A Design Method of PCB Rogowski Coil in Limited Space and Modified Integral Circuit

Abstract

Compared with the traditional current transformer with magnetic core, Rogowski coil has more advantages, such as non-saturation, high measurement accuracy, wide measurement range, simple fabrication technique and low cost. In recent years, Rogowski coil become an extremely popular method of measuring current in power grid. Rogowski coil is widely used to measure three - phase current in circuit breaker space. However, Rogowski coil brings the problems of low mutual inductance and phase angle difference. Integral circuit can address the issue of phase angle difference. But Rogowski coil with low mutual inductance has low signal-to-noise ratio and vulnerable to interference from external magnetic field. The design of Rogowski coil with large mutual inductance and integral circuit is required. This paper theoretically analyzes how to design a PCB Rogowski coil with many turns and large mutual inductance in the limited space. A modified integral circuit with excellent amplification and integration is proposed. Although the PCB Rogowski coil designed in this paper only occupies 1.435cm3 in volume, the value of mutual inductance is 89nH. The output voltage of PCB Rogowski coil is 0.023mV/A. In the range of 50Hz-1kHz, the integration and amplification of the circuit is reliable. The amplitude of the integral circuit is 62.2dB at power frequency and the crosstalk coefficient of the PCB Rogowski coil is no more than 0.26%. The temperature drift of the modified integral circuit is less than 0.16% and has no influence on the measurements.