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Mr. Hans Tiismus
Tallinn University of Technology (TalTech)

Basic Info


Research Keywords & Expertise

0 Additive Manufacturing
0 Electrical Machines
0 Optimization
0 Selective laser melting
0 soft magnetic materials

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Additive Manufacturing
Electrical Machines
Selective laser melting
Optimization
soft magnetic materials

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Short Biography

Hans Tiismus was born in 1989 in Tallinn, Estonia. He received his BSc and MSc degrees in engineering physics from Tallinn University of Technology, Estonia, in 2011, 2013 respectively. He is currently a junior researcher and a PhD student in Tallinn University of Technology, Department of Electrical Power Engineering and Mechatronics. His main research interest is the additive manufacturing of electrical machines, the material properties and optimization of 3D printed soft ferromagnetic materials and components.

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Journal article
Published: 18 June 2021 in Machines
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This paper presents the analytical calculation of the heat transfer coefficient of a complex housing shape of a Totally Enclosed Fan-Cooled (TEFC) industrial machine when it works below 20% of its nominal speed or close to stall. Therefore, passive cooling is dominant, and most of the heat is extracted by the combination of natural convection and radiation phenomena. Under these conditions, the area-based composite approach was used for the development of the analytical calculation method. A test rig using a TEFC Synchronous Reluctance Motor (SynRM) was constructed, and the collected experimental data was used to validate the proposed analytical method successfully.

ACS Style

Payam Shams Ghahfarokhi; Andrejs Podgornovs; Ants Kallaste; Antonio Cardoso; Anouar Belahcen; Toomas Vaimann; Bilal Asad; Hans Tiismus. Determination of Heat Transfer Coefficient from Housing Surface of a Totally Enclosed Fan-Cooled Machine during Passive Cooling. Machines 2021, 9, 120 .

AMA Style

Payam Shams Ghahfarokhi, Andrejs Podgornovs, Ants Kallaste, Antonio Cardoso, Anouar Belahcen, Toomas Vaimann, Bilal Asad, Hans Tiismus. Determination of Heat Transfer Coefficient from Housing Surface of a Totally Enclosed Fan-Cooled Machine during Passive Cooling. Machines. 2021; 9 (6):120.

Chicago/Turabian Style

Payam Shams Ghahfarokhi; Andrejs Podgornovs; Ants Kallaste; Antonio Cardoso; Anouar Belahcen; Toomas Vaimann; Bilal Asad; Hans Tiismus. 2021. "Determination of Heat Transfer Coefficient from Housing Surface of a Totally Enclosed Fan-Cooled Machine during Passive Cooling." Machines 9, no. 6: 120.

Journal article
Published: 03 June 2021 in Energies
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Additive manufacturing of ferromagnetic materials for electrical machine applications is maturing. In this work, a full E-type transformer core is printed, characterized, and compared in terms of performance with a conventional Goss textured core. For facilitating a modular winding and eddy current loss reduction, the 3D printed core is assembled from four novel interlocking components, which structurally imitate the E-type core laminations. Both cores are compared at approximately their respective optimal working conditions, at identical magnetizing currents. Due to the superior magnetic properties of the Goss sheet conventional transformer core, 10% reduced efficiency (from 80.5% to 70.1%) and 34% lower power density (from 59 VA/kg to 39 VA/kg) of the printed transformer are identified at operating temperature. The first prototype transformer core demonstrates the state of the art and initial optimization step for further development of additively manufactured soft ferromagnetic components. Further optimization of both the 3D printed material and core design are proposed for obtaining higher electrical performance for AC applications.

ACS Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Anton Rassolkin; Toomas Vaimann; Payam Shams Ghahfarokhi. Additive Manufacturing and Performance of E-Type Transformer Core. Energies 2021, 14, 3278 .

AMA Style

Hans Tiismus, Ants Kallaste, Anouar Belahcen, Anton Rassolkin, Toomas Vaimann, Payam Shams Ghahfarokhi. Additive Manufacturing and Performance of E-Type Transformer Core. Energies. 2021; 14 (11):3278.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Anton Rassolkin; Toomas Vaimann; Payam Shams Ghahfarokhi. 2021. "Additive Manufacturing and Performance of E-Type Transformer Core." Energies 14, no. 11: 3278.

Journal article
Published: 29 April 2021 in IEEE Access
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In the above article [1] , Figs. 3 and 19 are modified versions of Fig. 18 from the article. Although this source was cited in our article as [6], the captions for these figures are missing the appropriate citation/reference.

ACS Style

Payam Shams Ghahfarokhi; Andrejs Podgornovs; Ants Kallaste; Antonio J. Marques Cardoso; Anouar Belahcen; Toomas Vaimann; Hans Tiismus; Bilal Asad. Corrections to “Opportunities and Challenges of Utilizing Additive Manufacturing Approaches in Thermal Management of Electrical Machines”. IEEE Access 2021, 9, 62532 -62532.

AMA Style

Payam Shams Ghahfarokhi, Andrejs Podgornovs, Ants Kallaste, Antonio J. Marques Cardoso, Anouar Belahcen, Toomas Vaimann, Hans Tiismus, Bilal Asad. Corrections to “Opportunities and Challenges of Utilizing Additive Manufacturing Approaches in Thermal Management of Electrical Machines”. IEEE Access. 2021; 9 ():62532-62532.

Chicago/Turabian Style

Payam Shams Ghahfarokhi; Andrejs Podgornovs; Ants Kallaste; Antonio J. Marques Cardoso; Anouar Belahcen; Toomas Vaimann; Hans Tiismus; Bilal Asad. 2021. "Corrections to “Opportunities and Challenges of Utilizing Additive Manufacturing Approaches in Thermal Management of Electrical Machines”." IEEE Access 9, no. : 62532-62532.

Journal article
Published: 24 February 2021 in Energies
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Additively manufactured soft magnetic Fe-3.7%w.t.Si toroidal samples with solid and novel partitioned cross-sectional geometries are characterized through magnetic measurements. This study focuses on the effect of air gaps and annealing temperature on AC core losses at the 50 Hz frequency. In addition, DC electromagnetic material properties are presented, showing comparable results to conventional and other 3D-printed, high-grade, soft magnetic materials. The magnetization of 1.5 T was achieved at 1800 A/m, exhibiting a maximum relative permeability of 28,900 and hysteresis losses of 0.61 (1 T) and 1.7 (1.5 T) W/kg. A clear trend of total core loss reduction at 50 Hz was observed in relation to the segregation of the specimen cross-sectional topology. The lowest 50 Hz total core losses were measured for the toroidal specimen with four internal air gaps annealed at 1200 °C, exhibiting a total core loss of 1.2 (1 T) and 5.5 (1.5 T) W/kg. This is equal to an 860% total core loss reduction at 1 T and a 510% loss reduction at 1.5 T magnetization compared to solid bulk-printed material. Based on the findings, the advantages and disadvantages of printed air-gapped material internal structures are discussed in detail.

ACS Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Marek Tarraste; Toomas Vaimann; Anton Rassõlkin; Bilal Asad; Payam Shams Ghahfarokhi. AC Magnetic Loss Reduction of SLM Processed Fe-Si for Additive Manufacturing of Electrical Machines. Energies 2021, 14, 1241 .

AMA Style

Hans Tiismus, Ants Kallaste, Anouar Belahcen, Marek Tarraste, Toomas Vaimann, Anton Rassõlkin, Bilal Asad, Payam Shams Ghahfarokhi. AC Magnetic Loss Reduction of SLM Processed Fe-Si for Additive Manufacturing of Electrical Machines. Energies. 2021; 14 (5):1241.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Marek Tarraste; Toomas Vaimann; Anton Rassõlkin; Bilal Asad; Payam Shams Ghahfarokhi. 2021. "AC Magnetic Loss Reduction of SLM Processed Fe-Si for Additive Manufacturing of Electrical Machines." Energies 14, no. 5: 1241.

Journal article
Published: 20 February 2021 in Electronics
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In recent decades, the genetic algorithm (GA) has been extensively used in the design optimization of electromagnetic devices. Despite the great merits possessed by the GA, its processing procedure is highly time-consuming. On the contrary, the widely applied Taguchi optimization method is faster with comparable effectiveness in certain optimization problems. This study explores the abilities of both methods within the optimization of a permanent magnet coupling, where the optimization objectives are the minimization of coupling volume and maximization of transmitted torque. The optimal geometry of the coupling and the obtained characteristics achieved by both methods are nearly identical. The magnetic torque density is enhanced by more than 20%, while the volume is reduced by 17%. Yet, the Taguchi method is found to be more time-efficient and effective within the considered optimization problem. Thanks to the additive manufacturing techniques, the initial design and the sophisticated geometry of the Taguchi optimal designs are precisely fabricated. The performances of the coupling designs are validated using an experimental setup.

ACS Style

Ekaterina Andriushchenko; Ants Kallaste; Anouar Belahcen; Toomas Vaimann; Anton Rassõlkin; Hamidreza Heidari; Hans Tiismus. Optimization of a 3D-Printed Permanent Magnet Coupling Using Genetic Algorithm and Taguchi Method. Electronics 2021, 10, 494 .

AMA Style

Ekaterina Andriushchenko, Ants Kallaste, Anouar Belahcen, Toomas Vaimann, Anton Rassõlkin, Hamidreza Heidari, Hans Tiismus. Optimization of a 3D-Printed Permanent Magnet Coupling Using Genetic Algorithm and Taguchi Method. Electronics. 2021; 10 (4):494.

Chicago/Turabian Style

Ekaterina Andriushchenko; Ants Kallaste; Anouar Belahcen; Toomas Vaimann; Anton Rassõlkin; Hamidreza Heidari; Hans Tiismus. 2021. "Optimization of a 3D-Printed Permanent Magnet Coupling Using Genetic Algorithm and Taguchi Method." Electronics 10, no. 4: 494.

Journal article
Published: 06 January 2021 in Energies
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This paper presents an algorithm to remove the DC drift from the B-H curve of an additively manufactured soft ferromagnetic material. The removal of DC drift from the magnetization curve is crucial for the accurate estimation of iron losses. The algorithm is based on the sliding mean value subtraction from each cycle of calculated magnetic flux density (B) signal. The sliding mean values (SMVs) are calculated using the convolution theorem, where a DC kernel with a length equal to the size of one cycle is convolved with B to recover the drifting signal. The results are based on the toroid measurements made by selective laser melting (SLM)-based 3D printing mechanism. The measurements taken at different flux density values show the effectiveness of the method.

ACS Style

Bilal Asad; Hans Tiismus; Toomas Vaimann; Anouar Belahcen; Ants Kallaste; Anton Rassõlkin; Payam Shams Ghafarokhi. Sliding Mean Value Subtraction-Based DC Drift Correction of B-H Curve for 3D-Printed Magnetic Materials. Energies 2021, 14, 284 .

AMA Style

Bilal Asad, Hans Tiismus, Toomas Vaimann, Anouar Belahcen, Ants Kallaste, Anton Rassõlkin, Payam Shams Ghafarokhi. Sliding Mean Value Subtraction-Based DC Drift Correction of B-H Curve for 3D-Printed Magnetic Materials. Energies. 2021; 14 (2):284.

Chicago/Turabian Style

Bilal Asad; Hans Tiismus; Toomas Vaimann; Anouar Belahcen; Ants Kallaste; Anton Rassõlkin; Payam Shams Ghafarokhi. 2021. "Sliding Mean Value Subtraction-Based DC Drift Correction of B-H Curve for 3D-Printed Magnetic Materials." Energies 14, no. 2: 284.

Journal article
Published: 18 September 2020 in Applied Sciences
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Samples from FeSi4 powder were fabricated with a low power selective laser melting (SLM) system using a laser re-melting strategy. The sample material was characterized through magnetic measurements. The study showed excellent DC magnetic properties, comparable to commercial and other 3D printed soft ferromagnetic materials from the literature at low (1 T) magnetization. Empirical total core losses were segregated into hysteresis, eddy and excessive losses via the subtraction of finite element method (FEM) simulated eddy current losses and hysteresis losses measured at quasi-static conditions. Hysteresis losses were found to decrease from 3.65 to 0.95 W/kg (1 T, 50 Hz) after the annealing. Both empirical and FEM results confirm considerable eddy currents generated in the printed bulk toroidal sample, which increase dramatically at high material saturation after annealing. These losses could potentially be reduced by using partitioned material internal structure realized by printed airgaps. Similarly, with regard to the samples characterized in this study, the substantially increased core losses induced by material oversaturation due to reduced filling factor may present a challenge in realizing 3D printed electrical machines with comparable performance to established 2D laminated designs.

ACS Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Toomas Vaimann; Anton Rassõlkin; Dmitry Lukichev. Hysteresis Measurements and Numerical Losses Segregation of Additively Manufactured Silicon Steel for 3D Printing Electrical Machines. Applied Sciences 2020, 10, 6515 .

AMA Style

Hans Tiismus, Ants Kallaste, Anouar Belahcen, Toomas Vaimann, Anton Rassõlkin, Dmitry Lukichev. Hysteresis Measurements and Numerical Losses Segregation of Additively Manufactured Silicon Steel for 3D Printing Electrical Machines. Applied Sciences. 2020; 10 (18):6515.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Toomas Vaimann; Anton Rassõlkin; Dmitry Lukichev. 2020. "Hysteresis Measurements and Numerical Losses Segregation of Additively Manufactured Silicon Steel for 3D Printing Electrical Machines." Applied Sciences 10, no. 18: 6515.

Conference paper
Published: 01 October 2019 in 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
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Today, dedicated metal 3D printing platforms can produce industrial grade homo-material metal components, promoting the fabrication of soft magnetic components for electrical machines with three-dimensionally optimized topologies. The printed components have been shown to exhibit excellent DC magnetic properties, indicating the maturity of the technology for applications incorporating quasi-static magnetic fields, such as magnetic couplings or rotors of synchronous machines. In the paper, finite element modeling of a synchronous reluctance magnetic coupling is investigated. Previously 3D printed and researched material of electrical steel with 6.5% added silicon content with selective laser melting is adopted in the model, alongside the printing limitations of the printing system. Commercial finite element modeling software COMSOL Multiphysics is employed for modeling. Printing of the modeled coupling was currently unsuccessful due to unoptimized printing parameters.

ACS Style

Hans Tiismus; Ants Kallaste; Toomas Vaimann; Anton Rassõlkin; Anouar Belahcen. Axial Synchronous Magnetic Coupling Modeling and Printing with Selective Laser Melting. 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) 2019, 1 -4.

AMA Style

Hans Tiismus, Ants Kallaste, Toomas Vaimann, Anton Rassõlkin, Anouar Belahcen. Axial Synchronous Magnetic Coupling Modeling and Printing with Selective Laser Melting. 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON). 2019; ():1-4.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Toomas Vaimann; Anton Rassõlkin; Anouar Belahcen. 2019. "Axial Synchronous Magnetic Coupling Modeling and Printing with Selective Laser Melting." 2019 IEEE 60th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON) , no. : 1-4.

Conference paper
Published: 01 August 2019 in 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED)
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3D printing or additive manufacturing (AM) technology is considered an essential component of the Industry 4.0 revolution due to its improved capabilities over traditional manufacturing systems, facilitating the shift towards next generation smart factories. The three-dimensional fabrication freedom also suggests a new epoch in the design of electrical machines, as the process can finally be liberated from the constraints of 2D laminations. Despite the multi-material nature of 3D printing electrical machines, due to the availability and maturity of dedicated metal printing systems, most of the research and development on the field is concentrated on material optimization and rapid prototyping on these systems. In this paper we present the challenges of 3D printing electrical machines with current manufacturing systems and solutions offered by different authors. Challenges of selective laser melting (SLM) fabrication are discussed in greater detail due to its recognition and popularity in the electrical machine community.

ACS Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Anton Rassõlkin; Toomas Vaimann. Challenges of Additive Manufacturing of Electrical Machines. 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) 2019, 44 -48.

AMA Style

Hans Tiismus, Ants Kallaste, Anouar Belahcen, Anton Rassõlkin, Toomas Vaimann. Challenges of Additive Manufacturing of Electrical Machines. 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED). 2019; ():44-48.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Anouar Belahcen; Anton Rassõlkin; Toomas Vaimann. 2019. "Challenges of Additive Manufacturing of Electrical Machines." 2019 IEEE 12th International Symposium on Diagnostics for Electrical Machines, Power Electronics and Drives (SDEMPED) , no. : 44-48.

Conference paper
Published: 01 June 2019 in 2019 20th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM)
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Additive manufacturing (AM) technology is considered an essential component of the Industry 4.0 revolution, due to its capability for decentralized production of highly customizable complex objects. Its design and fabrication freedom also suggest for the production capacity of goods with embedded electromechanical components and even electrical machines with enhanced performance. Currently, due to the maturity of homo-material and limited multi-material capabilities of current AM systems, prototyping of 3D printed electrical machines has taken the path of manual assembly of printed components. For fully printed end-user products containing integrated electromechanical components to emerge, evolution of the multi-material printing systems is required. This paper discusses the technical demands of additively manufacturing electrical machines and current promising technologies on the horizon to bring us one step closer to mass produced fully 3D printed electrical machines.

ACS Style

Hans Tiismus; Ants Kallaste; Toomas Vaimann; Anton Rassõlkin; Anouar Belahcen. Technologies for Additive Manufacturing of Electrical Machines. 2019 20th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) 2019, 651 -655.

AMA Style

Hans Tiismus, Ants Kallaste, Toomas Vaimann, Anton Rassõlkin, Anouar Belahcen. Technologies for Additive Manufacturing of Electrical Machines. 2019 20th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM). 2019; ():651-655.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Toomas Vaimann; Anton Rassõlkin; Anouar Belahcen. 2019. "Technologies for Additive Manufacturing of Electrical Machines." 2019 20th International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM) , no. : 651-655.

Conference paper
Published: 01 June 2019 in 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM)
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Additive manufacturing, commonly labeled as 3D printing is an essential component of the next industrial revolution, enabling both unprecedented fabrication freedom and streamlined production and logistics. Traditionally, the electrical machine cores are stacked from varnished soft magnetic laminations, which deliver reduced eddy and hysteresis losses during machine operation. Presently, dedicated metal printing platforms can produce industrial grade homo-material metal components, promoting the fabrication of machines with highly complex topologies, but also increasing the eddy current induced in these components, due to lack of laminated structure. In this paper, we present experimental resistivity measurement results of 3% and 6.5% silicon content steel fabricated with selective laser melting.

ACS Style

Hans Tiismus; Ants Kallaste; Toomas Vaimann; Anton Rassõlkin; Anouar Belahcen. Electrical Resistivity of Additively Manufactured Silicon Steel for Electrical Machine Fabrication. 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) 2019, 1 -4.

AMA Style

Hans Tiismus, Ants Kallaste, Toomas Vaimann, Anton Rassõlkin, Anouar Belahcen. Electrical Resistivity of Additively Manufactured Silicon Steel for Electrical Machine Fabrication. 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM). 2019; ():1-4.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Toomas Vaimann; Anton Rassõlkin; Anouar Belahcen. 2019. "Electrical Resistivity of Additively Manufactured Silicon Steel for Electrical Machine Fabrication." 2019 Electric Power Quality and Supply Reliability Conference (PQ) & 2019 Symposium on Electrical Engineering and Mechatronics (SEEM) , no. : 1-4.

Journal article
Published: 01 April 2019 in Key Engineering Materials
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Additive manufacturing (AM) technology has the potential to revolutionize multiple fields of industry Defect formation is a common problem in all AM processes. For the applicability of this technology for manufacturing electrical machines, specific mechanical and electromagnetic properties of printed material are necessary. In this paper we present a literature review on the effects of production parameters on the printed material properties, alongside experimental results of printed electrical steel sample properties with default processing parameters.

ACS Style

Hans Tiismus; Ants Kallaste; Anton Rassõlkin; Toomas Vaimann. Preliminary Analysis of Soft Magnetic Material Properties for Additive Manufacturing of Electrical Machines. Key Engineering Materials 2019, 799, 270 -275.

AMA Style

Hans Tiismus, Ants Kallaste, Anton Rassõlkin, Toomas Vaimann. Preliminary Analysis of Soft Magnetic Material Properties for Additive Manufacturing of Electrical Machines. Key Engineering Materials. 2019; 799 ():270-275.

Chicago/Turabian Style

Hans Tiismus; Ants Kallaste; Anton Rassõlkin; Toomas Vaimann. 2019. "Preliminary Analysis of Soft Magnetic Material Properties for Additive Manufacturing of Electrical Machines." Key Engineering Materials 799, no. : 270-275.

Conference paper
Published: 01 January 2019 in 2019 26th International Workshop on Electric Drives: Improvement in Efficiency of Electric Drives (IWED)
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Additive manufacturing, also known as 3D printing, is opening up new ground for innovations in low-volume production due to faster and cheaper prototyping, reduced lead time and shorter supply chains. Using the 3D printing in design of electrical machines is also facing different challenges in control of machines. This paper discusses material and manufacture drawbacks caused by Selective Laser Melting technology, mainly mechanical defects. Special attention is paid to control algorithms of first prototypes and design of converter. Moreover, an overview of control strategies for small Switched Reluctance Motors is presented.

ACS Style

Anton Rassõlkin; Ants Kallaste; Toomas Vaimann; Hans Tiismus. Control Challenges of 3D Printed Switched Reluctance Motor. 2019 26th International Workshop on Electric Drives: Improvement in Efficiency of Electric Drives (IWED) 2019, 1 -5.

AMA Style

Anton Rassõlkin, Ants Kallaste, Toomas Vaimann, Hans Tiismus. Control Challenges of 3D Printed Switched Reluctance Motor. 2019 26th International Workshop on Electric Drives: Improvement in Efficiency of Electric Drives (IWED). 2019; ():1-5.

Chicago/Turabian Style

Anton Rassõlkin; Ants Kallaste; Toomas Vaimann; Hans Tiismus. 2019. "Control Challenges of 3D Printed Switched Reluctance Motor." 2019 26th International Workshop on Electric Drives: Improvement in Efficiency of Electric Drives (IWED) , no. : 1-5.