Magnetics Business & Technology - November/December 2019 - 17

FEATURE ARTICLE
ment side, it's about charge and discharge current management
in the middle. There are other applications like home appliances,
especially those with motors, like refrigerators and dishwashers.
Looking forward
So, overall, when it comes to power supplies, variable motor control inverters, uninterruptible power and electrical vehicles, AMR
sensors are often the best choice for applications involving power
transfer or motor control. Because of the construction and materials used, these sensors have an inherently high sensitivity, fast
response, and wide bandwidth. This makes AMR-based current
sensors the logical choice for advanced power management in
next generation power systems for a plethora of reasons.
To ensure high accuracy, the two AMR current sensors (green) measure the field from both current directions, essentially canceling out
external magnetic fields
curacy and bandwidth, it also enables a high step response which
is the ability of a sensor to rapidly react to changes in the magnetic
fields it is measuring. This high level of precision reduces phase
differences in the signal, and other artifacts of slow and inaccurate
measurements.
AMR sensor features
When it comes to power flow in applications like power supplies
in servers and telecom, where you have a front-end AC-DC PFC
converter feeding a DC-DC bus converter driving DC-DC Point-ofLoad converters on the board, an AMR sensor is the best choice.
Additional advantages of an AMR-based integrated single-chip
solution include a reduced offset voltage, the undesirable voltage representing the difference between the actual output and the
specified value under various conditions, affecting the accuracy of
the measurement. There is also less noise due to the high level of
integration, which can impact the accuracy of any system. A highly
accurate sensor can help optimize how much the processor is being used, especially for applications involving AI and the Cloud,
using power tracking for performance monitoring's sake.
Application advantages
Knowing how much energy each proxy server is using can help
determine whether there's still room for more power, so more
number crunching can be put into the system, or to determine if
it's already running at a limit. The other side of knowing how your
power is consumed is so you can charge your customer based
on how much processor time or processing power is being used.
Accurate current measurement can therefore empower (pun intended) system performance.
Beyond power supplies and data centers, there are a myriad of
other applications that can benefit from AMR sensing, like motor
drives and inverters. Inverter and motor drives are very similar
circuits, but instead of a motor at the end on the load, you get a
grid being connected with the inverters. Another application that
can benefit is in uninterruptible power supplies, from the front ACDC converter to the battery management to the final stage DC-AC
inverter and where it connects to the grid.
On the output side, you'll have a synthesis of the sine waves to
connect to the grid. On the power factor correction, if you use a
totem-pole type, an AMR sensor will give you a measurement of
the current, for the control and protection. On the battery manage-

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About the author: Khagendra Thapa is vice president of business development of Aceinna's current sensing business. He
holds a bachelor's degree in electronics and communication, a
master degree in power electronics from University of Birmingham
in UK and MBA from Manchester Business School in UK.

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Magnetics Business & Technology - November/December 2019

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