You Need an Electric Motor for Your Application — Which One Do You Choose?

You Need an Electric Motor for Your Application — Which One Do You Choose?

Often I get asked the generic question — “Which motor should I use?”

But the answer is not quick or easy.

The proper choice of the motor may depend on the application, the industry, and in some cases, your marketing department.

First, you must always select a motor that is compatible with your specific application requirement; i.e., if very high efficiency and low heating are a must, then you should probably not select a universal or a single phase motor.

If the industry you are working in has a de-facto standard, you will need to weigh the improvements against the standard to determine if the better choice may be a harder sell and simply not worth the effort to try to promote the technology.

Lastly, while electric motors are definitely proliferating, there are viable alternatives, such as hydraulic and pneumatic systems that must always be considered, especially for applications that already have hydraulic and/or pneumatic infrastructure built-in. While we are often lead to think that this application requires an electric motor, in some cases any of these actuators may, in fact, yield satisfactory overall system performance.

I have been involved in many design cycles where the component selection was pre-empted by certain vendor preferences, which has resulted in poor design choices at best and, in some cases, in a very costly mistake.

If, on the other hand, cost is the only concern and all other application requirements are “simple” and well defined, i.e. — low operating life, low starting torque, single speed, etc. — then the brush or the single phase motor may be very acceptable choices.

Suppliers can be a help, especially if they manufacture and promote a range of different product types and technologies. However, their input should always be taken with a grain of salt because they generally would like to sell what they have to offer. Manufacturer representatives that source a variety of complementing products may offer a more unbiased opinion, but they may not always be familiar with all the detailed technical details of the different product options.

Confused? Rightfully so, and you are not alone. I plan to write about the different motor types in greater detail in this column in the near future and explain the highlights and drawbacks of each of the different motor choices in greater detail; this may help to sort through the confusion. But, even after working many years in the field, I often wrestle with the different options to make suitable recommendations.

Thus, designers that need an electric motor must educate themselves, take all the different inputs from marketing, vendors and manufacturer representatives, look at the resulting cost and then make a decision as to which motor will most likely meet all the performance and cost goals and pick from that list. In the final selection personal preference, experience with certain vendors, and similar factors can all be legitimate decision factors — but only then — with the final selection coming from amongst competing, suitable products.

About Author

George Holling

With over 70 publications and 9 U.S. patents on sensorless and efficient motor controls and low-cost power circuits to his credit, George Holling (PI) is an in-demand consultant to many major U.S. and International corporations for motors and drives. At present he holds significant influence in two companies — as technical director of Electric Drivetrain Technologies (2011– present) Moab, UT and as CTO of Rocky Mountain Technologies (2001– present), Basin, MT. Holling is a graduate of the University of Aachen, earning his B.S. (1974), M.S. (1978) and Ph.D. degrees there, while picking up his MBA here at the University of Wisconsin. His career has spanned both the commercial and academic arenas, the latter including stops at (Dean, Computer Science & Engineering) Utah Valley University, 2001 – 2003; and (Adjunct Professor), Western Michigan University, 1997 – 2002. From the commercial side, apart from his current positions, Holling has served as Project Engineer and Product Line Manager, UNICO; Franksville, WI (1978-1981); Project Engineer, General Electric, Medical Products Division, Milwaukee, WI (1981-1983; Manager R&D, Pacific Scientific/Honeywell Motor Products, Rockford, IL (1983-1985); Vice President of Engineering, Regdon Solenoid, Brookfield, IL (1988-1990); President, Advanced Motor Controls, Sun Prairie, WI (1990 – 1999); and Vice President of Engineering, Cordin Company, Salt Lake City, UT (1999 – 2000). Holling has also spearheaded projects for the development of high-efficiency motors and drives up to 400 kW, and has successfully negotiated licensing agreements with U.S., Chinese, Japanese and Indian customers for the licensing of motor and drive technology.

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