可调频旋转磁场仪的装置设计与磁场测量

Device Design and Magnetic Field Measurement of Frequency-Adjustable Rotating Magnetometer

在教学演示仪器中利用三相交流电产生旋转磁场的传统方法存在仪器损耗大、安全隐患多、成本昂贵等问题。本论文设计了一种可调频旋转磁场的产生装置,在四个辐射状横放的带铁芯螺线管中通入低压直流电,通过PLC板编程对电流进行换向,同时改变换向时间可使置入装置中心的小磁针的偏转周期发生变化,从而达到可调频的效果。螺线管中通入单相恒定直流电时,小磁针不发生偏转;通入双相矩形脉冲电流时,小磁针以45°角步进旋转。磁场方向的转速取决于电流的换向频率。该装置不仅规避了传统方法的不足,且同时兼具定性演示和定量测量双重功能,可作为一款性能优异的实验教学仪器。

The traditional method of using three-phase alternating current to generate rotating magnetic field in teaching and demonstration instruments has many problems,such as high loss of instruments,potential safety hazards and high cost.A kind of frequency adjustable rotating magnetic field generation device is designed.Low voltage direct current is fed into the four radial horizontal solenoids with iron core,and the current reversal is controlled by programming the PLC board.At the same time,alter the reversal time can make the deflection cycle of the small magnetic needle placed in the center of the device change,so as to achieve the effect of frequency modulation.When single-phase constant direct current is passed through the solenoid,the small magnetic needle does not rotate;when the biphasic rectangular pulse current is passed through,the small magnetic needle rotates 45°per each step.The rotation speed of magnetic field depends on the frequency of current commutation.The device not only avoids the shortcomings of traditional methods,but also has functions of both qualitative demonstration and quantitative measurement.It can be used as an experimental teaching instrument with excellent performance.