B2384 - Powertrains for Sustainable Mobility

Learning outcomes

At the end of the course the student knows the basics of sustainable powertrain technologies, from the use of natural resources down to energy conversion, including power and emissions control.

Course contents

Module 1

Introduction to Sustainable Mobility

Life Cycle Assessment (LCA)

Sustainable Fuels

• Hydrogen
• Bio-fuels
• E-Fuels

ICE Fundamentals

• Efficiency
• Torque delivery
• Heat release and main combustion indexes

SI and CI combustion characteristics

Emissions

• Emissions in SI engines
• Emissions in CI engines

Aftertreatment systems

• ATS for SI engines
• ATS for CI engines

Advanced Combustion Technologies

• Supercharging
• Downsizing
• Variable compression ratio
• Turbulent jet ignition (TJI)
• Spark assisted compression ignition (SACI)

Internal Combustion Engines with Sustainable Fuels

Hydrogen Engines

 

Module 2

Electric vehicles: introduction

• Electric vehicle history
• Ragone Plot (Specific power vs specific energy); volumetric vs gravimetric energy density; actual performance (range, charging time…)
• Electric/electrified vehicle definitions: BEV, EREV, PHEV, FHEV, MHEV, FCEV
• Topology: main components of EVs

Batteries:

• battery system components (cells, modules, packs, system)
• Cell types
• Batteries: definitions (nominal, cut-off, open circuit voltage; rated capacity/energy, C-rate, E-rate, SOC, DOD, IR, SOH, …)
• BMS functionalities
• Other system components: cooling system, BJB, housing

Battery Cells:

• Cells fundamentals: electrodes, electrolyte, separator roles
• Lead-acid batteries: reactions at the cathode/anode/overall during charging/discharging
• Li-Ion batteries: reactions at the cathode/anode/overall during charging/discharging
• Cell potential based on Gibbs free energy variation
• Voltage drop: internal resistance, activation polarization (Butler-Volmer approach, Nernst equation, Fick’s law), concentration polarization
• Cell modeling
• Charging strategies
• Thermal runaway: root causes, steps, mitigation
• Charging systems standards
• DC-DC: buck converter circuit
• DC-DC: boost converter, evaluation of voltage ratio and efficiency
• DC-DC: switching losses and conduction losses

E-motors:

• DC motors: structure and Torque-speed characteristic (dependance on current, voltage and flux)
• DC motors efficiency: copper losses, iron losses, friction and windage losses; iso-efficiency curves
• DC motors: regenerative braking, power limits (heat)
• BLDC motors (structure, working principle)
• SRS motors (structure, working principle)
• Induction motors (structure, working principle, torque-speed characteristic)
• PMSM motors (structure, working principle, torque-speed characteristic)
• Motors materials: conductors, magnets
• Single phase inverter circuit (H-bridge&PWM)
• Three phase 6 steps inverter circuit

Fuel Cells:

• History, applications
• Types of fuel cells: schematic and reactions of PEM, SOFC, AFC, PAFC, DMFC, MCFC
• PEMFC components/detailed schematic
• Polarization curve: standard potential variation with temperature and pressure; Nernst potential;
• Activation polarization
• Ohmic polarization
• Concentration polarization
• Open Circuit Voltage Loss
• FC actual performance
• FC system efficiency
• FC BoP: topology
• Storage system
• Hydrogen feeding
• Air feeding: compressor
• Humidifier
• Cooling system
• Vehicle layout

Hybrid powertrains

• Hybrid vehicles: definitions
• Hybrid systems architecture
• Series
• Parallel
• Series-parallel (Mechanical Torque Split and 2x2)
• Pre/post transmission
• P0
• P1
• P2
• P3/P4
• Driving Modes: Torque assist, cold engine cranking, stop/start, stop-in motion, engine load shifting, energy harvesting, regenerative braking, creep
• Vehicle supervisory controller: model selection strategy
• Mechanical power split: working principle
• Electric only
• Series
• Parallel
• Power split
• Engine brake
• Regeneration
• Series-parallel 2x2
• Electric only
• Series
• Parallel
• Power split
• Modal control strategies
• Series control
• Parallel control
• Series parallel control, mechanical split
• Energy storage control
• regeneration control

Teaching methods

The topics of the course will be presented by means of Power Point slides (shared with the students on the data exchange area, accessible after the students enroll in the distribution list), data from the literature and data collected in the labs.

The students will visit the Sustainable Mobility Laboratory , where sustainable powertrain solutions are being developed, based on internal combustion engines and fuel cells.

Assessment methods

Oral examination (one hour approximately).

Three questions will be asked, concerning the following topics (randomly selected from the program):

- synthetic fuels, ICE potential with synthetic fuels

- H2 ICE

-Fuel cell powertrains

-BEV

- Hybrid electric vehicles

- LCA assessment and comparison between different powertrains

Each answer will grant up to 10 points, the final grade is the sum of the points earned in the three questions. One question can be substituted by the presentation of a personal project on a subject agreed with the professor. The program is available on the data exchange area at the end of the course.

The exam dates are communicated in advance through the AlmaEsami web platform of the University of Bologna. It is possible to enroll to the exam from 10 to 5 days before the exam date. At the time of the exam the student must show an identification document.

Teaching tools

The students will be given presentations referring to the topics listed in the program, as well as other material from the literature.

Office hours

See the website of Vittorio Ravaglioli

See the website of Enrico Corti