High-efficiency over a wide speed range is one reason why switched reluctance or S/R motor drives stand ready to take-off in teh next few years. Other reasons for engineering interest in S/R motors, which are brushless dc motors without permanent magnets, include a combination of increased reliability, decreased maintenance, and high-speed capability. Source: Drives Research Corp.
Engineers looking for ways to cut energy costs will increasingly look to electronic motor drives in the next few years. Switched-reluctance motor drives in particular could well help them achieve their energy-conservation objectives, sources say, because of their reliability, low maintenance costs, and high-speed capability.
"Motors consume 60% of all electricity, and fewer than 15% have drives on them," says W.S. Lightfoot, co-author of an ac drive report from Motion Tech Trends (MTT) of Inglewood, CA. The report foresees demand-side management programs helping the ac drive market grow over the next five years.
ARC Advisory Group (Dedham, MA) predicts lower prices and high-energy costs will propel the low-power ac drive segment of the market in North America. ARC Senior Analyst Himanshu Shah expects the market to flourish at a much higher rate beyond 2001, growing at a healthy compounded annual growth rate (CAGR) of 6.3% over the next five years. For high power ac drives, ARC predicts a CAGR of 5.3%.
Thomas Kaporch, president of Drives Research Corporation (San Juan Capistrano, CA), says the overall EMD market revenue growth rate has gradually been slowing. "It's declined from 35% in the 1960s to 16.6% in the 1970s, 11.3% in the 1980s, 10.2% in the early-1990s, 7.8% in the late-1990s, and 5.5% in 2000."
When the final tally is in, Kaporch expects only 5.3% growth in 2001. However, he predicts that technological advances, government mandates, and globalization will reverse the declining trend. In fact, a recent DRC study predicts the worldwide electronic motor drive market will grow from $12.5 billion in 2000 to $19.1 billion in 2005.
"Building infrastructure in developing countriesóled by Chinaówill combine with renewal and expansion in the developed countries to drive growth of worldwide market revenue at a 7.1% rate in 2002 and at 8.8% over the five-year period from 2001 to 2005," Kaporch explains. "However, the greatest growth will come from newer motor drive segments such as switched-reluctance, brushless ac, and brushless dc with CAGRs of 32%, 14%, and 13% over the next five years, respectively. Together, these three segments should account for about 32% of worldwide market value by the end of 2005."
Switched reluctance, or S/R motors, are brushless dc motors without permanent magnets. "Advanced power semiconductors, HVICs, DSPs, and improved motor designs and control schemes achieve high-efficiency over a wide speed range," Kaporch explains. "This makes S/R technology very attractive to engineers working on emerging low-power automotive, appliance, and consumer-product applications."