Engineers involved in the design and manufacture of products in the appliance industry are increasingly faced with new state and federal regulations governing the energy efficiency of the products they are designing.
As many of these products require motors for a wide variety of applications, the engineer is faced with the problem of determining the most energy-efficient motor while at the same time designing a cost-efficient product to meet market pricing.
In order to provide the most energy-efficient and cost-efficient motor, it is helpful to have a good understanding of the various types of motors available in the marketplace, along with their relative cost. The table provides a comparison of the more common motors used in the appliance industry.
An ac three-phase motor can produce efficiency in the 70–90% range but has not been included in the above table because most appliances are run on single-phase ac.
*“EC” motor refers to any motor that is electronically commutated, but in most instances it is actually a brushless dc (BLDC) motor. In some motors, the electronics are integral to the motor itself and can be attached directly to ac. In other cases, the motor electronics are packaged with an existing circuit board in the appliance and the motor is a lower-cost 12-V-dc brushless motor with a small circuit board attached to house the Hall devices (for commutation).
The challenge facing the appliance engineer is to select the best option that provides the lowest-cost device while meeting the energy standards mandated by government regulation. In addition to the motors shown in the table, there are many other motor types (stepper motors, dc servomotors, variable-reluctance motors, etc.).
This information provided by Roger E. Hollis, board member of SMMA—The Motor & Motion Association and vice president of sales for ElectroCraft Inc. SMMA provides motor-related courses such as “Motor Fundamentals for Appliance Engineers,” through the SMMA Motor & Motion College. Visit www.smma.org for more information.
