感应电机在线监测磁场传感器设计

Design of induction magnetometer for online monitoring of induction machine

[目的]为了实时获取感应电机运行状态下的杂散磁场弱信号,提出一种优化设计的低噪声感应式磁场传感器(IM)。[方法]通过分析磁场传感器的频率响应和噪声模型,找出不同频率段影响磁场传感器性能的主要噪声源,获得等效输入磁场噪声水平公式。以此为依据,设计专用的低噪声放大电路,采用多参数优化方法,针对不同的限定条件,得到优化公式和优化结果,设计出10 kHz线性频率响应的小型磁场传感器,并对感应电机在正常和故障情况下的磁场进行测试。[结果]测试结果表明,10 Hz处的等效噪声水平为2 pT/Hz,20 kHz处的等效噪声水平为0.7 fT/Hz。[结论]采用优化设计的磁场传感器能够有效监测感应电机的磁场变化,可应用于感应电机的在线监测。

[Objectives]In order to detect the weak stray magnetic field signal of the induction machine during operation,this paper presents an optimized design method of low noise Induction Magnetometer(IM).[Methods]By analyzing the frequency response and noise model of the IM,the main noise sources that affect the performance of the IM at different frequency bands are proposed,and the formula of the equivalent input magnetic field noise level is obtained.Based on this,a special low-noise amplifier circuit is designed.And the optimal design method of the IM is proposed.Besides,for different restrictions,the optimization formulas and results are given.In addition,a small IM with a linear response to 10 kHz is fabricated,and the magnetic field of an induction machine under normal and fault condition is tested.[Results]The test results show that the equivalent magnetic field noise level is 2 pT√Hz at 10 Hz,and 0.7 fT√Hz at 20 kHz.[Conclusions]Through optimized design,the IM can effectively monitor the magnetic field change of the induction machine,and can be used for online monitoring.