Current Measurement Method of Multiple Chips Using Rectangular PCB Rogowski Coils Integrated in Press Pack IGBT Device

Abstract

Unbalance of transient currents of multiple chips inside press-pack insulated-gate bipolar transistor (PP IGBT) results in degrading operation and even device damage. Chip currents measurement plays an essential role to understand and solve this problem. Printed-circuit board Rogowski coil (PCB RC), as a small, noninvasive, and high bandwidth current sensor, is very suitable for this application. However, PCB RC integrated with multiple Rogowski coils (RCs) is still difficult to be applied to measure the current of multiple chips in press pack IGBT device because of the low measurement accuracy due to the large interference. In this letter, a high accuracy PCB RC with ten rectangular RCs inside PP IGBT is proposed to measure ten chip currents at the same time. Different from single RC measuring single chip current, the interference of adjacent chip currents has to be considered, and is reduced to 0.6% by optimizing the turns arrangement and lead wires of RCs. The noise of cross talk of adjacent RCs is 1.7% by decreasing the capacitance coupling between RCs. Shielding layers and grounding patter of lead wires for ten RCs are proposed to eliminate the interference of collector voltage. The experiment of transient process of ten chips verifies the effectiveness of proposed PCB RC, and measurement error is only 1.8%.