异步电动机的负载噪声分析

Analysis on the Noise of Induction Motors With Loading

电机的噪声一般是在空载稳定状态下测取的，但某些电机负载时的噪声与空载时有较大的差异，特别是由变频器供电的电机噪声比工频正弦电源供电时的噪声可高出３～２２ｄＢ（Ａ）。该文通过负载对电机系统振动模态特性的影响，从几个方面分析了负载对异步电动机电磁噪声所产生的影响，并对实验测得的数据进行了分析。对于小型异步电机，在工频５０Ｈｚ运转情况下，由于其共振频率远离激振力的频率，负载引起的电机噪声的变化不大，一般在±３．０ｄＢ（Ａ）左右。但在变频供电情况下，由于激振力频率发生很大的变化，在有些状态下负载引起的电机噪声的变化很大。

According to the noise measure standard of electric motors, the noise of induction motors is normally measured in the state of nonload and steady operation. In some motors, however, the variation of noise under load and nonload conditions is quite big, especially in the motors powered by the frequency converters, the sound power level can reach a maximum exceeding 3～22 dB(A). Yet electric machines are always run under load condition, so the noise level of induction motors under such condition will be more accurate. The effects of load on the electromagnetic noise of induction motors were analyzed through those on the vibration modal behaviours of the electric machinery system. The paper also analyzed the data gathered from the experiments. When working frequency is 50 Hz, the variation of the load noise is insignificant, often about ±3.0 dB(A), for the resonant frequency of motor and the frequency of exciting force are far apart. But when the motor is powered under frequency converter condition, the frequency of exciting force changes greatly, the variation of the load noise in some circumstances may be significant.