Browsing by Author "Dignath, Florian"

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Open Access
Coupled vehicle-guideway dynamics simulations of the Transrapid with discretized levitation magnet forces
(2022) Schneider, Georg; Schmid, Patrick; Dignath, Florian; Eberhard, Peter
Magnetic levitation (maglev) is a promising technology for high-speed transportation systems, as shown by the Transrapid line in Shanghai operating successfully for nearly 20 years. Currently, a new high-speed train based on this technology is being developed, driven by China's Ministry of Science and Technology. Magnets are one of the key components of a maglev vehicle's suspension system. Attractive magnet forces ensure the contactless coupling of the vehicle to the guideway. Electromagnets are usually described using finite element (FE) models, electromagnetic circuit models, or simple analytical models for simulation purposes. However, FE magnet models are computationally often overwhelming, especially for transient studies, and thus too slow to use them in large vehicle models for vehicle dynamics simulations. Moreover, the parameterization of FE models often is non-trivial. Therefore, less detailed but fast-computable models are used in such simulations, often providing only a coarse discrete distribution of magnet forces along the vehicle. In this contribution, the coupled vehicle-guideway dynamics is investigated regarding different discretizations of levitation magnet forces. A two-dimensional model of the maglev vehicle Transrapid moving along an infinite elastic guideway is used, considering the heave-pitch motion of the vehicle and the vertical guideway bending. Simulations are performed using either a coarse distribution with two magnet forces per magnet or a fine distribution with twelve magnet forces per magnet, i.e., one magnet force at each magnet pole. It is shown that the simplification of two magnet forces per levitation magnet is valid for vehicle dynamics simulations. The model is parameterized with data from the Transrapid TR08 and uses a self-developed model predictive control (MPC) scheme to control the magnets.
Open Access
Modeling of the Transrapid’s electromagnets and the application to large mechatronic vehicle models
(2022) Schmid, Patrick; Schneider, Georg; Kargl, Arnim; Dignath, Florian; Liang, Xin; Eberhard, Peter
This work gives an overview of a general approach for modeling the electromagnets of a magnetic levitation (Maglev) vehicle based on electromagnetic suspension. The method intends to map the magnets’ static and dynamic behavior in a frequency range relevant for use in mechatronic simulation models and Maglev control or observer design. The methodology starts with setting up the equivalent magnetic circuit considering magnetic reluctances, fringing and leakage flux, magnetic saturation, and eddy currents. Then, the resulting equations are coupled with the magnet’s electric circuits using Ampère’s law and Faraday’s law of induction. Further, a numerical model reduction technique is sketched, which yields a simplified version of the previously derived magnet model with nearly the same input-output structure and input-output behavior, suitable for large simulation models and control design. The approach’s capabilities and strengths are shown by the agreement to measurements and by implementing the resulting models in large mechatronic vehicle models of the Transrapid.
Open Access
Ride Comfort Transfer Function for the MAGLEV Vehicle Transrapid
(2018) Zheng, Qinghua; Dignath, Florian; Eberhard, Peter; Schmid, Patrick
In order to predict the ride comfort for the MAGLEV vehicle Transrapid TR09 for various scenarios, e.g. for higher vehicle speeds than hitherto travelled, a transfer function from the excitations given by the guideway position to the relevant car body acceleration is calculated by two different methods. Method A is based on a mechatronic simulation model of the Transrapid TR09 which describes a two- dimensional lateral cross section of the vehicle. The simulation model consists of a 2D multibody system describing the mechanical part, four network models of the electro-magnets - two levitation magnets and two guidance magnets - and a signal model of each magnet controller. These signal models contain a representation of the authentic C-Code of the control law used within the actual magnet control units within the vehicle TR09. The overall model can be exploited to calculate the accelerations of the car body for given excitations at the interfaces between guideway and vehicle. Moreover, it is possible to generate a model-based transfer function in the frequency domain from the guideway excitations to the car body accelerations. For method B, measurement results of test runs of the Transrapid TR09 at the test track TVE in Northern Germany are exploited which were recorded for vehicle dynamics analysis and ride comfort evaluation in 2009. From these measurement results two characteristic quantities are generated for several different velocities of the vehicle: Firstly, the position of the guideway is reconstructed by using an integration of the absolute accelerations of the magnets and the signals of the magnet's sensors for the air gap. Secondly, the relation between the accelerations at the car body of the vehicle and the guideway position is calculated as a transfer function in the frequency domain. For this, the measurement data and the reconstructed guideway position are both transformed into the frequency domain by a Fast Fourier Transformation (FFT). The resulting transfer function gives the relevant accelerations for the ride comfort for given excitations of the vehicle as calculated by Method A above. The two transfer functions from Method A and B are compared for validation. Then, a smoothed version of the validated transfer function is applied for estimating the ride comfort for travelling scenarios which have not yet been measured in practical operation, e.g. for higher velocities of the vehicle.
Open Access
Simulation of a high-speed maglev train on an elastic guideway of infinite length
(2022) Schneider, Georg; Schmid, Patrick; Kargl, Arnim; Liang, Xin; Dignath, Florian; Eberhard, Peter
Simulations of the coupled vehicle/guideway dynamics are an essential part in the development of high-speed magnetic levitation (maglev) systems with higher speed than traveled so far. In this contribution, a two-dimensional rigid multibody model mapping the heave-pitch motion of the vehicle is presented and used for dynamics simulations of the vehicle traveling along an infinite elastic guideway. The concept of moving system boundaries is applied for the guideway model to efficiently implement an infinite series of elastic Euler-Bernoulli beams while keeping the number of system states small. Guideway deflection interpolation and computation of equivalent nodal forces and torques are realized using Hermite polynomials. Together with a physically advanced magnet model and a model predictive control scheme, the coupled system is applied for vehicle and guideway dynamics analysis for different vehicle speeds and guideway elasticities.