What are EC Motors? The benefits of EC motors vs AC motors.

What are EC motors?

EC (Electronically Commutated, or Electronically Controlled) motors are new generation electric motors that have permanent magnets on the rotor and use electronics to regulate the voltage and current applied to the motor. At TerraBloom for many years we have been developing our proprietary EC motor technology and offer a wide variety of standard (non-insulated) EC Duct Fans and silenced (sound insulated) EC Duct Fans

How do EC motors operate?

All electric motors work by the interaction of two magnetic fields pushing on one another. 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. EC Motors are essentially brushless DC (BLDC) motors with the power control board built into them.
  • 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 don’t have any brushes, so they don’t produce sparks and have longer lifetime compared to brushed DC motors. Because EC motors use electronics to control the stator and don't waste any power inducing the rotor field, they have superior energy efficiency and speed controllability and run cooler than induction motors. EC motors are used today in many fractional-horsepower applications where high motor efficiency, reliability, and/or granular controllability is required.

What are the advantages of EC motors?

EC motors are very high efficiency motors and maintain high-efficiency levels even at part speed. This means that in most cases they use less than one-third to one-half of the electricity used by the traditional "shaded pole" induction motors used in the ventilation and refrigeration industries, which successively translates into lower operating costs and short payback periods.

EC motors’ high efficiency also means the motors run “cool”, and dramatically reduce the quantity of waste heat produced. Reduced waste heat at the evaporator motor level also typically leads to reduced operation at the compressor level, which allows further energy savings. Furthermore, a cooler operation improves the lifetime of highly loaded motor parts like windings and bearings.

EC motors also have a wider operating speed range than traditional induction motors, which suggests that one EC motor can replace a variety of 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 most common reason why EC motor product lines usually include fewer 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 the application, and to incorporate features like data communications, constant volume control, variable speed, etc.

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

Why AC motors “hum” and are extremely hot to the touch once I reduce the speed. Do EC motors also have this humming noise and get hot when the speed is reduced?

The “hum” you're hearing is probably going to be the noise produced from the resonance of the motor lamination stack once you speed reduce an AC motor with a TRIAC, voltage chopper, or some other phase chopping device. The noise tends to become more prevalent the further the speed is reduced. The heat generated from altering the sine wave to a chopped waveform will also create an additional temperature rise in the motor leading to a shorter motor lifetime.

In summary, EC motors are the future of the ventilation industry due to their superb controllability, improved efficiency and longer useful life. The power cost savings from using EC motor based fans often make up for their price difference versus compatible AC motor based fans within the first year of operation. For more details on power cost savings which our ECMF series fans offer to our customers, please refer to the following article.

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