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What is the difference between an AC and EC motor?

Motor and fan related questions

A motor which is referred to as ‘AC motor’ has a stator winding. The AC power supplied to the motor stator creates a magnetic field that rotates in time with the AC oscillations. This magnetic field is used to generate the motor torque. AC motors (and certainly induction motors) are relatively cheap and have a simple construction, compared to DC motors. At the other hand, DC motors offer a very high energy efficiency.

Brushless DC motors are also known as EC motors (or Electronically Commutated motors). They are synchronous DC motors, powered by a DC electric source via an integrated fan speed controller which produces an AC electric signal to drive the motor. The integrated controller uses a DC current switched on and off at high frequency for voltage modulation and passes it through three or more non-adjacent windings. Because the controller must direct the rotor rotation, the controller requires some means of determining the rotor's orientation/position (relative to the stator coils). Some designs use Hall effect sensors or a rotary encoder to directly measure the rotor's position.

An EC motor can be seen as an AC motor with integrated fan speed controller. This means that an EC motor requires an indication of the desired fan speed or a fan speed setpoint. Many EC motors can be controlled via an analogue 0-10 VDC or PWM signal. More and more EC motors feature Modbus RTU communication. The advantage is that they cannot only be controlled via Modbus RTU, but all the motor parameters (Rpm, consumed power, motor status, motor temperature, etc.) are also available via Modbus RTU.