| 1. |
- Amirpour, Sepideh, 1980, et al.
(författare)
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Highly thermal conductive graphene-based heatsink tailored for electric propulsion SiC-based inverter
- 2024
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Ingår i: Applied Thermal Engineering. - 1359-4311. ; 243
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Tidskriftsartikel (refereegranskat)abstract
- This study introduces an innovative multidisciplinary design approach for highly conductive and lightweight pin-fin-based heatsinks leveraging the advantages of graphene technology. The primary objective is to optimize the thermal management of silicon carbide (SiC) based inverters within electric vehicles (EVs). To closely emulate the real SiC power module, comprehensive analyses, including scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), are performed on the module. A detailed fluid dynamics model utilizing a 3D-conjugate heat transfer (CHT) methodology is employed to evaluate the thermal behavior of SiC power switches in contact with the coolant. The multidisciplinary analysis is initially implemented on an aluminum-based heatsink, validated experimentally, and subsequently compared to graphene. The integration of graphene in the heatsink design demonstrates notable improvements, including a 24.4 % increase in the heat transfer coefficient (HTC) and a 19.6 % reduction in thermal resistance (sink to fluid) at a 6 l/min fluid flow rate compared to its aluminum counterpart. Consequently, the SiC chips within the graphene-based heatsink exhibit an 11.5 % lower temperature rise compared to the aluminum version. The improvements in the cooling solution for SiC inverters in EVs, achieved through the adoption of graphene instead of traditional metals, serve as a proof of concept. This signifies a step forward in prioritizing the crucial balance between performance and power density.
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| 2. |
- Boscaglia, Luca, 1991, et al.
(författare)
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Balancing Peak-torque and Drive-cycle Efficiency with Magnet Dimensioning of Permanent Magnet Synchronous Machines
- 2020
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2577-1647 .- 2162-4704. ; 2020-October, s. 883-888
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Konferensbidrag (refereegranskat)abstract
- There is an increasing trend in reducing rare-earth materials due to environmental and cost concerns. It affects design and manufacturing of Permanent Magnet Synchronous Machines (PMSM). Changes in parameters such as size and shape of the magnets will affect requirements as operating efficiency and maximum torque. In this paper, the design of a 250 kW PMSM for a commercial heavy-duty vehicle application is considered in order to evaluate effects of magnets thickness variation on performance and driving cycle efficiency. With this aim, an electromagnetic model is built using Finite Element Method (FEM) and efficiency map computations are carried out to investigate the effects of the magnet variation. System simulations are then implemented in MATLAB/PLECS to evaluate the driving cycle efficiency. Simulation results shown that the reduction of magnet thickness leads to significantly improved operating efficiency with reduction of maximum torque.
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| 3. |
- Larsson, Carl, et al.
(författare)
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Overvoltage Mitigation of Medium Voltage Electric Drives with Long Cables using Multilevel-Converters and Passive Filters
- 2019
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Ingår i: 2019 21st European Conference on Power Electronics and Applications, EPE 2019 ECCE Europe.
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Konferensbidrag (refereegranskat)abstract
- Variable-speed drives with long cables between the electrical machine and the power converters suffer from overvoltages at the connection terminals of the cables. These overvoltages which are caused by reflections of the PWM voltage pulses to the two ends of the cable are investigated in this paper. Suitable passive filters are proposed in order to mitigate the overvoltages to an acceptable level, which is not harmful for the devices of the system. Additionally, the use of multilevel power converters can help to minimize the size of the passive filters. The filter design for drives with up to 7-level converters is described in this paper and simulations results on LTspice are presented in order to validate the mathematical analysis.
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| 4. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Circulating Current Reduction in Common DC-Link Power-HIL for Drives using SVM with Zero-Sequence Compensation
- 2020
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. ; , s. 4673-4678
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Konferensbidrag (refereegranskat)abstract
- A new zero-sequence control technique is presented in this paper in order to eliminate the circulating current flowing in power hardware-in-the-loop test benches for electrical machine emulators. The machine emulator studied in this paper is made up of two three-phase inverters with an inductor connecting their ac-side. Both inverters share the same dc-link allowing circulating flow of the electric energy within this loop in order to emulate the operation of high power machine drives. Unfortunately, common-mode voltage is also freely developed within the loop and creates high circulating currents that act as a disturbance for the control of the inverters. Available control techniques have not managed to completely eliminate this current and common-mode filters are used additionally in order to solve the problem. The proposed zero-sequence control utilizes a modified version of the space vector modulation and reduces the circulating current amplitude up to 2.1% of the phase current, eliminating the need for hardware filters. Simulation results from Matlab/PLECS verify the effectiveness of the developed controller.
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| 5. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Combined Voltage Balancing Techniques of the DC Link in Five-Level Medium Voltage NPC Back-to-Back Converters for Offshore Renewable Generation
- 2017
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Ingår i: 2017 19th European Conference on Power Electronics and Applications. - 2325-0313. - 9789075815276 ; 2017-January
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Konferensbidrag (refereegranskat)abstract
- The voltage balancing of the dc-link capacitors in an electric drive system with five-level neutral-pointclamped converters is investigated in this paper. A properly modified space-vector-modulation technique is utilized in combination with a multilevel dc/dc converter for controlling the capacitor voltages. An advanced algorithm has been developed for reducing the losses of the electric drive system and for ensuring that the capacitor voltages are balanced in every operating condition. The developed electric drive system can be used in offshore power plants for driving medium voltage generators. Selective simulation results are presented to validate the theoretical considerations.
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| 6. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Comparative Study of the Torque Ripple and Iron Losses of a Permanent Magnet Synchronous Generator Driven by Multilevel Converters
- 2018
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Ingår i: 2018 23rd International Conference on Electrical Machines (ICEM). - 2381-4802. - 9781538624777
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Konferensbidrag (refereegranskat)abstract
- This paper studies and analyzes the performance of permanent magnet synchronous generator (PMSG) drives with multilevel power converters used in medium voltage renewable power generation systems. The cases of electrical machine drives with 2-level back-to-back-connected voltage source converters as well as 3-and 5-level neutral-point-clamped converters are examined. The converters have been constructed with silicon-carbide (SiC) power switches. The comparison in the power converters efficiency and power quality is conducted by using simulation results obtained by the Matlab/Simulink and PLECS programs for several operating conditions. For the needs of the comparison, a medium voltage PMSG is designed and its efficiency and torque ripple are calculated by using the finite element software ANSYS Maxwell. Several simulation results are presented and discussed throughout the paper in order to demonstrate the improvements in the PMSG torque ripple and the iron loss reduction that can be achieved by using multilevel converters.
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| 7. |
- Mademlis, Georgios, 1992, et al.
(författare)
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DC-DC Converter based on the Asymmetric Multistage Stacked Boost Architecture with Feed-Forward Control for Photovoltaic Plants
- 2016
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Ingår i: PCIM Europe 2016; International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management. - 9783800741861 ; , s. 445-452
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Konferensbidrag (refereegranskat)abstract
- A new feed-forward control technique for a DC-DC step-up converter based on the asymmetric Multistage Stacked Boost Architecture (MSBA) is presented in this paper. The proposed closed loop control scheme can provide improved accuracy in the steady-state operation and high dynamic performance. The asymmetric MSBA converter is a single output high-voltage DC-DC step-up converter that comprises several in-series connected capacitors with active voltage balancing circuits. The converter can attain high voltage ratios and thus, it is a suitable solution for the high voltage transmission requirements of the large photovoltaic (PV) plants. Selective simulation and experimental results are presented in order to validate the effectiveness and the operational improvements of the proposed control system.
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| 8. |
- Mademlis, Georgios, 1992, et al.
(författare)
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DC Link Voltage Balancing Technique Utilizing Space Vector Control in SiC-based Five-Level Back-to-Back-Connected NPC Converters
- 2018
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Ingår i: 2018 IEEE Energy Conversion Congress and Exposition (ECCE). - 2329-3748. - 9781479973125 - 9781479973118 ; , s. 3032-3037
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Konferensbidrag (refereegranskat)abstract
- This paper presents an improved voltage balancing algorithm of the dc-link capacitors in an electric drive with back-to-back connected five-level neutral-point-clamped (NPC) converters. A properly modified space-vector-pulse-width-modulation (SVPWM) algorithm is developed, which balances the capacitor voltages effectively by utilizing the redundant states of the space vector plane. The dc link voltage balancing is attained by the proper control of the NPC converters without requiring any additional hardware and, thus, the cost of the electric drive can be minimized. This paper presents the theoretical analysis of the proposed voltage balancing technique for all the operating conditions of the converters. A 50kW electric drive is simulated on Matlab/Simulink and modelled using PLECS in order to accurately calculate the losses of the converters. SiC power switches are used for the prototypes of the 5-level NPC converters. Selective experimental results are also shown.
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| 9. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Design of Maximum Power Point Tracking for Dynamic Power Response of Tidal Undersea Kite Systems
- 2020
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Ingår i: IEEE Transactions on Industry Applications. - 0093-9994 .- 1939-9367. ; 56:2, s. 2048-2060
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Tidskriftsartikel (refereegranskat)abstract
- The Tethered-Undersea-Kite (TUSK) represents a new electric power generation concept for harvesting energy from tidal currents, with higher power density compared to traditional static tidal turbines. However, the power and rotating speed of the turbine fluctuate periodically depending on the kite's motion in the sea creating an additional challenge for the speed control of the generator. The mathematical model of the system's power generation is developed. Two alternative Maximum-Power-Point-Tracking (MPPT) algorithms suitable for this application are designed. The electrical torque of the generator is controlled directly or a more accurate closed-loop speed controller is used. The turbine inertia creates an error between the optimal-reference power and the actual generated power. This error is evaluated experimentally for both MPPT-algorithms when fluctuating mechanical torque typical for the TUSK-system is applied on the generator. Experimental results on a 35kVA laboratory emulator are presented, where an accurate representation of the system dynamics and inertia are implemented.
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| 10. |
- Mademlis, Georgios, 1992, et al.
(författare)
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Designing Thermally Uniform Heatsink with Rectangular Pins for High-Power Automotive SiC Inverters
- 2020
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Ingår i: IECON Proceedings (Industrial Electronics Conference). - 2162-4704 .- 2577-1647. ; 2020-October, s. 1317-1322
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Konferensbidrag (refereegranskat)abstract
- This paper presents the design of a high-performance liquid-cooled heatsink for three-phase automotive inverters that attains uniform thermal distribution at the surface of the three power modules. Power modules with SiC-MOSFETs are used in this study and a uniform thermal distribution on the heatsink guarantees equal thermal loading of the semiconductor devices. A comparative study of various cooling plate geometries is made and their effectiveness in meeting the design objectives of low sink-temperature and coolant pressure drop and the highest possible temperature uniformity along the surface of the plate is presented. Plates with straight and wavy fins are compared with designs accommodating rectangular pins and the advantages of each case is shown with the corresponding simulation results. Key design parameters of the cooling plate geometries are optimized with an iterative process, which is presented with selective simulation results of 3D Conjugate Heat Transfer computations for coolant flow rates up to 10~l/min. The final heatsink design accommodates multiple rectangular pins and attains temperature difference of less than 2oC among the three SiC power modules.
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