Remco offer two models of 4 pole External Rotor Motors for use with our Tangential Fan Wheels. Compared to rotor centric permanent magnet motors, the external rotor motor topology has a larger magnetic flux. Outer Rotor Brushless DC. Motor Technology. Outer rotor brushless DC motors differ from typical brushless DC motors in that the rotor (item 2 above) is situated.
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External Rotor Asynchronous Motors AC Easy-to-install and easy-to-manage, external rotor motor AC motors are designed for reliable and low-noise functioning according to current standards. They can be supplied with a wide range of impeller configurations: Plastic or steel impellers have to be selected external rotor motor to motor type and performance.
Key characteristics Large variety of designs based on customer requirements Low noise emission Electronic Motors Cebi's electronic motors have been designed for energy efficiency purposes.
The no-load speed depends on the applied voltage and the number of windings of the stator winding.
External Rotor Motor (ømm) | Remco
Therefore in the limits which are defined by the physical parameters such as output power, torque, temperature rise etc. For example, if a fan is operated with an EC motor, the speed can always be adapted to the requirements of the ventilation system or the process. In external rotor motor operation, therefore, the energy consumption can be significantly reduced, because the required input power of a fan external rotor motor according to the speed to the power of 3.
Aside from this, EC motors feature a significantly higher efficiency Figure 2 than mains-powered AC motors both in partial-load operation and at full load, and they usually do this with a smaller size. One reason is that EC motors do not require a magnetising current, so that current heat losses of the rotor disappear.
Even if the rare earth magnet discussion does not favour these motors, they are simply the best choice in terms of energy efficiency. Dynamic requirements determine the choice of magnets With EC motors you are not always forced to rely on the strong rare earth magnets, because their excellent magnetic quality is really needed only for highly dynamic servo drives, such as those used in robotics.
On the one hand, compact dimensions are required; on the other hand, external rotor motor, the lowest possible rotor mass is required to minimise the moment of inertia.
These external rotor motor are attainable only with highly remanent and highly-coercive rare earth magnets. Therefore, manufacturers of such servo drives primarily concentrate on reducing the required magnet mass and height by means of complex optimisations; and they have already achieved very remarkable savings here.
Motor and fan specialist ebm-papst Mulfingen is not even faced by this problem with its fans, which are equipped with energy-efficient GreenTech External rotor motor motors.
Despite the high efficiency, these drives run without rare earth magnets. The external-rotor motor principle provides the key for this: The rotor is on the outside Figure 3: Cutaway drawing of centrifugal fan with external rotor external rotor motor — the rotor rotates not in, but about the stator.
External Rotor Motor (ø157mm)
external rotor motor At this kind of motor, the still-standing part, the stator, is located on the inside and is surrounded by the rotating part, the rotor Figure 3. The externally positioned rotor rotates about the internal stator.
Conditioned by this arrangement, the external rotor motor can achieve a higher torque magnet volume, air gap surface, radius than the internal rotor motor of the same package length, the same magnet system and the same magnet thickness reduced magnet volume, reduced air gap surface, smaller radius.
By cleverly using the design parameters in the fan and blower area, an external rotor motor using external rotor motor ferrite magnets can attain torques and efficiencies which the internal rotor motor can achieve only with rare earth magnets because of the limited volume and mass.
Unlike servo drives, fans do not require high dynamics. Quite the opposite is required: Without restrictions external rotor motor earth magnets can be given up and ferrite magnets can be used, which are not only significantly more cost-effective, but also have stable market prices due to their availability.
The motor design with an external rotor is advantageous for fans in another regard as well.