Three-Phase Busbar Current Transducer

A true three-phase 1000 A busbar current transducer is based on six micro-fluxgate sensors. Instead of using three independent single-phase current transducers, we use the full information from each sensor. Two TI DRV425 microfluxgate sensors are inserted into a hole drilled in each busbar. Our method of data processing is optimized to compensate the crosstalk between the three phases and external fields and gradients up to second order. The crosstalk error between the phases was 0.23% or smaller. The suppression of field from an external current at a distance of 10 cm is improved by a factor of 25 to 150. Our transducer has compact size, high temperature offset stability of 8.5 mA/°C, high current range up to 1000 A, low power consumption, and linearity of 0.1%. The results from a three-dimensional finite-element model and analytical computations confirm the measurements.

I. INTRODUCTION

Busbars are used for distribution of high currents inside racks and also at electrical switchyards and stations. Modern grids and electric drives require to measure currents in individual busbars [Mota 2015, Salman 2017]. With the use of transformerless inverters, the requirement for the current sensors is wide bandwidth including the dc component, which is generated during transients and due to nonsymmetry in switching times and switched-on resistances for both polarities [Buticchi 2009].