Attention, it’s getting technical!
The European fan market is undergoing a significant change: while the sales figures for fans with AC motors are stagnating, EC motors are recording a steady increase. This is mainly due to the ErP requirements, which stipulate a minimum efficiency for the overall ‘fan’ component.
Conventional AC external rotor motors typically achieve a maximum efficiency of around 85%. In contrast, external rotor motors in the Ecnity ECblue series achieve efficiencies of up to 93%. In order to fulfil the increasingly stringent ErP requirements, highly efficient motors are essential, even if the impeller is already efficient. This is where EC motors come into their own.
More about the efficiency of electric motors
The way the motors work plays a decisive role here.How are these impressive differences in efficiency achieved?
In an AC motor, the current in the motor windings creates a magnetic field that induces a current in the rotor’s short-circuit cage. The current generates a magnetic field that lags behind that of the stator windings. The difference in speed creates a torque that drives the rotor.
EC motors also generate a magnetic field in the motor windings, but this attracts the permanent magnets in the rotor without the need for an additional magnetic field.
The difference in efficiency is due to the different way the motors work. With AC motors, a lot of energy is required to build up the magnetic field in the rotor, whereas with EC motors, this energy is already used during production and is no longer required during operation. The control also differs between the motor types: EC motors are typically controlled analogue (e.g. via a 0-10V signal) or digitally (e.g. via Modbus or other protocols). The speed can be flexibly adjusted and the components can be monitored and optimised by a higher-level control system. In the case of the more simply designed AC motors, the control depends on the control component connected upstream of the motor.
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