
9-6 Power Electronics and Motor Drives
high speeds (two and four poles); the stator magnetic circuit is saturated and consequences on noise
are shown on the acoustic spectrum, which is composed of lines of frequency multiple of 300 Hz with
particularly high levels.
9.3 Magnetic Noise of AC Electrical Rotating Machines
9.3.1 Description of the Phenomenon
9.3.1.1 Flux Density in the Air Gap
e electrical currents owing in the wires generate in the air gap of the rotating machines a magnetic
eld, which acts on the stator and rotor iron. ree kinds of forces appear:
1. Tangential forces, which create torque and rotor rotation.
2. Magnetost