Improved Current Shunt Characterization Method for Core Loss Measurement

With the increasing switching frequencies and power densities in modern power converters, magnetic core losses are becoming more essential for efficiency and thermal optimization. Traditionally, the two-winding method suffers from sensitivity to phase error in practical measurements; this is mainly created by the unknown phase shift of a current-sensing resistor. Several methods have been developed to characterize the phase shift of a current shunt resistor; however, the load effects of oscilloscopes are ignored. As a result, the corresponding phase shift can he significantly underestimated. This article proposes an improved method for phase shift extraction of a current shunt to solve the problem. The effectiveness of the shunt characterization method is experimentally verified up to 50 MHz. Benefits from the proposed method, the time-consuming component tuning process is not required for core loss measurement. A measurement verification at 10 MHz shows its validity. Finally, a current shunt implemented with a coaxial resistor array is designed with a phase shift of 0.05 degrees at 10 MHz and a parasitic inductance as low as 42 pH.

Automated summary

This article discusses the importance of magnetic core losses for efficiency and thermal optimization in modern power converters, as well as the limitations of traditional two-winding methods. An improved method for phase shift extraction of a current shunt is proposed and experimentally verified up to 50 MHz. Utilizing this new method eliminates the need for time-consuming component tuning and results in a current shunt design with a phase shift of 0.05 degrees at 10 MHz and a low parasitic inductance of 42 pH.