Here is something that sounds good: In every application, EC fans, EC blowers and EC drives made by ebm-papst provide perfect power that can barely be heard!
ebm-papst EC technology is really something to hear – or, actually, not to hear. You hear no motor noise across the entire speed range. The advantage: When demand for cooling is low, such as at night, very low operating speeds can be selected. The resonance levels typical for frequency inverter operation – which, by the way, are not always eliminated even in our competitors' EC products – or "phase noise" do not exist in our products, as a different operating principle is involved.
Furthermore, combining AC motors with frequency inverter without an all-pole sinusoidal filter can cause winding and bearing damage.
A: Phase-angle control, hum noise (300 Hz)
B: Frequency inverter whistle – motor and device resonance caused by a motor with a frequency inverter