Insulated Gate Bipolar Transistor Modules Research Articles

On-Line Measurement of Chip Temperature Based on Blocking Leakage Current of the Insulated-Gate Bipolar Transistor Module in the High-Temperature Reverse-Bias Test

In high-temperature reverse-bias test of an insulated-gate bipolar transistor module, the problem of self-heating in chip resulting from power loss arises with high frequency. To address this problem, the law of the variation in leakage current with temperature for the reverse-bias state of a device is derived and utilized to establish a temperature calibration curve, with which the online measurement of the insulate-gate bipolar transistor module chip temperature can be implemented directly by real-time monitoring of device leakage current in high-temperature reverse-bias test. The method we proposed solves the problem of large measurement error in chip temperature obtained by traditional thermal resistance calculation method. In addition, real-time chip temperature can be monitored without introducing additional test circuit or HTRB interruption experiment. To demonstrate the effectiveness of the proposed method, the switching small-current temperature measurement method is used to make comparison, and the experiment result indicates that the temperature of the chip in the blocking test can be obtained with high precision by using the leakage current measurement method presented in this work.

Comparison of TSEP Performances Operating at Homogeneous and Inhomogeneous Temperature Distribution in Multichip IGBT Power Modules

Temperature sensitive electrical parameters (TSEPs) are used to determine the chip temperature of a single-chip insulated gate bipolar transistors (IGBT) power module by measuring one electrical device parameter. Commonly, most TSEPs have a linear relationship between the chip temperature and the electrical parameter. Like any sensor, preferred attributes of TSEPs include good accuracy, linearity, and sensitivity. For multichip IGBTs (mIGBTs) modules, these can only be achieved when all chips have the same temperature. Equal chip temperatures among different semiconductor chips can be achieved when placing mIGBTs in environmental chambers to produce a homogeneous temperature distribution (HTD). In real applications, however, mIGBTs are power cycled and are exposed to inhomogeneous temperature distribution (ITD) where temperature differences exist between chips. Consequently, measuring one electric parameter only cannot represent each chip temperature which impacts the TSEP sensitivity, linearity, and accuracy. This article compares the performance of ten TSEPs applied to an mIGBT module operating at HTD and ITD conditions in order to determine which TSEPs are most suitable for mIGBTs in real applications.

Prediction of Chip Solder Fatigue in IGBTs

Chip solder degradation is one of the main factors affecting the reliable operation of insulated gate bipolar transistor (IGBT) modules. However, there are still many challenges to get the real lifetime of chip solder. This paper proposes a lifetime consumption prediction method based on chip solder failure. First, the constant high junction temperature fluctuations are applied to IGBT modules for the power cycling tests. The transient thermal resistance is measured to monitor the degradation process of IGBT modules for every 1000 times of aging tests. And the failure degree of chip solder is analyzed by the integral structure function. With the help of scanning acoustic microscope, the failure analysis of aging modules is carried out. The finite element simulation model is established to analyze the transient thermomechanical characteristics of chip solder. Then, the influences of different power cycling conditions on the viscoplastic strain of chip solder are analyzed quantitatively. The average value of the viscoplastic strain increment is obtained by the integral method under large thermal loading. Meanwhile, the method is also applicable to the low thermal loading. Finally, a study case of IGBT modules in a 1.5 MW grid‐side wind power converter is given to demonstrate the validity of the proposed method. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Radiated disturbance characteristics of SiC MOSFET module

Wide band gap semiconductor device silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) have many advantages and are considered to be the most promising alternative to silicon (Si) insulated gate bipolar transistors (IGBTs) in low-/medium-voltage fields. However, a faster switching speed results in more serious electromagnetic disturbance problems in the application of SiC MOSFET. In this paper, an experiment system is established to measure the radiated disturbance of a single SiC MOSFET module operating at 9 kHz–300 MHz. The radiated electric fields of the SiC MOSFET module are mainly concentrated within 160 MHz. The switching voltage and radiated disturbance of the Si IGBT module are measured and compared with those of the SiC MOSFET module. The voltage of the SiC MOSFET has a faster change rate and a higher overshoot, which results in the radiated electric fields of SiC MOSFET module being 5–10 dB higher than those of the Si IGBT module below 8 MHz. The measurement results in the time-domain and frequency-domain correspond. A detailed model of a SiC MOSFET module is established and the radiated electric fields are calculated using the method of moments (MOM). The calculated results show the effectiveness of the model for radiated disturbance prediction. In this paper, the radiated electric fields of a SiC MOSFET module are measured and analyzed, and the calculation model can be used to further evaluate the radiated disturbance characteristics of SiC MOSFET and influencing factors.

Reconfiguration modulation strategy analysis for proactive adaptability of the monitored inverter to on-line monitoring system of IGBT modules

To realize on-line monitoring for insulated-gate bipolar transistor (IGBT) modules in the three-level neutral point clamped (NPC) inverters, a reconfiguration modulation strategy is proposed. The saturated voltage drop (VCE) is one of the most common diagnostic signs of IGBTs’ healthy status due to the advantages of monitoring method such as simple theory, mature implementation, and accurate measurement, and the method to extract VCE in the monitoring system has been researched in the previous study. On this basis, considering realizing on-line monitoring process, essential supported hardware and proactive on-line monitoring environment are needed to guarantee the safe and friendly on-line monitoring implementation. Analysis has been made to show that the on-line monitoring system is able to work regularly by just making use of the inherent O state of a three-level NPC inverter in some circumstances. But to guarantee the monitoring process and the safety of the monitored NPC inverter, the novel reconfiguration strategy is a kind of necessary and essential means to create an on-line monitoring environment, and it is proposed and researched in this paper. Through theoretical derivation, the optimization of reconfiguration strategy is obtained. The reconfiguration strategy proposed in this research has been achieved and its validity is proved based on experimental results.

Research on IGBT junction temperature model based on united-parameters

The insulated gate bipolar transistor (IGBT) is the most expensive central component in the converter interior, but it is also one of the most vulnerable to failure. The failure of power electronic system is mainly due to temperature change. Therefore, the accurate extraction of IGBT module junction temperature is the basis of life prediction and reliability evaluation of high-power power conversion equipment. There is a great advantage in the non-invasive process of obtaining junction temperature through the dynamic temperature sensitive electrical parameter method; However, the measurement results are easily interfered with by a single dynamic temperature sensitive electrical parameter method. In this paper, a high-precision IGBT online junction temperature model based on united-parameters is proposed. The single dynamic thermosensitive electrical parameter only considers the change of a certain capacitance or inductance, which leads to the inaccurate measurement. A large number of effective temperature sensitive electrical parameters can be added to the model in order to reduce other disturbances and improve the accuracy and reliability of junction temperature prediction. Firstly, the limitations of each temperature sensitive electrical parameter were determined by comparing the existing temperature sensitive parameter method. Secondly, the appropriate united-parameters can be determined by theoretical analysis and practical verification. Finally, a junction temperature extraction model based on united-parameters was established by multiple linear regression method. Compared with the single dynamic TSEP-junction temperature, the proposed method has advantages in on-line temperature extraction and high precision monitoring.

A bio-inspired, low pressure drop liquid cooling system for high-power IGBT modules for EV/HEV applications

Thermal management of high power density insulated gate bipolar transistors (IGBTs) using a low pumping power is crucial for the development of high-performance electric vehicles (EVs) and hybrid electric vehicles (HEVs). In the present work, the liquid cooling module inspired by a human respiratory system was developed to provide enhanced thermohydraulic performance. The suggested cooling module consists of a multiscale flow manifold connected to a metal foam layer bonded to the bottom substrate of IGBT module. The unique flow path uniformly distributes the coolant to multiple IGBTs with minimizing the required pumping power, while maximizing the heat exchange area. The porosity of the metal foam was determined considering the conflict between the conductive and convective heat flux. The developed cooling module was applied to the single IGBT module, including 6 IGBT/diode pairs generating 1.55 kW of heat. The proposed cooling module provided a low (0.2 K/W) thermal resistance using only ~2 kPa of the pressure drop that is approximately 10 and 100 times lower than that of previously reported turbulator and microchannel systems, respectively. Even when the number of IGBT/diode pairs is increased from 6 to 24 (single to quadruple IGBT modules), only ~8 kPa of the pressure drop was required, which shows the high scalability of the proposed solution. This work will help develop a compact, low pumping power cooling solution for high-performance EV/HEV applications.

A 3-D thermal network model for the temperature monitoring of thermal grease as interface material

In the cooling system of insulated gate bipolar transistor (IGBT) module, the reliability of thermal grease is of crucial importance in the heat dissipation of IGBT module. In order to study the influence of thermal grease, thermal interface material (TIM) between IGBT module and heat sink, on the junction temperature of IGBT module under long-term load profiles, a 3-D thermal network based on thermal grease temperature monitoring is proposed. Firstly, the finite element method (FEM) simulation model of IGBT module using thermal grease as TIM is established. Then, considering thermal coupling effect, the temperature distribution of thermal grease is obtained and the temperature monitoring points of thermal grease are determined in FEM simulation. Finally, a 3-D thermal network is established to monitor the temperature in all regions of thermal grease. The influence of thermal grease degradation on the junction temperature of IGBT module is analyzed and the temperature distribution of thermal grease under long-term load profiles is obtained. The proposed 3-D thermal network model based on the temperature monitoring of thermal grease can increase the accuracy of IGBT module reliability analysis.

Packaging reliability estimation of high-power device modules by utilizing silver sintering technology

A high-power packaging device composed of 600 V/450 A insulated gate bipolar transistor (IGBT) module is presented. Thermal dissipation is improved, and the temperature of junction declines after Ag paste sintering is applied instead of conventional soldering. A 100 μm-thick sintered Ag preform is utilized to assemble two IGBTs and two diodes on Al2O3 direct bonded copper (DBC) substrate during reflow in a vacuum oven. Three DBCs are attached on a copper baseplate to construct a power module. After a thermal cycling test is conducted for up to 2000 cycles, the die shear strength of the sintered Ag is as high as 24.8 MPa. Lowering the induced stress to fracture failure by using finite element simulation is carefully suggested. Furthermore, the measured thermal resistance is reduced by approximately 22%, and the noise during the electrical performance is eliminated by using Ag sintering. This research reveals the successful application of Ag paste sintering in 600 V/450 A IGBT module.

Thermal behaviour evolution of an IGBT module after aging measured by thermoreflectance

In this paper, we propose to study the thermal mapping evolution of the Insulated gate bipolar transistor (IGBT) emitter metallization after aging by thermoreflectance. Thermoreflectance measurements were done in static regime before and after aging by DC power cycling. The aim of this study is to observe the change in thermal behaviour at the cell level due to power cycling aging. Preliminary results indicate that a pixel-by-pixel calibration which takes into account the topography and chemical changes of the metallization is essential to eliminate artefacts in thermal images and to allow to follow metallization thermal evolution with aging.

Base solder voids identification of IGBT modules using case temperature

Solder voids has an important impact on healthy operation of insulated-gate bipolar transistor (IGBT) modules, but voids damage is difficult to be estimated accurately by conventional methods due to the lack of calculation in mutual thermal effect between chips. So this paper proposes a base solder voids identification method by using case temperature, takes into account both self-thermal diffusion and coupling inside module, and adopts case temperature distribution on bottom of baseplate to assess voids damage indirectly. Firstly, finite element method (FEM) of IGBT module with base solder voids was established to study junction and case temperature response with different voids distribution, the practicability of base solder voids identification based on case temperature is verified. Then the influence mechanism of voids on case temperature was discussed theoretically, voids identification is extended to dynamic load conditions, temperature-to-thermal resistance conversion and dynamic thermal resistance reference calibration with different power loss ratio were realized by improved thermal network, recursive least square (RLS) algorithm was designed for dynamic identification of real-time identifiable thermal resistance, the difference between RLS results and thermal resistance reference was compared to confirm the severity of base solder voids, two or more groups of comparison results with different power conditions are used to complete the voids analysis. Finally, validity of proposed method is demonstrated by simulation. Compared with conventional method, it shows better ability in dynamic identification.

Multi-Chip IGBT Module Failure Monitoring Based on Module Transconductance with Temperature Calibration

The Insulated Gate Bipolar Transistor (IGBT) is the component with the highest failure rate in power converters, and its reliability is a critical issue in power electronics. IGBT module failure is largely caused by solder layer fatigue or bond wires fall-off. This paper proposes a multi-chip IGBT module failure monitoring method based on the module transconductance, which can accurately monitor IGBT module chip failures and bond wire failures. The paper first introduces the failure mechanism and module structure of the multi-chip IGBT module; then, it proposes a reliability model based on the module transconductance and analyzes the relationship between chip failure, bond wire failure, and the transmission characteristic curve of the IGBT module. Finally, the module transconductance under chip failure and bond wire failure is measured and calculated through simulation, and the temperature is calibrated, which can eliminate the influence of temperature on health monitoring. The results show that the method has a high sensitivity to chip failures and bond wire failures, can realize the failure monitoring of multi-chip IGBT modules, and is of great significance for improving the reliability of power converters.

Numerical junction temperature calculation method for reliability evaluation of power semiconductors in power electronics converters

The junction temperature of power semiconductors is a critical parameter during reliability evaluation. The incorporation of long-term mission profiles, such as power loadings and ambient temperature, into lifetime and reliability evaluations of power semiconductors increases the computational burden. Thus, there is an urgent need for a more accurate method for junction temperature acquisition. Current methods for junction temperature calculation are computationally inefficient and do not comprehensively incorporate long-term factors into junction temperature calculation and power semiconductor reliability evaluation. Here, a junction temperature calculation method is proposed that enables reliability evaluation for insulated gate bipolar transistor (IGBT) power semiconductors. This approach calculates the IGBT module junction temperature on the basis of an electro-thermal analogy using Gauss–Seidel iteration. When compared with electrical–thermal simulation and other numerical calculation methods, the proposed method guarantees accuracy, while greatly reducing the computational time and load. A performance comparison between the proposed method, electro-thermal simulation based on a Fuji IGBT simulator, and experimental results was carried out using a three-phase DC/AC inverter as a case study.

A Transient 3-D Thermal Modeling Method for IGBT Modules Considering Uneven Power Losses and Cooling Conditions

Junction temperature is a key parameter for the safe operation of power semiconductor devices in power electronic systems. However, it is difficult to forecast the accurate thermal stress of the device in field use. Consequently, engineers tend to use higher rated devices to maintain excessive margin, resulting in a higher cost. In this article, a transient 3-D thermal modeling method for insulated gate bipolar transistor (IGBT) modules is proposed to obtain accurate temperature distribution considering uneven power losses and cooling conditions. The analytical model of uneven switching energy losses among the parallel IGBT chips in modules is built according to the analysis of device simulation results. The effect of uneven cooling conditions on temperature distribution in IGBT modules is considered by thermal-fluid cosimulation. Furthermore, a hybrid simulation strategy is proposed to obtain the transient thermal behavior in three dimensions. Through appropriate interface design, the power loss model is connected with the finite element model to achieve field-circuit cosimulation with multiple time steps, which takes full consideration of the multiphysical coupling effects among power loss, temperature, and flow fields. Finally, the thermal stresses of IGBT modules under different operating conditions are forecast by the proposed method.

Effect of Crack Evolution on the Resistance and Current Density of the Al Metallization in the IGBT Module During Power Cycling

This study quantifies the correlations between crack evolution and electrical performance degradation of the Al metallization in insulated gate bipolar transistor (IGBT) modules. The resistance of the Al metallization under different power cycling times was measured by the four-point probe method. The cracks that occur in the Al metallization were investigated by measuring crack geometric parameters, e.g., shape, geometric size and density. Simplified analytical models containing different crack geometric parameters were established by the finite element method (FEM). The influences of crack evolution on the resistance and current density of the Al metallization were quantitatively analyzed. The results indicate that the crack depth has the largest effect on the Al metallization resistance compared with the crack length and width. At the later stage of power cycling, increasing the crack depth plays a critical role in metallization resistance degradation. In addition, cracks affect the current flow direction and the maximum current density in the Al metallization. With increasing crack depth and length, the maximum current density in the crack vicinity increases continuously. However, increasing the crack width reduces the maximum current density.

Transient three-dimensional heat conduction in heterogeneous media: Integral transforms and single domain formulation

A hybrid numerical-analytical methodology based on integral transforms is employed for solving transient three-dimensional heat conduction problems in heterogeneous media comprising arbitrarily space variable thermophysical properties, including configurations with multiple subdomains of different materials and geometries. The Generalized Integral Transform Technique (GITT) is used to solve for both the temperature distribution and the corresponding eigenvalue problem accounting for the spatially variable coefficients. A previously introduced single domain reformulation strategy is adopted when multiple subdomains are involved, so as to rewrite the heat conduction equation in terms of coefficients with abrupt variations in the spatial coordinates. The hybrid numerical-analytical approach is demonstrated for three classes of problems in which the thermophysical properties undergo significant variations throughout the domain, such as: (i) FGMs (Functionally Graded Materials) with three-dimensional space variable thermophysical properties; (ii) composite medium with inclusions of different geometries and thermophysical properties; (iii) a multi-scale/multi-material heat conduction problem in a IGBT (Insulated Gate Bipolar Transistor) module. In each considered application, both the temperature eigenfunction expansions and the associated eigenvalue problem solutions are critically analyzed in terms of convergence rates and co-verified with purely numerical solutions.

Remaining Useful Life Prediction of an IGBT Module in Electric Vehicles Statistical Analysis

The whole life cycle of an insulated gate bipolar transistor (IGBT) is a kind of asymmetry process, while the whole life cycles of a set of IGBTs can be regarded as a symmetry process. Modelling these symmetry characteristics of the IGBT life cycles enables the improvement of the remaining useful life (RUL) prediction performance. For this purpose, based on the key failure mechanism of IGBT in electric vehicles, a new method for estimating the RUL of an IGBT module is proposed based on the two-stress acceleration synthesis environment of junction temperature and vibration. The maximum likelihood estimation (MLE) was employed to estimate the logarithmic standard deviation and covariance matrix. The Shapiro–Wilk (S–W) test was performed to investigate the satisfaction degree of the RUL of the IGBT module to the lognormal distribution. The accelerated life test datasets of the IGBT module were analyzed using the Weibull++ software. The analysis results demonstrate that the IGBT lifetime is confirmed to lognormal distribution, and the accelerated model accords with the generalized Eyring acceleration model. The proposed method can estimate IGBT RUL in a short time, which provides a certain technical reference for the reliability analysis of the IGBT module.

The Distributed Heat Source Modeling Method for the Finite Element Simulation of IGBTs

The determination of the heat source has a great influence on the results of the thermal simulation in the insulated gate bipolar transistor (IGBT) module. Different from the widely used uniform heat source model, a distributed heat source model consisting of a body heat source and two boundary heat sources is proposed in this article, which is based on the ON-state model of the IGBT module. Meanwhile, a novel parameter extraction method is developed only by using I-V characteristics. And the accuracy of the extraction method is verified by comparing the calculated package resistance with the measured package resistance. Finally, the proposed distributed heat source and the traditional uniform heat source under different situations are compared in thermal simulation. The results show that the proposed model can improve the accuracy of thermal simulation results, especially the transient results in a short time, and the model parameters can be easily extracted by the I-V characteristics from the product datasheet, which will help the model be more easily applied in practical applications.

Design and Analysis of the IGBT Heat Dissipation Structure Based on Computational Continuum Mechanics.

With the trend of high integration and high power of insulated gate bipolar transistor (IGBT) components, strict requirements have been placed on the heat dissipation capabilities of the IGBT devices. On the basis of traditional rectangular fins, this paper developed two new types of heat-dissipating fins to meet the high requirements of heat dissipation for the IGBT devices. One is the rectangular radiator with a groove length of 2.5 mm and a width of 0.85 mm, the other is the arc radiator with the angle of 125 arc angle, 0.8 mm arc height, and 1.4 mm circle radius. After theoretically calculating the IGBT junction temperature, numerical simulations have been implemented to verify the theoretical result. The commercial CFD software, STAR-CCM+, was employed to simulate the heat dissipation characteristics of the IGBT module under different wind speeds, power, and fin structures. By analyzing the temperature field and vector field of the IGBT module, the analysis results demonstrate that the error between the simulation result and the theoretical calculation is within 5%, which proves the feasibility of the newly designed heat-dissipating fins. When the wind speed is 12.5 m/s, the power is 110 W, the fin height is 31.2 mm, and the fin thickness is 2.3 mm, the rectangular radiator can achieve the best heat dissipation performance.

Least Squares Method for Identification of IGBT Thermal Impedance Networks Using Direct Temperature Measurements

State-of-the-art methods for determining thermal impedance networks for IGBT (Insulated Gate Bipolar Transistor) modules usually involves the establishment of the relationship between the measured transistor or diode voltage and temperature under homogenous temperature distribution across the IGBT module. The junction temperature is recomputed from the established voltage–temperature relationship and used in determining the thermal impedance network. This method requires accurate measurement of voltage drop across the transistors and diodes under specific designed heating and cooling profiles. Validation of the junction temperature is usually done using infrared camera or sensors placed close to the transistors or diodes (in some cases and open IGBT module) so that the measured temperature is as close to the junction as possible. In this paper, we propose an alternative method for determining the IGBT thermal impedance network using the principles of least squares. This method uses measured temperatures for defined heating and cooling cycles under different cooling conditions to determine the thermal impedance network. The results from the proposed method are compared with those obtained using state-of-the-art methods.