Mauro Ciappa

Bio: Mauro Ciappa is an academic researcher from ETH Zurich. The author has contributed to research in topics: Monte Carlo method & Silicon carbide. The author has an hindex of 23, co-authored 129 publications receiving 2532 citations. Previous affiliations of Mauro Ciappa include École Polytechnique Fédérale de Lausanne.

Thermal component model for electrothermal analysis of IGBT module systems

Abstract: 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.

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

Abstract: 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 of IGBT modules for traction applications

Abstract: Bond wire lift-off caused by low-cycle fatigue is one among the dominant failure mechanisms of modern high power Insulated Gate Bipolar Transistors multichip modules used in traction applications. A model is proposed which is calibrated basing on data from accelerated tests and which predicts quantitatively the lifetime of devices submitted to cyclic loads as they are encountered in current converters of railway systems. It assumes linear accumulation of the thermal-cycle fatigue damage and takes into account the redundancy of the bond wires within a complex multichip module.

An Industry-Based Survey of Reliability in Power Electronic Converters

Abstract: A questionnaire survey was carried out to determine the industrial requirements and expectations of reliability in power electronic converters. The survey was subjective and conducted with a number of high-profile semiconductor manufacturers, integrators, and users in the aerospace, automation, motor drive, utility power, and other industry sectors. According to the survey, power semiconductor devices ranked the most fragile components. It was concluded that main stresses were from the environment, transients, and heavy loads, which should be considered during power electronic system design and normal operation. This paper has also highlighted that there is a significant need identified by the responders for better reliability-monitoring methods and indicators.

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

Abstract: 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.

Survey on Reliability of Power Electronic Systems

Abstract: With wide-spread application of power electronic systems across many different industries, their reliability is being studied extensively. This paper presents a comprehensive review of reliability assessment and improvement of power electronic systems from three levels: 1) metrics and methodologies of reliability assessment of existing system; 2) reliability improvement of existing system by means of algorithmic solutions without change of the hardware; and 3) reliability-oriented design solutions that are based on fault-tolerant operation of the overall systems. The intent of this review is to provide a clear picture of the landscape of reliability research in power electronics. The limitations of the current research have been identified and the direction for future research is suggested.