直流电流比较仪闭环传递特性的理论研究与试验验证

Theoretical research and experimental verification on the closed-loop transfer characteristic of DC current comparator

为分析直流电流比较仪的稳态误差,从其结构原理入手,结合现代控制理论,推导直流电流比例相对误差理论值公式。解析直流电流比较仪各部分的传递函数,合成闭环传递特性函数。采用奈奎斯特稳定性判据判定了系统稳定,在仿真软件中建立闭环传递特性模型,以单位安匝数值为例,对仿真结果进行分析。结果表明,一次侧有信号后,二次侧迅速追踪并平稳输出,无明显的过冲、振荡等过渡现象发生,符合直流电流比较仪的工作原理;直流电流比例的稳态误差为2.5×10^(-8)。实际绕制一台1A∶1A的直流电流比较仪,试验后得到全量程实际误差为5×10^(-8)~9×10^(-8),与理论值一致,满足预期设计要求。

To analyze the steady-state error of DC current comparator(DCC),starting with the structure and principle of DCC,combining with modern control theory,theoretical value formula of relative error of DC current ratio is derived.Each part of transfer function is resolved and then the closed-loop transfer function is compounded.Nyquist stability criterion is employed to judge the system stability;the closed-loop transfer characteristic simulation model is established;taking unit ampere turn value as example,the simulation result is analyzed.The results showed that the secondary side fast track the primary side signal and output signal smoothly,without obvious transition appearance such as overshoot and oscillation,according with the principle of DCC.The steady-state error of DC current ratio is 2.5×10^(-8).Winding a DCC with the ratio of 1 A∶1 A,its full range actual error is 5×10^(-8) to 9×10^(-8),consisting with the derived theoretical value,meeting the expected design requirements.