TY  - CHAP
A1  - Wittig, M.
A1  - Rütters, René
A1  - Bragard, Michael
ED  - Reiff-Stephan, Jörg
ED  - Jäkel, Jens
ED  - Schwarz, André
T1  - Application of RL in control systems using the example of a rotatory inverted pendulum
T2  - Tagungsband AALE 2024 : Fit für die Zukunft: praktische Lösungen für die industrielle Automation
N2  - In this paper, the use of reinforcement learning (RL) in control systems is investigated using a rotatory inverted pendulum as an example. The control behavior of an RL controller is compared to that of traditional LQR and MPC controllers. This is done by evaluating their behavior under optimal conditions, their disturbance behavior, their robustness and their development process. All the investigated controllers are developed using MATLAB and the Simulink simulation environment and later deployed to a real pendulum model powered by a Raspberry Pi. The RL algorithm used is Proximal Policy Optimization (PPO). The LQR controller exhibits an easy development process, an average to good control behavior and average to good robustness. A linear MPC controller could show excellent results under optimal operating conditions. However, when subjected to disturbances or deviations from the equilibrium point, it showed poor performance and sometimes instable behavior. Employing a nonlinear MPC Controller in real time was not possible due to the high computational effort involved. The RL controller exhibits by far the most versatile and robust control behavior. When operated in the simulation environment, it achieved a high control accuracy. When employed in the real system, however, it only shows average accuracy and a significantly greater performance loss compared to the simulation than the traditional controllers. With MATLAB, it is not yet possible to directly post-train the RL controller on the Raspberry Pi, which is an obstacle to the practical application of RL in a prototyping or teaching setting. Nevertheless, RL in general proves to be a flexible and powerful control method, which is well suited for complex or nonlinear systems where traditional controllers struggle.
KW  - Rotatory Inverted Pendulum
KW  - MPC
KW  - LQR
KW  - PPO
KW  - Reinforcement Learning
Y1  - 2024
SN  - 978-3-910103-02-3
U6  - http://dx.doi.org/10.33968/2024.53
N1  - 20. AALE-Konferenz. Bielefeld, 06.03.-08.03.2024.
(Tagungsband unter https://doi.org/10.33968/2024.29)
SP  - 241
EP  - 248
PB  - le-tex publishing services GmbH
CY  - Leipzig
ER  - 
TY  - PAT
A1  - Bragard, Michael
A1  - Hüning, Felix
A1  - Kowalewski, Paul
T1  - Vorrichtung zur Relativlagenbestimmung [Offenlegungschrift]
N2  - Die Erfindung betrifft eine Vorrichtung zur Bestimmung einer Relativlage zwischen einem feststehenden Teil und einem zu demselben in eine Bewegungsrichtung bewegbaren beweglichen Teil, wobei der feststehende Teil mit einem Wiegandsensor versehen ist, wobei der Wiegandsensor zwischen zwei gegenpolig zueinander ausgebildeten Permanentmagneten angeordnet ist und dass der bewegliche Teil eine Mehrzahl von beabstandet zueinander angeordneten Magnetisierungsstegen aus einem magnetisch leitenden Material aufweist, die in der Bewegungsrichtung zumindest eine gleich große Erstreckung aufweisen wie der Permanentmagnet, dass ein Abstand zwischen benachbarten Magnetisierungsstegen derart gewählt ist, dass in einer ersten Relativlage ein erster Permanentmagnet von einem der Magnetisierungsstege überdeckt ist und ein zweiter Permanentmagnet nicht von einem der Magnetisierungsstege überdeckt ist.
Y1  - 2023
N1  - Offenlegungschrift zu DE102022115350A1 2023.12.21
ER  - 
TY  - JOUR
A1  - Kowalewski, Paul
A1  - Bragard, Michael
A1  - Hüning, Felix
A1  - De Doncker, Rik W.
T1  - An inexpensive Wiegand-sensor-based rotary encoder without rotating magnets for use in electrical drives
JF  - IEEE Transactions on Instrumentation and Measurement
N2  - This paper introduces an inexpensive Wiegand-sensor-based rotary encoder that avoids rotating magnets and is suitable for electrical-drive applications. So far, Wiegand-sensor-based encoders usually include a magnetic pole wheel with rotating permanent magnets. These encoders combine the disadvantages of an increased magnet demand and a limited maximal speed due to the centripetal force acting on the rotating magnets. The proposed approach reduces the total demand of permanent magnets drastically. Moreover, the rotating part is manufacturable from a single piece of steel, which makes it very robust and cheap. This work presents the theoretical operating principle of the proposed approach and validates its benefits on a hardware prototype. The presented proof-of-concept prototype achieves a mechanical resolution of 4.5 ° by using only 4 permanent magnets, 2Wiegand sensors and a rotating steel gear wheel with 20 teeth.
KW  - Rotary encoder
KW  - Wiegand sensor
Y1  - 2023
U6  - http://dx.doi.org/10.1109/TIM.2023.3326166
SN  - 0018-9456 (Print)
SN  - 1557-9662 (Online)
N1  - Early Access
SP  - 10 Seiten
PB  - IEEE
ER  - 
TY  - CHAP
A1  - Ostkotte, Sebastian
A1  - Peters, Constantin
A1  - Hüning, Felix
A1  - Bragard, Michael
T1  - Design, implementation and verification of an rotational incremental position encoder based on the magnetic Wiegand effect
T2  - 2022 ELEKTRO (ELEKTRO)
N2  - This paper covers the use of the magnetic Wiegand effect to design an innovative incremental encoder. First, a theoretical design is given, followed by an estimation of the achievable accuracy and an optimization in open-loop operation.
Finally, a successful experimental verification is presented. For this purpose, a permanent magnet synchronous machine is controlled in a field-oriented manner, using the angle information of the prototype.
KW  - Position Encoder
KW  - Rotational Encoder
KW  - Wiegand Effect
KW  - Angle Sensor
KW  - Incremental Encoder
Y1  - 2022
SN  - 978-1-6654-6726-1
SN  - 978-1-6654-6727-8
U6  - http://dx.doi.org/10.1109/ELEKTRO53996.2022.9803477
SN  - 2691-0616
N1  - 2022 ELEKTRO (ELEKTRO), 23-26 Mai 2022, Krakow, Poland.
PB  - IEEE
ER  - 
TY  - CHAP
A1  - Hoegen, Anne von
A1  - Doncker, Rik W. De
A1  - Bragard, Michael
A1  - Hoegen, Svenja von
T1  - Problem-Based Learning in Automation Engineering: Performing a Remote Laboratory Session Serving Various Educational Attainments
T2  - 2021 IEEE Global Engineering Education Conference (EDUCON)
Y1  - 2021
U6  - http://dx.doi.org/10.1109/EDUCON46332.2021.9453925
SP  - 1605
EP  - 1614
ER  - 
TY  - CHAP
A1  - Schiffer, Fabian
A1  - Bragard, Michael
T1  - Cascaded LQ and Field-Oriented Control of a Mobile Inverse Pendulum (Segway) with Permanent Magnet Synchronous Machines
T2  - 2019 20th International Conference on Research and Education in Mechatronics (REM)
Y1  - 2019
SN  - 978-1-5386-9257-8
U6  - http://dx.doi.org/10.1109/REM.2019.8744101
SP  - 1
EP  - 8
ER  - 
TY  - CHAP
A1  - Bragard, Michael
A1  - Sube, Maike
A1  - Schneider, Maike
A1  - Jungemann, Christoph
T1  - Introducing a Cross-University Bachelor’s Programme with Orientation Semester - Enabling a Permeable Academic Education System
T2  - 2019 20th International Conference on Research and Education in Mechatronics (REM)
Y1  - 2019
SN  - 978-1-5386-9257-8
U6  - http://dx.doi.org/10.1109/REM.2019.8744132
SP  - 1
EP  - 6
ER  - 
TY  - CHAP
A1  - Finger, Felix
A1  - Khalsa, R.
A1  - Kreyer, Jörg
A1  - Mayntz, Joscha
A1  - Braun, Carsten
A1  - Dahmann, Peter
A1  - Esch, Thomas
A1  - Kemper, Hans
A1  - Schmitz, O.
A1  - Bragard, Michael
T1  - An approach to propulsion system modelling for the conceptual design of hybrid-electric general aviation aircraft
T2  - Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt
N2  - In this paper, an approach to propulsion system modelling for hybrid-electric general aviation aircraft is presented. Because the focus is on general aviation aircraft, only combinations of electric motors and reciprocating combustion engines are explored. Gas turbine hybrids will not be considered. The level of the component's models is appropriate for the conceptual design stage. They are simple and adaptable, so that a wide range of designs with morphologically different propulsive system architectures can be quickly compared. Modelling strategies for both mass and efficiency of each part of the propulsion system (engine, motor, battery and propeller) will be presented.
Y1  - 2019
ER  - 
TY  - CHAP
A1  - Bindzus, Manuel
A1  - Bragard, Michael
T1  - Motivating Intuitive Understanding of the Switched Reluctance Machine in the Education of Undergraduate Students
T2  - 2018 IEEE 59th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
Y1  - 2018
SN  - 978-1-5386-6903-7
U6  - http://dx.doi.org/10.1109/RTUCON.2018.8659870
SP  - 1
EP  - 6
ER  - 
TY  - CHAP
A1  - Bragard, Michael
A1  - Hoek, Hauke van
A1  - Hoegen, Anne von
A1  - Doncker, Rik W. De
T1  - Motivation-based Learning: Teaching Fundamentals of Electrical Engineering with an LED Spinning Top
T2  - 2018 IEEE 59th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
Y1  - 2018
SN  - 978-1-5386-6903-7
U6  - http://dx.doi.org/10.1109/RTUCON.2018.8659810
SP  - 1
EP  - 6
ER  - 
TY  - CHAP
A1  - Rütters, René
A1  - Weinheimer, Marius
A1  - Bragard, Michael
T1  - Teaching Control Theory with a Simplified Helicopter Model and a Classroom Fitting Hardware Test-Bench
T2  - 2018 IEEE 59th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
Y1  - 2018
SN  - 978-1-5386-6903-7
U6  - http://dx.doi.org/10.1109/RTUCON.2018.8659871
ER  - 
TY  - JOUR
A1  - Lambers, Andreas
A1  - Bragard, Michael
T1  - Kinetische Skulptur - Treffen sich ein E-Techniker und ein Künstler ...
JF  - Elektor : learn, design, share
N2  - Die Verbindung der Welten dressierter Elektronen und grenzenloser Kreativität bietet ein großes Potential; zum Beispiel bei modernen Skulpturen, deren Form sich durch Motoren verändern kann. An der FH Aachen wurde ein solches Projekt verwirklicht: Eine Matrix aus Holzkugeln kann Piktogramme anzeigen, aber auch mathematische Funktionen visualisieren. In diesem Artikel beschreiben wir die clevere Ansteuerung der Motoren.
Y1  - 2017
SN  - 0932-5468
VL  - 48
IS  - 9
SP  - 78
EP  - 83
PB  - Elektor-Verlag
CY  - Aachen
ER  - 
TY  - CHAP
A1  - Endress, Tim
A1  - Bragard, Michael
T1  - Recording of efficiency-maps of low-power electric drive systems using a flexible matlab-based test bench
T2  - 2017 IEEE 58th International Scientific Conference on Power and Electrical Engineering of Riga Technical University (RTUCON)
N2  - This paper introduces a hardware setup to measure efficiency maps of low-power electric motors and their associated inverters. Here, the power of the device under test (DUT) ranges from some Watts to a few hundred Watts. The torque and speed of the DUT are measured independent of voltage and current in multiple load points. A Matlab-based software approach in combination with an open Texas-Instruments (TI) hardware setup ensures flexibility. Exemplarily, the efficiency field of a Permanent Magnet Synchronous Machine (PMSM) is measured to proof the concept. Brushless-DC (BLDC) motors can be tested as well. The nomenclature in this paper is based on the new European standard DIN EN 50598. Special attention is paid to the calculation of the measurement error.
Y1  - 2017
SN  - 978-1-5386-3846-0
U6  - http://dx.doi.org/10.1109/RTUCON.2017.8124775
PB  - IEEE
CY  - New York
ER  - 
TY  - PAT
A1  - Nötzold, K.
A1  - Bragard, Michael
A1  - Fink, K.
A1  - Griessel, R.
A1  - Wegener, R.
T1  - Cascaded H-bridge converter with transformer based cell power balancing in each voltage level  : [Patentschrift]
Y1  - 2014
N1  - Titel des US-Patents: Bypassed cascaded cell converter : [patent of invention]. - Außerdem veröffentlicht als CN103997231 (A)
PB  - Europäisches Patentamt / United States Patent and Trademark Office [u.a.]
CY  - Den Haag / Alexandria, VA
ER  - 
TY  - CHAP
A1  - Nötzold, K.
A1  - Uphues, A.
A1  - Wegener, R.
A1  - Fink, K.
A1  - Bragard, Michael
A1  - Griessel, R.
A1  - Soter, S.
T1  - Inverter based test setup for LVRT verification of a full-scale 2 MW wind power converter
T2  - 15th European Conference on Power Electronics and Applications (EPE), 2013 : 2 - 6 Sept. 2013, Lille, France / [EPE Association; PELS, IEEE Power Electronics Society]
Y1  - 2013
SN  - 978-1-4799-0115-9 (Online-Ausg.)
U6  - http://dx.doi.org/10.1109/EPE.2013.6634752
SP  - 1037
EP  - 1042
PB  - IEEE
CY  - Piscataway, NJ
ER  - 
TY  - JOUR
A1  - Bragard, Michael
A1  - van Hoek, H.
A1  - De Doncker, R. W.
T1  - A major design step in IETO concept realization that allows overcurrent protection and pushes limits of switching performance
JF  - IEEE transactions on power electronics
N2  - This paper presents the latest prototype of the integrated emitter turn-off thyristor concept, which potentially ranks among thyristor high-power devices like the gate turn-off thyristor and the integrated gate-commutated thyristor (IGCT). Due to modifications of the external driver stage and mechanical press-pack design optimization, this prototype allows for full device characterization. The turn-off capability was increased to 1600 A with an active silicon area of 823mm2 . This leads to a transient peak power of 672.1kW/cm² . Within this paper, measurements and concept assessment are presented and a comparison to state-of-the-art IGCT devices is provided.
Y1  - 2012
U6  - http://dx.doi.org/10.1109/TPEL.2012.2189136
SN  - 0885-8993
VL  - 27
IS  - 9
SP  - 4163
EP  - 4171
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Bragard, G.
A1  - Bragard, Michael
T1  - Ein kostengünstiges, universelles Modellbauinterface
JF  - Der mathematische und naturwissenschaftliche Unterricht : MNU ; Organ des Deutschen Vereins zur Förderung des Mathematischen und Naturwissenschaftlichen Unterrichts e.V.
N2  - Wir stellen einen USB-Baustein vor, der eine kostengünstige und universelle Möglichkeit schafft , im Unterricht den Themenkreis Messen-Steuern-Regeln zu behandeln. Die Funktionalität orientiert sich am CVK-Interface der Firma Fischertechnik. Im Gegensatz zu kommerziellen Lösungen erlaubt unser Aufbau auch den preiswerten Einsatz in Gruppen- oder Einzelarbeit. Abschließend berichten wir über ein Beispiel aus dem Unterrichtseinsatz.
Y1  - 2012
SN  - 0025-5866
VL  - 65
IS  - 5
SP  - 290
EP  - 293
PB  - Seeberger
CY  - Neuss
ER  - 
TY  - THES
A1  - Bragard, Michael
T1  - The integrated emitter turn-off thyristor : an innovative MOS-gated high-power device. - (Aachener Beiträge des ISEA ; 62)
N2  - This thesis introduces the Integrated Emitter Turn-Off (IETO) Thyristor as a new high-power device. Known state-of-the-art research activities like the Dual GCT, the ETO thyristor and the ICT were presented and critically reviewed. A comparison with commercialized solutions identifies the pros and cons of each type of device family. Based on this analysis, the IETO structure is proposed, covering most benefits of each device class. In particular the combination of a MOS-assisted turn-off with a thyristor-based device allows a voltage-controlled MOS switching and the low on-state voltage of the thyristors. The following synthesis of an IETO device stands on a three-dimensional field of optimization spanned by electric, mechanical and thermal aspects. From an electric point of view, the lowest possible parasitic inductance and resistance within the commutation path are optimization criteria. The mechanical construction has to withstand the required contact pressure of multiple kilo Newtons. Finally, thermal borders limit the maximum average current of the device. FEM simulations covering these three aspects are performed for several design proposals. An IETO prototype is constructed and measurements on various test benches attest thermal, mechanical and electric performance. A local decoupling of the external driver stage and the presspack housing is presented by a cable connection. This separation enables a thermal and mechanical independence, which is advantageous in terms of vibrations and thermal cycles including increased reliability. The electric pulse performance of the prototype device is a factor of 3.1 above today''s solutions. In single-pulse measurements, a current up to 1600 A was successfully turned off at 115°C with an active silicon area of 823 mm². One reason for this increased turn-off capability is the extremely low-inductive construction. Additional functionality of the IETO thyristor like over-current self-protection and defined short-circuit failure state are successfully verified.
Y1  - 2012
SN  - 978-3-8440-1152-4
N1  - Zugl.: Aachen, Techn. Hochsch., Diss., 2012
PB  - Shaker
CY  - Aachen
ER  - 
TY  - CHAP
A1  - Nötzold, K.
A1  - Uphues, A.
A1  - Wegener, R.
A1  - Soter, S.
A1  - Fink, K.
A1  - Bragard, Michael
A1  - Griessel, R.
T1  - Inverter based test setup for LVRT verification of a full-scale 2 MW wind power converter
T2  - EPE Joint Wind Energy and T&D Chapters Seminar : 28th and 29th of June 2012, in the Utzon Centre, Aalborg, Denmark ; papers, posters, presentations. - Session 2: Grid connection, compliance
Y1  - 2012
PB  - EPE Association
CY  - Brussels
ER  - 
TY  - CHAP
A1  - Bragard, Michael
A1  - Ronge, C.
A1  - De Doncker, R. W.
T1  - Sandwich design of high-power thyristor based devices with integrated MOSFET structure
T2  - Proceedings of the 2011 - 14th - European Conference on Power Electronics and Applications (EPE 2011) : Aug. 30, 2011 - Sept. 1, 2011, Birmingham, United Kingdom
Y1  - 2011
SN  - 978-1-61284-167-0 (Print)
SN  - 978-90-75815-15-3 (Online)
PB  - IEEE
CY  - Piscataway, NJ
ER  -