EC fan speed control

EC fans

EC fans are powered by brushless DC motors. These motors are also known as Electronically Commutated motors or EC motors. A typical EC motor has an external rotor of permanent magnets which rotates around the stator windings. The control electronics (fan speed controller) are always integrated in the EC motor since this motor type requires a coordination between rotor position and motor currents. This integrated fan speed controller converts the mains (AC voltage) into a DC voltage that is required to control the motor. The main advantages of EC motors are: their high efficiency, the reduced noise and overall reduction of electromagnetic interference (EMI).

However, the permanent magnets and the integrated electronics make this type of motor rather expensive. Since the fan speed controller is always integrated in the EC motor, these motor types always require a control signal to specify the requested fan speed. This control signal can be digital (Modbus RTU) or analogue (typical 0-10V).

Most EC fans with Modbus RTU communication can be controlled via SenteraWeb – an online HVAC control platform. This type of control offers many advantages compared to the classic 0-10V control signal. Significantly longer cable lengths are possible without the risk of interferences. The motor speed, motor temperature and other parameters can be monitored on a continuous basis, even online. Local or remote control is possible. The combination with Sentera HVAC sensors, offers you demand based fan speed control. For manual control, you can add a digital potentiometer with Modbus RTU communication.

The following devices can be used to generate a 0-10V control signal:

Type of controllers for EC fans