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Image of Allegro Microsystems Magnetic High-Current Sensors - Using Core-Based Solutions

Among the biggest challenges that arise when the currents are getting high (>200A), are that any small impedance can lead to a lot of power loss as well as unwanted heat generation that is causing many side problems, like measurement errors, or accelerated aging. Usually, having a high current flowing through a relatively high impedance means investing in expensive cooling mechanisms to limit the effects this could have on the system. Furthermore, having no mechanical connection between the two circuit domains improves the reliability of the whole solution, providing better long-term term performance without maintenance. Another element to take into account is that these high currents can damage the electronics used for monitoring as well as pose risks to the life. So, the isolation aspect is an important safety feature in favor of using a galvanically isolated magnetic sensor. In order to get an accurate measurement of the current flowing through a wire/busbar, there needs to be a good magnetic coupling between the high power application and the sensing/controlling part of the system. That is why the most common technique is based on sensing high currents via a magnetic core surrounding the conductor. It is called a “concentrator” as it allows to pick up the magnetic field flowing in a conductor and concentrate it towards the sensor. With the right dimensions, the magnetic field (H) in the air gap is perfectly proportional to the input current (I) in the busbar or current conducting wire.

PTM Published on: 2021-02-18