基于Modbus/TCP的数字式电流互感器设计

Design of digital current transformer based on Modbus/TCP

设计了一种带温度补偿和可通信功能的数字式电流互感器。该数字式互感器以STM32F103芯片为核心,利用霍尔电流传感器ACS712采集交流电流信号,经STM32F103模数转换和真有效值计算处理,并进行Modbus/TCP数据封装,通过工业以太网传给上位机,实现了数字式电流互感器与上位机之间的通信。由于温度是影响ACS712测量精度的最主要因素,所以采用插值法对数字式电流互感器进行温度补偿,消除了温度对霍尔电流传感器测量精度的影响。实验表明,所设计的数字式电流互感器具有可通信、精度高、性能稳定等优点。

This paper proposes a design of communication-capable digital current transformer with the function of temperature compensation. The digital current transformer adopts an STM32F103 microchip as the microprocessor. An ACS712 Hall current sen- sor is used to capture alternating current signal. The captured signal is digitalized by the A/D convertor of the processor and the RMS values of the signal are calculated. The data is encapsulated according to the Modbus/TCP protocol, and then transferred to a host computer via an industrial Ethernet network. This design realizes the communication between a host computer and a digital cur- rent transformer. ACS712 sensors need temperature compensation because the main factor determining measurement accuracy is tem- perature disturbance. In order to eliminate the influence of temperature on the Hall current sensor, an interpolation method is pro- posed to achieve temperature compensation for the digital current transformer. Experiments indicate that the digital current trans- former is characterized by communication, stability and high precision.