Explaining what ECR Motors are and how they work.
EC (Electronically Commuted Rotor or Electronically Controlled Rotor) 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:
- ECR 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.
ECR 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).
ECR motors are used today in many fractional-horsepower applications, wherein high motor efficiency, reliability, and/or controllability is desired.
Lifespan
Engineers are occasionally asked to predict average motor life or mean time between failures for a given motor.
The life expectancy will depend strongly on:
- ambient temperature
- motor load
- number of starts
- grid voltage conditions.
Wellington motors are designed for 10+ years of life under nominal operating conditions.