用于旋转磁场标准装置的低频双路交流恒流源

A Low Frequency AC Constant Current Source for a Rotating Magnetic Field Standard Device

为产生稳定的旋转磁场,设计了一种频率、幅值及相位均可控双路交流恒流源。恒流源以STM32单片机为核心,通过信号发生器、增益放大器和恒流源电路设计,使得恒流源输出频率分辨率优于0.1 Hz,相位差分辨率优于0.1°;利用ADS1281对两路输出电流同步采样,并采用参数估计法拟合信号幅度,拟合结果结合PID控制器对电流进行动态调整,实现输出电流的闭环控制,测试结果表明:恒流源在0.1 mA～1 A范围内输出幅值分辨率为0.1 mA,电流输出相对误差优于5‰。

To produce stable rotating magnetic field,a dual channel AC constant current source with controllable frequency,amplitude and phase is designed.The core of the constant current source is STM32 single chip microcomputer.Through designing the signal generator,gain amplifier and constant current source circuit,the output frequency resolution of the constant current source is better than 0.1 Hz,and the phase difference resolution is better than 0.1°;Two output currents are simultaneously sampled by ADS1281 and the signal amplitude is fitted using the parameter estimation method.The result of the fitting is combined with the PID controller to dynamically adjust the current to realize the closed-loop control of the output current.The test result shows that the constant current source is output in the range of 0.1 mA^1 A.The amplitude resolution is 0.1 mA and the current output relative error is better than 5‰.