Johannes V. Gragger

A fast inverter model for electro-thermal simulation

An averaged model of a two-level IGBT inverter with consideration of temperature dependent switching and conduction losses is presented and compared to two other inverter models. In the presented model the influence of the conduction losses on the output voltage waveforms is considered and power balance is guaranteed. The model is not restricted to sinusoidal output currents. Therefore, the model is suitable for calculating the inverter losses in drives at any load and speed down to standstill, either in motor or generator mode. The model is designed such way that typical data sheet information is sufficient for parametrization. In this work emphasize is given to the calculation of losses. A thermal network is used to calculate the junction temperatures. The relations of the proposed model are described and simulation results as well as experimental results are compared and discussed.

Phenomenon Rotor Fault-Multiple Electrical Rotor Asymmetries in Induction Machines

In the literature the effects caused by a single or several adjacently broken rotor bars, or a broken end ring are thoroughly investigated. The phenomenon of various non-adjacently broken rotor bars has not been studied, so far. Since non-adjacently broken rotor bars may give rise to fault signatures which are not directly related with the fault extent, it is important to understand the nature of multiple electrical rotor asymmetries in induction machines. The purpose of this paper is thus to investigate several combinations of electrical rotor asymmetries to systematically elaborate the phenomena related with broken bars and end rings. In this paper a sophisticated simulation model and measurement results are used to analyze the phenomenon rotor fault.

Detection of mechanical imbalances during transient torque operating conditions

Mechanical rotor imbalances and rotor eccentricities give rise to specific mechanical vibration, and certain electric, electromagnetic and mechanical harmonics. The extent and location of these harmonics depends on the actual severity of the imbalance, machine supply and load torque. Many fault detection techniques evaluate the spectral components of any of the mentioned electric or mechanical quantities. Such techniques are therefore usually only applicable for steady state operating conditions. To realize an imbalance detection technique working under transient conditions, load dependencies have to be taken into account. In this contribution a technique is used that employs a phase locked loop to track the imbalance-specific harmonics of the electrical power. This technique, therefore, overcomes the slip and load dependency of the imbalance-specific harmonics. The proposed imbalance detection technique is applied to measured data. Results for steady state and transient operating conditions are then compared.

Innovative design of an air cooled ferrite permanent magnet assisted synchronous reluctance machine for automotive traction application

This paper presents the innovative design of an air cooled permanent magnet assisted synchronous reluctance machine (PMaSyRM) for automotive traction application. Key design features include low cost ferrite magnets in an optimized rotor geometry with high saliency ratio, low weight and sufficient mechanical strength as well as a tailored hairpin stator winding in order to meet the demands of an A-segment battery electric vehicle (BEV). Effective torque ripple reduction techniques are analyzed and a suitable combination is chosen to keep additional manufacturing measures as low as possible. Although the ferrite magnets exhibit low remanence, it is shown that their contribution to the electrical machines performance is essential in the field weakening region. Efficiency optimized torque-speed-characteristics are identified, including additional losses of the inverter, showing an overall system efficiency of more than 94 %. Lastly, the results of no load measurements of a prototype are compared to the FEM simulation results, indicating the proposed design of a PMaSyRM as a cost-effective alternative to state-of-the-art permanent magnet synchronous machines (PMSM) for vehicle traction purposes.

Phenomenon rotor fault — Multiple electrical rotor asymmetries in induction machines

In the literature, the effects caused by a single or several adjacently broken rotor bars, or a broken end ring are thoroughly investigated. The phenomenon of various nonadjacently broken rotor bars has not been studied so far in detail. Since nonadjacently broken rotor bars may give rise to fault signatures, which are not directly related with the fault extent, it is important to understand the nature of multiple electrical rotor asymmetries in induction machines. The purpose of this paper is thus to investigate several combinations of electrical rotor asymmetries, to systematically elaborate the phenomena related to the broken bars and end rings. In this paper, a sophisticated simulation model and measurement results are used to analyze the phenomenon rotor fault.

PM-Assisted Synchronous Reluctance Machine Flux Weakening Control for EV and HEV Applications

In this paper, a novel robust torque control strategy for permanent magnet assisted synchronous reluctance machine drives applied to electric vehicles and hybrid electric vehicles is presented. Conventional control techniques can highly depend on machine electrical parameters, leading to poor regulation under electrical parameters deviations or, in more serious cases, instabilities. Additionally, machine control can be lost if field weakening is not properly controlled and, as a consequence, uncontrolled regeneration is produced. Thus, advanced control techniques are desirable to guarantee electric vehicle drive controllability in the whole speed/torque operation range and during the whole propulsion system lifetime. In order to achieve these goals, a combination of a robust second-order current-based sliding mode control and a look-up table/voltage constraint tracking based hybrid field weakening control is proposed, improving the overall control algorithm robustness under parameter deviations. The proposed strategy has been validated experimentally in a full-scale automotive test bench (51-kW prototype) for being further implemented in real hybrid and electric vehicles.

A Full Vehicle Simulation of an HEV Starter-Generator Concept with the SmartElectricDrives Library

The presented work proposes a simulation environment using Modelica programming language for full vehicle simulations. A special software library suitable for Modelica simulations is used - the SmartElectricDrives (SED) library. This software is developed to simulate all parts of the electrical drive systems, and furthermore, allows to choose different levels of abstraction in the simulation design. Typical applications for the SED library are simulations of vehicular systems such as full vehicle simulations of hybrid electric vehicles (HEVs) and electric vehicles (EVs), simulations of electrified auxiliary drives, et c. In this work a full vehicle simulation of an HEV concept with a starter-generator is presented and all the parameters of the electrical components are discussed.

Modeling of iron losses in an induction machine based on a magnetic equivalent circuit in Modelica

Finite element methods (FEM) allow estimating iron core losses including saturation effects in electric machines. Nevertheless, the analysis is computationally intense and not reflecting hysteresis behavior correctly. This work presents a 1D magnetic equivalent circuit (MEC) modeling approach for an induction machine, which allows performing accurate calculations of iron losses in the laminated core. This offers to consider spatial dependencies like in FEM, but with less computational effort. The developed magnetic non-linear lumped circuit elements (i.e. permeances) of the laminated iron core are specialized for pulsed operation. This enables to consider saturation- and hysteresis effects correctly. The proposed approach is implemented in Modelica; the model setup and the simulations are performed in Dymola. The validation of the developed 1D approach with FEM points out, that the MEC model is capable of estimating static and dynamic hysteresis losses during the electromagnetic energy conversion processes in the core lamination of an induction machine correctly.

Design and performance analysis of a 48V electric drive system for a cargo tricycle

This paper describes the main components of an electric drive in a novel electric cargo tricycle. The main components are a Mosfet inverter, an axial flux synchronous machine, and a Li-Ion battery package. The most important specifications and functions of the tricycle and the electric drive are explained. Particular focus is laid on the inverter design and the experimental setup that was used for the performance tests. Measurement results of lab tests and on-the-road tests are presented.

System Optimization and Vehicle Integration

This chapter deals with the most important possibilities for improving the overall vehicle performance of electrified vehicles. Thus, it describes the results and the key messages of several IEA-IA-HEV-Task 17 workshops and studies, by focusing on the following topics: E-Motors: This section is focusing on the advantages and disadvantages of Permanent Magnet Motors with rare-earth permanent magnets, representing one of the most common motors being used so far (based on the reporting year 2012). Additionally it focuses on alternatives for permanent magnet motors, which are currently at a few level. Battery Management Systems (BMS): A BMS constantly controls the functionality and charge of the battery cells. Therefore, it is necessary to lengthen battery life. This chapter addresses concerns for current BMS, provides an overview about their basics and highlights the most important BMS-Tasks for High Voltage batteries as well as the demonstration of a Lithium-Ion battery performance and cost model for electrified vehicles. Thermal Management Systems: The optimization of thermal management has become an important business segment, as it is essential for effective operation of electrified vehicles in all climates. The results and outcomes of a study (Argonne National Laboratory) as well as various workshops addressed innovative methods for Thermal Management Systems. The results are described within this chapter and include specific thermal management technologies, explored innovations on components and Phase-Change-Materials. Simulation Tools: For many years now numerical simulation has become an essential tool to engineers in the product development process. Computing methods have been refined to such an extent that today simulations are more and more referred to as a basis for important product decisions. This chapter deals with a few simulation tools in the field of system optimization and vehicle integration, including “Autonomie”, “Cruise” and “Dymola/Modelica”. Functional and Innovative Lightweight Concepts and Materials: In the future, the proportion of high-tensile steels, aluminium and carbon-fibre-reinforced plastics in vehicles is set to increase from 30 % today to up to 70 % in 2030 (McKinsey & Company, Lightweight, heavy impact, 2013). High-tensile steel will remain the most important lightweight material and carbon-fiber-reinforced plastics are expected to experience annual growth of 20 %. As Lightweight construction of the vehicle body has become a very important field of R&D activities, this chapter focus on the outcomes of a study on the impacts of the vehicle’s mass efficiency and fuel consumption (Argonne National Laboratory) as well as on various methods of light weighting a vehicle, like simulation tools, advanced “smart” materials, bionic concepts and functional integration. Power Electronics and future Drive Train Technologies: Around 40 years ago, the first piece of software was used in a vehicle to control the ignition of the engine. Today, up to 90 % of all innovations in a car are realized with electronics and software, based on the customers demand for new safety and convenience functions—Advanced Driver Assistance Systems—which are the basics for autonomous driving. This chapter points out that modular drivetrain topologies are as much important as the requirement of layered, flexible and scalable architectures. The further improvement of the power control unit as well as the E/E-Architecture will play a key role in the future of electrified vehicles.