Practical Application of Renewable Energy Technology

This article discusses the practical application of renewable energy technology in electric and hybrid vehicles. It explores different battery types and charging methods, highlighting their advantages and disadvantages. The article also covers the importance of battery management systems and the different types of charging stations.

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PRACTICAL APPLICATION OF RENEWABLE ENERGY TECHNOLOGY
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Electric & Hybrid Vehicle: An evaluation on current battery types and charging methods.
Emerging Energy Technology
Electric vehicles are a new emerging technology that is currently being used in both the
power and transportation sector. This is due to the several benefits that portray to the
environment as well as the economy. The past decade has therefore witnessed an increased
attention towards electric vehicles mainly because of their explicit characteristics that other
conventional vehicles cannot offer. An increased deployment of electric vehicles can help lower
the total intake of fossil fuel hence will also lower the greenhouse emission. Most importantly,
due to its increased energy efficiency, it is possible to achieve a reduced running cost as
compared to other conventional internal combustion engine vehicles (Arai et al, 2015). Till now,
there are only 4 different types of electric vehicles that have been developed and are fully
running. They include; plug-in hybrid electric vehicles (PHEV), fuel-cell electric vehicle
(FCEV), conventional hybrid electric vehicle (HEV) and battery electric vehicle (BEV). The
conventional hybrid electric vehicle combines internal combustion engine and electric motor,
therefore, it is also fitted with a battery in order to power the motor and also store electricity. The
energy that powers the motor is generated from the engine as well as the regenerative breaking
(Bauerle et al, 2011).
One major vital component of electric and hybrid electric vehicles is the battery
management system (BMS). The main aim of the battery management system is to assure safe
and reliable operation of the battery. In order to maintain the reliability as well as safety of the
battery, evaluation and state monitoring, cell balancing and charge control are the main
functionalities that have been put in place in the battery management system. Being an

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electrochemical product, the battery performs differently when under varying conditions of the
environment. Batteries are a main source of energy that is widely used in several applications
from electric vehicles to portable electronics (Blanke et al 2015). The performances of the
batteries therefore have a huge effect on the salability of the electric vehicles. Manufacturers
therefore are looking for breakthroughs in the battery management systems as well as the battery
technology.
Types of battery for PHEVs and BEVs
An electric vehicle battery is a battery that is used to power the propulsion of both plug-in
hybrid electric vehicles and battery electric vehicles. Vehicle batteries re commonly used as a
secondary battery and they often vary as compared to other starting, lighting and ignition
vehicles (SLI) due to the fact that they are developed to provide more power over longer time
periods. For instance, deep cycle batteries are the most used batteries for the BEVs and PHEVs.
Such batteries are often characterized by their specific energy, increased power to weight ratio as
well as energy density (Cao & Emadi, 2012).
The most common types of battery for BEVs and PHEVs include lead acid, lithium ion,
ultra capacitors and nickel metal hydride. Lithium ion batteries are the most commonly used due
to their increased energy per unit mass that is relative to other electrical energy batteries. It has
higher energy efficiency, increased power to weight ratio and reduced self-discharge. Nickel
metal hydride batteries provide reasonable specific power and energy capabilities. They have an
increased life cycle than other batteries. They are the most commonly used batteries in plug-in
hybrid electric vehicles. They however have a high cost and have an increased self-discharge as
well as generation of heat at high temperatures (Karner & Francfort, 2011). Ultra capacitors store

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energy in a polarized liquid between an electrolyte and an electrode. They can offer extra power
during hill climbing and acceleration and also assist recovery of braking energy.
Types of battery chargers
An electric vehicle battery charger is a blend of electronics that are used for recharging
the banks of the battery in an electric vehicle or a plug in hybrid electric vehicle. An electric
vehicle charger can be installed in offices, houses, public places and shopping centers in order to
allow the owners of the electric vehicles to charge their EVs or plug-in hybrid electric vehicles
(HEVs). There are two types of charging that are reliant on the method of energy transfer, either
inductive or conductive. The conductive type of battery chargers has a connection of direct plug
to the supply through the use of an extension power cord that is plug into the EV from the wall
outlet. It is very common, has a simple design and has a greater efficiency (Kutt et al, 2013). The
inductive type EV battery charger makes use of magnetic coupling as the main method of
transferring energy. By the use inductive chargers, a station of charging is used to transmit high
current and voltage directly from the grid to an inductive pad or paddle that has electro-magnet
that can be used as half a transformer. The other half of the transformer is located within the EV
and the moment there is full contact between the magnets, current will flow across and into the
battery hence the battery is charged at an increased rate as a result of the connection of charging
stations direct power grid (Majeau-Bettez, Hawkins, Strømman, 2011).

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Figure 1: Illustrating the Inductive concept of charging using two inductive pads (Blanke et
al 2015)
Figure 2: Showing the inductive charging system (Muller, Hainer & Sepanak, 2015).
The major benefit of the inductive type EV battery charger is that it guarantees electrical
safety in all conditions of the weather. It however has a relatively longer time of charging as well
as low efficiency.

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Table 1: Summary of the advantages and disadvantages of inductive charging (Muller,
Hainer & Sepanak, 2015)
Types of charging stations
When categorizing the charging stations of an electric vehicle on the basis of voltage rating,
place of application and power rating, they can be classified into 3 various types of charging
stations. They include domestic charger at places of residence, off street and robust charger at
offices or commercial places and rapid charger t strategic location. The charging stations that
have been discussed in this writing will be based on the conductive chargers because of the fact
that inductive charging has not been fully established (Morrow, Darner & Francfort, 2013).
Majority of the rechargeable electric vehicles can be charged through a domestic wall socket but
a charging station is important because of the reasons below;
 Multiple EV owners are able to charge their EVs all at the same time
 The charging station can have extra mechanisms for connection or current sensing that
can disconnect power whenever the electric vehicle is not charging.

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 Readily offer the suppliers an option to monitor or charge for the consumed electricity
Charging systems for battery electric vehicles and plug-in hybrid electric vehicles
The charging system for BEVs and PHEVs have a strong correlation with some of the
parameters that include charging cost, charging devices, location, charging rate, condition of grid
and time. This implies that correct selection as well as distribution of charges is very important
in order to accommodate the parameters effectively. BEVs and PHEVs generally share the same
standards of charging and hence there are no strange requirements or features of the charger for
each vehicle (Morrow, Karner & Francfort, 2015). Their chargers are developed in such a way
that they are able to communicate with the vehicle in order to guarantee the safety as well as
effective flow of electricity. The charger is also able to monitor the leakage of earth within the
surrounding ground.
The BEVs and PHEVs also have an installed battery management system in the vehicle
that is a very crucial component. The battery management system performs cell balancing,
thermal management as well as checking the discharge and over-charge of the battery pack. The
battery pack comprises of several individual cells that have a given safe low working voltage.
This implies that it is very important to ensure that the individual cells are functioning within the
allowed range in order to prevent reduced battery life as well as battery failures such as fire
(Muller, Hainer & Sepanak, 2015).
Chargers can either be installed off-board or on-board. The on-board charger controls the
flow of electricity due to constraints that include space and weight. This installation can be
carried out through inductive and conductive ways. Conductive way involves direct contact
using a cable and a charging connector whereas inductive way involves the use of

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electromagnetic fields. The off-board charger is always installed externally hence there is no
limit with regard to weight and size. The flow of electricity from the charger to the vehicle is
through a direct current flow; therefore, it is possible to achieve an increased rate of charging
(Pesaran, Vlahinos & Stuart, 2013).
The electricity direction between vehicle and charger can be grouped as either
bidirectional or unidirectional flows. Unidirectional flow allows for only a single charging
direction from an external charger to the vehicle whereas bidirectional flow allows for the
charging as well as discharging of the electricity to and from the EV. The concept of
bidirectional charging is thus widened in BEVs and PHEVs. Associated to the rate of charging,
electric vehicle supply equipment (EVSEs) or chargers can be grouped according to the highest
level of electricity that is charged to the battery of the BEV or PHEV (Shafiei, Momeni &
Williamson, 2011). The classifications are as follows;
Level- 1 charging
It makes use of the on-board charger. It is compatible with several household electrical
power and socket. Most household power has a voltage that ranges between 100 to 200 volts of
alternating current. This charging level can allow foe a charging rate of up to 4kw and is best
suited for overnight charging at common households without requiring further installation of
devices.
Level-2 charging

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This charging level performs the duty of improving the rete of charging through the use
of a dedicated mounted box. It can supply power that ranges from 4 to 20 kw as well as a highest
voltage of 400v of alternating current, all that depends on the capacity of local supply that is
available. It is generally installed at designated charging facilities such as public areas or
residential places (Sloan, Kidston & Wu, 2013). The charging connectors for theses level of
charging often differ across manufacturers and countries.
Level-3 charging
In this level, charging is performed in the direct current system. The charger supplies
Direct Current electricity that by passes the on-board charger. This leads to attaining a higher
charging rate of more than 50 kw. The charging plugs as well as the communication protocol
between the vehicles and the charger have got different standards besides having similar basic
principles.
Charging standards
There currently exist only three main standards of charger, mainly for quick charging. They
include;
 Combined charging system (CCS)
 Tesla Supercharger
 CHAdeMO
The following table illustrates the detailed specifications of all the charging standards.

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Figure 3: Showing detailed specification of charging standards that facilitate DC fast
charging (Blanke et al 2015).
Advanced charging system
The increased deployment of BEV and PHEV charging has had vital effects on the
electrical grid such as grid overload and quality deterioration. It is therefore proper to control and
schedule the charging of BEVs and PHEVs. A strategic method that is used to charge the
vehicles with reduced effect on the electrical grid is to embrace the use of a battery that will help
in the charging (Waag, Fleischer & Sauer, 2014). The most suggested battery is the Battery

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Assisted Charger for BEVs and PHEVs. This battery is embedded within the charger in order to
enhance the quick charging performance as well as reducing the concentrated load to the grid.
This development is able to control the power that is received from electrical grid and also
control the rate of charging to the vehicles. It is necessary to control the power received from the
grid so as to prevent the demand for electricity that is higher than the contracted capacity
(Yilmaz & Krein, 2013.). It also aims at optimizing the demand for electricity due to the
conditions of the grid. In order to achieve optimum performance, the BAC is able to control the
distribution of electricity within the system, including the electricity received, from the chargers,
batter as well as the grid.

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Figure 4: A Schematic presentation of the BAC system for BEV and PHEV (Blanke
et al 2015).
The operation of BAC implies that it is able to attain both the demand and supply side.
The demand side involves quick charging during peak hours whereas supply side involves
reducing the grid load through lowering the electricity cost and shifting of load (Zheng et al,
2014).

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