DISTINCTION OF TOOTHING AND SATURATION EFFECTS ON MAGNETIC NOISE OF INDUCTION MOTORS

This paper focuses on the noise and vibrations of induction motors. It proposes an analytical method to distinguish the phenomenon responsible on the magnetic noise, especially the toothing and the saturation. A 3-speed 3-phase induction motor, which works sporadically at low speed for hoisting, serve as a support for experiments. Its acoustic noise during this operating mode is really important. A complete diagnosis is proposed with a 2D analytical model. The approach is progressive and it shows analytically that magnetic saturation is mainly responsible on these noise level. Then, the presented developments makes it possible to identify, in simple way, the noise components due to the both magnetic saturation and toothing efiects. Analysis of vibrations and noise of magnetic origin of electrical rotating machines is di-cult and requires some experience. Indeed, design methods for three phase Induction Motor (IM) are generally well established for conventional motors; the designers typically use analytical methods embedded in dedicated softwares While such traditional designs are nowadays routine, it should be stressed that some more di-cult compromises may be needed to design a speciflc, less conventional, motor. This paper presents an acoustic study which is particularly challenging as it concerns an industrial three- speed three-phase IM. This IM operates mainly at two high speeds (synchronous speeds: 1500 and 3000rpm), while the third one (375rpm) is used only sporadically for hoisting. Designing the machine