Low Electromagnetic Noise Squirrel Cage Motor Analysis and Optimization of Slot Coordination

Abstract

The electromagnetic noise of motor is mainly caused by the main magnetic fluxing into the air gap along the radial direction, generating radial force in the tooth of stator and rotor, which causes electromagnetic vibration and noise. The paper analyzes the theory of the production principle of electromagnetic force by selecting different slot combination to verify the influence on the electromagnetic wave, further conducts through the finite element analysis and modal analysis to prove the validity of the theory, and finally to prove that the choice of slot combination has an important influence on the noise of squirrel cage induction motor through noise test tank. Keywords-Slot Combination; Electromagnetic Force; Finite Element Analysis; Modal Analysis; Noise Test I. INT RODUCT ION At present, harmonic magnetic field of stator and rotor of the squirrel cage induction motor will interact with each other which will produce radial electro magnetic wave changing with time and space when it is electricity in engineering. Radial electro magnetic wave will cause vibration of stator, which will cause the noise. This is the main reason for the motor to generate electromagnetic noise. Intrinsic mode of motor stator structure and radial electromagnetic wave on the surface of the stator core are two major factors to determine the size of induction motor electromagnetic noise .At the same time the selection of slot coordination of the motor is mainly based on experience, and sometime the electromagnetic noise will exceeds standard. Therefore, it is necessary to research the slot coordination selection method of squirrel-cage motor. At the same time, the appropriate or not of slot coordination, not only should consider the order, amplitude and size of the wave force, must also consider the frequency of force wave and the natural frequency of the stator size, to avoid resonance. The generation of electromagnetic noise have a close relationship with the radial electro magnetic force wave and the existing mechanical mode, these two aspects should be in consider when choosing low noise slot coordination. Literature 2 studied effect on noise of 8 poles with 28 slots, 8 poles with 36 slots and 8 poles with 48 slots, when this three pole with slot coordination. Literature 3 only studied the electromagnetic wave through groove cooperates select to limit the influence of noise, but did not consider the modal effect. Literatures 4 studied the mode of traction drive motor, but had no contrast on slots with different effects on noise. Based on the squirrel cage induction motor as an examp le for slot coordination which is commonly used in engineering analysis the influence of the electromagnetic wave in theoretically in this paper, And in this paper a calculation is made for a company to provide prototype theory analysis and simulation, and through the prototype experiments validate the importance of selecting slot coordination and shorten the design cycle, to reduce the electromagnetic noise in the primary stage fullest.