Co-axial current transformer for test and characterization of high power semiconductor devices under hard and soft-switching

Abstract

Abstract-The use of a coaxial current transformer (CCT) is an interesting choice for pulsed measurement of current through power devices during switching transients. The CCT is used to reflect current for convenient external measurement with minimal insertion impedance in the critical power circuit. This paper analyzes the characteristics of the CCT and explains how it can be integrated into test setups for both press-pack and module packages. Finite-element techniques are applied to the study of the CCT to obtain detailed electrical and magnetic characteristics. Current distribution in the primary and secondary circuits, flux densities, and insertion inductance and resistance are among the design information that can be obtained through finite-element analysis. Analytical and numerical results are obtained for the proposed CCT that is integrated in test setups for MOS turn-off thyristors (press-pack) and high-voltage insulated gate bipolar transistors (module) characterization.

Reduction of DC-Bus Capacitor Ripple Current With PAM/PWM Converter

“…It can be seen that sinusoidal segments match up reasonable well in the sets of waveforms. The measured waveform for was captured with a low insertion impedance coaxial current transformer put in the output dc-link current path [9]. The inverted ac coupled waveform is shown on the oscilloscope trace after digital filtering (80-kHz bandwidth) to remove the high frequency current spikes.…”

“…Using the capacitor current harmonic components from (6) the power loss is calculated by (9) The dissipative losses were calculated for each set of harmonics produced from the ripple current calculation. Thus the full rated range of speed and load for the 10-hp induction machine was covered.…”