| 1. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
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Analytical Conduction Loss Calculation of a MOSFET Three-Phase Inverter Accounting for the Reverse Conduction and the Blanking Time
- 2021
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Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 68:8, s. 6682-6691
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Tidskriftsartikel (refereegranskat)abstract
- The reverse conduction capability of MOSFETs is beneficial for the efficiency of a three-phase inverter. In this paper analytical expressions in closed form are presented which allow to quickly evaluate the conduction losses, considering the effect of the reverse conduction and blanking time for both sinusoidal PWM operation with and without third harmonic injection. The losses of a three-phase SiC MOSFET inverter suitable for traction applications are estimated with the proposed method and show good agreement of about 98.5 % with measurements, performed with a calorimetric setup.
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| 2. |
- Acquaviva, Alessandro, 1987
(författare)
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Analytical Electromagnetic Sizing of Inner Rotor Brushless PM Machines Based on Split Ratio Optimization
- 2018
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Ingår i: 2018 XIII International Conference on Electrical Machines (ICEM). - 2381-4802. - 9781538624777 ; , s. 576-582
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Konferensbidrag (refereegranskat)abstract
- This paper presents an analytical procedure to size brushless PM Machines from a set of required performance specifications. The sizing is obtained by optimizing the machine's split ratio, defined as the ratio of the stator inner to outer diameter. This ratio is key in the design of the machine and it is a compromise among several performance factors, and in particular it is shown to be a trade-off between efficiency and torque density. The split ratio also affects the volume of each material and in turn the cost of the machine. The algorithm outputs the machine performance and cost curves as a function of the split ratio, giving the possibility to the user to decide the best compromise for a certain application. The analytical sizing procedure is built and integrated with a 2D FEM simulator for refinement and verification of the design. A case study is presented and validated to prove the effectiveness of the sizing procedure.
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| 3. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
-
Computationally Efficient Modeling of Electrical Machines With Cooling Jacket
- 2019
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Ingår i: IEEE Transactions on Transportation Electrification. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2332-7782. ; 5:3, s. 618-629
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Tidskriftsartikel (refereegranskat)abstract
- Modeling of electrical machines is a multiphysics problem. Depending on the phenomena of interest and the computational time constraint, this can be done at different levels of detail. In this article, the main approaches to model the thermal behavior of electrical machines with a liquid cooled casing around the stator (often referred to as cooling jacket) are analyzed and a novel approach is presented. The proposed method aims at creating computationally efficient 3-D multiphysics models of electrical machines with liquid cooled jacket. This model is based on the assumption of a fully developed flow in the cooling jacket which allows to scale the computational fluid dynamics (CFD) simulation to 1-D. The slot with a two layer concentrated winding and potting material is modeled using a composite material comprising of both the conductors and slot filler. Similarly, a unified material is used to model the end-windings. Experimental results on a traction machine for vehicle applications are presented showing good agreement with the simulations. Also, a comparison with a 3-D CFD is presented to verify the pressure drop in the pipe bend. Finally, the model is used to simulate a dynamic load cycle, which would be computationally extremely demanding with combined 3-D CFD and thermal FEA of the machine and its cooling.
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| 4. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
-
Design and Verification of In-slot Oil-Cooled Tooth Coil Winding PM Machine for Traction Application
- 2021
-
Ingår i: IEEE Transactions on Industrial Electronics. - 0278-0046 .- 1557-9948. ; 68:5, s. 3719-3727
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Tidskriftsartikel (refereegranskat)abstract
- Tooth coil windings, in particular when using a double layer structure, present opportunities for in-slot liquid cooling. Since the windings are not overlapping, access to the slot from the end section for coolant liquids is enabled. In this paper, a solution for in-slot and instator direct oil cooling for a tooth coil winding machine is presented. The coils are pre-wound on bobbins and inserted on the stator teeth. The novelty of the design consists in the integration of the cooling, using a thermally conductive epoxy resin to create the channels within the slot as well as the positioning of the stator yoke cooling channels. A 50 kW machine for an automotive traction application is designed, manufactured and tested. Conjugate heat transfer simulations are used in the design process in combination with finite element analysis for the loss mapping. The thermal model is verified with measurements at 6 l/min oil flow and 17.5 A/mm2 continuous and 35 A/mm2 30 s peak. The thermal model is then used to establish a continuous operating point of 25 A/mm2 .
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| 5. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
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Electromagnetic and Calorimetric Validation of a Direct Oil Cooled Tooth Coil Winding PM Machine for Traction Application
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 13:13
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Tidskriftsartikel (refereegranskat)abstract
- Tooth coil winding machines offer a low cost manufacturing process, high efficiency and high power density, making these attractive for traction applications. Using direct oil cooling in combination with tooth coil windings is an effective way of reaching higher power densities compared to an external cooling jacket. In this paper, the validation of the electromagnetic design for an automotive 600 V, 50 kW tooth coil winding traction machine is presented. The design process is a combination of an analytical sizing process and FEA optimization. It is shown that removing iron in the stator yoke for cooling channels does not affect electromagnetic performance significantly. In a previous publication, the machine is shown to be thermally capable of 25 A/mm2 (105 Nm) continuously, and 35 A/mm2 (140 Nm) during a 10 s peak with 6 l/min oil cooling. In this paper, inductance, torque and back EMF are measured and compared with FEA results showing very good agreement with the numerical design. Furthermore, the efficiency of the machine is validated by direct loss measurements, using a custom built calorimetric set-up in six operating points with an agreement within 0.9 units of percent between FEA and measured results.
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| 6. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
-
Energy efficiency of a SiC MOSFET propulsion inverter accounting for the MOSFET's reverse conduction and the blanking time
- 2017
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Ingår i: 2017 19th European Conference on Power Electronics and Applications. - 2325-0313. - 9789075815276
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Konferensbidrag (refereegranskat)abstract
- MOSFET devices have a body diode that allows reverse conduction, additionally, when a negative drain-source voltage is present, the MOSFET channel conduction can also be controlled by applying a gate-source voltage above the threshold voltage level. In a three phase inverter this results in parallel conduction of the diode and MOSFET when voltage and current differ in sign. This paper analyzes the beneficial effect of parallel operation of the two devices, taking into account the blanking time, on the conduction losses and total efficiency for a three phase SiC MOSFET inverter for traction application in electrified vehicles. The losses of the inverter are derived and presented as an analytical expression and compared with a numerical implementation showing a perfect match of the two. The total losses and efficiency of the inverter are derived and analyzed with and without reverse conduction for different operating points.
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| 7. |
- Acquaviva, Alessandro, 1987
(författare)
-
High Performance Cooling of Traction Brushless Machines
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The work presented in this thesis covers several aspects of traction electric drive system design. Particular attention is given to the traction electrical machine with focus on the cooling solution, thermal modelling and testing. A 60 kW peak power traction machine is designed to achieve high power density and high efficiency thanks to direct oil cooling. The machine selected has a tooth coil winding, also defined as non-overlapping fractional slot concentrated winding. This winding concept is state of the art for many applications with high volumes and powers below 10 kW. Also, these have been proven successful in high power applications such as wind power generators. In this thesis, it is shown that this technology is promising also for traction machines and, with some suggested design solutions, can present certain unique advantages when it comes to manufacturing and cooling. The traction machine in this work is designed for a small two-seater electric vehicle but could as well be used in a parallel hybrid. The proposed solution has the advantage of having a simple winding design and of integrating the cooling within the stator slot and core. A prototype of the machine has been built and tested, showing that the machine can operate with current densities of up to 35 A/mm^2 for 30 seconds and 25 A/mm^2 continuously. This results in a net power density of the built prototype of 24 kW/l and a gross power density of 8 kW/l with a peak efficiency above 94%. It is shown that a version of the same design optimized for mass manufacturing has the potential of having a gross power density of 15.5 kW/l which would be comparable with the best in class traction machines found on the automotive industry. The cooling solution proposed is resulting in significantly lower winding temperature and an efficiency gain between 1.5% and 3.5% points, depending on the drivecycle, compared to an external jacket cooling, which is a common solution for traction motors.
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| 8. |
- Acquaviva, Alessandro, 1987
(författare)
-
High Performance Cooling Traction Brushless Machine Design for Mass Production
- 2019
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the last few years electric vehicles (EVs) are coming on the market. The shift from niche market to main stream is challenging. It took many years to reach the current internal combustion engine quality in the manufacturing process. However, a much faster process is needed for the electric drive-train if sustainability goals about CO2 emissions are to be met. It is extremely important to think about the manufacturing process during the design of a piece of hardware if this is meant for mass production. In a few years from now, traction electric motors for EVs will be produced with the rate of millions per year and ensuring a simple, effective and reliable manufacturing process is key in the success of the electric vehicle industry. This thesis presents an innovative brushless machine design meant for mass production. The machine is designed to achieve high power density and high reliability thanks to a novel cooling concept. The machine selected has a tooth coil winding, also defined as non-overlapping fractional slot concentrated winding. This winding concept is state of the art for many applications with high volumes and powers below 10 kW. Also, these have been proven successful in high power applications such as wind power generators. In this thesis the ambition is to show that this technology is promising as well for traction machines and it presents certain unique advantages when it comes to manufacturing and cooling. The traction machine in this work is designed for a small two-seater electric vehicle but could as well be used in a parallel hybrid.
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| 9. |
- Acquaviva, Alessandro, 1987, et al.
(författare)
-
Manufacturing of tooth coil winding PM machines with in-slot oil cooling
- 2020
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Ingår i: Proceedings - 2020 International Conference on Electrical Machines, ICEM 2020. - 9781728199450 ; , s. 2314-2320
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Konferensbidrag (refereegranskat)abstract
- This paper presents a description of the manufacturing challenges and solutions of two 50 kW radial flux inner-rotor tooth coil winding PM machines with in-slot cooling for vehicle application. The two machines are designed for different DC link voltages, 600 V and 48 V, and to achieve high efficiency and high power density. To enable this, liquid cooling is necessary. In the solution presented, the oil coolant is pushed through the stator yoke and in the slots with the intent of removing the heat close to the loss generation. The cooling channels in the slots are built during the stator potting process using a high thermally conductive potting material. The machines presented in this paper are designed for high speed operation and capable to withstand RMS current densities of 25 A/mm2 in continuous operation and 35 A/mm2 for 30 s peaks, at 6 1/min oil flow and a inlet temperature of 20oC. It is shown that stator is designed to be compatible with automated manufacturing for high volume production with a set of suggested improvements.
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| 10. |
- Lundmark, Sonja, 1966, et al.
(författare)
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Coupled 3-D Thermal and Electromagnetic Modelling of a Liquid-cooled Transverse Flux Traction Motor
- 2018
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Ingår i: Proceedings - 2018 23rd International Conference on Electrical Machines, ICEM 2018. - 9781538624777 ; , s. 2640-2646
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Konferensbidrag (refereegranskat)abstract
- Modelling of electrical machines is constantly refined and it is now possible to couple CFD thermal models with FEM electromagnetic models, thereby considering the thermal effects on motor materials. Usually, the models are reduced as much as possible (i.e. 2-D instead of 3-D or using symmetry conditions) in order to reduce calculation time and computer resources. However, in this paper it is shown how to model an interior permanent magnet transverse flux (TF -IPM) motor in 3-D so to be able to include magnet, core and copper loss and the effect of air and liquid cooling. The simulation results are compared with results of a comparably sized liquid-cooled radial flux IPM (RF-IPM) motor. It is shown that the TF-motor cooling is very efficient due to the lack of end-windings.
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