Press-pack IGBT Devices Research Articles

The influence of external conditions on the physical characteristics of Press-Pack IGBTs

In order to solve the problem of unclear factors affecting the physical characteristics of Press-Pack IGBT devices, this paper explores the influence characteristics of the two main external conditions of fixture pressure and heat dissipation capacity on the physical parameters of Press-Pack IGBTs by building IGBT models with different chip structure layout considering various physical characteristics of materials. The results show that the effect of fixture pressure on the stress characteristics of the device is more obvious than the heat dissipation ability of the device, and the water-cooling heat flux has more influence on the electrical-thermal characteristics of the device. The research results provide a reference for the external conditions and structure selection of Press-Pack IGBTs.

Lifetime prediction for press pack IGBT device by considering fretting wear failure

The reliability of the Press-Pack Insulated Gate Bipolar Transistor (PP-IGBT) device is important to guarantee the safety of modular multilevel converter (MMC). The fretting wear failure is the typical failure mode of long-time operation in the PP-IGBT device. However, the traditional fretting wear lifetime model of the PP-IGBT device only considers the fretting wear failure of the IGBT chip, which is difficult to accurately predict the reliability of the PP-IGBT device. The influence of fretting wear failure of all layers on the device's lifetime is ignored. This paper proposes a lifetime model of the PP-IGBT device by considering the fretting wear failure of all layers using the fault tree method. First, a finite element (FE) model of the PP-IGBT device is established by considering the multi-physics coupling, and the contact surface roughness change of each layer is obtained by power cycling simulation. Then, based on fretting wear failure and Basquin law, the lifetime of each layer is obtained, and a fault tree method is established to build the fretting wear lifetime model of the PP-IGBT device by considering the fretting wear failure of all layers. Finally, the power cycling experiment of the PP-IGBT device is established, and the experiment results are used to verify the effectiveness of the proposed lifetime model. The results show that the relative error between the proposed lifetime model and the experimental results is nearly 5 %.

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

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%.

Performance limits of high voltage press-pack SiC IGBT and SiC MOSFET devices

Considering the switching frequency limit and electromagnetic interference, the selection of high voltage SiC IGBT and SiC MOSFET is confusing due to punch-through effect and bipolar characteristics of SiC IGBT. The thermal resistance, static characteristics and dynamic characteristics of SiC IGBT and SiC MOSFET module with Press-Pack packaging are measured to evaluate the switching frequency limit and electromagnetic interfere of them. The tradeoffs of SiC IGBT between switching frequency limit and electromagnetic interfere are less attractive due to the intrinsic characteristics, such as high power loss and punch-through effect. The possible solutions for SiC IGBT are proposed based on the improvement of driving resistor and driving voltage.

Thermal Contact Resistance Optimization of Press-Pack IGBT Device Based on Liquid Metal Thermal Interface Material

Thermal contact resistances usually account for more than 50% of the total thermal resistance in a press-pack insulated-gate bipolar transistor (PP-IGBT) device, which affect the heat dissipation of the PP-IGBT device and lead to a high junction temperature. In this article, a method for optimizing the thermal contact resistances of the PP-IGBT device is proposed by filling the liquid metal thermal interface materials in the contact surface. Bismuth-based liquid metal with high thermal conductivity and electrical conductivity is chosen, and the material is used for filling between the insulated-gate bipolar transistor chip and the molybdenum layers. The thermal characteristics are compared with the traditional commercial PP-IGBT device using finite-element simulation and experimental methods. The high-voltage insulation reliability of the proposed optimized method is verified by blocking voltage test, and the long-term reliability of the device is verified by a power cycling test. The results show that the junction-to-case thermal resistance of the optimized PP-IGBT device can be reduced by more than 30%, which is helpful for improving the thermal reliability of large-capacity PP-IGBT devices.

Modeling and Analysis on Overall Fatigue Failure Evolution of Press-Pack IGBT Device

Press-pack insulated-gate bipolar transistor (PP-IGBT) device is used in high-power modular multilevel converter high-voltage direct current (MMC-HVDC) system due to the advantages of high reliability and short-circuit failure. Considering safeties and stable operations, it is necessary to model and analyze the fatigue failure evolution of PP-IGBT device that improves the reliability of MMC-HVDC system. This paper proposes a method to analyze from fretting wear failure to short-circuit failure in PP-IGBT device. First, a multiphysics coupling model of a single-chip 3.3-kV/50-A PP-IGBT device is presented to analyze the fretting wear failure, and the weak layer and the fatigue effect are obtained by power cycling simulation. Second, considering the Al-Si diffusion reaction mechanism on the interface of IGBT chip, the short-circuit failure is investigated by the finite-element method model of PP-IGBT device with Al-Si osmotic hole, and the changing trend of characteristic parameters is estimated during short-circuit failure process. Finally, the steady state, power cycling, and short-circuit tests are used to verify the multiphysics coupling model, fretting wear failure, and short-circuit failure. The experiment indicates that the fatigue failure evolution of PP-IGBT device occurs from fretting wear failure to short-circuit failure, and it suggests that the proposed method can be applied to optimize design and condition monitoring of PP-IGBT device.

Study of pressure balance for Press-Pack IGBTs and its influence on temperature distribution

Pressure balance is a key technology for Press-Pack IGBT packaging, and is studied in this paper with its influence on the temperature distribution discussed in further when the device is turned on. By establishing the physical model of the Press-Pack IGBT device in the finite element simulation software, the influence of the internal flatness condition on the pressure balance is analyzed, and the variation of the average pressure difference with the flatness in different parallel scale of the chips is obtained. The thermal contact resistance and the electrical contact resistance parameters, which are dependent on the pressure, are then imported to perform the multi-field coupling, further investigating the effect of different pressure distributions on temperature distribution. The junction-case thermal resistance of the device with different flatness is compared experimentally. The results have demonstrated the influence of the flatness on the thermal resistance of the Press-Pack IGBT device.