Anisotropy of the ΔE effect in Ni-based magnetoelectric cantilevers: a finite element method analysis

In recent investigations of magnetoelectric sensors based on microelectromechanical cantilevers made of TiN/AlN/Ni, a complex eigenfrequency behavior arising from the anisotropic ΔE effect was demonstrated. Within this work, a FEM simulation model based on this material system is presented to allow an investigation of the vibrational properties of cantilever-based sensors derived from magnetocrystalline anisotropy while avoiding other anisotropic contributions. Using the magnetocrystalline ΔE effect, a magnetic hardening of Nickel is demonstrated for the (110) as well as the (111) orientation. The sensitivity is extracted from the field-dependent eigenfrequency curves. It is found, that the transitions of the individual magnetic domain states in the magnetization process are the dominant influencing factor on the sensitivity for all crystal orientations. It is shown, that Nickel layers in the sensor aligned along the medium or hard axis yield a higher sensitivity than layers along the easy axis. The peak sensitivity was determined to 41.3 T −1 for (110) in-plane-oriented Nickel at a magnetic bias flux of 1.78 mT. The results achieved by FEM simulations are compared to the results calculated by the Euler–Bernoulli theory

Automated parameter extraction of ScAlN MEMS devices using an extended Euler-Bernoulli beam theory

Magnetoelectric sensors provide the ability to measure magnetic fields down to the pico tesla range and are currently the subject of intense research. Such sensors usually combine a piezoelectric and a magnetostrictive material, so that magnetically induced stresses can be measured electrically. Scandium aluminium nitride gained a lot of attraction in the last few years due to its enhanced piezoelectric properties. Its usage as resonantly driven microelectromechanical system (MEMS) in such sensors is accompanied by a manifold of influences from crystal growth leading to impacts on the electrical and mechanical parameters. Usual investigations via nanoindentation allow a fast determination of mechanical properties with the disadvantage of lacking the access to the anisotropy of specific properties. Such anisotropy effects are investigated in this work in terms of the Young’s modulus and the strain on basis of a MEMS structures through a newly developed fully automated procedure of eigenfrequency fitting based on a new non-Lorentzian fit function and subsequent analysis using an extended Euler–Bernoulli theory. The introduced procedure is able to increase the resolution of the derived parameters compared to the common nanoindentation technique and hence allows detailed investigations of the behavior of magnetoelectric sensors, especially of the magnetic field dependent Young‘s modulus of the magnetostrictive layer

Electrified Powertrain Development: Distributed Co-Simulation Protocol Extension for Coupled Test Bench Operations

The increasingly stringent CO2 emissions standards require innovative solutions in the vehicle development process. One possibility to reduce CO2 emissions is the electrification of powertrains. The resulting increased complexity, as well as the increased competition and time pressure make the use of simulation software and test benches indispensable in the early development phases. This publication therefore presents a methodology for test bench coupling to enable early testing of electrified powertrains. For this purpose, an internal combustion engine test bench and an electric motor test bench are virtually interconnected. By applying and extending the Distributed Co-Simulation Protocol Standard for the presented hybrid electric powertrain use case, real-time-capable communication between the two test benches is achieved. Insights into the test bench setups, and the communication between the test benches and the protocol extension, especially with regard to temperature measurements, enable the extension to be applied to other powertrain or test bench configurations. The shown results from coupled test bench operations emphasize the applicability. The discussed experiences from the test bench coupling experiments complete the insights

Online Identification of Semiconductor Switching Times in Inverters with Inductive Load Using an FPGA and Potential Separated Comparators

The nonlinear behavior of inverters is largely impacted by the interlocking and switching times. A method for online identifying the switching times of semiconductors in inverters is presented in the following work. By being able to identify these times, it is possible to compensate for the nonlinear behavior, reduce interlocking time, and use the information for diagnostic purposes. The method is first theoretically derived by examining different inverter switching cases and determining potential identification possibilities. It is then modified to consider the entire module for more robust identification. The methodology, including limitations and boundary conditions, is investigated and a comparison of two methods of measurement acquisition is provided. Subsequently the developed hardware is described and the implementation in an FPGA is carried out. Finally, the results are presented, discussed, and potential challenges are encountered

Current Harmonics Control Algorithm for inverter-fed Nonlinear Synchronous Electrical Machines

Current harmonics are a well known challenge of electrical machines. They can be undesirable as they can cause instabilities in the control, generate additional losses and lead to torque ripples with noise. However, they can also be specifically generated in new methods in order to improve the machine behavior. In this paper, an algorithm for controlling current harmonics is proposed. It can be described as a combination of different PI controllers for defined angles of the machine with repetitive control characteristics for whole revolutions. The controller design is explained and important points where linearization is necessary are shown. Furthermore, the limits are analyzed and, for validation, measurement results with a permanently excited synchronous machine on the test bench are considered

Extended algorithm for current slope estimation in inverter fed synchronous machines

The present work describes an extension of current slope estimation for parameter estimation of permanent magnet synchronous machines operated at inverters. The area of operation for current slope estimation in the individual switching states of the inverter is limited due to measurement noise, bandwidth limitation of the current sensors and the commutation processes of the inverter's switching operations. Therefore, a minimum duration of each switching state is necessary, limiting the final area of operation of a robust current slope estimation. This paper presents an extension of existing current slope estimation algorithms resulting in a greater area of operation and a more robust estimation result

Circuit pour véhicule automobile, en particulier pour véhicule hybride ou électrique

Die Erfindung betrifft eine Schaltungsanordnung (10) für ein Kraftfahrzeug, mit einer Hochvolt-Batterie (12) zum Speichern von elektrischer Energie, mit wenigstens einer elektrischen Maschine (14) zum Antreiben des Kraftfahrzeugs, mit einem Stromrichter (16), mittels welchem von der Hochvolt-Batterie (12) bereitstellbare Hochvolt-Gleichspannung in Hochvolt-Wechselspannung zum Betreiben der elektrischen Maschine (14) umwandelbar ist, und mit einem Ladeanschluss (20) zum Bereitstellen von elektrischer Energie zum Laden der Hochvolt-Batterie (12), wobei der Stromrichter (16) als ein Drei-Stufen-Stromrichter ausgebildet ist und wenigstens eine einer Phase (u) der elektrischen Maschine (14) zugeordnete Schaltereinheit (46) aufweist, welche zwei in Reihe geschaltete Schaltergruppen (52, 54) umfasst, die jeweils zwei in Reihe geschaltete IGBTs (T11, T12, T13, T14) aufweisen, wobei zwischen den IGBTs (T11, T12) einer der Schaltergruppen (52, 54) ein Anschluss (64) angeordnet ist, welcher direkt mit einer Leitung (34) des Ladeanschlusses (20) elektrisch verbunden ist.The invention relates to a circuit assembly (10) for a motor vehicle, comprising a high-voltage battery (12) for storing electric energy, at least one electric machine (14) for driving the motor vehicle, a converter (16), by means of which a high-voltage DC current which can be provided by the high-voltage battery (12) can be converted into a high-voltage AC current in order to drive the electric machine (14), and a charging terminal (20) for providing electric energy in order to charge the high-voltage battery (12). The converter (16) is designed as a three-level converter and has at least one switch unit (46) that is assigned one phase (u) of the electric machine (14) and comprises two switch groups (52, 54) which are connected in series and each of which has two IGBTs (T11, T12, T13, T14) connected in series, wherein a terminal (64) is arranged between the IGBTs (T11, T12) of one of the switch groups (52, 54), said terminal being directly electrically connected to a line (34) of the charging connection (20).L'invention concerne un circuit (10) pour un véhicule automobile, pourvu d'une batterie à haute tension (12) pour l'accumulation d'énergie électrique, d'au moins un moteur électrique (14) pour l'entraînement du véhicule automobile, d'un convertisseur de puissance (16), au moyen duquel la tension continue à haute tension pouvant être fournie par la batterie à haute tension (12) peut être convertie en tension alternative à haute tension pour le fonctionnement du moteur électrique (14), et d'un raccordement de charge (20) pour la fourniture d'énergie électrique permettant la charge de la batterie à haute tension (12), le convertisseur de puissance (16) étant réalisé sous la forme d'un convertisseur de puissance à trois étages et présentant au moins une unité de commutation (46) qui est associée à une phase (u) du moteur électrique (14) et qui comprend deux groupes de commutateurs (52, 54) montés en série, qui présentent respectivement deux transistors bipolaires à porte isolée (T11, T12, T13, T14) montés en série, un raccordement (64), lequel est relié électriquement directement à une ligne (34) du raccordement de charge (20), étant disposé entre les transistors bipolaires à porte isolée (T11, T12) d'un des groupes de commutateurs (52, 54)