Ultrafast Current Shunt (UFCS): A Gigahertz Bandwidth Ultra-Low-Inductance Current Sensor

Abstract

In an effort to reduce switching loss, increase switching frequencies and shrink passive component sizes, power device switching times are being pushed into nanosecond and sub-nanosecond intervals. However these fast switching times require high rates of change of current making the power devices susceptible to over-voltage damage from parasitic inductance in the power loop. This presents challenges in measuring the device switching current accurately and in turn makes accurate measurements of device switching energy and stored charge difficult. Traditional current measurement methods either do not have the required frequency response to view the switching edge accurately or have a high parasitic inductance that can significantly alter switching performance and cause damage to the power device. In this paper an active current measurement system is developed. This circuit achieves up to 1.6 GHz bandwidth with zero overshoot. By utilizing mutual inductance cancellation an insertion inductance down to 20 pH has been achieved. The research performed in this paper thereby allows for accurate measurement of device switching loss with minimal power circuit disturbance. The performance of this current measurement is experimentally verified in the frequency domain using a vector network analyzer (VNA) and time domain switching measurements are compared with state of the art current measurement.

Current Sensor Integration Issues with Wide-Bandgap Power Converters

“…In resistive methods (such as coaxial shunt), an ultra-high BW can be achieved (even up to a GHz [ 19 , 20 ]) by lowering parasitic inductance techniques. Their other advantages include simple passive circuitry (except the signal-conditioning part), small size, and cheap cost.…”

On performance evaluation of high‐power, high‐bandwidth current measurement technologies for SiC switching devices

“…Discrete SiC power MOSFETs are typically rated for currents of 5 A to 100 A [5][6][7][8][9]. Even at high voltage and current levels, the switching speed of SiC power MOSFETs reaches 10 kA∕μs and beyond [10][11][12], and more than 50 kV∕μs [5,[13][14][15]]. This highlights one major challenge in characterizing and operating SiC power MOSFETs, that is to accurately measure switched currents at both high amplitudes and fast transition speeds.…”

“…As a result of these issues, the research community has moved towards custom current sensors. These custom designs employ different measurement principles and achieve high measurement bandwidth at varying maximum measured currents [10][11][12][16][17][18]. While this work focuses on four particular commercially available current sensors, its methodology can be likewise applied to custom current sensors.…”

“…Discrete SiC power MOSFETs are typically rated for currents of $$5 \,\mathrm{A}$$ to $$100 \,\mathrm{A}$$ [5–9]. Even at high voltage and current levels, the switching speed of SiC power MOSFETs reaches $$10 \,\mathrm{k}\mathrm{A}/\umu\mathrm{s}$$ and beyond [10–12], and more than $$50 \,\mathrm{k}\mathrm{V}/\umu \mathrm{s}$$ [5, 13–15]. This highlights one major challenge in characterizing and operating SiC power MOSFETs, that is to accurately measure switched currents at both high amplitudes and fast transition speeds.…”

Research on Temperature Compensation of Shunt Type Current Sensor

“…High-precision current sensors are essential for current monitoring in aerospace, new energy vehicles, smart grids, and other fields. Shunt, as a way to measure direct current (DC), the working principle is simple, small size, low cost, no initial offset, having an ultrawide measurement range, and high reliability, so based on the current sensor designed by the shunt in the field of DC measurement is widely used [2][3] .…”