Abstract : This thesis focuses on the reduction of the audible magnetic noise radiated by induction machines due to air-gap radial Maxwell forces in variable-speed traction application (e.g. subways and light-rail vehicles).
In a first part, an overview of the electrical and vibro-acoustic modelling techniques of induction machines and their associated assumptions is done. A review of the existing low magnetic noise design rules is done, and the influence of the motor and inverter design variables is discussed. Finally, the optimisation works applied to the induction machines are reported.
In a second part, a fully analytical model of the vibro-acoustic and electrical behaviour of the induction machine is established. Some simulation results are validated with finite element or boundary element methods, or tests. Saturation, load and pulse-width modulation (PWM) effects are considered.
In a third part, an exhaustive analytical description of the main magnetic forces is done. The exciting force harmonics are classified, and their characteristics are validated using experimental sonagrams and operational deflection shapes. On the ground on this analysis and DIVA simulations, some new low-noise design rules are inferred.
The model is then coupled to an optimisation algorithm in order to design a new low-noise motor achieving specified traction characteristics. Two rotor prototypes are designed to decrease the noise of a given industrialised motor.
Some tests are run on the first prototype, and up to a 15 dB decrease is observed in on-load PWM case. Furthermore, this new prototype successfully reached specified output torque without increasing iron losses neither phase current.