An Effective Approach for the Analysis of the Electromechanical-Coupling Vibration in the Inverter-Fed PM Synchronous Motors Using Concise Mechanical Model

The utilization of high-speed permanent magnet machines as power and propulsion system is to be preferred in plenty of underwater vehicle applications. Among these applications, the inverter-fed PM motors are widely accepted for the need of variable speed. In the performance evaluation of the inverter-fed permanent magnet synchronous motors, of great interest is the analysis of its vibration and noise characteristics. The normal electromagnetic force, generated from the air gap magnetic field in between the stator and rotor of the motor, is the main cause for the vibration and acoustic noise of PM motors. Former researchers need first to build a 2-D, or 3-D for the simple structured motor, FEM model to calculate the electromagnetic field, which is necessary for the following computation of the electromagnetic force according to the Maxwell stress tensor method. These calculation results need to be saved and then applied as load for the examination of radiated noise and vibratory response of the motor under electric excitation. Although some scholars have contributed to the noise and vibration analysis of electric motor using this conventional method, there do exist a number of limitations for its applications in practice due to its nonlinearity and great consuming time and memory requirements. Premised on the analytical expression of the normal electromagnet force of the inverter-fed PM motor, an effective approach is introduced to convert the complex electromechanical coupling problem to a concise mechanical problem, which is combined with FEM to evaluate the performance of different vibration control schemes for the electric motors. Experimental data are also included for the efficiency evaluation of the proposed method.