Experimental Investigations on Current Sharing Characteristics of Parallel Chips Inside Press-Pack IGBT Devices

Abstract

Press-pack insulated gate bipolar transistor (IGBT) devices have multiple chips paralleled to enhance their power density. However, the current imbalance among chips limits the increase of the power, which is mainly attributed to external factors, like stray inductance, temperature, and mechanical pressure. Besides, for the difficulties in decoupling multiple external factors, the current imbalance in press-pack IGBT devices has been extensively studied by simulation, and lack of experimental investigations. In this article, a multifactor decoupling experimental approach for the current sharing characteristics is proposed. The stray inductance, temperature, and mechanical pressure of the two parallel branches can be adjusted independently for investigating chips’ current sharing. Then, the experimental platform for the parallel 3.3 kV/50 A IGBT chips under differentiated external factors is implemented. Measured results show that the stray inductance affects the transient current sharing during turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> greatly, and the maximum current imbalance can reach 25.46%. The temperature mainly affects the steady state and the maximum current imbalance is 11.7%. Otherwise, mechanical pressure is negligible on the steady and transient current imbalances, which are less than 3%. Finally, the influence mechanisms of the external factors are proposed to explain the current sharing characteristics of parallel chips.