ECE 760 – Module 6

Transportation
Electrification
Electrical and Computer Engineering
University of Waterloo
Instructor: Mehrdad Kazerani
E-mail: mkazerani@uwaterloo.ca
Lecture Date: October 27, 2020
 What is Transportation Electrification?

♦ Transportation Electrification (electric mobility/e-mobility) is the

transition from the conventional Internal Combustion Engine
(ICE)-based vehicles to vehicles with electrified powertrains.
♦ Even though it is commonly believed that “the future of
transportation is electric”, fuel cell vehicles (FCVs), hybrid
electric vehicles (HEVs), and plugin hybrid electric vehicles
(PHEVs) are also considered as temporary or permanent
participants in this transition.
♦ The transition to EVs is not limited to passenger vehicles, but
also includes fleet vehicles (e.g., trucks), buses, light rail and
subway systems, ships, airplanes and even non-road vehicles
(e.g., forklifts).

“The future of transportation is electric”, white paper by ABB (abb.cpm/us),

2018.

2
Main Drivers of Transportation Electrification-1
– lower total cost of ownership (TCO): lower running
(operation and maintenance, O&M) costs offset the (falling)
are lower in EV which can offset higher initial cost. Over time
higher initial cost higher initial cost is decreasing
• Operation/Fuel Cost: According to EPRI, the cost of electricity per
mile of driving of light-duty vehicles is less than one-third of that of
gasoline. Also, cost of electricity does not experience the variability of
fuel cost (hence a more predictable business model). A study in 2016
found that even though each electric bus costs about $300,000 more
than a diesel bus, operating costs provide annual savings of $39,000 in
the 12-year typical lifetime of the bus, resulting in a drop of total cost of
ownership by $150,000 per bus.
• Maintenance Cost: Lower number of moving parts in drivetrain results
in lower maintenance costs and longer life.
• Initial Cost: Advances in battery technology and reduction in $/kWh
results in lower initial cost.
“The future of transportation is electric”, white paper by ABB (abb.cpm/us), 2018.
Dan Leistikow, “The eGallon: How Much Cheaper is it to Drive on Electricity?”
https://www. Energy.gov/articles/egallon-how-muchcheaper-it-drive-electricity; EPRI
paper
Judah Aber, “Electric Buc Analysis for New York City Transit”, Columbia State
University, May 2016.
http://www.columbia.edu/~ja3041/Electric%20Bus%20Analysis%20for%20NYC%20T
ransit%20by%20J%20Aber%20Columbia%20University%20-%20May%202016.pdf
3
Main Drivers of Transportation Electrification-2

– Sustainability
• The current transportation system is not sustainable due to strong
dependence on fossil fuels (limited and diminishing supply, insecure
due to political conflicts)
– lower adverse environmental impact
• The transportation sector is responsible for 27% of GHG emissions in
the US and 24% in Canada. ICE-based vehicles cannot keep up with the
ever-rising fuel efficiency standards. Also, their environmental
performance will decline in the course of their lifetime. EVs, however,
become more environmentally friendly as electricity generation
becomes more environmentally friendly.

“The future of transportation is electric”, white paper by ABB (abb.cpm/us), 2018.

US Environmental Protection Agency, “Fast Facts on Transportation Greenhouse Gas
Emissions”. https://www.epa.gov/greenvehicles/fast-facts-transportation-greenhouse-
gas-emissions; US data
Environment and Climate Change Canada, “Canadian Environmental Sustainability
Indicators: Greenhouse Gas Emissions”, 2017, http://www.ec.gc.ca/indicateurs-
indicators/FBF8455E-66C1-4691-9333-5D304E66918D/GHGEmissions_EN.pdf
(Canada Data)
4
Main Drivers of Transportation Electrification-3

– enabling emerging/future technologies and mobility business

models
• EVs have been adopted by almost all autonomous vehicle (AV)
developers/manufacturers as the platform, for the following reasons:
drive-by-wire feature of EVs is a perfect fit for computer control; large
battery packs of EVs can handle the power requirements of sensors and
control systems used in AVs; EVs are the only option that can satisfy
the requirements on fuel economy and emissions of vehicles of future;
and EVs offer a lower total cost of ownership (TCO) than ICE-based
vehicles.
• Adopting EVs as the platform for AVs is serving as a positive factor in
promoting EV technologies development.

“The future of transportation is electric”, white paper by ABB (abb.cpm/us), 2018.

5
Main Drivers of Transportation Electrification-4

– Higher Overall Efficiency/Better Fuel Economy

• Higher overall efficiency translates into lower fuel consumption and
better fuel economy. In 2012, the US government announced new fuel
economy standards that mandates the fuel economy of passenger and
light-duty vehicles to rise to 54.5 mi/gal (4.3 L/100km) by 2025. These
fuel economies cannot be achieved by the conventional or even
improved ICE-based vehicles (average efficiency of ICE is about 30%),
but the set goals are within the reach of electrified vehicles thanks to
high efficiency of their components, i.e., electric energy storage
systems, electric machines ( > 90%) and power electronic converters, as
well as high performance of electric powertrain architecture and control
design and software.

Berker Bilgin, Pierre Magne, Pawel Malysz, Yinye Yang, Vera Patelic, Alexandre Korobkine, Weisheng Jiang,
Mark Lawford and Ali Emadi, “Making the Case for Electrified Transporttation”, IEEE Transactions on
Transportation Electrification, Vol. 1, No. 1, June 2015, pp. 4-17.

US Environmental Protection Agency (EPA), Regulations and Standards: Light-Duty, http://www.epa.gov/

6
 E-Mobility Challenges & Opportunities
♦ Governments should develop the needed policies to support investment
in e-mobility solutions by developers/manufacturers, especially in
electric transit buses, port electrification and shore-to-ship power
connection (which has proved very effective in reducing production of
harmful pollutants, since docked ships do not have to run their engines
for power generation any more), and EV charging infrastructure. Canada
and US are behind other industrialized countries in this respect and need
to act fast if they want to be exporters of the related technologies, instead
of importers.
♦ Governments should support research and development in DC fast
chargers to facilitate adoption of EVs by car owners.
♦ Charging connection standards for electric buses and medium to heavy-
duty vehicles need to be developed and disclosed, as they exist for AC
charging and DC fast charging for EVs.
♦ Coordinated charging and vehicle-to-Grid transactions should be enabled
in collaboration with grid operators.
♦ Governments should provide tax incentives for adoption of EVs and
deployment of charging infrastructures.

“The future of transportation is electric”, white paper by ABB (abb.cpm/us), 2018.

7
 Degree of Electrification
♦ Degree of Electrification: ratio of electrical power available to total power.
♦ Electrification applies to both propulsion and non-propulsion loads.
♦ Most presently-manufactured vehicles have electrification level of 10-20%.
♦ The higher the electrification level, the higher the fuel efficiency
improvement with respect to baseline (0% electrification in the same
vehicle platform).

S.G. Wirasingha, M. Khan and O. Gross, “48-V electrification: Belt-driven starter generator systems”, in Advanced
Electric Drive Vehicles, Boca Raton, FL, USA, CRC Press, 2014.
B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015. 8
 Fuel Economy
♦ Fuel economy is given in terms of mile per gallon, mpg, (or mile per gallon
equivalent, mpge) and liters per 100 kilometers.
♦ Fuel economy mandate: 54.5 mpg, by 2025, in the USA, for light duty
vehicles.
♦ New regulations is expected to result in reduction of oil consumption by 12
billion barrels, cost saving of $1.7 trillion, and reduction in GHG emissions
by 6 billion metric tons.
Current
Status of
Vehicles

Fuel
Economy
Targets

U.S. Environment Protection Agency (EPA), August 2012, “Infographic: Driving to 54.5 MPG by 2025”, http://www.epa.gov/.
9
 Components of Electrified Powertrain-1
Mechanical Power (ICE)

Inverter
Electric
Machine ICE
A
Series Operation
Battery Charging (ICE) Electric Traction (ICE) (Range Extender)
Mechanical Power
Regenerative Braking Electric Traction (Battery) to and from Wheel

Converter
DC/DC Electric
Charger

Inverter
Battery

Machine
B
(Boost) ♦ DC/DC converter (Boost): Toyota
SDS II & Ford Fusion Hybrid
DC/DC

♦ Electric Machine A: Toyota SDS II,

12 V Ford Fusion Hybrid, Hyundai Sonata
Hybrid & Chevrolet Volt
♦ Charger: Chevrolet Volt, Nissan Leaf
& Ford Focus Electric
B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1, No.
1, June 2015.
10
 Components of Electrified Powertrain-2
Power Electronic Converters-1
♦ In electrified powertrains, power electronic converters are placed between
energy sources (e.g., battery pack) and actuators (i.e., traction motors).
♦ These power electronic converters are mostly bidirectional and enjoy high
efficiencies ( > 90%).
♦ In some electrified vehicles, a bidirectional DC/DC Converter is used
between the battery pack and traction motor inverter(s) to step up the
battery pack voltage, offering higher flexibility in selecting the battery pack
and traction motor voltage ratings, as well as controlling the vehicle system.
♦ In EVs, usually one inverter is used, allowing the flow of electrical traction
power from the battery pack to the traction motor and electrical braking
power from the traction motor to the battery pack.
♦ In HEVs and PHEVs, a second inverter is used, allowing the flow of
electrical power originating from ICE to battery pack and to main traction
motor to assist in propulsion.
♦ Due to multidisciplinary nature of the environment in which power
electronic converters operate, their design must fulfill electrical,
mechanical, thermal, and control requirements.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1, No.
1, June 2015.
11
 Components of Electrified Powertrain-3
Power Electronic Converters-2
Semiconductor Devices/Switches-1
♦ The two common switches in power electronic converters in automotive
applications are IGBT and MOSFET.
♦ IGBTs are medium-power, medium-frequency switches that are used for
systems at voltage ratings in the range 200-1200V.
♦ MOSFETs are low-power, high-frequency switches that are used in lower
voltage systems, such as 12V or 48V systems. Since for the same processed
power, a higher voltage requires a lower current, resulting in lower power
losses, the trend in vehicular systems is to move from 12V to 48V platform.
♦ Wide band gap devices based on SiC (Silicon Carbide) and GaN (Gallium
Nitride), that have been introduced in the last decade, offer numerous attractive
advantages, with respect to Silicon-based devices, in terms of blocking voltage,
losses/efficiency, power density, switching frequency and thermal conductivity.
♦ High-frequency operation reduces the volume and weight of capacitors,
inductors and isolation transformers, resulting in reduction of overall size and
weight, that is very critical in automotive applications.
♦ Higher thermal conductivity and lower losses results in lower thermal
management/cooling requirements.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1, No.
1, June 2015.
12
 Components of Electrified Powertrain-4
Power Electronic Converters-3
Semiconductor Devices/Switches-2
♦ The SiC-based drive unit developed by Toyota and Denso has resulted in
10 times increase in switching frequency and 80% reduction in the overall
volume of the drive with respect to the existing converter.
♦ A study performed by the Oak Ridge National Laboratory estimates an
increase of 14.7% in fuel economy of a Toyota Prius 2004 for the UDDS
drive cycle with the use of SiC components.
♦ To date, there is no commercially-available vehicle using wide band gap
devices, mainly due to the relatively high cost of these devices. This is
however expected to change in the near future.
♦ Standard packages of switches include discrete (1 switch), dual (2
switches), fourpack (4 switches), and sixpack (6 switches). Some packaging
options feature built-in switch drivers and protection towards better and
safer performance.
♦ Customized packaging is also possible. For example, Toyota SDS II
(Synergy Drive System II) uses a module comprised of 14 IGBTs and
diodes that realize 2 inverters and a boost DC/DC converter.
“Toyota and Denso Develop SiC Power Semiconductor for Power Control Units; Targeting 10% Improvement in
Hybrid Fuel Efficiency”, May 2014, http://www.greencarcongress.com/.
H. Zhang, L. M. Tolbert, and B. Ozpineci, “Impact of SiC devices on hybrid electric and plug-in hybrid electric
vehicles”, in IEEE Trans. Ind. Appl., Vl. 47, No. 2, pp. 912–921, Mar./Apr. 2011.
B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1, No.
1, June 2015. 13
 Components of Electrified Powertrain-5
Power Electronic Converters-4
Passive Components
♦ Main passive components in power electronic converters are capacitors and
magnetic components (inductors and high-frequency transformers).
♦ Capacitors usually play the role of a first-order low-pass filter for input and
output currents of converters. A major role is to filter the battery pack terminal
current.
♦ Electrolytic capacitors are normally used at lower-voltage applications such as
12V and 48V auxiliary systems.
♦ Film capacitors are generally preferred in higher-voltage applications, such as dc-
link voltage filtering in HEVs, PHEVs and EVs.
♦ Magnetic design has a critical position in all power electronic systems, especially
those in automotive applications, due to the impact on efficiency and size.
♦ Ferrite is usually the material of choice for high-frequency transformers,
operating at hundreds of kHz, due to its low cost and low core losses.
♦ In high-power applications, the inductor cores are usually made of Iron Powder
or Silicon Steel, rather than Ferrite, due to their higher saturation flux density
with respect to that of Ferrite, and to avoid a bulky design.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.
14
 Components of Electrified Powertrain-6
Power Electronic Converters-5
Thermal Management/Cooling
♦ Thermal management/cooling is very critical in power electronic converters.
A well-designed thermal management system will result in a higher power
density and will significantly improve the safety and reliability of the system.
♦ In cooling, the idea is to provide a highly-conductive path (with very low
thermal resistance) for the flow of heat from the semiconductor device to the
ambient so that a safe margin is maintained between the junction temperature
and its upper limit.
♦ Forced convection, using fans together with heatsinks, is normally used in
low-power applications.
♦ In high-power applications, such as traction inverters in the electrified
powertrains, forced liquid cooling is usually used due to its superior
performance.

Y. Wang, S. Jones, A. Dai, and G. Liu, “Reliability enhancement by integrated liquid cooling in power IGBT modules
for hybrid and electric vehicles”, Microelectron. Rel., Vol. 54, No. 9–10, pp. 1911–1915, Sep./Oct. 2014.
B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.
15
 Components of Electrified Powertrain-7
Power Electronic Converters-6
Challenges
♦ The targets set by the US Department of Energy (DOE) for 2020 for
traction power electronics specify:
– 13.4 kW/L for power density
– 3.3 $/kW and
– 105°C for coolant temperature
♦ It has been shown through constructing and testing prototypes that the
target for power density can be exceeded thanks to SiC-based devices;
however, the targets for cost and coolant temperature cannot be reached.
♦ To meet the coolant temperature target, either cooling systems have to be
improved or switches with higher thermal limits have to be manufactured.
♦ To meet the cost target, improvements in both manufacturing processes and
component and system integration are necessary.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.

16
 Components of Electrified Powertrain-8
Electric Machines-1
♦ Electric machines are very important components of electrified vehicles.
Their design and characteristics have huge impacts on fuel economy,
performance (acceleration, high-speed operation) and driving comfort.
♦ In EVs, high-efficiency and high-performance electric motors result in
extending the all-electric range.
♦ In HEVs and PHEVs, where electric motors and ICEs cooperate, high-
efficiency and high-performance motors allows the ICEs to operate in their
high-efficiency region, resulting in better fuel economy.
♦ In order to improve overall efficiency and fuel economy, traction motors
must be highly efficient in their most frequent operating region.
♦ The electric machines currently used in electrified vehicles are:
– Interior Permanent Magnet Synchronous Machine (IPMSM) and
– Induction Machine (IM)
♦ Switched Reluctance Machines, even though not presently used in any
electrified vehicle on the market, have a lot of potential as a future
replacement for the currently used machines.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.

17
 Components of Electrified Powertrain-9
Electric Machines-2 – IPMSM-1
♦ IPMSM is the electric machine type used in most of EVs, HEVs and PHEVs on
the market.
♦ In IPMSM, the permanent magnets are embedded in the rotor.
♦ IPMSM features high torque density and superior efficiency in the low and
medium speed ranges.
♦ In Toyota Prius (a power-split hybrid), the IPMSM has the following specs:
– Peak Power: 60 kW
– Maximum Torque: 207 N·m
– Maximum Speed: 13,500 rpm
♦ In Nissan Leaf, (an EV), the IPMSM has the following specs:
– Peak Power: 80 kW
– Maximum Torque: 280 N·m
– Maximum Speed: 10,390 rpm

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015. 18
 Components of Electrified Powertrain-10
Electric Machines-3 – IPMSM-2
issues!

♦ Permanent magnet traction motors use high-energy, rare-earth permanent

magnets to provide high torque density.
♦ Main disadvantages of permanent magnet machines are:
– Temperature sensitivity
– High cost
– Vulnerability of monopolized rare-earth magnet market

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.
19
 Components of Electrified Powertrain-11
Electric Machines-4 – IM
♦ In comparison with IPMSM, IM has a lower power factor and efficiency at low
speeds. This is due to lack of independent excitation on the rotor.
♦ Rotor copper losses is considered a serious disadvantage for IM. It is difficult to
remove the generated heat from rotor, especially at high torque, limiting the
torque per unit volume that can be achieved by IM.
♦ Using copper rotor bars, instead of aluminum rotor bars, results in less heat in
high-torque, high-speed operation, thanks to lower resistivity of copper. This is
at the cost of larger weight and higher cost.
♦ In Tesla EV, the IM has the following specs:
– Peak Power: 310 kW
– Maximum Torque: 600 N·m
– Maximum Speed: 14,000 rpm

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.
20
 Components of Electrified Powertrain-12
Electric Machines-5 – SRM
♦ SRM is superior to IPMSM and IM in simplicity and robustness/ruggedness
of structure, as well as the cost.
♦ In SRM both stator and rotor have salient poles.
♦ The rotor is very simple. It has neither conductor bars (unlike IM) nor
permanent magnets (unlike IPMSM). This makes SRM very suitable for
high-speed operation and high-temperature conditions.
♦ Main disadvantage of SRM is significant ripple contents in the torque, due
to double saliency and rotor position dependence of torque. Also, strong
radial forces can lead to vibration and noise. These tend to limit SRM
power density, unless advanced designs and controls are implemented.
♦ SRM is not presently used in any electrified on-road vehicle on the market,
as traction motor.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015. 21
 Components of Electrified Powertrain-13
Energy Storage System (ESS)-1
♦ In conventional ICE-based vehicles, the services provided by energy
storage system are limited to Starting, Lighting and Ignition (SLI).
♦ As degree of electrification rises, the requirements on power, energy and
cycling of ESS grows.
♦ Size and technology of ESS are indicative of degree of electrification and
thus improvement in fuel economy.
♦ Every of ESS technology requires a dedicated Energy Management System
(EMS) for safe and efficient delivery of power and energy by the ESS.
♦ In battery-based ESS (the most commonly-used ESS type in electrified
vehicles), EMS is called Battery Management System (BMS).
♦ BMS takes care of balancing the battery cells comprising the battery pack,
estimating state of charge (SoC), fault diagnosis, power/energy availability
reporting, and communicating with other vehicle’s systems (e.g., charger,
and traction control), whose operation relies on battery condition and
performance

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.
22
 Components of Electrified Powertrain-14
Energy Storage System (ESS)-2
♦ The Ragone diagram shown below provides a comparison of cost per unit energy
($/kWh), specific energy (Wh/kg) and specific power (W/kg) for common ESS
technologies in electrified vehicles, i.e., electric double-layer capacitor (EDLC),
lead-acid battery, Lithium-Ion (Li-ion) battery, Nickel-Metal- Hydride (NiMH)
battery, and Sodium-Nickel-Chloride (Na-Ni-Cl) battery.

EDLC

Li-ion Power

Li-ion Energy
NiMH

Lead Acid

Na-Ni-Cl

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015. 23
 Components of Electrified Powertrain-15
Energy Storage System (ESS)-3 – Batteries-1
♦ Flooded Lead-Acid (FLA) batteries are commonly used to serve SLI loads.
♦ Typical cell voltage is 2.17-2.22 V.
♦ FLA battery advantages: mature technology, highly recyclable
♦ FLA battery disadvantages: relatively low cycle life and low Depth of
Discharge (DoD)
♦ Enhanced FLA (EFLA) batteries offer 2×cycle life of FLA batteries.
♦ Sealed Lead Acid (SLA) or Valve-Regulated Lead Acid (VRLA) batteries
are maintenance-free and offer 3.5×cycle life of FLA batteries, at the cost
of less maturity in technology and higher costs.

FLA battery EFLA battery SLA battery

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1,
No. 1, June 2015.
24
 Components of Electrified Powertrain-16
Energy Storage System (ESS)-4 – Batteries-2
♦ Nickel-Metal-Hydride (NiMH) batteries have been in service in HEVs for more
than 15 years.
♦ NiMH batteries enjoy a rather mature technology and long life cycle.
♦ NiMH batteries have proven performance witnessed by 10 years and over
160,000 km of service in Toyota RAV 4 EV.
♦ Typical cell voltage is 1.2-1.35 V.
♦ NiMH batteries’ coulombic efficiency* is 10% less than that of Lead-Acid
Battery, whereas their power/energy capabilities are 2-3 times those of Lead-
Acid batteries.
♦ A serious disadvantage for NiMH batteries is their high self-discharge.

NiMH battery pack

*Coulombic Efficiency:
The ratio of output charge
to input charge.

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A.
Emadi, “Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification,
Vol. 1, No. 1, June 2015.
25
 Components of Electrified Powertrain-17
Energy Storage System (ESS)-5 – Batteries-3
♦ Sodium-Nickel-Chloride (Na-Ni-Cl) or ZEBRA battery enjoys a mature
technology developed over the past 25 years.
♦ ZEBRA battery’s operating temperature is in the range 270-350°C.
♦ ZEBRA batteries are insensitive to ambient temperature, thus very
appropriate for extreme climates. Also, they can tolerate short-circuit faults
due to internal cell damage.
♦ ZEBRA batteries have greater specific energy and cycle life, and lower
cost, but lower specific power when compared with NiMH batteries.
♦ Some European EVs, such as Iveco Electric Daily, Think EV, and Modec
Evvans have used ZEBRA batteries.

ZEBRA battery pack

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A.
Emadi, “Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification,
Vol. 1, No. 1, June 2015.
26
 Components of Electrified Powertrain-18
Energy Storage System (ESS)-6 – Batteries-4
♦ Lithium-ion battery is currently the preferred technology for PHEVs and
EVs.
♦ Major concerns about Li-ion batteries are safety, long-term reliability and
low-temperature performance.
♦ The source of concern about safety is thermal runaway that can happen at
high cell temperatures and in cases of overvoltage. The flammability of
electrolyte make the safety concern more severe.
♦ Lithium-ion batteries are manufactured in high-energy or high-power
designs.

Lithium-ion battery pack

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A.
Emadi, “Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification,
Vol. 1, No. 1, June 2015.
27
 Safety Concerns of Li-ion Batteries-1
♦ One of the main sources of concern in electrified vehicles is the
Li-ion battery pack.
♦ Li-ion battery cell has the potential of thermal runaway. This
implies quick rise of temperature to the melting point of the
metallic lithium. At high temperatures, the flammable electrolyte
can ignite or even explode when exposed to the Oxygen in the
air.
♦ To ensure safety, certain precautions have to be implemented
when charging and discharging the Li-ion cells. These include
protecting the cells from being overcharged or discharged, and
maintaining the cell current within safe limits.
♦ Effective cell balancing/equalization can also protect battery cells
against overcharging, thus reducing safety hazard.
♦ Effective thermal management can also improve the safety of Li-
ion battery cells.

28
 Safety Concerns of Li-ion Batteries-2

Tesla Model S battery caught fire, leading to total

destruction of the car in 5 minutes.
Time: August 18, 2016
Place: Southwest of France

https://arstechnica.com/cars/2016/08/tesla-model-s-france-battery-fire/
29
 Safety Concerns of Li-ion Batteries-3

Chinese Electric Bus (a hybrid Ultracapacitor/Li-ion bus)

battery caught fire
Time: July 19, 2011
Place: Shanghai

https://mnordan.com/2011/07/20/chinese-electric-bus-fire/
30
 Safety Concerns of Li-ion Batteries-4

Li-ion Battery Pack caught fire

Time: October 18, 2019
Place: GAIA Lab, BTC (University of Waterloo)

Courtesy of Ross McKenzie, Managing Director, WatCAR, University of Waterloo

31
 Components of Electrified Powertrain-19
ESS-7 – Battery Pack Design
♦ Modular design is a common approach in battery-based energy storage
systems of electrified vehicles. To realize the pack’s required high voltage,
a number of modules are connected in series. Each module is composed of
a number of battery cells in series-parallel configuration.
♦ Weight of the battery pack is an important factor affecting vehicle
performance (acceleration time, deceleration time and fuel economy).
♦ ½ to ¾ of the battery pack weight is due to battery cells. This makes an EV
heavier than its counterpart, i.e., an ICE-based vehicle of comparable
performance.
♦ In most of the electrified vehicles, thermal management of battery cells is
performed through a liquid coolant with the exception of Nissan Leaf,
which features air cooling for the battery cells.

Chevrolet Volt Battery Pack

https://www.msn.com/en-ca/autos/news/replacement-
batteries-to-affect-used-ev-sales/ar-BBPKw9J2016

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A.
Emadi, “Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification,
Vol. 1, No. 1, June 2015.
32
Components of Electrified Powertrain-20
Battery Pack Integrated within Vehicle

https://www.xingmobility.com/products/EV-battery-solutions
33
 Cell Balancing/Equalization
♦ The battery packs used in EVs and HEVs are made up of long strings of
series cells in order to achieve the desired operating voltages.
♦ In multi-cell batteries, the failure rate is higher than in a single-cell
battery, worsening the reliability. The problem can be compounded if
parallel combination of cells are also used to achieve the desired capacity
and/or power level. In an n-cell battery, the failure rate is n times that of
individual cells.
♦ Due to production tolerances, uneven temperature distribution and
differences in ageing characteristics of cells, individual cells in a series
string could become overstressed, leading to premature failure.
♦ In the charging cycle, a degraded cell in a series string could be
overcharged once it has reached its full charge, before the rest of the
cells in the string reach their full charge, leading to temperature and
pressure build-up and possible damage to the cell.
♦ In the discharging cycle, the weaker cells will experience greatest depths
of discharge, with a possibility of premature failure.
♦ Cell balancing techniques are implemented to address the above-
mentioned issues by equalising the stress on the battery cells.
https://www.mpoweruk.com/balancing.htm 34
 Cell Balancing/Equalization Techniques-1

• Dissipative methods: (Resistor equalizer, Switched-

resistor equalizer)
 Simple structure
 Low manufacturing cost
 Low reliability
wasteful too as dissipates

• Non-dissipative methods: (DC/DC converters and

transformers)
 Complex design
 Expensive due to use of DC-DC converters
 High reliability

35
 Cell Balancing/Equalization Techniques-2

cell cell cell cell

cell cell
cell cell

cell cell

cell cell

♦ Since battery packs are made up of a number of modules, inter-

modular balancing/equalization is also deemed necessary.
♦ Cell balancing/equalization is not limited to batteries and applies to
series-connected ultracapacitor cells as well.

36
 Hybrid Energy Storage Systems

♦ In a Hybrid Energy Storage System (HESS), at least two energy storage

technologies are integrated to combine the complementary characteristics
of participating technologies.
♦ HESS has been a hot subject for research and development in the current
decade. Most of the work in this area has appeared as research articles and
lab prototypes. HESS has not replaced battery pack in any commercial
electrified vehicle yet.
♦ Most of proposed and developed HESSs combine two different battery
technologies or a battery technology and ultracapacitor or supercapacitor.
The most common ultracapacitor employed in HESS of electrified vehicles
has been electric double-layer capacitor (EDLC). Here are some examples:
– Lead-Acid Battery + NiMH Battery
– Lead-Acid Battery + Li-ion Battery
– Lead-Acid Battery + Ultracapacitor
– ZEBRA battery + Ultracapacitor

B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A.
Emadi, “Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification,
Vol. 1, No. 1, June 2015.
37
 Hybrid Energy Storage System Research at
University of Waterloo-1
HESS combines Li-ion battery’s high specific energy and ultracapacitor’s high specific power.

HESS
+
Ragone
Diagram

K. Zhuge and M. Kazerani, “A Novel Capacitor-Switched Active Snubber for Single-Module and Interleaved Two-Module Bidirectional
Buck-Boost Converter Topologies”, in Proceedings of 2014 IEEE Industrial Electronics Conference (IECON 2014), Dallas, Texas, USA,
Oct. 29-Nov.1, 2014.
K. Zhuge and M. Kazerani, “Development of a Hybrid Energy Storage System (HESS) for Electric and Hybrid Electric Vehicles”, in
Proceedings of 2014 IEEE Transportation Electrification Conference & Expo (ITEC14), Metro Detroit, Michigan, USA, June 15-18, 2014.
A. Ostadi and M. Kazerani, “Hybrid Energy Storage System (HESS) in Vehicular Applications: A Review on Interfacing Battery and Ultra-
capacitor Units”, in Proceedings of the 2013 IEEE Transportation Electrification Conference & Expo (ITEC13), Metro Detroit, Michigan,
USA, June 16-19, 2013.
A. Ostadi and M. Kazerani, “Optimal Sizing of the Energy Storage System (ESS) in a Battery-Electric Vehicle”, in Proceedings of the 2013
IEEE Transportation Electrification Conference & Expo (ITEC13), Metro Detroit, Michigan, USA, June 16-19, 2013.
38
Hybrid Energy Storage System Configurations-1
♦ Choice of a specific configuration for interfacing a battery unit
(BU) and an ultracapacitor unit (UC) to the high-voltage DC-bus
of an electrified vehicle affects several parameters of the system:
 Manufacturing and maintenance cost
 Performance and reliability
 Complexity of the system

Partially-
Direct Fully-decoupled
decoupled
connection connection
connection

Either BU or UC is Both BU and UC are

BU and UC are
decoupled from the decoupled from the
directly connected to
DC bus via a DC-DC DC bus via DC-DC
the DC bus
converter converters

Configurations for Interfacing BU and UC to High-Voltage DC-Bus

39
 Hybrid Energy Storage System Configurations-2

No Power Surge for BU

Flexible Sizing of DC/DC
Selected
Topology

Improved BU Cycle Life

Lower-Power DC/DC

A. Ostadi and M. Kazerani, “Hybrid Energy Storage System (HESS) in Vehicular Applications: A Review on Interfacing Battery and Ultra-
capacitor Units”, in Proceedings of the 2013 IEEE Transportation Electrification Conference & Expo (ITEC13), Metro Detroit, Michigan,
USA, June 16-19, 2013.
40
Hybrid Energy Storage System Research at UW-2
HESS Configuration

C
Buck Switch
G

E
L2

C
Boost Switch
G

E
DC/DC Converter-2
High-Voltage
Side
Low-Voltage
Side

C
Buck Switch
G

E
Lf L1
Cdcbus UC

C
Boost Switch
BU
LC Filter
Cf G E
DC/DC Converter-1
Side-1 Side-2

Interleaved Bidirectional Buck-Boost

DC/DC Converters
41
Hybrid Energy Storage System Research at UW-3
Vehicular Load Demand
Bi-directional
DC/DC
Converter
Ultracapacitor Constant-
Battery +++ Current
Unit Unit
HESS Prototype Bi-directional
DC/DC
Source

Converter
Controllable-
Current Load
HESS

DC Power Source

Oscillocope
Lithium-ion
PC Battery Pack
with EMS
DC/DC
Inductor Converter

Electronic Power
LC Filter Load
42
Ultra-capacitor

42
Hybrid Energy Storage System Research at UW-4
/100

Experimental
Results
Vehicular
HESS
+++ Load
Demand

Battery
Discharge Battery Voltage
Ultracapacitor Voltage
Current
Ultracapacitor
Discharge
Current
Vehicular load demand is
distributed between battery and
ultracapacitor, respecting battery
limits for current and rate of
change of current. Also,
ultracapacitor voltage is restored
to the desired level (for better
Traction Inverter performance) via
power/energy transactions with
battery. 43
Used/Repurposed EV Batteries as Stationary ESS-1
♦ The number of available used EV batteries is on the rise.
♦ Even though these batteries, with State of Health (SoH) fallen below 80%
of initial value, and reduced functionality, are not suitable for handling
vehicle load demand any longer, there is still a lot of life in them, making
them good candidates for stationary ESSs after repurposing. This helps (i)
avoid disposal of potentially hazardous material and (ii) delay expensive
recycling.

Predication of number of EVs and the available used (2nd Life) EV Batteries (EVBs)

IRENA Battery Storage Report

http://www.irena.org /documentdownloads /publications/ rena_battery_storage_report.pdf
44
Used/Repurposed EV Batteries as Stationary ESS-2

Forecast of battery storage power capacity and

annual revenue for utility-scale applications

IRENA Battery Storage Report

http://www.irena.org /documentdownloads /publications/ rena_battery_storage_report.pdf

45
Used/Repurposed EV Batteries as Stationary ESS-3
Repurposing/Recycling of EV Batteries

The world’s largest 2nd life battery storage, composed of 1000 EV battery systems, with
capacity of 13 MWh, nearing completion in Lünen, Westphalia, Germany.

https://theictscoop.com/reusing-ev-batteries-a-game-changer-in-renewable-energy-b1e758d5f7fe
46
Used/Repurposed EV Batteries as Stationary ESS-4

Re-purposed, 2nd-Life Chevrolet Volt batteries, together with an array

of solar panels and a couple of wind turbines help to supply power to
GM's data center in Milford, MI
https://greentecauto.com/green-world/off-grid-power-chevy-volt-battery

47
Used/Repurposed EV Batteries as Stationary ESS-5

Assembly of re-purposed, 2nd-Life Chevrolet Volt batteries

Critical Issues with

Repurposed EVBs: A re-purposed, 2nd-
• BMS requirements Life Chevrolet Volt
battery Pack
• Safety concerns
• End-of-life prediction

https://greentecauto.com/green-world/off-grid-power-chevy-volt-battery 48
Used/Repurposed EV Batteries as Stationary ESS-6
Research at UW

♦ Developing a framework for modelling and costing of

Repurposed EVBs and their inclusion as Battery ESS
(BESS) option in microgrid supply planning studies

T. Alharbi, K. Bhattacharya and M. Kazerani, “Planning and Operation of Isolated

Microgrids Based on Repurposed Electric Vehicle Batteries”, in the IEEE Transactions
on Industrial Informatics, Vol. 15, Issue 7, July 2019, pp. 4319-4331. DOI:
10.1109/TII.2019.2895038.

49
 Ultracapacitor ESS for City Buses

♦ Ultracapacitors seem to be a
viable option for ESS of city
buses, due to the opportunity
for frequent and fast
charging at the designated
stops along the route, while
passengers get off and get on
the bus.

Buses in the Shanghai pilot project are made by

Sunwin Bus, a Chinese joint venture company
with Volvo of Sweden, and use ultracapacitors
manufactured by Shanghai Aowei.

https://www.technologyreview.com/s/415773/next-stop-ultracapacitor-buses/

50
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-1

Battery-Only EV

Ultracapacitor-
Only Bus

51
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-2

Battery-Only Electrified Powertrain

52
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-3

Ultracapacitor-Only Electrified Powertrain

53
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-4

Battery-Ultracapacitor HESS Electrified Powertrain

54
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-5

Battery Unit Ultracapacitor Unit

55
 Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-6
Rshort transient Rlong transient
Battery Model Rseries ib
• Open-Circuit Voltage +
• Effective series resistance C Clong transient
voc short transient vt
• Short-transient RC branch −
• Long-transient RC branch

E cell = 8.3 Wh m bu = 43 g Q b = 2.25 Ah

−1.031 e −35 SoC + 3.685 + 0.2156 SoC − 0.1178 SoC 2 + 0.3201 SoC 3
voc =
Rseries 0.1562 e −24.37 SoC + 0.07446
Rshort transient 0.3208 e −29.14 SoC + 0.04669
=
−752.9 e −13.51 SoC + 703.6
Cshort transient =
Rlong transient = 6.603 e −155.2 SoC + 0.04984
−6056 e −27.12 SoC + 4475
Clong transient =
M. Chen and G.A. Rincon-Mora, “Accurate Electrical Battery Model Capable of Predicting Runtime and I-
V Performance,” IEEE Transactions on Energy Conversion, Vol. 21, No. 2, pp. 504 - 511, Apr. 2008
56
 Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-7
Rseries iuc
Ultracapacitor Model
+ +
• Voltage-dependent capacitance
• Effective series resistance vuc1 vt
C0 C1 −
−
C1 = kVuc1

Vuc − max =
2.85 V m uc 510 g
Rseries = 0.29 m Ω C0 = 521.4 F k = 918 F / V

www.Maxwell.com
R. Faranda, M. Gallina, and D.T. Son, “A new simplified model of double-layer capacitors,” Proceedings of
International Conference on Clean Electrical Power (ICCEP), pp. 706-710, Capri, Italy, 21-23 May 2007

57
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-8
• Traction motor should be able to keep Mechanical
Torque constant at maximum level up to base speed.

Torque-Speed Characteristics of an Induction Motor as Traction Motor

58
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-9
Parameters of Traction Induction Motor

59
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-10
Parameters of DC/AC Converter Switches
400V ,150 A IGBT Switches
Rsw = 0.0132 Ω RD = 0.016 Ω Vsw =
1.25 V
VD =
0.7 V =
tc ,on 0.09 µs tc ,off 0.15 µ s
Total Loss = 5% of load power

DC/DC Converter Efficiency in Buck Mode

(%)

DC/DC Converter Efficiency in Boost Mode

(%)

60
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-11
Calculating the vehicle power demand

61
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-12
Optimization Problem: Optimal sizing of ESS towards
minimum overall cost for a city bus driving on a Start-
Stop driving cycle for three cases of:
– Battery-only ESS
– Ultracapacitor-only ESS
– Battery-Ultracapacitor HESS

Assumptions:
– Transmission efficiency = 96 % (fixed)
– Permissible range for SoC: 30 - 90%
– Temperature = 25°C
– Total traction motor power loss = 10% of load power

62
 Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-13
Drive Cycle:
– UDDS: 11.988 km (1370 s), average speed = 31.50 km/h, maximum speed = 91.23 km/h
– 20 times (almost 240 km)
– Ultracapacitor unit is charged at the end of each UDDS driving cycle. Maximum
charging time is 1200s.
– Maximum and minimum numbers of series-connected cells on DC bus must respect the
DC bus open circuit voltage range of 200-600V.

UDDS Drive Cycle

63
 Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-14
Selected HESS Configuration:
–Partially-Decoupled, with Ultracapacitor Unit (UC) connected directly
across DC bus and Battery Unit (BU) behind a bidirectional DC/DC
converter

EM: Electric Machine

64
 Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-15
HESS Configuration:
– Compared to the Partially-Decoupled configuration with BU connected
directly across DC bus and UC behind a bidirectional DC/DC converter,
• BU is immune from large current pulses.
• BU power can be controlled effectively.
• Voltage balancing circuits for BU can be more easily implemented.
• DC-DC converter has a lower power rating.
– Compared to Fully-Decoupled configuration with BU and UC both
behind bidirectional DC/DC converters,
• The configuration is simpler and less expensive.

65
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-16
Optimization Result for the battery-only case (TLBO)

• Increasing frequency of replacements lowers the mass and

initial manufacturing cost of battery unit; however, it requires
faster charging and discharging of BU, which shortens the life
of battery cells.
66
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-17
Optimization Result for the Ultracapacitor-only case (TLBO)

Variation of DC bus voltage over two UDDS drive cycles

67
 Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-18
Optimization Result for the Battery-Ultracapacitor HESS (TLBO)
• Ultracapacitor Unit’s Charging Power Limit = 50kW
• In case of HESS, relative cost of battery and ultracapacitor cell costs,
as well as cost per kW of DC/DC converter affect the results.

A. Ostadi and M. Kazerani, "Optimal Sizing of the Battery Unit in a Plug-in Electric Vehicle (PEV)”, in
the IEEE Transactions on Vehicular Technology, Volume 63, Issue 7, September 2014, pp. 3077-3084.

68
Optimal Sizing of Battery-Ultracapacitor HESS
in Electrified Vehicles – Research at UW-19

A. Ostadi and M. Kazerani, "A Comparative Analysis of Optimal Sizing of Battery-only,

Ultracapacitor-only, and Battery-Ultracapacitor Hybrid Energy Storage Systems for a City Bus”, in the
IEEE Transactions on Vehicular Technology, Vol. 64, Issue 10, Oct. 2015, pp. 4449-4460.
69
 New and Continuing Research Trends in
Transportation Electrification
♦ Hybrid ESS (HESS) for Electrified Vehicles
♦ Smart Charging of Electrified Vehicles with Vehicle-to-Grid
(V2G) and Vehicle-to-Home (V2H) Capabilities
♦ Provision of Ancillary Services to Grid by Electrified Vehicle
Batteries
♦ Off-Board Charging, Fast Chargers and Fast Charging Stations
♦ Wireless Charging of Electrified Vehicles
♦ Ultracapacitor ESS for Mass Electric Transit
♦ Cell Balancing of Li-ion Batteries and Ultracapacitors
♦ Battery Cell Detailed Modeling
♦ Using 2nd-Life EV Batteries as Stationary ESS
♦ Non-Rare-Earth Machines and Drives, including SRM

70
 EV Battery Charger
A Standard On-Board Charger-1

AC to DC control charge of battery

main battery

1-Phase Isolated
Diode PFC Traction
AC LPF DC/DC
Rectifier Stage Battery
Supply Converter

12V
DC/DC
Battery &
Converter
Auxiliaries

71
 EV Battery Charger
A Standard On-Board Charger-2
1-Phase Isolated
Diode PFC Traction
AC LPF DC/DC
Rectifier Stage Battery
Supply Converter

12V
DC/DC
usually single phase this is a boost Battery &
converter Converter
full-bridge rectifier Auxiliaries
two in parallel

Interleaved PFC Boost

Converter

unidirectional

72
 EV Battery Charger
A Standard On-Board Charger-3
1-Phase Isolated
Diode PFC Traction
AC LPF DC/DC
Rectifier Stage Battery
Supply Converter

12V
DC/DC
Battery &
full bridge DC-DC rectifer Converter
Auxiliaries

unidirectional

isolation

diode rectifier

Isolated DC/DC Converter featuring a Full-Bridge

Converter with Zero-Voltage Switching (ZVS) capability
soft switching 73
 Smart Chargers
♦ Continuous growth in the number of EVs (1.26 million
at the end of 2015) will create problems in distribution
systems due to charging demand.
♦ Smart chargers, as vital components of Smart Grid, can
help in:
– Energy loss and cost minimization,
valley filling, and load shifting
(Utility Perspective)
– Charging cost minimization
and Charging rate maximization CHARGER

EVSE
(User Perspective)

MOTOR
BATTERY
DRIVER

74
Smart Charging/Smart EV Charger Operation
4-Quadrant EV Charger Research at UW-1
♦ Four-Quadrant EV charger:
– Uses two-stage power electronic converter topologies to provide
decoupled P and Q control and higher power quality on battery side.
– DC-link capacitor is carefully sized to allow reactive power support to
low-voltage (LV) grid. Q

– Average models are used for chargers

in LV system studies for high Inductive - Inductive -
Discharging Charging
P
penetration of EVs. Capacitive - Capacitive -
Discharging Charging

– V2G is not a focus in the study,

even though enabled. CHARGER

EVSE

MOTOR
BATTERY
DRIVER

75
 Smart Charging/Smart EV Charger Operation
4-Quadrant EV Charger Research at UW-2
♦ Stage 1: Full-bridge AC/DC converter
– DC-link voltage regulation
– AC-side power factor adjustment according to reactive power set-point
♦ Stage 2: Bidirectional buck-boost converter
– Battery current control according to active power set-point

76
Smart Charging/Smart EV Charger Operation
4-Quadrant EV Charger Research at UW-3
♦ Smart 4-Quadrant Charger Prototype:

– Rating: 1.92 kVA/ 120 V ac

(Level 1)
– DC link Voltage: 280 V
– Switching Frequency: 20 kHz
– Central Control Unit (CCU) :
TMS320F2808 DSP
– Battery Pack: Lithium-Ion 4.1
kWh, 102.4 V
– Communication Controller :
Murata Wi-Fi Module SN8200

J. Morris, “Design and Testing of a Bidirectional Smart Charger Prototype,"

Master's thesis, University of Waterloo, 2015.
77
Smart Charging/Smart EV Charger Operation
4-Quadrant EV Charger Research at UW-4
♦ Smart 4-Quadrant Charger Prototype:

3
4 2

5 1 P

6 8
7

78
 Smart Charging/Smart EV Charger Operation
4-Quadrant EV Charger Research at UW-5
♦ 3-Stage Feeder Control with 4-Quadrant Chargers:
♦ Objectives:
– Reduce peak load
– Provide adequate volt/var support
– Fairly allocate EV charging load

M. Restrepo, C. Canizares and M. Kazerani, “Three-Stage Distribution Feeder Control Considering Four-Quadrant EV Chargers”, in
the IEEE Transactions on Smart Grid, Vol. 9, Issue 4, pp. 3736-3747, July 2018.
M. Restrepo, J. Morris, M. Kazerani and C. Canizares, “Modeling and Testing of a Bidirectional Smart Charger for Distribution
System EV Integration”, in the IEEE Transactions on Smart Grid, Vol. 9, Issue 1, pp. 152-162, January 2018. 79
 Charging Standards
SAE J1772 AC Charging Standards-1
In North America, the Society of Automotive Engineers (SAE) standard
J1772 addresses levels of charging and a control protocol that connects
charging stations and vehicles.
Charge Nominal Maximum Branch Output
Method Supply Current (A) Circuit Power Level
Voltage (V) Breaker (kW)
Rating (A)
AC Level 1 120V AC 12A 15A 1.08
1-phase
120V AC 16A 20A 1.44
1-phase
AC Level 2 208-240V AC 16A 20A 3.3
1-phase
208-240V AC 32A 40A 6.6
1-phase
208-240V AC ≤ 80A per NEC 635 ≤ 14.4
1-phase

80
 Charging Standards
SAE J1772 AC Charging Standards-2

♦ Level 1 is used when the charger is simply plugged into a 120-V wall
socket, and it requires that the charger electronics be built into the
car.
♦ Level 2 charging also assumes the electronics are in the car. But the
charging source is single-phase ac at a nominal voltage of 240 V,
with a maximum current capability of 32 A.
♦ Level 3 assumes that the vehicles charging electronics can handle
either 120 or 240-V ac, via charging ports.
♦ The drawback to either type of charging direct from a typical home
ac power socket is low charging rate/speed.

81
 Charging Standards
SAE J1772 DC Charging Standards-3
Charge Supplied DC Maximum Power Level
Method Voltage Range (V) Current (A) (kW)
DC Level 1 200-450V DC ≤ 80A DC ≤ 36KW

DC Level 2 200-450V DC ≤ 200A DC ≤ 90kW

DC Level 3 200-600V DC ≤ 400A DC ≤ 240kW

♦ DC charging, using a three-phase industrial-capacity ac power

drop, can supply up to 600 V at 400 A. This could theoretically
deliver 35 kWh in less than 10 minutes.

82
 EV Charging Connectors-1

https://en.wikipedia.org/wiki/SAE_J1772

https://evcharging.enelx.com/eu/about/news/blog/552-ev-charging-connector-types
83
 EV Charging Connectors-2

https://www.electronicdesign.com/power/vehicle-charging-standards-quick-primer
84
 Hybrid Electric Vehicles-1

♦ Hybrid Electric Vehicles (HEVs) combine the power of an

internal combustion engine (ICE) with that of one or more
electric motors for traction.
♦ With respect to ICE-only vehicles, they provide advantages
in terms of flexibility, efficiency, performance, range, and
environmental impact.

85
 Hybrid Electric Vehicles-2
Categories from Capability Viewpoint
• Micro Hybrid (Stop-Start): stops the engine when the vehicle
comes to a halt.
• Mild Hybrid: builds on the stop/start by providing limited boost
and regeneration.
• Medium Hybrid: further building on the micro hybrid capability
with increased electric assist, allowing engine downsizing.
• Full Hybrid: can drive for a limited time (~ 3 km) as a pure EV.
• Plug-in Hybrid Electric Vehicles (PHEV): an HEV that has the
ability to be recharged through a mains supply. These have a larger
electric machine and battery and are capable of significant
operation in electric drive-only mode.
• Range Extended Electric Vehicle: this is primarily an electric
vehicle with an onboard electricity generator, thus allowing the
range of the vehicle to be increased with an energy dense fuel.
• Pure electric vehicles: not a hybrid, but likely to make a substantial
contribution to CO2 reduction in the future.

https://www.sciencedirect.com/topics/engineering/hybrid-electric-vehicle
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 Hybrid Electric Vehicles-3
Series Hybrid Electric Vehicle

Fuel Tank ICE

range extender

Generator

Transmission

Wheels
Power Electronic Electric
Battery
Converter Motor

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 Hybrid Electric Vehicles-4
Series Hybrid Electric Vehicle
• The ICE drives the generator and is mechanically disconnected from the
wheels.
• On-board ESS supplements traction power.
• Electric motor is directly connected to the drive shaft.
• A transmission to switch gears is usually not needed, as electric motors are
efficient over a wide speed range.
• During driving, an intelligent hybrid control system decides whether to feed
the electric drive motor from the ESS, or the ICE via generator, or both.
• During coasting (deceleration), braking and stand-still, where no traction
power is required, auxiliaries can be completely fed from the ESS, and the
ICE can be shut down.
• When hybrid control system determines that more power is needed than is
available from the energy storage, ICE is started to provide the required
traction power via generator.
• This scheme can be used for all-electric operation, with the ICE as a range
extender (Chevrolet Volt).
• Stop-start capability allows all electric operation for city driving.

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 Hybrid Electric Vehicles-5
Parallel Hybrid Electric Vehicle

Mechanical Coupling
Fuel Tank ICE

Transmission

Wheels
Power Electronic Electric
Battery
Converter Motor

supply from battery to wheelsand also bring from

wheels

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 Hybrid Electric Vehicles-6
Parallel Hybrid Electric Vehicle
• Both electric motor and ICE are mechanically connected to the drive
shaft through a mechanical coupling, to deliver power to the wheels in
parallel.
• The vehicle can be propelled by the ICE alone, by the electric motor
alone, or by both in parallel.
• Electric machine operates as a generator to charge the batteries from
regenerative braking or from ICE power
• As the ICE is connected to the wheels via mechanical coupling, it
makes this type of HEV quite efficient for highway driving.
• Compact system design
• Fewer components than a series hybrid (more compact design) results
in a more cost-effective solution.
• A centralized control system optimizes energy flow.

90
 Hybrid Electric Vehicles-7
Series-Parallel Hybrid Electric Vehicle

Mechanical Coupling
Fuel Tank ICE

Transmission

Wheels
Generator

Power Electronic Electric

Battery
Converter Motor

91
 Hybrid Electric Vehicles-8
Series-Parallel Hybrid Electric Vehicle
• Series/parallel structure merges the advantages and complications of
series and parallel structures. The ICE and electric motor can provide
power independently or in conjunction with one another.
• ICE-only and electric motor-only options allow the ICE operate at near
optimum efficiency more often. At lower speeds, the vehicle operates
more as a series hybrid, while at high speeds, where the series
drivetrain is less efficient, the ICE takes over and energy loss is
minimized.
• High efficiencies that can be achieved by series-parallel justify the
higher costs with respect to a parallel hybrid (due to an additional
generator, a larger battery pack, and more computing power to control
the dual system).
• The Toyota Prius is a series-parallel hybrid. This is possible because of
the Prius' power split device, a special gearbox that connects the ICE,
electric motor and generator together into one unit.

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 Comparison of Electrified Powertrain Structures
Parallel

Power-Split Conventional

Two-Mode EV

PHEV
Series-Parallel Electrification Degree
Powertrain Complexity
Fuel Economy
EREV Emissions
B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1, No. 1,
June 2015.
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 Electrified Powertrain Control
♦ Electrified powertrains adopt multilevel control systems.
♦ The top-level powertrain control unit measures or estimates vehicle
states, such as the torque applied to the wheels, and inputs, such as
throttle actuation, and generates commands for the lower-level
control units, such as ICE, battery pack, electric drive systems, and
power electronics.
♦ Typical objectives of the powertrain control are maximizing fuel
economy, minimizing emissions, and meeting the driving
performance requirements. The powertrain control goals can be
achieved through rule-based or optimization-based techniques.
♦ An example for desired powertrain performance is combined
mechanical and electrical braking actions towards higher safety and
efficiency.
♦ Even though electrical braking is preferred to mechanical braking due
to the advantages it offers in the forms of higher efficiency and fuel
economy, as well as lower brake system maintenance costs, the
limitations of electric machine torque and battery current do not allow
the braking performance (e.g., deceleration, on-spot stopping, and
safety) to be achieved solely through electrical braking.
B. Bilgin, P. Magne, P. Malysz, Y. Yang, V. Pantelic, M. Preindl, A. Korobkine, W. Jiang, M. Lawford and A. Emadi,
“Making the Case for Electrified Transportation”, in IEEE Transac5tions on Transportation Electrification, Vol. 1, No. 1,
June 2015.
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 Well-to-Wheels Efficiency

Efficiency ICE Vehicle Series HEV EV

Well-to-Vehicle 0.86 0.86 0.36
Vehicle-to-Wheels 0.16 0.27 0.80
Well-to-Wheels 0.137 0.232 0.28

H. Moghbelli, A. Halvaei, and R. Langari, “New generation of passenger vehicles: FCV or HEV?”, in Proceedings of 2006
IEEE International Conference on Industrial Technology (ICIT 2006).

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 Solar Carport
♦ Solar carport is a structure featuring PV generation for
local consumption, including EV charging, and
connection to the grid.
♦ Solar carport offers the following advantages:
– Zero-emission electricity generation
– Dual use of area (parking and PV panels)
– Low transmission loss due to the proximity of generation to the load
– Convenience for EV owners
– Peak shaving for the local utility
– Possibility of services such as reactive power/voltage support and power
factor correction
– Possibility of uninterruptible power supply (UPS) for the building

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 Solar Carport

Evolv1 in Waterloo, Ontario, Canada – A net positive building

A large PV array installed on the roof and in the parking lot helps the building
to produce 105% of its own energy requirements.

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Thanks For Your
Attention!