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Motors Continue to Evolve
Improving the state-of-the-art is created by refinements in many areas
Al Presher, Contributing Editor -- Design News, November 4, 2007
The latest trends in motors, whether they are servos, steppers, induction motors or brushless dc, keep coming back to detailed fundamentals and each aspect of the overall motor package. Suppliers are focusing on more compact sizes, improved power density, better integration of feedback devices and lowering costs.
But the practical goal is incremental improvements in every area of motor development, perfecting an art and a group of diverse technologies that have been developing over a long period of time.
“Smaller packages using segmented lamination technology, stronger magnets, kit motors and higher efficiency of overall systems are all helping to perfect the state-of-the-art in motor design,” says Pat Berkner, product sales manager, rotary servo motors, for Parker Hannifin.
Berkner says all areas of motor development provide opportunities for increasing performance and producing more cost-effective solutions. Inexpensive motors; high-performance, lower inertia motors and ways to produce more with the same machinery are priorities, plus the ability to customize a motor to individual customer needs. This could include hollow shafts for vacuum applications or fluid porting, dual output shafts, extended shafts, special connectors, stainless-steel construction and motors for food-grade applications.
Higher motor/drive efficiencies, reaching up to 92 to 96 percent, are important for hybrid and military vehicles. Gaining 10 to 15 efficiency points over the course of a year, can offer substantial savings. And with more customers able to design their own equipment, where space is at a high premium, kit motors which integrate the motors directly into the machine itself are increasingly an option.
“A primary trend in motor design is options and technology for feedback devices,” says Berkner. He says absolute encoder technology is making an impact and offer different technologies and solutions for battery backed feedback, geared multi-turn encoders and specific feedback options including Endat Versions 2.1 and 2.2 and the BiSS interface. He notes BiSS, in particular, is an extremely fast, all-digital solution that provides high levels of noise immunity.
“The next 'standardization quest' for motor technology is which feedback device customers will use,” says Berkner. We know it is absolute encoder technology, but which specific standards will emerge will be up to the end customer.
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 AC servo motors continue to offer higher performance than induction motors for motion control applications. |
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