A Method to Design Open Loop Current Transducers for Busbar Applications

Non-contact current measurements are largely required in the context of smart grid applications, in which the flexibility, reduced size and low cost play a fundamental role. In this field, the current transducers based on magnetic field sensors has attracted the attention of many research activities. Several methods were proposed in literature to overcome the skin effect impact on the accuracy of this type of current transducers and to increase the immunity from the external magnetic fields, especially for rectangular conductors (e.g. flat busbars), characterized by a non-uniform distribution of the magnetic field with the frequency. In this context, this paper suggests a methodology to design a current transducer based on magnetic field sensors that identifies the best positioning of the magnetic sensors to achieve the required accuracy. The method is able to guarantee the accuracy in the full required frequency bandwidth and it can release the usage of the current transducer from the conductor geometry. The main idea of this methodology consists of calculating a linear combination of the magnetic sensors measurements, ensuring the linearity of the current transducer. The linear coefficients of this linear combination are optimized in the methodology to minimize the current measurement error related to the frequency.