Thomas Bäuml

Thermal Model and Behavior of a Totally-Enclosed-Water-Cooled Squirrel-Cage Induction Machine for Traction Applications

A thermal model of a totally enclosed water-cooled induction machine is presented. The axially and radially discretized physical regions of the machine are modeled in the object-oriented language Modelica. Additionally, the water-cooling jacket is modeled. The parameters of the thermal network are derived from geometric, physical, and empirical data. The main focus of the presented highly extensible model was to achieve a good compromise between accuracy and simulation performance. Simulation and measurement results of a 6-kW prototype induction machine are presented and compared.

A Detailed Heat and Fluid Flow Analysis of an Internal Permanent Magnet Synchronous Machine by Means of Computational Fluid Dynamics

This paper presents a comprehensive computational fluid dynamics (CFD) model of a radial flux permanent magnet synchronous machine with interior magnets. In the CFD model, the water jacket cooling and a simplified model of the topology of the distributed stator winding are considered. The heat sources of the CFD model are determined from a finite-element analysis of the machine. The numerically determined temperature distributions of the machine are compared with measurement results from sensors located both in the stator and rotor. The particular focus of this paper is the analysis of the temperatures and the heat flow in the air gap and from the stator winding heads and the rotor to the inner air. Different operating conditions and two particular rotor designs with different inner air flow configurations are investigated. The potential of improving the thermal utilization of a rotor design with fan blades attached to the mounting plates of the rotor is shown.

An innovative parametrization method for a thermal equivalent circuit model of an interior permanent magnet synchronous machine

In this paper an accurate and fast thermal equivalent circuit (TEC) model of an interior permanent magnet synchronous machine (IPMSM) is presented. This model is capable of simulating transient thermal effects. The key parameters of the presented model are the heat transfer coefficients which consider heat transfer from the solid to the fluid regions, and vice versa. An innovative parametrization method is introduced to determine these coefficients: First, the heat flows between adjacent regions are calculated by utilizing a 3D computational fluid dynamics (CFD) simulation. Second, the heat transfer coefficients of the TEC model are determined by minimizing an objective function which takes the heat flow deviation between the TEC model and the CFD model into account. The TEC model parametrized this way can be used to predict the thermal behavior of a permanent magnet machine drive under varying speed and torque conditions. The validity of the TEC model is verified by means of measurement results. For this purpose a prototype of the investigated IPMSM is equipped with temperature sensors in the stator, rotor, and cooling circuit, respectively.

An Advanced Simulation Tool Based on Physical Modelling of Electric Drives in Automotive Applications

In this paper a comparison of two different modelled permanent magnet synchronous machines will be shown. A simulation of a vehicle concept with both models will be described and investigated by means of an advanced simulation tool - the SmartElectricDrives (SED) Library - and a Modelica/Dymola simulation environment. The SED library provides the most important electric drive types including controlled electric machines which are described by algebraic and differential equations. Due to this kind of modelling, the machines provide higher flexibility in case of parameter variation and a more realistic behaviour. With the aim of achieving the highest efficiency possible for the automotive drive, which means finding an optimal setting regarding fuel and power consumption, it is necessary to simulate the entire drive train of the vehicle. This includes the internal combustion engine (ICE) as well as electric traction machines or additional electric auxiliary drives. These vehicle simulations may be performed by the car manufacturer to obtain specifications for the vehicle components to be constructed by fulfilling the given boundary conditions like electric machines speed, power and torque and therefore the resulting currents and voltages for the optimal dimensioning of each component.

Heat and fluid flow analysis of an internal permanent magnet synchronous machine by means of computational fluid dynamics

This paper presents a comprehensive computational fluid (CFD) model of a radial flux permanent magnet synchronous machine with interior magnets. In the CFD model the water jacket cooling and a simplified model of the topology of the distributed stator winding are considered. The heat sources of the CFD model are determined from a finite element analysis of the machine. The numerically determined temperature distributions of the machine are compared with measurement results from sensors located both in the stator and rotor. The particular focus of this paper is the analysis of the temperatures and the heat flow in the air gap and from the stator winding head and the rotor to the inner air.

Enhanced Thermal Model of a Totally Enclosed Fan Cooled Squirrel Cage Induction Machine

Thermal simulations are a very important tool for optimizing the design of electric machines. In this paper, two thermal simulation models for totally enclosed fan cooled (TEFC) induction machines are compared with thermal measurement results. For both one dimensional models of the induction machine a thermal equivalent circuit of the machine is presented. The enhanced model was built with the possibility to split the middle part into equal sized parts to model a more detailed axial temperature distribution in the machine. For modelling the circuits, MODELICA language was used in combination with the simulation tool DYMOLA. Simulation results are obtained for both thermal models at the thermal equilibrium. For a comparison between simulated and measured results two measurements on an 18.5 kW four pole induction machine have been accomplished. With iron-copper-nickel sensors embedded in the winding, the housing and between the ribs of the machine temperatures have been determined.

Simulation, Design and Realisation of an entire Electrical Off-Road Motorbike

This work presents the modeling, simulation, realization and validation of an entire electrical two-wheel off-road motorbike in cooperation between arsenal research and KTM-Sportmotorcycle AG. All components of the motorbike such as electrical machines, batteries, power train, etc., are implemented and modeled in the simulation environment Dymola, using Modelica programming language. The power train set of this electrical motorbike is founded on a battery powered electric traction machine and a transmission with only one gear and chain drive. The variation of type and size of the electrical sources and mechanical power train components is considered and explained. For the validation of the entire electrical motorbike simulation model, all electrical and mechanical components of the motorbike are measured. Based on the measuring of the electrical and mechanical motorbike components and the simulation results performed at arsenal research a prototype of the electrical motorbike is constructed and realized. The entire way from simulation, to optimization and the choice of the components to the realization of the electrical motorbike prototype will be explained. The motivation for electrifying an off-road motorbike is the reduction of the exhaust emissions to zero and furthermore a significant reduction of noise.

Geometry based reduced order thermal model for totally enclosed machines

In this work, a general simplified thermal model for totally enclosed variable speed radial machines is proposed. The parameters of the thermal model are calculated with simple equations based on the geometrical dimensions and material of the electrical machine. In this paper, the design procedure is described in detail and the obtained results are compared with test bench and full order model results. The model has been tested on three different induction machines and two permanent magnet machines.

Development, design and realization of an electric powertrain for a small range bus

This work deals with the development and prototyping process of an entire electric small range bus. The work includes also simulation, design, prototyping, evaluation, integration and realization with special emphasis on the electric powertrain. All components of the powertrain of the small range bus such as electrical machine, battery, power units, transmission, chassis etc. were implemented and modelen in a simulation environment. Some modeled components such as electric machine and battery were variegated in type and size. The design, realization and prototyping process of key components based on simulation results is presented as well as validation of the powertrain components, the entire vehicle concept and realization.

Modelling, simulation and validation of an electrical zero emission off-road motorcycle

This paper deals with the modelling of an electrical zero emission off-road motorcycle. The design and dimensioning of the electrical components was completely achieved by simulations. Libraries focused on automotive applications and developed at the Austrian Institute of Technology have been used to model the vehicle. All simulation models were described by the object oriented simulation language Modelica which is used to model interdisciplinary applications.