一种用于低频漏磁检测的交流恒流激励源

摘要

Design scheme based on current closed loop feedback control and linear high power amplifier is proposed.The system adopts the PID control algorithm,and uses the current sampling value as the feedback quantity to form the closed loop feedback control.By adjusting the output voltage of the amplitude control unit dynamically,the closed-loop regulation of the output current is realized.A linear high power amplifier and a differential output structure are used to design a power amplifier unit,which effectively improves the amplitude and linearity of the output voltage.By using the least square method to correct the output current,the constant current regulation precision of the excitation source is effectively raised.Finally,the low frequency magnetic flux leakage test is carried out by using the constant current source.The experimental results show that the constant current source has the advantages of stable output,high regulation accuracy and good linearity.The constant current source is used as the excitation source to overcome the change of the exciting current caused by the change of excitation frequency,lift off value,coil heating and environment,so as to ensure the stability of the exciting magnetic field.Therefore,the detection accuracy and stability can be effectively improved.%提出了一种基于电流闭环反馈控制和线性大功率放大器的恒流源设计方案.该系统采用增量型PID控制算法,以输出电流采样值为反馈量形成闭环反馈控制,通过动态调节幅度控制单元输出电压,实现对输出电流的闭环调节.选用线性大功率放大器,并采用双运放差分放大方式设计了功率放大单元,有效提升了输出电压幅度和线性度.采用最小二乘法修正了输出电流,恒流源输出精度获得了提升.利用所研制恒流源开展了低频漏磁检测实验研究.实验结果表明:该恒流源输出稳定,调节精度高,线性度好,以其作为低频交流漏磁检测激励源,有效避免了因激励信号频率、提离值发生变化和线圈自身发热等因素所造成的激励电流改变,保证了激励磁场的稳定,可有效提高低频漏磁检测精度和稳定性.