Wide Bandwidth Current Sensor Combining a Coreless Current Transformer and TMR Sensors

This paper presents a current sensor which is able to measure commutation currents in power electronic circuits. The current sensor consists of a coaxial housing, which has to be placed into the current carrying conductor, to achieve a low insertion inductance. A wide bandwidth is achieved by a combination of a coreless current transformer and tunnelmagnetoresistive (TMR) sensors. The TMR sensors measure the magnetic field inside of the current transformer. The output voltages of the TMR sensors are summed up with the output voltage of the transformer to achieve a bandwidth from DC up to several tens of megahertz. The sensor is designed for a current amplitude of 50 Ampere.