Motors Monthly: No end in sight for motor efficiency gains

I read an interesting sentence that lead off an offer to one of those many industry market reports we receive here. The sentence read, and I quote, "Today, the motors that propel electric vehicles on land, through water and in the air are mainly brushless because brushed commutator motors are on the way out." *blink blink* That's almost as good as saying an airplane crashes because it hits the ground.

Don't misunderstand me, the statement is true. It's the cause and effect that concerns me. I don't think brushless motors jumped into the vacuum left behind because people were throwing out their brushed motors. I rather think brushless motors offered advantages over brushed motors, and that those advantages pushed aside the older brush technology.

But, as they say, everything old is new again, and brushed technology is starting to see a resurgence thanks to new materials and a growing fear about a possible scarcity of rare earth materials that go into the magnets used in brushless applications.

The fear of not being able to get those rare earths isn't a major factor in the decision to reexplore brushed technologies. While China today controls 98% of the world's production of rare earths, it only has an estimated 30% of the world's supply. Other countries, including the U.S., can step in to replace any lost production. Research into new brushed technology creates alternative choices if the need should arise. Better to work on those designs now, then under pressure to develop them as an emergency replacement.

Is it possible that brushed motors can compete with brushless? Only time and engineering will answer that question.

— Robert Repas, Assoc. Editor

Articles

No end in sight for motor efficiency gains

Many engineers look at NEMA Premium grade as the gold standard for induction motor efficiency. But technical innovations now make possible even more power-miserly designs.

Eliminating EMI in motion systems

When working with grounds and shielding, it’s common to hear complaints ranging from “It’s just black art!” to “The rules change all the time!” and “There’s no way to understand it!” Though often repeated, these emotional statements are simply not true. Effective grounding and shields work on solid engineering principles. No wizard hats, no witchcraft — just sound mathematical and logical processes that can resolve or reduce electromagnetic interference (EMI) problems.

How servos and steppers stack up

Engineers who work in motion control often start out using a relatively simple approach involving stepper motors to synthesize moves. Steppers are appealing in that their controllers can be simple and inexpensive, at least for undemanding tasks. And most steppers run open loop, needing no position or velocity feedback to hit their targets.

Rugged hollow-shaft encoder can be user programmed

HS35F is an industrial square-wave encoder with TTL, HTL, and OC (open-collector) outputs. Direct read resolution can be up to 56,000 ppr, but internal interpolation can boost that to 80,000 ppr. And signal quality is good, even at low speeds. The HS35S sine-wave encoder provides good signal quality at all speeds and prevents drive overheating while saving energy.

Videos

Video: Trends in Brush and Brushless Motors

Paul McGrath from Maxon Motor looks at the up and coming trends in brush and brushless motors. Length: 4:28

New Products

Ac drives with EtherNet/IP interface

The 3G3AX-MX2-EIP-A EtherNet/IP interface communicates network slave capabilities to 3G3AX-MX2 ac drives. The front-panel mounting interface is equipped with Safe Torque Off (STO) and an External Device Monitoring output circuit (EDM).
Omron Industrial Automation

Miniature dc motor

The 3272 CR dc micromotor offers graphite commutation and materials produced with cutting-edge technologies. The drive provides 120-mNm torque, while measuring only 32 × 72 mm.
MICROMO

Miniature motor drivers simplify appliance designs, boost efficiency

STMicroelectronics (ST) announces the addition of two miniature motor drivers to its range of SLLIMM (Small Low-Loss Intelligent Molded Modules), which will enable domestic appliances to offer better energy ratings. Energy marking and labeling schemes, such as the ENERGY STAR mark and in-store energy rating labels, which are mandatory in many countries, give consumers the tools to identify energy efficient products in each price range.
STMicroelectronics