Condition monitoring (CM) has already been proven to be a cost effective means of enhancing reliability and improving customer service in power equipment, such as transformers and rotating electrical machinery. CM for power semiconductor devices in power electronic converters is at a more embryonic stage; however, as progress is made in understanding semiconductor device failure modes, appropriate sensor technologies, and signal processing techniques, this situation will rapidly improve. This technical review is carried out with the aim of describing the current state of the art in CM research for power electronics. Reliability models for power electronics, including dominant failure mechanisms of devices are described first. This is followed by a description of recently proposed CM techniques. The benefits and limitations of these techniques are then discussed. It is intended that this review will provide the basis for future developments in power electronics CM.

Condition Monitoring for Device Reliability in Power Electronic Converters: A Review

Active thermal control techniques make it feasible to regulate the steady state and transient thermal-mechanical stress in power electronic modules for applications such as motor drives. Online junction temperature estimation and manipulation of the switching frequency and current limit to regulate the losses are used to prevent overtemperature and power cycling failures in insulated gate bipolar transistor (IGBT) power modules. The techniques developed in this work are used to actively control the junction temperature of the power module. This control strategy improves power module reliability and increases utilization of the silicon thermal capacity by providing sustained operation at maximum attainable performance limits.

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Active thermal control of power electronics modules

As an increasing attention towards sustainable development of energy and environment, the power electronics (PEs) are gaining more and more attraction on various energy systems. The insulated gate bipolar transistor (IGBT), as one of the PEs with numerous advantages and potentials for development of higher voltage and current ratings, has been used in a board range of applications. However, the continuing miniaturization and rapid increasing power ratings of IGBTs have remarkable high heat flux, which requires complex thermal management. In this paper, studies of the thermal management on IGBTs are generally reviewed including analyzing, comparing, and classifying the results originating from these researches. The thermal models to accurately calculate the dynamic heat dissipation are divided into analytical models, numerical models, and thermal network models, respectively. The thermal resistances of current IGBT modules are also studied. According to the current products on a number of IGBTs, we observe that the junction-to-case thermal resistance generally decreases inversely in terms of the total thermal power. In addition, the cooling solutions of IGBTs are reviewed and the performance of the various solutions are studied and compared. At last, we have proposed a quick and efficient evaluation judgment for the thermal management of the IGBTs depended on the requirements on the junction-to-case thermal resistance and equivalent heat transfer coefficient of the test samples.

Thermal Management on IGBT Power Electronic Devices and Modules

Different procedures are defined and compared to extract the statistical distribution of the thermal cycles experienced by power devices that are installed in hybrid vehicles and operated according to arbitrary mission profiles. This enables both to design efficient accelerated tests tailored on realistic data and to provide the input for lifetime prediction models. Initially, the system lifetime is predicted under the assumption of linear accumulation of the damage produced by low cycling fatigue. Also, a novel prediction model based on some fundamental equations is introduced which takes into consideration the creep experienced by compliant materials when they are submitted to thermal cycles.

Lifetime prediction and design of reliability tests for high-power devices in automotive applications

A thermal resistor-capacitor (RC) model is introduced for the power insulated gate bipolar transistor (IGBT) modules used in a three-phase inverter. The parameters of the model are extracted from the experimental data for the transient thermal impedance from-junction-to-case Z/sub jc/ and case-to-ambient Z/sub ca/. The accuracy of the RC model is verified by comparing its predictions with those resulting from the three-dimensional finite element method simulation. The parameter extraction algorithm is easy to adapt to other types of power modules in an industrial application environment.

A thermal model for insulated gate bipolar transistor module

The insulated gate bipolar transistor (IGBT) modules are getting more accepted and increasingly used in power electronic systems as high power and high voltage switching components. However, IGBT technology with high speed and greater packaging density leads to higher power densities on the chips and increases higher operating temperatures. These operating temperatures in turn lead to an increase of the failure rate and a reduction of the reliability. In this paper, the static and dynamic thermal behavior of IGBT module system mounted on a water-cooled heat sink is analyzed. Although three-dimensional finite element method (3-D FEM) delivers very accurate results, its usage is limited by an imposed computation time in arbitrary load cycles. Therefore, an RC component model (RCCM) is investigated to extract thermal resistances and time constants for a thermal network. The uniqueness of the RCCM is an introduction of the time constants based on the Elmore delay, which represents the propagation delay of the heat flux through the physical geometry of each layer. The dynamic behavior predicted by the thermal network is equivalent to numerical solutions of the 3-D FEM. The RCCM quickly offers insight into the physical layers of the components and provides useful information in a few minutes for the arbitrary or periodic power waveforms. This approach enables a system designer to couple the thermal prediction with a circuit simulator to analyze the electrothermal behavior of IGBT module system, simultaneously.

P. Malberti

Papers

Thermal component model for electrothermal analysis of IGBT module systems