IGBT Modules Research Articles

A novel modular power converter for SRM drive

In this paper, a novel modular power converter for four-phase switched reluctance motor (SRM) is proposed. Firstly, a converter with motor phases grouped in pairs which share one common converter phase is introduced. This discrete-type converter is equivalent to the asymmetrical half-bridge converter (AHBC) in terms of the number of semiconductor components and functionality. The common converter phase concept enables modularization using two standard, commercially available six-pack IGBT modules, thus simplifying mass production. Compared to existing modular topologies, the proposed modular converter has the advantage of enabling an overlap of current pulses, which is a key feature for the SRM performance at elevated speeds while retaining a minimal number of standard power switch modules. In addition, owing to inherent operating regimes, the proposed modular converter enhances the motor performance over almost the entire range of the exploitation characteristics compared to AHBC and existing modular topologies. The advantages of the proposed modular topology were determined by means of finite element method (FEM) simulations. Experiments confirm the conclusions obtained from FEM analysis and verify the feasibility of the proposed modular converter.

In-situ health monitoring of IGBT modules of an on-line medium-voltage inverter system using for industrial Internet of Things

Requirements of the Internet of things for the network includes the ability to monitor the equipment and devices. Nowadays, the reliability of a power electronics converter has raised concerns of both academia and industry. In particular, power semiconductor devices are continuously exposed to excessive stress while being designed with high power handling capability and are considered as the most fragile component in power converters suffering from a high failure rate. Aiming to find an effective monitoring method which is also helpful for the Internet of Things and improve the reliability of a three-level neutral-point-clamped power inverter, an in-situ health monitoring method is proposed by harnessing the inverter operational characteristics and degradation sensitive electrical parameters to address the IGBT wire bonding faults. The zero voltage state provides an inherent redundant feature that allows for a power switch to be diagnosed during its normal operation in a neutral-point-clamped power inverter. The proposed prognostic approach obtains both the wire bonding failure features and junction temperature from the terminals of an IGBT module, which is regarded as non-invasive on-line health monitoring. The system performance can be affected by the designated testing point and testing window, which is discussed and experimentally validated. The proposed technique allows unhealthy wire bonding in IGBT modules online monitoring during the operational period of the inverter. And the proposed in-situ health monitoring of IGBT modules can be used for the industrial Internet of things.

IGBT Remaining Useful Life Prediction Based on Particle Filter With Fusing Precursor

The remaining useful life (RUL) prediction is essential for the IGBT module when setting a reasonable maintenance schedule and improving IGBT reliability by design. In this article, an RUL prediction method is proposed based on the particle filter (P.F.) algorithm with a multi-parameter precursor developed from the IGBT aging data. By fusing the junction temperature ( $T_{j}$ ) and collector-emitter on-voltage( $V_{CE(on)})$ , a new fault precursor is established to monitor IGBTs’ condition. A simplified aging model of the precursor is also developed based on a two-stage fitting. After input the historical aging data of the selected IGBT module, the RUL of IGBT can be predicted by the proposed fault precursor based on P.F. algorithm. According to the aging data collected from accelerated aging experiments, the performance of RUL prediction using the fusing precursor is superior to those with the single parameter precursor.

Junction Temperature Control System to Increase the Lifetime of IGBT-Power-Modules in Synchronous Motor Drives Without Affecting Torque and Speed

Load changes of electrical machines driven by inverters cause temperature swings of the semiconductor devices in IGBT modules of the inverters. These temperature swings lead to mechanical strain in the different material layers of the IGBT-power-modules and limit the numbers of cycles to failure and therefore reduce the lifetime of the IGBTs. This paper presents a temperature control system which is paralleled to the standard torque control system. It aims to reduce the magnitude of temperature swings of the semiconductor devices of IGBT modules caused by load changes of an interior permanent magnet synchronous machine. The principle method is, to increase the temperature of the semiconductor devices of the IGBT-modules by creating higher power losses during low load conditions of the machine without affecting torque and speed. This reduces the magnitude of the load induced temperature swings of the semiconductor devices of IGBT-modules and increases its lifetime at the cost of increased power losses. Three variables have been identified that influence the power losses in inverter modules without necessarily affecting the output power of the permanent synchronous machine. These variables are switching frequency of the inverter, length of the clamping area when a discontinuous modulation is applied and the reactive component of the inverter current. The influence of each variable which regards to the losses in the IGBT-power-modules is explained and the related control methodology is described. The analytic results are verified by experimental results obtained from a test set up.

Switching Performance of a 3.3-kV SiC Hybrid Power Module for Railcar Converters

The unique properties of a SiC hybrid 3.3-kV/450-A half-bridge IGBT power module which is designed for enhanced reliability of railcar converters are presented in this paper. The hybrid technique enabled by utilizing the state-of-the-art 3.3-kV SiC SBDs has shown impressive electrical performances during switching. The switching waveforms, switching time lengths, voltage overshooting, current overshooting and information contained therein have been exploited in detail, in comparison with the corresponding fully Si-based IGBT module as a control sample. The potential of reliability enhancement by this SiC hybrid concept at the rated voltage and current levels will provide essential benchmark for railcar converter designs.

Evaluation of Frequency and Temperature Dependence of Power Losses Difference in Parallel IGBTs

With the development of high power converters, safe operation of IGBT modules with parallel chips is of increasing importance. IGBT can work normally in safe range in the initial operation even if current imbalance is happening. However, if the uneven current state lasts too long, it is difficult to keep a uniform junction temperature, which can further lead to uneven distribution of the power losses. In severe cases, the device and converter may be damaged due to overheating. This paper studies the stability of such an interactive process with mathematical modelling backed by experiment. Because of the opposite sensitivities of switching and conduction losses to temperature under high current injection, the concept of `inflection point frequency characteristic' is introduced to evaluate the trend of junction temperature mismatches between the parallel IGBT chips. The inflection point frequency at different current and temperature levels is tested to verify the model prediction, and the applicability of this approach in multi-chip parallel module is discussed. By establishing the relationship between the switching frequency and the thermal stability limit of parallel IGBTs, it can provide a feasible reference for improving the reliability of multi-chip parallel power devices.

A Framework for Optimum Determination of LCL-Filter Parameters for N-Level Voltage Source Inverters Using Heuristic Approach

The use of voltage source multilevel inverters (VS-MLIs) has grown enormously over the last decade, and it is expected that these inverters will be deployed in future power grids (smart grids), especially for medium voltage–high power applications. This paper investigates the application of passive power filters (PPFs) for harmonic mitigation at the output of VS-MLIs for more efficient grid integration of renewable energy sources. It proposes a generic model, using a heuristic approach, for the optimum design of an LCL power filter at the output of VS-MLIs. The proposed model transforms the LCL filter design problem into an optimization problem and applies a genetic algorithm (GA) to solve it. The objective function to be optimized is a multi-objective function based on inverters’ total harmonic distortion and energy losses. The optimization problem is subject to applied design constraints. As a main optimization objective, a precise evaluation methodology for the inverter power losses is presented, which was built according to a practical switching device datasheet. The method is applicable to any VS-MLI topology and any number of levels (N). As a case study, the proposed design optimization approach was implemented to optimally design the LCL filter at the output of a grid connected 11 KV, 5 MVA 7-level cascaded H-bridge multilevel invert (CHB-MLI). The IGBT module Device IGBT of type FZ400R65KE3 by Infineon was used for simulation. MATLAB-SIMULINK is used for the modelling and simulation. We found that the proposed design approach is more generic, efficient, and simple to apply than conventional design approaches which requires more system detail, relies more on the designer’s experience, and normally does not results in optimum design. The proposed approach is generic and can be applied for different VS-MLIs topologies and for any number of levels (N).

Electro-thermal modelling and Tj estimation of wire-bonded IGBT power module with multi-chip switches subject to wire-bond lift-off

Wire-bonded multi-chip IGBT power modules constitute the heart of high-current power electronic motor drives. The most common failure mechanism is the degradation of the top-side wires. This deterioration impacts the electrical path and the individual dies’ temperature. The temperature is thus not only a stressor, but also a failure precursor. It is thus typically sensed in health monitoring methods based on damage-accumulation-models and failure precursors. One way to estimate the temperature is through the on-state voltage at low load current as a temperature sensitive electrical parameter. The on-state voltage being sensitive to the quality of the top-side connection, the obtained temperature estimate is drifting with degradation. This drift typically leads to under-estimating the temperature, thus reducing the precision of health monitoring. Drift compensation methods based on re-calibration are effective in single-chip switches, but their performances are not viable in multi-chip switches. This is due to the different temperature and current conditions during the calibration and the estimation phases. This paper addresses the relation between wire-bond degradation and temperature in multi-chip switches and proposes a simple model to explain and reproduce the electro-thermal behaviours. The model is based on experimental results where the degradation of wire-bonds is reproduced by cutting the wires sequentially. The model is further used to explain the drift in temperature estimation and the performance of the drift compensation methods based on re-calibration. Overall, the paper provides new results and understandings of the thermo-electrical behaviour of multi-chip power IGBT modules subject to wear-out.

The research and development of Soldering materials applied in IGBT modules packaging

Power modules have attracted much attention in the market, especially for high-voltage applications like switch mode power, automotive powertrain. As the requirement of high reliability, high-temperature operation improves, the packaging materials should develop to meet the applications with high properties. In this paper, the soldering materials such as Sn based lead free solder, SnPb solder, Ag-sinter are demonstrated. Soldering materials reliability is described on reliability testing especially for power cycling, temperature cycling testing, thermal shock testing. The concept is based on different applications and soldering process on Si power modules and SiC power modules. Important materials properties of thermal conductivity, CTE (coefficient of thermal expansion), elastic modulus, melting point are discussed. By comparison, Ag sintering process has a good application in high power modulus especially for SiC. SnAg solder also has the potential application in SiC modulus by IMC diffusion soldering technology.

A New EMI Modeling Method for Mixed-Mode Noise Analysis in Three-Phase Inverter System

A novel frequency-domain EMC modeling technique is proposed to predict the conducted electromagnetic interference (EMI) in a three-phase inverter system. On the basis of the frequency-domain model, a three-terminal behavior model for analyzing mixed-model (MM) noise is derived. Different from the traditional model, the CM and DM noise sources are independent of each other, thus help to understand the MM phenomenon directly. It is shown that three stray capacitors in the IGBT module determine the amplitude of the MM noise, and the influence of the load current on the traditional CM and DM noise sources can be used for the MM noise observation. The simulation and experimental results are illustrated to verify the prediction technique and the MM noise analysis is confirmed.

An Improved Behavior Model for IGBT Modules Driven by Datasheet and Measurement

This article describes an improved behavior model for IGBT modules. The new steady-state characteristic model of the IGBT with a correction function was built to improve the saturation current for different gate-emitter voltages. Two important nonlinear capacitances were described by two continuous functions to solve the convergence problem in the circuit simulation. The parasitic parameters generated by the package were extracted by the impedance measurement. All the parameters of the model are derived from datasheet and measurement. The improved model was implemented by MAST language in SABER circuit simulation. A double-pulse test was applied to verify the improved model. Compared with the conventional model for transient waveforms, switching losses, and electromagnetic interference (EMI), the improved model shows a better agreement with experiments. The satisfactory results indicate that the improved model can offer a simple, fast, and generic modeling approach.

Components Sharing Based Integrated HVDC Circuit Breaker for Meshed HVDC Grids

DC fault isolation is one of the main challenges of the HVDC grid. DC fault current can be interrupted within several milliseconds by employing hybrid HVDC circuit breaker. However, this scheme is not cost-effective, especially in meshed HVDC grid. In this paper, a novel integrated HVDC circuit breaker by sharing components is proposed to overcome these drawbacks. Suppose that a converter in a meshed HVDC grid is connected to m DC lines. The integrated HVDC circuit breaker consists of m + 1 ultra-fast disconnectors (UFDs), m + 1 load commutation switches (LCSs), m + 1 mechanical disconnectors (DSs), and only one main breaker (MB) and surge arrester (SA). The behavior of the proposed integrated HVDC circuit breaker is similar to that of the conventional hybrid HVDC circuit breaker. These two kinds of breakers have the same operating time, which means the integrated HVDC circuit breaker is fast enough to clear DC faults. Besides, the IGBT modules in the MB and LCSs of the proposed integrated HVDC circuit breaker are connected in one direction, and the m DC lines share a single MB. Therefore, this scheme is more cost-effective compared to the conventional hybrid HVDC circuit breaker. Moreover, the adjacent lines can still be used to transmit power after DC bus faults. Simulation results on a three-terminal HVDC grid are presented to verify the effectiveness and feasibility of the proposed scheme.

DC-Biased Magnetization Based Eddy Current Thermography for Subsurface Defect Detection

Eddy current thermography (ECT) as one of the emerging nondestructive testing and evaluation techniques has been used for defects detection in critical components, e.g., fatigue cracks in turbine blades, bond wire lift-off in IGBT modules, lack of fusion in welded parts, etc. However, in fast inspection using the early thermal response, the thin eddy current penetration depth (skin depth) of ferromagnetic materials limits ECT's capability of detecting subsurface defects. In order to increase the detectable depth range, this paper proposes a dc-biased magnetization based ECT (DCMECT) technique. Based on the nonlinear magnetic permeability in ferromagnetic material, DCMECT can increase the thermal contrast between the defective and sound areas by the enhanced permeability distortion in the skin-depth layer. Specifically, the influences of dc-biased magnetization direction and intensity on the thermal responses (of the defective and sound areas) and their thermal contrast are investigated. Results show that the dc-biased magnetization direction has the strongest influence on the thermal response when it is parallel to the ac magnetization direction generated by the coil. Both the thermal responses of defective and sound areas decrease with the magnetization intensity increasing. Whereas, the thermal contrast between two areas increases with the magnetization intensity, which presents the enhanced defect detectability of DCMECT. The proposed technique can detect the subsurface defect with a buried depth up to 6 mm.

Investigation on the Effects of Unbalanced Clamping Force on Multichip Press Pack IGBT Modules

Press-pack packaging technology has been widely used in insulated-gate bipolar transistors for high-voltage and high-power density applications. The effects of unbalanced internal pressure, which occurs frequently within large-scale press-pack modules, remain unclear, and thermal parameters within modules cannot be directly measured due to the pressure-type package structure. Current and temperature distribution within 3300 V/1500 A modules are investigated to determine module reliability characteristics and derive future lifetime models using multiphysics models. Unbalanced clamping force causes extremely uneven temperature stress and electrical stress in spatial distribution. It indicates that partial chips must withstand high stresses that cause the initial fatigue of large-scale press-pack modules. Junction temperature difference reaches up to 53.6 °C among chips at chip surface roughness of $1.27~\mu \text{m}$ . This condition shows that the aging of modules will accelerate at the onset of partial chips degradation. Finite-element modeling and equivalent test are utilized to verify the multiphysics model by using single-chip devices in parallel.

Wear-Out Condition Monitoring of IGBT and mosfet Power Modules in Inverter Operation

In this article, a condition monitoring system for the degradation assessment of power semiconductor modules under switching conditions is presented. The proposed monitoring system is based on the online measurement of two damage indicators: the on -state voltage of the semiconductor and the voltage drop in the bond wires. The on-state voltage of a semiconductor can be employed for temperature estimation, in order to anticipate failures in the solder joints that increase the thermal resistance of the cooling path. Moreover, by measuring the voltage drop in the bond wires, the degradation of the bond wires can be detected. The described monitoring system has been implemented in an inverter prototype, and tests have been performed in different scenarios to verify its capabilities in healthy and degraded states. Furthermore, a monitoring routine has been proposed in order to perform the required measurements in high switching frequency applications.

Low thermal resistance packaging for high power electronics

Abstract Alumina and aluminum nitride substrates are routinely used in micro-electronic packaging where large quantity of heat needs to be dissipated, such as in LED packaging, high power electronics and laser packaging. Heat management in high power electronics or LED's is crucial for their lifespan and reliability. The ever-increasing need for higher power keeps challenging the packaging engineers to become more sophisticated in their packaging. With the availability of a 40 μm thick, high thermal conductivity ribbon alumina from Corning, the options available for packaging engineers has widened. This product has very high dielectric breakdown (~10kV at 40 μm thick), high thermal conductivity (>36 W/mK) and is rugged enough to be handled (with components attached) during packaging. These characteristics make ribbon alumina a cost-effective alternative to incumbent materials such as thick aluminum nitride, for use in high power microelectronics packaging. In this paper, high power LED and IGBT modules are modeled using commercially available code from ANSYS®. A geometry representative of typical LED packaging and IGBT packaging is constructed with Ansys Design Modeler platform and the allied meshing is done employing in-built Meshing tool in ANSYS Workbench®. We show that packaging with ~40 μm ribbon alumina delivers performance on par with or better than packaging with thicker aluminum nitride substrates.

Full-Bridge Converter with Soft Commutation in All Load Range

The development of converters with soft commutation improves issues of radiation interference and electromagnetic compatibility, reduce weight and size parameters by increasing efficiency and conversion frequency. A significant reduction in commutation losses allows the use of high-power IGBT modules at higher frequencies which they are not able to withstand in traditional converters with pulse-width commutation.

Prognostics Framework for Power Semiconductor IGBT Modules through Monitoring of the On-State Voltage

This paper presents a literature review and an overview of original contributions on diagnostic and prognostic technologies for IGBT power modules based on the monitoring of the on-state voltage (Von). 
 First, different kinds of Von sensing circuits are discussed in terms of specifications, implementation, performance and cost. A low-cost and practical circuit is experimentally demonstrated. Then, a method is presented and evaluated for estimating wire-bond degradation. Wire-bond lift-off is the most common wear-out mechanism for industrial power semiconductor IGBT modules. It is effectively detected by measuring Von at the Zero Temperature Coefficient (ZTC) current value. Next, a method is presented to estimate the die temperature. Knowing the die temperature allows estimating the thermo-mechanical stress imposed to the wire-bonds. It is demonstrated to be feasible with ±3°C accuracy/precision using after careful calibration of Von as a Temperature Sensitive Electrical Parameter (TSEP). Finally, an algorithm is presented to process the information generated from the monitoring of Von and estimate the Remaining Useful Life (RUL). It considers Von evolution prior the first wire-bond lift-off and it combines both condition-based and damage accumulation based predictions.
 The major contribution of this paper is to present, for the first time, a complete framework for diagnostics and prognostics of power semi-conductor IGBT modules.

Effects of power cycling test condition and test strategy on lifetime estimation of power modules in power electronic systems

One of the main purposes of an accelerated power cycling test is to develop a lifetime model for the lifetime prediction of power modules. It is important to select proper test conditions when the power cycling test is performed since it is closely related to the lifetime model parameters and also to the testing time. In this paper, the effects of power cycling test condition and test strategy on the lifetime estimation of power modules are studied. The lifetime models of the IGBT module are developed by the accelerated power cycling tests with different test conditions and also by calibrated accelerated power cycling test. As a case study, the lifetime of IGBT module in motor drive system is estimated with different lifetime models and the results are compared.

Reliability analysis of the optimized Y-source inverter with clamping circuit

Y-source inverter has been proposed for a few years, but it still has some drawbacks. So, many studies of related topologies have been carried out to address the issues of traditional Y-source inverter (T-YSI). This paper proposes an optimized topology of Y-source inverter to solve the problems such as discontinuous input current and dc-link voltage spikes. However, the additional circuits probably influence the electrical and thermal stress of the IGBT modules, which affect their lifetime. And the lifetime of IGBT modules contribute to the lifetime of the inverter. Thus, it is important to predict the lifetime of the inverter based on the lifetime of the IGBT module. The lifetime of the IGBT modules is predicted by using the Coffin-Manson-Arrhenius model. The thermal behaviour is obtained considering real mission profile. Then the reliability of the IGBT module in the optimized Y-source inverter with clamping circuit is derived using Weibull distribution. Finally, the lifetime of the proposed inverter is analysed by Reliability Block Diagram (RBD) based on component-level reliability.