| 1. |
- Bitsi, Konstantina, 1992-, et al.
(author)
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3-D FEM Investigation of Eddy Current Losses in Rotor Lamination Steel Sheets
- 2018
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In: Proceedings 2018 XIII International Conference on Electrical Machines (ICEM). - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- In this paper, a test setup that emulates field conditions equivalent to the ones of the rotor of a Salient Pole Synchronous Machine (SPSM) is presented. A 3-D Finite Element Method (FEM) model of the test setup is used to examine the induced eddy currents and to estimate losses using direct eddy current calculation method. The high mesh resolution of the model enables an accurate calculation and detailed illustration of the induced eddy currents as well as the estimation of related losses via direct computation within the volume of the test samples. A comparison of the estimated eddy current losses is made for different lamination thicknesses and materials of the test object. In the paper it is shown that the approximation that the eddy current losses are directly proportional to the square of the lamination thickness is not valid in the considered cases.
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| 2. |
- Bitsi, Konstantina, et al.
(author)
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A Case Study of Pole-Phase Changing Induction Machine Performance
- 2022
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In: 2022 24Th European Conference On Power Electronics And Applications (EPE'22 ECCE EUROPE). - : IEEE.
-
Conference paper (peer-reviewed)abstract
- Pole-phase changing (PPC) induction machines (IMs) can achieve improved efficiency as well as wider torque-speed range compared to their fixed pole-phase counterparts. In this paper, a 4-pole IM is designed and evaluated in terms of its pole-phase changing performance.
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| 3. |
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| 4. |
- Bitsi, Konstantina, et al.
(author)
-
An Induction Machine with Wound Independently-Controlled Stator Coils
- 2019
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In: Proceedings of the 22nd International Conference on Electrical Machines and Systems (ICEMS). - : IEEE.
-
Conference paper (peer-reviewed)abstract
- In this paper, a novel induction machine topology with wound, independently-controlled stator coils is presented. The introduced configuration of the stator-winding enables the individual energization and control of the coils in each stator slot. Therefore, the possibility of changing the number of poles and active phases in the stator winding during operation is explored in this study.
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| 5. |
- Bitsi, Konstantina, et al.
(author)
-
Design Aspects and Performance Evaluation of Pole-Phase Changing Induction Machines
- 2022
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In: Energies. - : MDPI AG. - 1996-1073. ; 15:19, s. 7012-7012
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Journal article (peer-reviewed)abstract
- Pole-phase changing induction machines (IMs) offer the capability to extend the torque-speed envelope compared to their fixed pole-phase counterparts. Dynamic pole-changing can achieve higher torque levels at lower speeds, utilizing higher pole numbers, and extended flux-weakening range with lower pole-number operations. This paper investigates the design impact on the optimum pole-phase changing behavior and respective split of the operating region to different pole-phase operations. Additionally, the improvement in terms of the overall torque per ampere capability and efficiency is illustrated. For the purposes of the analysis, two different IMs with wound independently-controlled stator coils (WICSC) and different original pole numbers are evaluated in an effort to quantify the extent of the benefits of pole-phase changing. These geometries correspond to machines that were originally designed with 2- and 6 magnetic poles, respectively. It is shown that, in the case of the original 2-pole WICSC machine, shifting to a higher pole number is notably beneficial in terms of efficiency in a significant part of the operating region, whereas in the original 6-pole, both higher and lower pole numbers significantly enhance the overall torque capability and efficiency. The results highlight the notable benefits of pole-phase changing IMs and offer deep insight towards the derivation of standard design guidelines for these machines.
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| 6. |
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| 7. |
- Bitsi, Konstantina, et al.
(author)
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Many-objective Optimization of IPM and Induction Motors for Automotive Application
- 2019
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Conference paper (peer-reviewed)abstract
- This paper presents a Pareto-optimality-based optimization methodology suitable for the design of electrical motors in automotive applications. The proposed many-objective evolutionary algorithm is utilized in this study case for the optimization of an interior permanent-magnet (IPM) synchronous motor and an induction motor (IM), considering as criteria the motors' torque capability, efficiency as well as torque density. Finite-element (FE) models of the investigated motor topologies are developed and incorporated in the optimization process in order to ensure an accurate estimation of their electromagnetic performance. The attainment of the targeted specifications by the final optimal designs validates the efficacy of the implemented optimization algorithm.
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| 8. |
- Bitsi, Konstantina, 1992-, et al.
(author)
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Novel approach in investigating the rotor lamination iron losses
- 2017
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In: 2017 IEEE International Electric Machines and Drives Conference (IEMDC). - : IEEE conference proceedings.
-
Conference paper (peer-reviewed)abstract
- This paper presents a 2-D design of a measurement setup that subjects laminated steel to field conditions corresponding to the ones of the rotor in a Salient Pole Synchronous Machine (SPSM). This stationary setup exposes the test samples to traveling magnetic waves in an air-gap. The purpose of this setup is to simulate the eddy current losses that result from high frequency magnetic fields within the volume of the test samples. The investigation of the design and the dimensioning of the model is conducted in a 2-D Finite Element Method (FEM) model. The study shows that it is possible to emulate traveling sinusoidal magnetic flux in the air-gap of a setup excluding motion. A rectangular shape of the setup was chosen due to the expected flexibility of the design as well as easy manufacturing. It was found that in order to achieve a constant amplitude of the traveling wave in the air-gap an implementation of an auxiliary winding is an effective solution.
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| 9. |
- Bitsi, Konstantina
(author)
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On Electrical Machine Topologies for Electric Vehicle Applications
- 2022
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Doctoral thesis (other academic/artistic)abstract
- The deployment of electric vehicles is considered a viable solution towardsreducing the global greenhouse-gas emissions and fossil-fuel consumption. Inorder to produce highly efficient and economically feasible electrical drivesystems, the selection of suitable electric motor designs is a key step.The target of this work is to identify, analyze and compare suitable elec-trical machine topologies for automotive applications based on highly coupledand conflicting criteria. For this purpose, an evolutionary multi-objective op-timization is developed that can yield a set of Pareto-optimal solutions and,thus, offer different compromises among the considered design-objectives. Theefficacy of the algorithm is demonstrated, rendering it an important tool forthe subsequent analysis.In the first part of this thesis, the investigation of pole-phase changinginduction machines is presented. A special induction machine topology withwound, independently-controlled stator coils (WICSC) is introduced. Thestator-winding configuration in this machine permits the individual energiza-tion and current control of the toroidal coil in each stator slot, thus facilitatingthe real-time change of both phase and pole number. The 2D magnetic and3D thermal finite-element method (FEM) models of this machine are devel-oped, as well as an analytical transient model of the current dynamics. Adetailed investigation of the behavior of pole-phase changing induction ma-chines and the impact of their design on the selection of optimum pole-phaseoperations throughout the entire operating region is performed. Specifically,three WICSC machines that were originally designed with 2, 4 and 6 fixedmagnetic poles are evaluated as pole-phase changing machines with the aim ofdetermining the overall improvement in terms of torque per ampere capabilityand efficiency.The second part of this work is focused on the design and performance ofaxial-flux induction machines (AFIMs). An electromagnetic sizing algorithmfor the design of AFIMs is developed, which adopts a geometrical approachto the design problem, while minimizing the use of empirical factors. Theeffectiveness of this algorithm is experimentally validated, using a commercialdouble-stator AFIM utilized as an integrated starter generator in a hybridelectric vehicle application. Moreover, in order to assess the benefits of pole-changing in axial-flux structures, the optimization of an interior-permanentmagnet synchronous machine, a radial-flux WICSC machine and a double-rotor axial-flux WICSC machine is carried out for a heavy vehicle applicationand the comparison of their Pareto-optimal solutions is presented.
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| 10. |
- Bitsi, Konstantina, et al.
(author)
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Preliminary Electromagnetic Sizing of Axial-Flux Induction Machines
- 2020
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In: Proceedings of the 2020 International Conference on Electrical Machines (ICEM). - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- This paper presents a preliminary electromagnetic sizing algorithm for double-rotor axial-flux induction machines (DR-AFIMs). The proposed algorithm is based on a geometrical approach and limits the use of empirical factors and past experience. The sizing equations for all the main geometrical and operational machine parameters are derived and a concise outline of the electromagnetic sizing algorithm is provided. The efficacy of the implemented algorithm is validated using finiteelement DR-AFIM models. The achievement of the targeted specifications in the preliminary DR-AFIM designs is proven and demonstrated.
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