Wellington ECR motors

EC (Electronically Commuted or Electronically Controlled) motors are electric motors which have permanent magnets on the rotor, and use electronics to control the voltage and current applied to the motor.

All electric motors work by the interaction of two magnetic fields pushing on each other. One field is created by the rotor, and one by the stator. The difference between motor types is in how these fields are created and controlled:

• EC motors use permanent magnets to create the rotor field, and a series of coils controlled by an electronic controller (or “commutator”) to create the stator field.
• Brushed DC motors use permanent magnets to create the stator field, and a series of coils powered by the DC input voltage and controlled by mechanical contacts (“brushes”) to create the rotor field.
• Induction motors use a series of coils powered and controlled by the AC input voltage to create the stator field, and the rotor field is created electromagnetically (or “induced”) by the stator field.

EC motors have no brushes, and so avoid the sparking and short lifespans that are more common of brushed motors. Because they have electronics controlling the stator, and do not need to waste power inducing the rotor field, they give better performance and controllability, and run cooler than induction motors (for small motors, at least: high horsepower 3 phase induction motors can be very efficient).

EC motors are used today in many fractional-horsepower applications, wherein high motor efficiency, reliability, and/or controllability is desired.

Terminology in the motor world is confusing, as many acronyms are used for the same thing, and people’s definitions are not always consistent. For all practical purposes, many of these terms are interchangeable.

• EC stands for Electronically Commutated. ECM stands for Electronically Commutated Motor. These are the same thing, and usually refer to motors which use AC mains power.
• BLDC stands for Brushless Direct Current motor: a BLDC motor may be the same as an EC motor, but it is more often used to refer to an electronically controlled motor which uses a DC power supply.
• PMSM stands for Permanent Magnet Synchronous Motor. Often this means the same thing as a BLDC motor, although in academic circles the two terms are sometimes used to distinguish between motors with different types of commutation algorithms.
• VFD, which stands for Variable Frequency Drive, is the one term which means something significantly different. A VFD is a type of electronic controller which is used to give an induction motor (usually a larger, 3 phase motor) improved controllability and part-load performance. Although VFD electronics are similar to those of an EC motor controller, the software is quite different and the two are not interchangeable.

EC motors have very high efficiency, and maintain a high-efficiency level at partial speed. This means that in most cases they use less than one third to one half of the electricity used by the traditional motors used in the ventilation and refrigeration industries. This translates into lower operating costs and short payback periods.

EC motor’s high efficiency also means that the motors run “cooler”, and dramatically reduce the amount of waste heat produced. Reduced waste heat at the evaporator motor level also typically results in reduced operation at the compressor level, which allows even further energy savings. Furthermore, running cooler improves the life of highly loaded motor parts, like windings and bearings.

EC motors also have a wider operating range than traditional induction motors, which means that one ECM motor can replace numerous induction motor models. In this way, the number of models required by a typical customer is significantly decreased, which decreases and simplifies inventory. This is the main reason why ECM product lines usually include less motor models than their induction counterparts.

In terms of speed control and features, because the motor’s operation is controlled by software, EC motors allow customers to optimize and integrate the motor, fan and controller with applications. This enables features like data communications, constant volume control, variable speed, etc.

EC motors are also quieter than traditional motors, have longer design life, and require less maintenance.

Our current EC range includes motors from 2-25W (1/375-1/30 hp) output power, in packages compatible with Q frame and unit bearing refrigeration fan motors. See our motors page for more information.

Efficiency varies depending on the manufacturer, power rating and each application’s conditions. However, as a general rule of thumb, shaded pole motors range from 15-25% efficiency, permanent split capacitor motors range from 30-50% efficiency, and EC motors achieve 60-75% efficiency.