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A questionnaire-based survey was carried out to determine the customers' requirements and the future expectations of Multi-Physics Simulation Software (MPSS) based on the finite element method (FEM) in various applications of power electronics. For this survey, several responses was collected from MPSS users in the power electronic industry and academia. Based on the survey, the current features of MPSS are analyzed, and the recent advancements made are ascertained. Also, the drawbacks of the current MPSS offerings are discussed from academic and industrial perspectives. Different user groups have highlighted the need to significantly enhance the sophistication of MPSS. It is concluded that the current limitations to MPSS are simulation speed and accuracy and there are bottlenecks in the software interface. Some suggestions are given to overcome the current drawbacks of MPSS.

Power modules are the most common components to fail in power converters that are employed in mass transportation systems, thus leading to high unscheduled maintenance cost. While operating, high junction temperature swings occur that result in high thermomechanical stress within the structure of the power module reducing the lifetime of the module. Liquid metals as a cooling medium received so far little attention in the area of power semiconductors cooling, despite being able to remove high heat fluxes. This paper shows for the first time how liquid metal is used to reduce actively the junction temperature swing. A magnetohydrodynamic (MHD) pump has been designed for this purpose allowing active control of the flow rate of the liquid metal that impinges against the baseplate of the module. The pump has been 3D printed and forms with the power module a unique unit. A closed-loop temperature control system is implemented, able to estimate the IGBT's junction temperature and thus, control the MHD power. The paper presents simulation and experimental results showing reductions in the temperature swing over the full load cycle with 12 o C as the highest observed reduction rate. The paper shows also detailed designs of the MHD pump and the controller hardware.

The press-pack packaging technology has been adopted in recent years for insulated-gate bipolar transistors (IGBTs) to be utilized in high voltage -high current applications, such as high-voltage direct current (HVDC) electric power transmission. Traditionally, the heat management of such systems is based on water coolant, however, there are numerous challenges associated with that method, such as the requirement to deionize the water to prevent electrical potentials and inherent problems of corrosion and leakage in the cooling piping structure. This paper presents the design and development of a liquid metal heat sink for press-pack IGBTs. The use of a thermal management system based on liquid metal increases the heat dissipation capability without corroding the cooling structure. Analytical work is performed on the design of the heat sink. Moreover, the thermal performance of the heat sink is experimentally validated against a commercial water-based cooling system. The presented results show that the cooling performance of the liquid metal system is increased, whereas the shortcomings of the water-based system are eliminated. Index Terms-Press-pack insulated-gate bipolar transistor (IGBT) power module cooling, junction temperature, liquid metal cooling, magnetohydrodynamic (MHD) pump, high-voltage direct current (HVDC) cooling.

Distributed generation (DG) systems are growing in number, diversifying in driving technologies and providing substantial energy quantities in covering the energy needs of the interconnected system in an optimal way. This evolution of technologies is a response to the needs of the energy transition to a low carbon economy. A nanogrid is dependent on local resources through appropriate DG, confined within the boundaries of an energy domain not exceeding 100 kW of power. It can be a single building that is equipped with a local electricity generation to fulfil the building’s load consumption requirements, it is electrically interconnected with the external power system and it can optionally be equipped with a storage system. It is, however, mandatory that a nanogrid is equipped with a controller for optimisation of the production/consumption curves. This study presents design consideretions for nanogrids and the design of a nanogrid system consisting of a 40 kWp photovoltaic (PV) system and a 50 kWh battery energy storage system (BESS) managed via a central converter able to perform demand-side management (DSM). The implementation of the nanogrid aims at reducing the CO2 footprint of the confined domain and increase its self-sufficiency.