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Everything You Need to Know About EC

When energy cost comes into the picture, selecting the most energy efficient motor design plays an important part. In this article we are going to provide a comprehensive introduction to EC motor.

Motor applications are deployed across a multitude of industries where motion-control functions are required. When it comes to motor designs, engineers have three main types of options – alternating current (AC), direct current (DC) and electronically commuted (EC) motors.

EC stands for Electronically Commutated. EC motors are the brushless electric motors that designed with permanent magnets on the rotor and on-board electronics to control the voltage and current applied to the motor.

So how does it work? The rotor of an EC motor is a permanent magnet and the stator has a coil arrangement. By apply DC power to the coil, the coil is enegised and become an electromagnet. The operation of an EC motor is based on the force interaction between the permanent magnet and the electromagnet. When one coil is energised, the opposite poles of the rotor and stator are attracted to each other. When the rotor moves near one coil, the next coil will be energised. This process is repeated and the rotor continues to rotate.

Now you might have some intriguing doubts in your mind: How do we know which coils to energise and when to energise to get a continuous rotation from the rotor? The answer is, electronic controller. A sensor determines the position of the rotor, and based on this information, the controller decides which coil to energise.

An EC motor comprises of an integrated system. It contains…

(a) Conversion Electronics
(b) Speed Control Electronics
(c) Stator and
(d) DC rotor.

EC Motor

Fig. 1: The EC Motor

The initial development of EC motors can be traced back to 1960s. ebm-papst, the pioneer in advancing EC technology, brought the world’s first EC/DC compact fan into the market in 1965. Today the popularity of EC motors continues to increase, mainly because of a number of benefits being widely recognised. Here we will just list a few of the most important benefits for you to understand why industry professionals tend to tap on EC technology more than ever.

The decisive advantage of motors with EC technology compared to conventional asynchronous motors is that EC motors can achieve a better efficiency than AC equivalent. The power will not be wasted because the electronics control the stator. The efficiency we are talking about is of up to 90 % as opposed to 20–70 % with AC motors. This also ensures tremendous energy savings of 30 % on average.

Secondly, EC motors provide better performance and controllability with speed control electronics. In terms of controlling speed, EC motors have multiple speed controls whereas AC motors have no such option.

Furthermore, same output can be achieved with a smaller size EC motor comparing to conventional AC or DC motor. The compact design can help save much space because of the external rotor.

Article by
Dina Bai
Marketing Department of ebm-papst SEA Pte Ltd