Insulated-gate Bipolar Transistor Power Modules Research Articles

Single PCB sensor-based output current reproduction for three-phase inverter systems

This study proposes a practical output current measurement system in a three-phase inverter with a single printed circuit board (PCB) Rogowski coil sensor inserted in the bus between the DC-link capacitor and the power semiconductor module. This system demonstrates its advantage over conventional output current sensors, such as the Hall effect current sensors, in terms of the size, weight, operation temperature and cost. The system can be applied to 6-in-1 power modules as it does not require sensors in the inverter phase legs.In our previous works, we have developed a method called “envelope tracking”, which is used in this system as well. This method traces the switching current instead of the output current to reproduce the output current signal in real-time. Envelope tracking successfully reproduced the output current waveform for single phase inverters under certain conditions. However, a large error is observed in the three-phase inverter demonstration under a high switching frequency (narrow pulse) or when the switching of different phases overlap each other. These errors must be completely suppressed to implement the system for feedback control in three-phase inverters.In this study, a new analog basis output current waveform reproduction system is introduced to suppress the above mentioned errors. This system is implemented in a three-phase insulated-gate bipolar transistor (IGBT) inverter and successfully reproduces the output current with a single PCB sensor inserted between a 6-in-1 IGBT power module and DC-link capacitor, operating under a switching frequency of 3.5–7.0 kHz and output current of 6 A with DC-link voltage of 150 V.

Thermal Performance Optimization of Integrated Microchannel Cooling Plate for IGBT Power Module.

In high-integration electronic components, the insulated-gate bipolar transistor (IGBT) power module has a high working temperature, which requires reasonable thermal analysis and a cooling process to improve the reliability of the IGBT module. This paper presents an investigation into the heat dissipation of the integrated microchannel cooling plate in the silicon carbide IGBT power module and reports the impact of the BL series micropump on the efficiency of the cooling plate. The IGBT power module was first simplified as an equivalent-mass block with a mass of 62.64 g, a volume of 15.27 cm3, a density of 4.10 g/cm3, and a specific heat capacity of 512.53 J/(kg·K), through an equivalent method. Then, the thermal performance of the microchannel cooling plate with a main channel and a secondary channel was analyzed and the design of experiment (DOE) method was used to provide three factors and three levels of orthogonal simulation experiments. The three factors included microchannel width, number of secondary inlets, and inlet diameter. The results show that the microchannel cooling plate significantly reduces the temperature of IGBT chips and, as the microchannel width, number of secondary inlets, and inlet diameter increase, the junction temperature of chips gradually decreases. The optimal structure of the cooling plate is a microchannel width of 0.58 mm, 13 secondary inlets, and an inlet diameter of 3.8 mm, and the chip-junction temperature of this structure is decreased from 677 °C to 77.7 °C. In addition, the BL series micropump was connected to the inlet of the cooling plate and the thermal performance of the microchannel cooling plate with a micropump was analyzed. The micropump increases the frictional resistance of fluid flow, resulting in an increase in chip-junction temperature to 110 °C. This work demonstrates the impact of micropumps on the heat dissipation of cooling plates and provides a foundation for the design of cooling plates for IGBT power modules.

Online Junction Temperature Measurement of Double-sided Cooling IGBT Power Module through On-state Voltage with High Current

The aim of this study is to achieve online monitoring of the junction temperature of double-sided-cooling insulated gate bipolar transistor (IGBT) power modules by using the on-state voltage under a high current to maximize the utilization of IGBT power chips. Online junction temperature measurement plays an important role in improving the reliability of the inverter with IGBT, increasing the power density of the motor controller of electric vehicles, and reducing the cost of electric vehicles.

FBG Head Size Influence on Localized On-Chip Thermal Measurement in IGBT Power Modules

This article studies the influence of fiber Bragg grating (FBG) head length on insulated gate bipolar transistor (IGBT) direct on-chip thermal sensing performance of FBG sensors. To this end, the surface of a commercial IGBT chip is thermally simulated and experimentally characterized. Uniform FBG sensors with three head sizes are then tested in two promising thermal sensing locations. The study has found that the large thermal gradients in this application create an additional constraint when using longer head lengths. A distortion in the reflected spectrum of the 5-mm FBG sensor is used to illustrate the underlying physical effect, which causes this limitation for IGBT junction temperature measurement. This additionally affects the length of head sizes providing accurate temperature readings of the IGBT surface hotspots, and significantly, this limit is location-dependent in a given IGBT geometry.

Design and Development of a Measurement System Dedicated to Estimate the Junction Temperature of Insulated Gate Bipolar Transistor Modules

The damage state estimation of an Insulated Gate Bipolar Transistor (IGBT) power module requires the measurement of the junction temperature (Tj) of the active region. However, the accurate measurement of the temperature Tj is not simple to achieve and several methods have been developed to improve the accuracy of Tj measurements. Some of the well-known methods include the use of thermo-sensitive electrical parameters (TSEP). Although the TSEP methods do not provide access to the thermal mapping of the IGBT surface, they have the advantage of not affecting the physical integrity of the module. This paper aims to present a reliable programmable measurement system dedicated to estimating with great accuracy the thermal performance of the IGBT power module on the microsecond scale using the TSEP method. The advantage of this system is to provide full control of the injection of the power current and allows quick measurements of the cooling curve just after the injection of the heating power in the chip. The junction temperature calculated from the TSEP was found to be equal to 97.5 °C, which was confirmed by using the thermal camera. The accuracy of the proposed technique was found to be less than 2%. A comparison with the thermal Resistor-Capacitor (RC) network model is also carried out in this work. Experimental results demonstrate that the designed system is high efficiency and can, therefore, be used by scientific researchers and industrial engineers for predictive maintenance to monitor the performance state of IGBT power modules, which will reduce the probability of its failure or degradation.

Separation and Validation of Bond-Wire and Solder Layer Failure Modes in IGBT Modules

Thermal stress of the power semiconductor is one of the most important indicators for the reliability assessment of power electronics-based power systems. The mapping of the Insulated-Gate Bipolar Transistor (IGBT) junction temperature is usually required to analyze the thermal stress and loss dissipation. However, it is difficult to identify inherent mechanisms of the bond-wire and solder layer failure modes in IGBT power modules. In order to solve the problem, an online method to identify inherent mechanisms of the bond-wire and solder layer failure modes in IGBT power modules is proposed. This method can separate the root causes of the bond-wire lift-off and solder layer fatigue by measuring the <small>on</small>-state voltage drop through a sinusoidal loading current based on an H-bridge circuit, together with its corresponding control and measurement. By comparing the on-state voltage drop at the intersection current and the peak current of the converter, the wear-out conditions of the IGBT power modules can be monitored in real-time with the determination of different failure modes. Finally, experimental results are presented in order to verify the effectiveness and feasibility of the proposed method.

Thermal Cycling in Converter IGBT Modules with Different Cooling Systems in Pitch- and Active Stall-Controlled Tidal Turbines

This paper compares active and passive cooling systems in tidal turbine power electronic converters. The comparison is based on the lifetime of the IGBT (insulated gate bipolar transistor) power modules, calculated from the accumulated fatigue due to thermal cycling. The lifetime analysis accounts for the influence of site conditions, namely turbulence and surface waves. Results indicate that active cooling results in a significant improvement in IGBT lifetime over passive cooling. However, since passive cooling systems are inherently more reliable than active systems, passive systems can present a better solution overall, provided adequate lifetime values are achieved. On another note, the influence of pitch control and active speed stall control on the IGBT lifetime was also investigated. It is shown that the IGBT modules in pitch-controlled turbines are likely to have longer lifetimes than their counterparts in active stall-controlled turbines for the same power rating. Overall, it is demonstrated that passive cooling systems can provide adequate cooling in tidal turbine converters to last longer than the typical lifetime of tidal turbines (&gt;25 years), both for pitch-controlled and active speed stall-controlled turbines.

High-Voltage Hybrid IGBT Power Modules for Miniaturization of Rolling Stock Traction Inverters

A type of 3.3-kV/450-A half-bridge insulated-gate bipolar transistor power module combining the silicon (Si) and silicon carbide (SiC) technologies has been developed and reported in this article, for the miniaturization of the Chinese high-speed railway rolling stock traction inverters. This module is developed by integrating the next-generation industrial standard high-voltage packaging topology and the state-of-the-art 3.3 kV wide bandgap semiconductor chip technology, to reduce the waste power dissipation during operation, which in turn can lead to effective downsizing of key components in the traction inverter design. The module layout characteristics and the SiC Schottky barrier diodes design for substitution of the conventional Si fast recovery diodes will be described in detail. The mechanical, thermal, and electrical performances of the hybrid module are compared comprehensively with the Si-based counterpart. Based on the experimental results, an inverter system level evaluation of both modules is also conducted by electro-thermal simulation. The hybrid module shows advantages in loss reduction leading to great potential of system miniaturization, which is a cost effective solution for massive upgrading of the existing high-speed train traction inverters.

Direct Phase-Change Cooling of Vapor Chamber Integrated With IGBT Power Electronic Module for Automotive Application

In electric vehicles and hybrid electric vehicles, insulated-gate bipolar transistor (IGBT) power module trends to dissipate higher heat flux due to increased power rating and reduced package size. An inefficient cooling method will result in stringent thermal reliability problems. Therefore, there is a strong need for innovative and efficient cooling technologies in order to tackle these issues. In this article, a localized direct phase-change cooling strategy is applied and integrated with direct bonded copper in IGBT power module. Vapor chamber with light weight, high thermal conductivity, and even temperature uniformity replaces original copper baseplate. Layers of thermal grease and original cooling plate are removed, leading to a further reduction in thermal resistance. In order to evaluate the new module, a thermal model and an experiment were built to analyze temperature distribution in layers, junction temperature, temperature uniformity, and thermal resistance. Results indicate the integrated thermal management system outperforms traditional cooling solutions on the cooling capacity. Improvements on junction temperature, temperature uniformity, and total thermal resistance are 34.6%, 76.6%, and 41.6%, respectively. The results illustrate the potential of phase-change cooling by vapor chamber. It provides a new perspective in the compact and efficient design of power electric modules.

Expert System-Based EMI Modeling Method for IGBT in Electric Drive System of EV

In the working process of the electric drive system, the transient, high-amplitude, high-frequency voltage and current generated by the turn-on and turn-off of the IGBT (Insulated Gate Bipolar Transistor) are the most important sources of electromagnetic interference in EVs (electric vehicles). To this end, this paper proposes an EMI (Electromagnetic interference) modeling method for IGBT power modules of electric drive systems, which can realize accurate simulation of EMI source characteristics. First, an expert system based on IGBT model library is proposed. Then the expert system is used to simulate the characteristic curves provided in the IGBT module datasheet and extract the key parameters. Based on the expert system, an IGBT behavioral model is established, and a double-pulse simulation circuit is built to evaluate the simulation waveforms of the collector-emitter voltage, gate-emitter voltage and collector current during the two pulse switching periods. At the same time, measure the collector-emitter voltage, gate-emitter voltage and collector current test waveforms collected in the above simulation test on the built double-pulse test circuit, and compare the turn-on and turn-off processes of the simulation and test respectively to evaluate the accuracy of the EMI source model. Finally, to further test the universality of the model, the IGBT behavior model and the double pulse simulation circuit are established on the Simulink platform, and the accuracy of the model is evaluated by comparing with the test waveform. The comparative analysis results show that the proposed EMI source modeling method for IGBT power module has good versatility and accuracy.

Electric field enhancement control in active junction of IGBT power module

Dielectric liquids are incompressible, able to fill voids and have selfhealing effect and hence are being considered as alternative encapsulation materials to establish power electronics at ambient high pressure at subsea conditions. In a long-term endurance test, insulated-gate bipolar transistor (IGBT) chips subjected to 6.5 kV DC stress in dielectric oil environment was reported to have failed after less than one week in operation. A critical look at the failed objects revealed contamination fibres at the surface and around the high field regions. This paper presents the numerical simulation of field distribution around a conducting fibre at the surface of the IGBT chip. It also evaluates the influence of the nature of the encapsulation material on the integrity of power electronic modules using a long-term experiment at a medium elevated temperature for high and low relative humidity operated close to service load using IGBT relevant chips. Finite element method (FEM) calculations show how the high field region can be shielded from impurities that can easily trigger partial discharge (PD) and breakdown. The simulation suggests that coating the surface of the module with a thin polymer layer with a thickness of 20 μm or more could be sufficient to improve the reliability of the encapsulation system. Additional polymer coat with thickness 27 μm on the chip made the system survive without failure for 67 weeks under test and dry operating condition. Meanwhile, thick coating such as silicone gel protected the object longer under higher relative humidity.

Understanding Turn-On Transients of SiC High-Power Modules: Drain-Source Voltage Plateau Characteristics

The SiC (silicon carbide) high-power module has great potential to replace the IGBT (insulated gate bipolar transistor) power module in high-frequency and high-power applications, due to the superior properties of fast switching and low power loss, however, when the SiC high-power module operates under inappropriate conditions, the advantages of the SiC high-power module will be probably eliminated. In this paper, four kinds of SiC high-power modules are fabricated to investigate fast switching performance. The variations in characteristics of drain-source voltage at turn-on transient under the combined conditions of multiple factors are studied. A characteristic of voltage plateau is observed from the drain-source voltage waveform at turn-on transient in the experiments, and the characteristic is reproduced by simulation. The mechanism behind the voltage plateau is studied, and it is revealed that the characteristic of drain-source voltage plateau is a reflection of the miller plateau effect of gate-source voltage on drain-source voltage under the combined conditions of fast turn-on speed and low DC bus voltage, while the different values of drain-source voltage plateau are attributed to the discrepancy of structure between upper-side and lower-side in the corresponding partial path of the drain circuit loop inside the module, with the standard 62 mm package outline.

Lifetime Analysis of IGBT Power Modules in Passively Cooled Tidal Turbine Converters

Thermal cycling is one of the major reasons for failure in power electronic converters. For submerged tidal turbine converters investigating this failure mode is critical in improving the reliability, and minimizing the cost of energy from tidal turbines. This paper considers a submerged tidal turbine converter which is passively cooled by seawater, and where the turbine has fixed-pitch blades. In this respect, this study is different from similar studies on wind turbine converters, which are mostly cooled by active methods, and where turbines are mostly pitch controlled. The main goal is to quantify the impact of surface waves and turbulence in tidal stream velocity on the lifetime of the converter IGBT (insulated gate bipolar transistor) modules. The lifetime model of the IGBT modules is based on the accumulation of fatigue due to thermal cycling. Results indicate that turbulence and surface waves can have a significant impact on the lifetime of the IGBT modules. Furthermore, to accelerate the speed of the lifetime calculation, this paper uses a modified approach by dividing the thermal models into low and high frequency models. The final calculated lifetime values suggest that relying on passive cooling could be adequate for the tidal converters as far as thermal cycling is concerned.

Statistical Method of Estimating Semiconductor Switching Transition Time Enabling Condition Monitoring of Megawatt Converters

Detection of insulated-gate bipolar transistor (IGBT) switching transition time ( $t_{\text {tr}}$ ) is a promising temperature-sensitive electrical parameter (TSEP) for condition monitoring of IGBT power modules in converters for wind turbines. The accuracy required on $t_{\text {tr}}$ detection is in nanoseconds, which typically requires precision timing circuitry, or analog-to-digital converter (ADC) rates in hundreds of megasamples per second (MS/s). A method of calculating the statistically estimated switching transition time ( $\hat {t}_{\text {tr}}$ ) is proposed in this article. During multiple switching transitions of an IGBT, the IGBT collector–emitter voltage (vce) may be sampled with sample rates in sub-MS/s rates, yet with statistical accuracy on estimated $\hat {t}_{\text {tr}}$ in nanoseconds. A standalone converter monitoring unit (CMU), which samples vce and IGBT current ( $i_{c}$ ), was mounted in the converter of a multi-megawatt (MW) field test wind turbine. The proposed method is validated by testing it on field data from the CMU and by testing it on synthetically generated data. The proposed method is an enabler for low-cost monitoring of converters for wind-turbine field applications.

Trap characteristics and its temperature-dependence of silicone gel for encapsulation in IGBT power modules

Silicone gel is a prevailing material for encapsulation in insulated gate bipolar transistor (IGBT) power modules. The space charge transport behavior in silicone gel is significant to evaluate the electrical insulation characteristics. This paper focuses on the trap characteristics and electrical properties of the silicone gel, which were rarely studied before. The experiments are performed on the surface potential decay of silicone gel after the charge injection. Then, the energy distributions of electron or hole traps are determined by a double-trap energy level model, which can be fitted by the Gaussian distribution. In addition, the mobilities of positive and negative charges are determined, which are 1.38 × 10 −12 m 2 ·V −1· s −1 and 1.74 × 10 −12 m 2 ·V −1 ·s −1 , respectively. Furthermore, considering the heat as a byproduct resulting in thermal issues, the temperature-dependence of surface potential decay characteristics are also studied in this paper. When temperature rises, the decay rate of surface potential increases, especially when the temperature is higher than 80 °C. Finally, the contrastive analysis illustrates that the trap characteristics of silicone gel are between the trap characteristics in liquid-state material and solid-state material, which supports the phenomenon that silicone gel is more resistive to the sharp edges in power modules. This work can provide a useful reference for the design of encapsulation in high-voltage IGBT power modules.

Thermal mapping at the cell level of chips in power modules through the silicone gel using thermoreflectance

Silicone gel is used in power electronics in order to provide a chemical protection and dielectric insulation in insulated gate bipolar transistor (IGBT) power modules. This gel prevents the direct mapping of surface temperature measurements of the component by classical infrared means. The temperature maps inside IGBT modules are usually performed after removal of the silicone gel which does not allow their operation in real environment. In this paper, we explore the ability of thermoreflectance to overcome this limitation in measuring the temperature surface of an IGBT chip through the silicone gel. Thermoreflectance is a non-contact technique, which measures temperature variation through reflectivity variation measurement. Using a “mean” calibration coefficient determinates from optical fiber thermal measurements, thermal images of IGBT modules with and without silicone gel can be compared. Preliminary results indicate that thermoreflectance enables the measurement of surface temperature change on high power IGBT modules with silicone gel and temperature distribution is affected by the presence of the gel.

PSpice-COMSOL-Based 3-D Electrothermal–Mechanical Modeling of IGBT Power Module

The behavior of the insulated gate bipolar transistor (IGBT) module results in the electric field, temperature field, and stress field, and there are strong coupling effects among its electrical, temperature, and mechanical characteristics. Meanwhile, the packaging failure of IGBT module is also the interaction results of multi-physical fields coupling. In this article, a multi-physical fields transient modeling method based on PSpice and COMSOL is proposed. This method synthesizes the advantages of the physical model and the finite-element model. According to the time constants of different physical fields, continuous simulation analysis is carried out on different timescales. Through flexible multispeed simulation strategy, the dynamic characteristics of IGBT devices at different timescales can be accurately characterized. First, the electric-thermal–mechanical coupling mechanism of IGBT is described. Then, the electrical model and thermomechanical coupling model of IGBT are constructed in PSpice and COMSOL, respectively, and the multi-physical fields simulation in multi-timescale is realized through the control file of MATLAB script. The proposed modeling approach is verified by a short-circuit test of Starpower 1200-V/50-A IGBT module. Finally, an example of multi-time-scale simulation analysis under short-circuit condition is given, and the reasons for module failure under multi-field coupling effect are studied.

Prediction of IGBT power module remaining lifetime using the aging state approach

Insulated Gate Bipolar Transistor (IGBT) is the core power device in the fields of railways, new energy sources, and automobiles. The safe and reliable operation of IGBT is the basis to ensure the sustained and steady development of all walks of life. The junction-to-case thermal resistance of the IGBT power modules can manifest the fatigue degree of the solder layer. The saturation voltage drop manifests the aging degree of the IGBT bonding wire. Therefore, the IGBT reliability can be judged by a certain rule along with the external parameters such as the junction-to-case thermal resistance Rth and the saturation voltage drop Vce. In order to grasp this rule, this study illustrates the correlations between the external parameters of IGBT and the number of power cycles. As a result, the functional relationships between the average change rate of junction-to-case thermal resistance and the number of power cycles (ΔR¯th—n) as well as the average saturation voltage drop rate of change and the number of power cycles (ΔV¯ce—n) have been gained from IGBT test samples. After obtaining these functional relationships, for any IGBT of the same model in working condition, a proposition of judging the aging degree can be obtained. Here, the aging degree of the IGBT is represented by a real number in the interval [0, 1] and the reliability of the above proposition is calculated from the standard deviation of the working lifetime of each test sample. The method proposed in this study can not only be used to judge the aging degree of IGBT, but also to estimate the remaining lifetime.

EM-Electrothermal Analysis of Semiconductor Power Modules

We present in this paper an advanced electromagnetic (EM)-electrothermal analysis approach for the semiconductor power devices, with illustration on the insulated-gate bipolar transistor (IGBT) modules. This method distinguishes itself by dynamically integrating the EM domain into the circuit-type electrothermal coupling analysis, thus enabling the multi-dimensional simulation that spans in time from nanoseconds to seconds, and in space from chip level to system level. In particular, it contains a parametric-extracted electrothermal model of the IGBT chip and a comprehensive 0-D thermal network as well as an EM network extracted from the 3-D module packaging structure for each paralleling chip. The incorporation of the EM, as well as thermal networks representing the 3-D packaging structure, reveals essential information about the current imbalance, power dissipation imbalance, and thermal imbalance inside the IGBT module with paralleling chips, which have a strong influence on the module reliability. To demonstrate the application of this approach, an unfavorably designed 1700-V/450-A half-bridge IGBT power module is evaluated in the simulation circuit, with experimentally verified electrothermal IGBT chip model and thermal as well as EM networks. The results have shown that the EM-electrothermal analysis can successfully reveal the dynamic interaction among different physical domains and, thus, the current as well as temperature imbalance among the paralleling chips inside the power module. The predicted current imbalance also agrees with that from the experimental test.

Exploring the Electro-Thermal Parameters of Reliable Power Modules: Insulated Gate Bipolar Transistor Junction and Case Temperature

In the exploration of new energy sources and the search for a path to sustainable development the reliable operation of wind turbines is of great importance to the stability of power systems. To ensure the stable and reliable operation of the Insulated Gate Bipolar Transistor (IGBT) power module, in this work the influence of changes with aging of different electro-thermal parameters on the junction temperature and the case temperature was studied. Firstly, power thermal cycling tests were performed on the IGBT power module, and the I-V characteristic curve, switching loss and transient thermal impedance are recorded every 1000 power cycles, and then the electrical parameters (saturation voltage drop and switching loss) and the thermal parameters (junction-to-case thermal resistance) of the IGBT are obtained under different aging states. The obtained electro-thermal parameters are substituted into the established electro-thermal coupling model to obtain the junction temperature and the case temperature under different aging states. The degrees of influence of these electro-thermal parameters on the junction temperature and case temperature under different aging states are analyzed by the single variable method. The results show that the changes of the electro-thermal parameters under different aging states affects the junction temperature and the case temperature as follows: (1) Compared with other parameters, the transient thermal impedance has the greatest influence on the junction temperature, which is 60.1%. (2) Compared with other parameters, the switching loss has the greatest influence on the case temperature, which is 79.8%. The result provides a novel method for the junction temperature calculation model and lays a foundation for evaluating the aging state by using the case temperature, which has important theoretical and practical significance for the stable operation of power electronic systems.