Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented

A multidisciplinary approach to identify priority areas for the monitoring of a vulnerable family of fishes in Spanish Marine National Parks

Background Syngnathid fishes (Actinopterygii, Syngnathidae) are flagship species strongly associated with seaweed and seagrass habitats. Seahorses and pipefishes are highly vulnerable to anthropogenic and environmental disturbances, but most species are currently Data Deficient according to the IUCN (2019), requiring more biological and ecological research. This study provides the first insights into syngnathid populations in the two marine Spanish National Parks (PNIA—Atlantic- and PNAC—Mediterranean). Fishes were collected periodically, marked, morphologically identified, analysed for size, weight, sex and sexual maturity, and sampled for stable isotope and genetic identification. Due the scarcity of previous information, habitat characteristics were also assessed in PNIA. Results Syngnathid diversity and abundance were low, with two species identified in PNIA (Hippocampus guttulatus and Syngnathus acus) and four in PNAC (S. abaster, S. acus, S. typhle and Nerophis maculatus). Syngnathids from both National Parks (NP) differed isotopically, with much lower δ15N in PNAC than in PNIA. The dominant species were S. abaster in PNAC and S. acus in PNIA. Syngnathids preferred less exposed sites in macroalgal assemblages in PNIA and Cymodocea meadows in PNAC. The occurrence of very large specimens, the absence of small-medium sizes and the isotopic comparison with a nearby population suggest that the population of Syngnathus acus (the dominant syngnathid in PNIA) mainly comprised breeders that migrate seasonally. Mitochondrial cytochrome b sequence variants were detected for H. guttulatus, S. acus, and S. abaster, and a novel 16S rDNA haplotype was obtained in N. maculatus. Our data suggest the presence of a cryptic divergent mitochondrial lineage of Syngnathus abaster species in PNAC. Conclusions This is the first multidisciplinary approach to the study of syngnathids in Spanish marine NPs. Habitat preferences and population characteristics in both NPs differed. Further studies are needed to assess the occurrence of a species complex for S. abaster, discarding potential misidentifications of genus Syngnathus in PNAC, and evaluate migratory events in PNIA. We propose several preferential sites in both NPs for future monitoring of syngnathid populations and some recommendations for their conservation.Postprin

Semi-passive piezoelectric noise control in transmission by synchronized switching damping on voltage source

This paper deals with the so called SSD (stands for Synchronized Switch Damping) technique that is a semi-passive approach developed to address the problem of structural vibration damping and noise reduction. Compared to standard passive piezoelectric damping, this technique offers the advantage of self-adaptation with environmental variations (e.g. temperature). On the contrary to the active damping systems, its implementation does not require any sophisticated signal processing or any bulk power. In the semi passive approach, the piezoelectric element is continuously switched from open circuit to short circuit synchronously to the strain. Due to this switching mechanism, a phase difference appears between the strain induced by an incident acoustic wave and the resulting voltage, thus creating energy dissipation. With the non-linear process, damping performances directly depend on the electromechanical coupling coefficient of the system. For the weakly coefficient coupling systems, the voltage amplitude of the piezoelectric elements can be artificially increased by switching on voltage sources. Using this new method SSDV (stands for Synchronized Switch Damping on Voltage source), 16.1 dB attenuation on the transmitted wave pressure in the tube is obtained whereas only 8 dB were achieved with the classical SSDI (stands for Synchronized Switch Damping on Inductor). Furthermore, as this method is adaptive, attenuation is observed over a 600 Hz-wide frequency band

Design and implementation of integrated common mode capacitors for SiC-JFET inverters

Abstract—This paper deals with the issue of electromagnetic interference (EMI) in SiC-JFET inverter power modules, and proposes a solution to limit conducted emissions at high frequencies. SiC-JFET inverters can achieve very fast switching, thereby reducing commutation losses, at the cost of a high level of EMI. In order to limit conducted EMI emissions, it is proposed to integrate small-value common mode (CM) capacitors, directly into the power module. High frequency noise, which is usually difficult to filter, is then contained within the module, thus keeping it far from the external network. This approach is in line with the current trend towards the integration of various functions (such as protection, sensors or drivers) around power devices in modern power modules. To demonstrate this concept, the resulting CM noise was investigated, and compared with a standard configuration. Simulations were used to design the integrated capacitors, and measurements were carried out on an experimental SiC-JFET half-bridge structure. A significant reduction was achieved in the experimentally observed CM conducted emissions, with a very minor influence on the switching waveforms, losses and overall size of the system. The benefits and limitations of this design are discussed, for the case of mid-power range inverters for aircraft applications. Index Terms—Electromagnetic compatibility, Inverters, Multichip modules

New Definition of Critical Energy for SiC MOSFET Robustness under Short- Circuit Operations: the Repetitive Critical Energy

International audiencePrevious research showed that Si devices could sustain a large number of Short Circuit (SC) events, as long as the energy dissipated during SC remains slightly below a given threshold (the so-called critical energy). In this paper, we show that this is not necessarily true for SiC MOSFETs, which can only withstand a few such SC events. This low robustness to repetitive short-circuit events is related to the gate degradation due to the cumulative carrier injection and leakage currents in the oxide. To ensure safe operation over a large number of SC events, we introduce a new parameter: the "repetitive critical energy", which corresponds to a SC energy low enough to avoid excessive temperature increase so as to limit the transient gate leakage current during SC events. Below this repetitive SC energy value, the SiC device is able to sustain a large number (more than 1000) of SC events

Compact double-side liquid-impingement-cooled integrated power electronic module

This paper presents a compact integrated power electronic module (IPEM) which seeks to overcome the volumetric power density limitations of conventional packaging technologies. A key innovation has been the development of a substrate sandwich structure which permits double side cooling of the embedded dies whilst controlling the mechanical stresses both within the module and at the heat exchanger interface. A 3-phase inverter module has been developed, integrating the sandwich structures with high efficiency impingement coolers, delink capacitance and gate drive units. Full details of the IPEM construction and electrical evaluation are given in the paper. © 2007 IEEE

High performance cooling system for automotive inverters

A novel double-side cooled power module is presented which delivers superior cooling performance with the potential for improved robustness to thermal cycling. The semiconductor dies are sandwiched between conventional DBC substrates, the substrates being directly cooled rather than through a conventional heat spreader heat sink assembly. A theoretical analysis is presented illustrating that direct cooling can offer a lower total thermal resistance provided the heat transfer coefficient at the cooled surface is sufficiently high. Experimental results demonstrate the effectiveness of the selected impingement cooling technique when applied in both single- and double-side cooled formats. Measurements on the double-side cooled structure show a total thermal resistance (junction to ambient) that is less than 40% of the junction to case resistance of a conventional module. Similar improvements are observed in the transient thermal impedance (step response) curve indicating that thermal cycling ranges will be reduced under all operational conditions

Compact inverter designed for high-temperature operation

This paper presents an integrated 10 kW inverter designed to operate in the demanding automotive environment. To achieve good compactness and high reliability to thermal cycling, several original approaches have been implemented together: the power modules are built with a sandwich structure, employing mechanical improvements compared to existing comparable structures; these sandwich modules are cooled directly (i.e without an intermediate base-plate layer), with the cooling fluid being sprayed to improve heat extraction; Anally, 1200 V silicon carbide devices are used for improved performance. The specific requirements of the automotive environment are described as well as the chosen approaches. Experimental results are presented, giving details of the electrical, thermal and reliability performance. © 2007 IEEE

SiC MOSFETs robustness for diode-less applications

International audienceSilicon-Carbide (SiC) technology presents several advantages over silicon for power electronics applications, such as lower losses. However, SiC technology is not totally mature, and some reliability problems remain. This paper studies the robustness of SiC MOSFETs in the case of diode-less applications and the associated phenomena, such as gate oxide degradation. Several devices were stressed under conditions of inductive switching and inverse current conduction. These devices were periodically characterised. As a result, a threshold voltage shift was observed in the MOSFET, with a dependence on the duty cycle of the transistor. On the contrary, no significant degradation of the internal P-N junction of the transistor was observed