality after 27 years with Ford Motor Company, where he held various positions at the automaker's plants in Kansas City and Chicago. He was promoted to Senior Vice President of Quality for MMNA in 2003, adding responsibility for all Manufacturing Operations in 2004. He will report directly to Gilligan.

"Jerry's leadership in Quality has been a linchpin in MMNA's rise to award-winning performance in the J.D. Power IQS rankings," said Gilligan. "He's a real 'people-person,' and the perfect choice to lead Manufacturing's contributions toward MMNA's return to profitability."

"I'm excited to lead the team in Normal at this challenging time for our company," said Berwanger. "We have a critical role to play in Mitsubishi's global revitalization, and I join our entire workforce in embracing that challenge, beginning with our production launch next month of the all-new Eclipse."

The 2006 Eclipse, which is expected to be in dealer showrooms by Memorial Day, ahead of an official sales launch in June, shocks the senses with an eye-catching bold design and dynamic performance enhancements that take the nameplate's legendary status among import sport enthusiasts to new heights. Mitsubishi has integrated refined power, futuristic styling and dynamic handling in the fourth-generation Eclipse to appeal to both upscale, affluent consumers and younger drivers who exhibit a passion for driving and life every day.

The new Eclipse is featured on the cover of Motor Trend magazine's March issue as one of the "Hot Drives Worth Waiting For."

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SuccessFactors, Inc., the market and Web business application leader in on-demand workforce performance management, today announced that T. Rowe Price Group, Inc., the global investment management firm, has implemented SuccessFactors' performance management technology. As part of an enterprise-wide initiative to automate and integrate global human resources functions, T. Rowe Price purchased SuccessFactors' performance management and goal management software modules as a replacement for multiple, less robust workforce performance processes and technologies that previously existed within the organization.

In addition to helping the firm promote a suite of role-specific competencies, SuccessFactors technology has enabled T. Rowe Price to build an organizational process that develops and manages its workforce in a manner that drives individual accountability for high performance. During this process, the company has been very pleased with SuccessFactors' implementation and business best practices.

"We prefer to invest in relationships with human capital management partners who are as committed to their customers as T. Rowe Price is committed to the success of its shareholders and clients and SuccessFactors has certainly met this mark," said Jeff Sube, Vice President of Organization Development and Diversity. "To demonstrate confidence in their products and their ability to satisfy customers, SuccessFactors offered 25 customer references during our vendor selection process. On the basis of system design and product implementation, SuccessFactors was unanimously recommended by all the companies we contacted. As we move into our second year of engagement, SuccessFactors' customer commitment at all levels within the organization has proven to support our initial findings and our high standards for service."

T. Rowe Price chose to work with SuccessFactors based on recommendations from leading technology industry analysts in addition to conducting a vigorous, in-house evaluation based on global business requirements and feedback from internal focus groups conducted with more than 200 of the firm's front-line managers.

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MUNICH, Germany -- Freescale Semiconductor (NYSE:FSL) (NYSE:FSL.B) is paving the way for the autonomous car by becoming the first company to offer both integrated and stand-alone FlexRay(TM) controllers -- the MC9S12XFR and MFR4300 -- based on the latest FlexRay version 2.1 protocol.

As the leading supplier of microcontrollers to the automotive industry and a founding member of the FlexRay Consortium, Freescale is positioned to help car manufacturers network in-car systems to make smarter, integrated active safety systems a reality.

The MC9S12XFR is Freescale's first microcontroller to integrate a FlexRay module with the 16-bit S12X core. By introducing the 9S12XFR & MFR4300 FlexRay node controller, Freescale has taken a significant step forward in providing the key semiconductor components for next generation X-by-wire subsystems.

"The automotive market is showing intense interest in FlexRay and is keen to see new technology developments supporting this protocol," said Chris Webber, vice president of the Automotive Practice at Strategy Analytics. "At this stage of the market development for the FlexRay protocol it is important that designers have the flexibility offered by components such as the ones announced by Freescale. As automobile makers continue to innovate in advanced safety, comfort, performance and infotainment features, FlexRay will help to make these concepts a reality."

The FlexRay protocol provides higher data rates and fault tolerance required for advanced control systems combining multiple sensors, actuators and electronic control units. Core member companies of the FlexRay Consortium include BMW, Bosch, DaimlerChrysler, Freescale, General Motors, Philips and Volkswagen. Other leading Japan-based manufacturers such as Honda, Nissan and Toyota have joined the consortium as premium associate members, adding momentum to the growing acceptance of the FlexRay protocol.

"FlexRay is rapidly becoming the de facto standard for high-speed in-vehicle networking," said Juergen Weyer, vice president and general manager of Freescale's transportation business in Europe. "As a founding member of the FlexRay Consortium, Freescale has made it a priority to proliferate this network protocol. The combined availability of integrated and stand alone products gives Freescale the opportunity to offer customers a choice with FlexRay devices, which was previously unattainable within the industry."

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Each stage must behave as expected for the startup to be successful

COMMISSION: "TO PUT INTO ACTIVE SERVICE (usually said of a ship)." That's one dictionary definition. For rotating electrical equipment, the term often used is startup. Getting any drive up and running, however, means more than just being able to push "start" and see it come up to speed.

It's said that flying a plane is no big deal; it's the takeoffs and landings that cause trouble. With land-based, stationary machines, an analogous concern is making sure the equipment starts and stops successfully over a reasonably long period, as well as continuing to run under whatever operating conditions may exist during that period.

So . . . what is needed to successfully commission a new three-phase electric motor? Foremost is the recognition that drive performance is what the pump industry terms a wire-to-water issue. From the upstream electrical supply system to the output of the driven process, each intermediate stage must behave as expected for the startup to be successful. In theory, whoever furnishes and installs the motor itself isn't responsible for anything either upstream or down.

When is it 'the motor's fault"?

Nevertheless, as any experienced service technician knows, when a motor-driven system malfunctions, it's commonly seen as "the motor's fault" until proven otherwise. That, plus the trend towards "turnkey" jobs, means that the motor supplier/installer's best defense is to possess-and use-at least some basic knowledge of how the rest of the system should work. Equally important, of course, is an even more complete awareness of safety regulations and safe work practices.

To put any new motor in service, then, here's what to consider:

* The motor itself.

* The electrical system.

* The connecting circuit.

* The motor controls.

* The motor mounting.

* The coupling between motor and load.

* The driven machine.

Obviously, some overlap will exist among these items.

Know your motor

Start with the motor. Why? Because you will need the motor nameplate information, the motor enclosure identity, and the motor instruction sheet or manual to begin evaluating several of the other conditions on the above list. Some of what comes next here will seem too obvious to include in any list of do's and don't's. Yet failures continue to occur because just such simple matters have been neglected.

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Oshkosh Truck Corp. has developed a hybrid drive system for use in severe-duty, military and commercial truck applications. The new hybrid technology, which the company calls ProPulse, has been installed on an overhauled and updated Heavy Expanded Mobility Tactical Truck (HEMTT) military truck. The ProPulse HEMTT is functional and has a cargo hauling capability, of 16.5 tons.

The project design starred a year and a half ago and the actual construction of the truck took six months. Included on the truck is Oshkosh's Command Zone electronics system with real-time diagnostics and prognostics capability (see related story).

"Oshkosh Truck began looking into the feasibility of a hybrid drive system about five years ago," said Chris Yakes, senior project engineer at Oshkosh. "We started looking into the technology, but did not have any definite plans. And then customers, both commercial and military, started asking us questions about hybrid systems and their feasibility. Once customers started asking questions, we began to look at the technology more carefully.

"We worked with hybrid system suppliers and integrators, companies that were developing complete systems and components for OEMs, trying to fit their technology and systems to our trucks. However, we found out that the technology just was not feasible."

Many of the systems proposed and tested required a large and heavy battery pack, which Oshkosh said greatly diminished payload capacity. In addition, the vehicle did not meet the performance requirements for torque, speed on grade, etc. The conclusion was that hybrid systems would not work in severe service applications.

Then about three years ago, Oshkosh took a second look at the hybrid drive technology, this time with the idea of integrating components into a system of its own. "We found that if we took care of the integration in-house, we could put together a system to do what we needed it to do," said Yakes. "We went out and studied the market and spent time working with many different component suppliers--motors, generators, battery and other storage systems, wiring, controllers, monitoring equipment--and picked what we believed was the best and most cost-effective components.

"This time, we let the performance requirements of the vehicle as a whole drive the system design. We let the vehicle platform drive down into the component requirements and the system design."

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VERNON HILLS, Ill. -- Mitsubishi Electric Automation Inc., a global supplier of automation products to all major industries, has introduced its A700 high-performance variable frequency drive (VFD) for controlling motors ranging from 1/2 to 600 horsepower. It will replace the company's highly successful A500 and A500L drives, which have been available since 1997.

The A700 is the first drive from Mitsubishi to feature a built-in programmable logic controller (PLC) and features many of the special technologies originally developed for Mitsubishi Electric servo drive products, such as adaptive auto-tuning which automatically compensates for changes in load inertia. The result is smoother operation, less downtime and ultimately, lower operating costs.

"The A700 is faster, smarter and more powerful than any standard VFD we've ever produced," said Chris Cusick, marketing manager for Mitsubishi Electric Automation. "And with its built-in programmable logic controller, users can customize the drive to their unique application."

Exceptionally versatile, the A700 achieves class-leading motor performance using encoder feedback to operate in "flux-vector" mode to generate torque at zero speed and allowing positioning control. With a speed response time of 300 radians per second -- 10 times faster than the A500 -- the A700 reacts quickly to sudden load changes with utmost efficiency.

Used without an encoder, the A700 uses the newly developed "Real Sensorless Vector" (RSV) algorithm to provide a 200:1 speed range. Its ability to control torque as well as speed makes it ideal for applications where constant tension must be maintained, such as wind/unwind control.

Communications to the A700 are supported with most popular protocols, including Profibus DP, CC-Link, DeviceNET, LonWorks, ControlNET, Modbus RTU, Metasys N2, EtherNET IP and Modbus TCP/IP, as well as Mitsubishi Electric's proprietary RS485 network. In addition, SSC Net III, Mitsubishi's high-performance, fiber-optic motion network is also supported, allowing the A700 to operate in conjunction with Mitsubishi Electric's new J3 servo drives and complete line of motion control products.

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The first demonstration system to result from the agreement between SEMIKRON and Chorus Motors plc (OTC: CHOMF) to develop the Chorus Meshcon motor and drive technology has been used to move a widebody Air Canada aircraft on the ground without using a tug or its own jet engines.

Following an approach from Chorus, the two companies agreed earlier this year for SEMIKRON to apply its design and applications expertise to the Chorus Meshcon drive concept, in exchange for exclusive supplier status for certain markets. SEMIKRON is designing Chorus Meshcon integrated power assemblies for test motor and drive systems and is expecting to design and manufacture these assemblies for the high end specialty markets.

The Chorus Meshcon drive operates with a very high number of phases -- up to 20 or more -- optimised for the specific application. This offers a system that, because of its small size, high power density, and torque-speed performance, achieves what no other motor-drive solution can. Applications are expected to be in areas as diverse as starter-alternators for cars, conveyors, locomotives, hoists, robotics and marine applications. Other aerospace applications, such as starter generators for jet turbines, are likely to be developed in the near-term. Another potential application is as a replacement for some hydraulic systems, where it is desirable for the motor to start and stop frequently, often under load.

SEMIKRON's solution is based on its MiniSKiiP® (SEMIKRON integrated intelligent power) subsystem. The compact design of MiniSKiiP integrates power semiconductor switches, a heat sink, a gate driver unit with protection, and current and heatsink temperature sensors. Its patented pressure contact technology allows a compact power module design with very low thermal resistances, high thermal cycling capability and low parasitic stray inductances, which is well suited to high-vibration environments. The SKiiP technology presses the direct bonded copper substrate onto the heatsink with a uniform pressure spreader, thus ensuring a consistent low thermal resistance without the need for a copper baseplate.

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They may be the key to high-speed machining

Real-world economics forces companies to look for ways to produce more products, faster, and with higher quality than ever before. This, search in turn, drives changes in processes and equipment to improve productivity.

Fortunately, changes in the design of CNC machine tools and machining equipment are helping production managers and engineers keep their sanity. One of the most dramatic changes to machine tool design today is the increasing use of linear motors, in preference to rotary motors and drivescrews. Linear motors offer a host of advantages, all of which contribute to improved manufacturing engineering.

Traditional drives are handicapped in relation to both current and future industry demands. Rotary motors have a limited maximum rotation speed, gear reducers add inertia and lower efficiency, motor couplings produce windup distortion, backlash, and hysteresis. Also, encoder couplings deflect during acceleration and deacceleration.

Additionally, traditional drives rely on drive screws, which come with their own set of limitations. These include: length restrictions, mechanical backlash, friction, windup, pitch-cyclic errors, long vibration decay times, coupled inertia to the motor, and the axial compression of the screw. These all limit the effectiveness and precision of conventional drives.

As the equipment wears, continual adjustments must be made to ensure ongoing accuracy. Once the machine is designed with rotary motors, it is locked into that design-even during scheduled equipment replacements. Incremental change is slow and evolutionary change is prohibitively expensive,

What Else Is New? Directdrive linear motor technology promises substantially higher levels of performance and greater simplicity than traditional motor drives that convert rotary motion to linear motion. Because the motor connects directly to the moving load there is no backlash and little compliance between the motor and load.

Speeds of less than 1 micron per second, or as high as 5 m/sec, are easily reached. Liear drive system can offer constant velocity characteristics with better than +/- 0.01% speed variation. In applications requiring high acceleration, smaller linear motors can easily deliver more than10gwhile conventional motors typically generate acceleration in the range of Ig. The accuracy of linear drive motors is only limited by feedback resolution, control algorithms, and motor construction.

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Electric Drives and Their Controls: R. M. CROWDER (Oxford University Press, 1998, 238 pp., L22.50 paperback)

This informative book has its origins in the machine tool industry and seeks to present a wide range of factual material which will provide the undergraduate with a thorough background in the multi-disciplinary field of controlled drives for manufacturing industry.

The text appears most suitable for a general course from second year to fourth year, depending on prior education. The student would be expected to have covered the basics of electronic circuits, digital electronics, simple mechanics and motors. There is modest academic depth in the book. The student will not find a mathematically rigorous development of either electrical machine theory or control systems here, though a number of equations are used to describe various processes. As these equations are often stated rather than derived, it would have been useful for more extensive references to have been given, in order that the student could find context, derivation and assumptions underlying each piece of theory; it is unlikely that there would be a complementary course to provide support for every area covered. The book does provide a limited bibliography but at the end, rather than in each chapter.

The material in the book is logically presented within the constraints of the various facets of the topic. After an introduction to set the scene, the selection and sizing of drive hardware is dealt with. A chapter on velocity and position transducers is followed by chapters on motors and their controllers brushed D, brushless D, a.c. induction and stepper. The final chapter considers control schemes (servo systems, motion controllers and programmable logic controllers). Powder semiconductors are covered by an appendix. Considering the author's experience and expertise in this field, it seems a pity that one or more case studies of system design have not been included.

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