Managing Pulse Top Decay Improves Accuracy Of Current Sensing Circuits
by Gregory Mirsky, Continental Automotive Systems, Deer Park, Ill., How2Power Today, Nov 15 2018
Focus:
When a current transformer senses current in switched-mode power supplies and other
applications, the current transformer and the associated burden resistor can alter the shape of
the switching waveform as seen by the current sensing circuit. This change in the shape of the
switching pulse can be described as pulse top decay and it degrades the accuracy of the current
sense signal. This article quantifies the effect of the current sensing circuit on the pulse
decay, providing guidance on how to properly determine the value of the burden resistor. This
article also aims to show that the secondary side of a current transformer should provide the
inductance energy discharge through a controllable voltage limiter, which ensures the zero
volt-second integral of the current transformer.
What you’ll learn:
- How to improve accuracy of current-sensing circuits using current transformers
- How to understand the effect of the current transformer and burden resistor on the sensed switching waveform in current-sensing circuits
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