Download Report

Newsletter
2
October 2014 - 2nd edition
ASTERICS
Facts & Figures
More than half of the ASTERICS project time is already past. The cornerstones
that are necessary to achieve our ambitious goals are laid and we would like to
take the opportunity to inform you about our major activities and results. We
hope you´ll enjoy reading our second Newsletter! Horst Pflügl /ASTERICS Coordinator
Full name: Ageing and efficiency
Simulation & TEsting under Real
world conditions for Innovative
electric vehicle Components and
Systems
• Acronym: ASTERICS
• Start date: 1/10/2012
• End date: 30/09/2015
• Total budget: 4.3 M€
• Total EU funding: 2.7 M€
Impact
Reduction of overall development time and testing efforts for
FEV and components by 50%
Enable improvement and optimization of overall efficiency and
performance of FEV by at least
20%
The basis is laid—WP1
Activities in WP1– Requirements and specifications - were dedicated to the
development of representative Driving Cycles (DCs) concerning typical vehicle use. A Driving Cycle (DC) is a standardized procedure aimed to evaluate
vehicle performances in a reproducible way under testing conditions. It includes a time– vehicle speed signal as main input data. DCs can be obtained
through a «synthesis» of measured data. Although there is a large number
of DCs already available, there is still a need for the development of new
ones since:
 significant variations in driving patterns can be sometimes identified on
a local scale
 electric vehicles can induce a different driving pattern from those
adopted on conventional vehicles by the same users
 regenerative braking capabilities can modify the driving style of the
user and can significantly modify vehicle energy consumption
 it is highly recommended to go for multi-varied simulation through the
use of a large amount of driving data instead of “synthetic” cycles so a
small database of real-world trips for EVs is needed.
DC definition — General methodology
Please contact Claudia Keinrath
for any questions concerning
this newsletter :
+43 316 787 7393 or
[email protected]
An ASTERICS tool (Fig. 1) was
developed that allows for simple DC data management. The
tool can be used to build new DCs
from raw data, according to user input, and/or to combine existing and
newly generated cycles.
It can also be used by command-line
for batch simulations (e.g. system tuning), proposing a different DC for each
simulated event.
60
Distance = 51586.8162
Speed (m/s)
by a financial contribution by the European
Commission under Framework Programme 7.
40
20
0
0
500
1000
1500
2000
Time (s)
2500
3000
3500
0
500
1000
1500
2000
Time (s)
2500
3000
3500
15
Energy needed (kWh)
The ASTERICS project has been made possible
The following process based on four steps was used for the definition of a
driving cycle :
1. road/vehicle data acquisition in a predefined context
2. data pre– processing and preparation for analysis (via filtering)
3. data processing e.g. kinematic parameters calculation or tripsmicrotrips recognition and grouping
4. cycle synthesis (e.g. data selection/ randomization, verification)
Three case studies, performed with Light and Heavy (Commercial) Vehicles in Turin, Lyon and Florence resulted in the definition of several driving
cycles. The goal is now to select a DC that is applicable to all vehicles, so it
can be used in the integration studies performed in WP5.
10
5
0
-5
Figure 1. ASTERICS tool and its typical output, that includes an approximated assessment
of the energy needed to run the cycle.
Newsletter
Page 2
2
WP2 Battery Systems
This activity within WP2 focuses on identification of battery parameters with electrochemical impedance spectroscopy (EIS) at different states of battery ageing. Some of the results are planned to be reported on an IEEE
conference in Florence late 2014. The life cycle testing is performed at ambient temperature and reference tests
are made at ±0°C and +22°C. The duty cycle applied is derived from speed samples of real-world city driving
characteristics for electric passenger cars. Selected points in the cell life of special interest are beginning-of-life
(BOL), middle-of-life (MOL), and EOL at which more extensive reference tests are run, compared to intermediate
steps which have shorter reference tests. An electric equivalent circuit (EEC) model is fitted to the measured
impedance and the fitted impedance parameters are used to compare and quantify results of the lifecycle test.
Figure 2. Nyquist plot of the impedance at
+22°C with red and purple points representing the BOL and MOL data.
The plot of EIS impedance in Fig.2 shows a notable decrease
of the semicircle diameter when comparing the MOL results
to the BOL results. Although this behaviour has been observed in previous work, it is not in accordance with most of
the work in this field, where the impedance of Li-ion cells is
often reported as monotonically increasing. The concurrent
decrease of the charge transfer resistance and the increase
of the double layer capacitance hint at the possible reason
and the aging mechanism behind, i.e. an increased active/
interfacial area as a consequence of micro-cracking of electrode caused by the cyclic stress and strain during
the operation between BOL and MOL. Although the decreased charge transfer impedance at MOL is beneficial
the overall battery performance is better at BOL. In addition, this ageing mechanism will inevitably lead to further capacity loss and a rapidly decreasing performance at later stages of ageing.
WP3 Inverter Systems—findings
Inverter Test-bed: When using a battery-emulator / e-machine-emulator currently a 50Hz –transformer is needed for galvanic isolation. Due to the high amount of transferred power the transformers´ framesize and cubic
capacity is huge. It can be replaced by a high frequency clocked, galvanically isolated DC-DC converter. Compared to the existing system the proposed one has several benefits: it is compact, has a low mass , and the
energy flows in a circle (see Figure 3).
Ageing: Based on the studies of FH-J the most practical (and fastest)
approach concerning the implementation of semiconductor ageing
in simulation models seems to be via the reliability-data of semiconductors.
Simulation models: An averaged model is sufficiently precise for the
investigation of standard-operating conditions regarding inverterirreversibilities. A more detailed investigation regarding irreversibilities in case of a coupled high resolution inverter model with an emachine model—taking torque-fluctuations, influence of control-
Figure 3. Scheme of the proposed DCDC Converter.
Siemens PLM implemented inverter arms models in Amesim including conduction and switching losses estimations based on semiconductor’s static characteristics, with different assumption levels. Switched modeling
enables to observe the instantaneous conduction state of a converter, while average modeling enables to discard high frequency switching for CPU time saving. Further, a generic approach for aging/reliability of semiconductors was proposed, where these inverter models were included in a vehicle model to evaluate the temperature profiles for the transistors and diodes on a realistic operating conditions (driving cycles). These temperature profiles can then be injected in a lifetime model, sometimes together with the voltage/currents profiles,
either directly to assess the aging and durability of each component or to generate test cycles for durability assessment.
Newsletter
Page 3
2
WP4 E-Motor
Figure 4. Improved methodology for accurate loss prediction
of SRM machine
A new LMS Amesim SRM dynamic model based on the
reluctant network approach, as well as an improved methodology for integrating results from magneto-static and
transient finite element analysis into system models for
accurate loss calculation of SRM models was developed.
The impact of different control strategies on losses and
torque ripples has also been studied. Reduced models are
prepared for integration with WP5.
WP5...where integration happens
Introduction
Main goal of Work Package 5 - „System Integration, evaluation and verification“ is to create a complete vehicle model for EV application, including different models of the electric powertrain, such as battery, inverter
and electric machine, developed by means of different simulation tools like AVL Cruise, LMS AMESIM, PerFECTS, GSP (whereby the last two tools are internally developed respectively by the FGA Group and Volvo
Group), in a unique environment to maximize the synergy with the other tools. After a numerical validation
phase, an experimental phase will be carried out. WP5 is the final step in the development, testing and validation of a product since it integrates the results of the previous work packages.
Next steps
Initially all activities will focus on the verification and definition of driving cycles (results of WP1) concerning
their feasibility for the test vehicles involved in the project. The test vehicles involve a light commercial vehicle, a heavy commercial vehicle and a passenger car. In fact the feasibility of the driving cycles depends on the
vehicle topology and the speed limit of each vehicle due to the powertrain performance. Hence, a preliminary analysis is necessary in order to get a better correspondence between the vehicle model and the real vehicle. After the definition of necessary Input/ Ouput interfaces for the simulation as well as for control and debug of the components developed in WP2, WP3, WP4, the integration in a co-simulation environment (i.e.
through the Functional Mock-up interface (FMI; developed in the former EU project: MODELISAR) or in Matlab/ Simulink environment using s-functions) will be feasible with the possibility to share libraries between all
partners that are included in a common database. The electric powertrain blocks could be either fully open
(built in Matlab/Simulink environment) or S-functions. Compared to S-functions, FMUs have several advantages among these are:

FMI is suited for embedded systems, since it doesn´t have the memory overhead like S-Functions .

FMI schema is licensed under BSD license—not proprietary

FMI can be easily integrated in simulators other than Simulink

The S-Functions format is specific to Simulink
Amesim
Each partner will be able to integrate different component models
for his complete vehicle and has the possibility to run simulations
and execute a numerical validation of the whole model. The simulations will also allow for an optimization of the components under
the “boundary conditions” of the driving cycles. After these phases,
the execution of experimental tests is possible in order to make a
comparison of simulation and measurements using the driving cycles and the criteria defined in WP1.
Figure 5. Functional Mock-up environment proposed by
WP5.
Page 4
Newsletter 2
ASTERICS meets ...
...EGVI in Brussels
On the 3rd of July 2014 Horst Pflügl and Lorenzo Berzi represented the
ASTERICS project at the EGVI (European Green Vehicles Initiative)
meeting in Brussels which was organized on the subject of “Testing of
Electric Vehicle Performance and Safety”.
The activities presented in the workshop highlighted that the efforts of
both industry and research centers are nowadays aimed to acquire
further know-how on EVs and to consolidate the methodologies for their
development. The research for improvement of electrochemical cells is
still one of the priorities while, in parallel, significant resources have been
spent to increase the availability of appropriate testing infrastructures for
batteries and other critical EV components. Innovative simulation tools
and testing methodologies are also proposed in order to increase the
knowledge about battery ageing under normal use conditions (coherently
with ASTERICS topics) and under "extreme" conditions, e.g. due to abuse
or to crash events. Such a trend is also aimed to improve the overall safety of the vehicle. Regarding charging infrastructure, a standardization
appears to be needed, since the existance of multiple solutions could
represent a critical factor in the future.
ASTERICS Consortium
The ASTERICS Consortium consists
of 10 partners from 7 EU countries
and comprises car manufacturers,
software and hardware suppliers,
research organisations and universities.
1. Coordinator: AVL List GmbH
www.avl.com
2. Centro Ricerche FIAT SCPA
www.crf.it
3. FH Joanneum
www.fh-joanneum.at
4. Gustav Klein
www.gustav-klein.de
5. LMS International
Picture 1. Impressions from the EGVI meeting in Brussels.
...in Goteborg
The 4th General Assembly meeting was held in Goteborg, hosted by our
partner Volvo. Initially, this meeting was planned as an official Review
Meeting but Mr. Sgarbi (ASTERICS Project Officer) was able to get a good
idea of the steady progress with regard to the ASTERICS objectives based
on the comprehensive deliverables and the 1st Periodic Report, so that a
review meeting was not necessary. Instead representatives of each work
package focused on planning the upcoming tasks in due consideration of
the Integration work that is done in work package 5.
www.lmsintl.com
6. LMS Imagine
www.lmsintl.com/LMS-ImagineLab-Platform
7. THIEN eDrives
www.thien-edrives.com
8. University of Ljubljana
www.uni-lj.si
9. Università degli Studi di Firenze
www.unifi.it
10. VOLVO
www.volvogroup.com
Picture 2. Representatives of the ASTERICS consortium when the
day´s work is done.
The ASTERICS project is part of the
European Green Cars Initiative
(EGCI) and is funded by European
Union’s
7th
Framework
Programme
(FP7/2007-2013)
under grant agreement n° 314157.
The Publication as provided reflects only the authors view. Every effort has been made to ensure complete and accurate information concerning the articles in
this newsletter. However, the author(s) and members of the consortia cannot be held legaly responsible for any mistake in printing or faulty instructions. The
authors and consortia members reserve the right not to be responsible for the topicality, correctness, completeness or quality of the information provided.