48-VOLT DEVELOPMENTS
HIGH-VOLTAGE AUTOMOTIVE
DEVELOPMENTS
Kevin Jost
Development of higher-voltage electrical About the Author
systems in vehicles has been slowly Kevin is currently the
progressing over the past few decades. Editorial Director for SAE
However, tightening vehicle efficiency International’s Magazines,
and emissions regulations and increasing Books, Videos, and
demand for onboard electrical power Intellectual Property in
means that higher voltages, in the form Warrendale PA. Prior
of supplemental 48 V subsystems, may to that he served various editorial roles
soon be nearing production as the most with SAE Magazines including Editor of
cost-effective way to meet regulations. Automotive Engineering and Off-Highway
The displacement of high-wattage loads to Engineering. His industry experience
more efficient 48 V networks is expected includes roles as first Project Engineer
to be the next step in the development of a for testing and then Product Engineer for
new generation of mild hybrid vehicles. seating and other trim systems at Lear
In addition to improved fuel economy Corp. in Southfield MI.
and reduced emissions, 48 V systems
could potentially save costs on new
electrical features and help better address
the emerging needs of future drivers.
Challenges to 48 V system implementation
remain, leading to discussions by experts
from leading car makers and suppliers
on the need for an international 48 V
standard. Initial steps toward a proposed
standard have already been taken. So the
consensus of global forecasts suggests
that 48 V mild hybrids will soon come
to dominate the market. Compared with
48-VOLT
200-600 V full hybrid and battery electric
Jost
vehicles, the lower-voltage approach
avoids the need for high-cost safety
DEVELOPMENTS
features and large battery packs.
.
TU-002
Kevin Jost
ISBN: 978-0-7680-8192-3
9 780768 081923
Table of Contents
Introduction............................................................................ix
Chapter 1 Fuel Consumption and Emissions Effects in
Passenger Car Diesel Engines through the Use of a Belt
Starter Generator..................................................................... 1
Drivetrain Architecture......................................................................................2
Methods................................................................................................................4
Thermodynamic Optimisation.................................................................4
Automated Cycle Driving.........................................................................4
Hybrid Operating Strategy........................................................................7
Results and Discussion.....................................................................................14
Conclusions........................................................................................................19
References...........................................................................................................21
Chapter 2 Requirements and Protection within a 48V
Automotive Wiring System.................................................. 23
Weight Saving Issues and Topology of a Multi-Voltage Wiring System...24
Operating Safety for the 48V Wiring System................................................25
Protection Concepts for the Different Arc Types..........................................27
Conclusions........................................................................................................30
Chapter 3 Mixed Voltages and Aluminum Conductors:
Assessing New Electrical Technologies................................ 31
Integrating Flow for 48V System Components and Aluminum Wires.....32
Build 48V Components into a 12V Vehicle System..............................32
Verification of a Mixed Voltage System.................................................34
Replacement of Copper with Aluminum Wires...................................35
Examine the Results of all Recommended Changes............................36
Summary............................................................................................................37
References...........................................................................................................37
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Chapter 4 Hybrid Cars Setting New Challenges for
Optimized Power Semiconductors...................................... 39
The Variety of Battery Voltages for Plug-In Vehicles - xEVs.......................40
Voltage Classes of the Semiconductors Tailored to the Application.........42
Simulation of a 12V ABS System............................................................42
Simulation of a 12V Engine Cooling Fan...............................................43
Dc-dc Converter Simulation of 250V/400V..........................................44
Summary....................................................................................................45
Semiconductors Tailored to Different Voltage Classes................................46
Conclusion.........................................................................................................51
Chapter 5 Specification and Design of a Switched
Reluctance 48 V Belt Integrated Starter Generator (B-ISG)
for Mild Hybrid Passenger Car Applications....................... 53
Electrical Implementation of 48V systems....................................................54
Vehicle Architecture Layouts...........................................................................55
Small Vehicle Segment.............................................................................55
Large Vehicle Segments...........................................................................56
Application Specific Motor Requirements....................................................57
Motor Design Challenges................................................................................58
Traditional Switched Reluctance Machine Challenges................................61
Torque, Voltage and Current Ripple......................................................61
Noise, Vibration, and Harshness............................................................62
Electronics Costs.......................................................................................63
Diverging Solutions with a Common Core...................................................64
Winding Variants......................................................................................64
Electronics Variants..................................................................................64
Control Systems and Modelling Variants..............................................64
SpeedStart Performance Data.........................................................................65
Energy Storage...................................................................................................66
Conclusions........................................................................................................67
References...........................................................................................................68
Chapter 6 Optimizing Lithium-Ion Batteries - Tailoring
Electrodes for Microhybrid Vehicle Applications............... 69
Experimental......................................................................................................70
Drive Cycles Used in this Work..............................................................70
Vehicle Simulation....................................................................................71
Electrochemical Simulation.....................................................................72
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Results.................................................................................................................73
Defining Metrics and Targets for Microhybrid.....................................73
Energy Density................................................................................74
Power Density.................................................................................75
Combining Fuel Economy and Volume......................................76
Limiting Constraints for Electrode Sizing.............................................78
Fundamental Limitation of Charge Acceptance........................78
Customizing Electrodes for Intended Life..................................79
Varying Conditions Over Battery Life.........................................79
Varying Vehicle-Level Requirements Over Battery Life.............80
Optimizing Electrodes for Microhybrid................................................82
Customizing Electrodes for Cell Capacity..................................82
Effects due to Motor/Generator Size..........................................84
Customizing Electrodes for Drive Cycles...................................84
Discussion..........................................................................................................86
Analysis of the Whrecov/L Metric.............................................................86
Applicability of WHrecov/L Metric................................................86
Variants of the Whrecov/L Metric...................................................87
Impacts of Vehicle Requirements...........................................................87
Definition of Battery Life...............................................................87
Vehicle Architecture Changes.......................................................88
Drive Cycle Impacts.................................................................................89
Summary and Conclusions..............................................................................89
Impact of Quantitative Optimization....................................................89
Other Vehicle Applications......................................................................89
References...........................................................................................................90
Chapter 7 Application of 48 Volt for Mild Hybrid Vehicles
and High Power Loads.......................................................... 93
Characteristics and Requirements of the 48V E/E System.........................94
Failure Modes in the 14V/48V E/E System..................................................95
Short to Ground........................................................................................95
Loss of Common Ground........................................................................96
Voltage Short Circuit................................................................................96
Broken Wire...............................................................................................97
Recommendations for 48V E/E System design..........................................100
Battery Box...............................................................................................100
Power Distribution Boxes......................................................................100
Pre-Fuse Boxes..............................................................................100
Bused Electrical Centers..............................................................101
vii
Electric/Electronic Centers (Smart E/E Centers)....................101
Electronic Modules (dc-dc converters)......................................101
Wires for 48V Application.....................................................................101
Routing..........................................................................................102
Materials........................................................................................102
Color Coding.................................................................................102
Connection Systems for 48V Application............................................102
Avoidance of Hot Plugging...................................................................103
Component Level ........................................................................103
System Level.................................................................................103
Summary and Conclusions............................................................................104
References.........................................................................................................104
Acknowledgments..........................................................................................104
Chapter 8 Advantages of a 48 Volt Belt Starter Generator in
an Ultra-Light Vehicle Powertrain.......................................105
CULT - Cars Ultra-Light Technology...........................................................106
Hybrid Approach - 12 V BSG........................................................................107
BSG (12 V) Hybrid Configuration........................................................107
Validation Process...................................................................................108
CO2 Saving Potentials and Comfort.....................................................109
Hybrid Approach - 48 V BSG........................................................................ 112
Introduction of 48 V Technology.......................................................... 112
BSG (48 V) Hybrid Configuration........................................................ 113
Electric Driving Potential....................................................................... 115
Energy Management.............................................................................. 118
CO2 Saving Potentials.............................................................................121
48 V Plug-In Concept.............................................................................123
Summary..........................................................................................................123
References.........................................................................................................124
Acknowledgments..........................................................................................125
About the Editor..............................................................................................127
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