Electrification of Ford Focus Using Lithium-ion Battery

Abstract – The main objective of this report is to achieve the full electrification of the ford focus sedan. Along with that the study of the battery packs placing in the ford focus sedan to enhance the vehicle performance in terms of the range, economy. To make the battery system works properly and to get most of out of it some other systems such as the battery regulator, battery cooling system and an energy storage system are used. This project report includes the introduction as well as the history about the vehicle, the detailed description about types of the electrical vehicles along with the battery sizing calculations, calculations of the power and ampere. After doing all the calculations the cost estimations for all are done so there could be correlation with the current vehicle and the vehicle that has been modified. And in the end, there is some discussion about the future scope of the study.

I. INTRODUCTION

From the days of innovation of the vehicle’s batteries and scope of use of electricity to run a vehicle has been subject undergoing intense study. As the use of the vehicles and the usage of the resources like petrol and diesel as primary fuel option has led the search for usage batteries to run vehicle. As the times pass by the research and innovation in the storage and usage in the electricity in the batteries the scope of running the vehicle totally run on electricity comes under spotlight.

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As with usage of the battery electrical vehicles comes many advantages to the environment as well as the humans like first of all BEV’s generates none or very less emissions. Second is that it gives better mileage and also saves very huge amount of very limited resources like petrol and diesel. As electric operated vehicles introduced somewhere around 1980. But its usage really starts in 19^th century. But around that time, they were not that much developed to go very far [1]. Beside many advantages BEV’s have some disadvantages also as lack of the low-cost high electricity storage batteries, and also commercialize charging stations. As we look now a day all the limitations such as charging stations and the cheaper battery packs are being overcome by some private companies.

Figure 1: Ford Focus Sedan [2]

In recent days almost all the big companies making some of their top selling models as electric models as well. Among them we have considered the Ford Focus Sedan. Because Ford is producing the electrical vehicle in the Focus hatch-back model since 2011. But with the increased mass and huge engine it is some what difficult to do the electrification of the Ford Focus Sedan. As it is bigger car in most of terms in compare to Hatch-back version it is difficult to make total electric version of the Sedan. In addition, with that we are opting for the Lithium-Ion battery. Because Li-Ion battery is the better choice for the BEV’s in compare to lead-acid, Nickle-Cadmium or Nickle-metal hydride batteries.

II. HISTORY

As the innovation and starting of an electric vehicle around 1800’s. The electric vehicle gained its popularity in early 1900’s. As in early 1900’s because of the road infrastructures and the very high prices of the hydrocarbon-based fuel, the pollution to environment and also some other advantages over conventional internal combustion engine such as very low noise generation and non-gear shifter. So, because these advantages electrical vehicle gained many likings in the USA around early 1900’s. [3] But as the era of the electric vehicle reaches to the mid 1900’s the crisis in the electrical vehicle section started. Because a huge amount of the new sources of the petroleum and due to that the prices of the fuel dropped down. Plus, the need of the long distance travelling and also because of the mass production of the internal combustion engine vehicle led to price hike in electric vehicle. So due to these reasons the crisis in the section of the electric vehicle has been coming around mid 1900’s. [3] But again in the late 1900’s and the beginning of the 20^th century because of the significant development and the new innovations in the electric vehicle the popularity rises. And now a day almost all the companies makes some of the models as the fully electric versions.

Figure 2: [4]

Ford focus first introduced in the Europe around 1998. Then in 2000 Ford has launched Ford Focus in the American market. After launching in the American market as 4-door Hatch-back and Sedan versions it gained popularity in no tome as the economic car. [4] Since 2000 Ford Focus has gained so much development. After introducing Ford Focus as BEV concept car Ford has started its Focus Electric car as a production car in 2011.  As in the starting Ford Focus electric has 23 KWh liquid-cooled battery pack. And it had range of 76 miles. But as of in 2017 it contains 33.5 KWh liquid-cooled battery and had range of 115 miles. [4]

III. PRINCIPLE OF BATTERY ELECTRIC VEHICLES (BEV)

Battery electric vehicles, or BEVs, use electricity stored in a battery pack to power an electric motor and turn the wheels. This battery packs are also used for the functioning of the wipers and lights. In battery operated cars IC engine is replaced by electric motor. This electric motor works from the power obtained from controller which get its power from sets of rechargeable batteries.

The main three components of BEVs are: Electric Motor, Controller of Motor and Battery  [5]

Speed of the car is controlled entirely by controller. When accelerator pedal connected to multiple set of resistors which are combined know as potentiometer is supposed to give signals to controller that how much power is needed to generate acceleration required by the car driver. So, when car is stopped there is no power being delivered by the controller. When the vehicle is in the motion the controller supplies either full power or any power in between.

Two types of controllers are possible:

1)    DC Controller

Simple DC controller is connected to batteries and DC motor. DC controller gets power from batteries and delivered it to the DC motor in a controlled manner. As shown in Fig 3.

2)    AC Controller

A simple AC controller get the power from the batteries with which it is connected. AC motor is used to convert DC current from batteries to AC current. As shown in Fig 3. In addition to this, controller also provides a system for the charging of batteries and a DC – DC converter for recharging of accessory battery.

Figure 3: [6]

IV. DESIGN PARAMETERS OF BEVS

While designing Battery Electric Vehicles some important parameters are there which should be known initially, and these parameters are as following.

• The main factor that affect the size of battery is the range of vehicle. Longer mile range will have resulted in the increased the battery size and reduced mile range will cause reduced battery size.
• To select the type of motor is also one of the major considerations while designing battery as it affects the energy consumption per mile for vehicle.
• Similar like range of vehicle, torque required also affect the size of battery. Higher torque required bigger battery size and vice versa.
• It also affects the system whether system is provided with any additional components like invertor or convertor.
• Different types of batteries are also available in the market, so the system has very huge impact upon which battery is chosen.

After choosing the battery and obtaining required data, battery sizing calculations also need to be done.

V:  ELECTRICVEHICLESTYPES

1)       Battery Electric Vehicles

Battery Electric Vehicles are entirely work on batteries and electric vehicles. Such Kind of vehicles are lack of IC Engines and exhaust pipes. BEVs must be plugged into external power sources to recharge its batteries. Because of this BEVs are also known as ‘Plug – in’ electric vehicles. This kind of plug – in BEVs usually use regenerative braking technique for recharging. [7]

In Regenerative Braking when gas pedal is released, some portion of kinetic energy the vehicle had during the acceleration was flown back to the motor and converted into electrical power and stored in the motor for the future use. [8]

  Figure 4: [9]

It has numerous benefits such as it is gas free and emission free and as it is gas free there no need to change the oil. One can easily charge BEVs at home without much operational cost. But the range of BEVs are very low as compared to IC Engine operated vehicles and BEVs are costly initially as compared to vehicles using IC Engine and gasoline.

2)       Plug-in Hybrid Electric Vehicles

It is the combination of contemporary IC Engine vehicle and a Battery Electric Vehicle. It has batteries and electric motor and in addition to the IC Engine for the support to recharge the battery or to replace electric power with gasoline fuel when battery level is low. Such type of vehicles usually does more saving in fuel cost by using power from power grid.

Plug – in Hybrid Electric Vehicles have comparatively longer range than BEVs and fuel consumption and emission are also less than the gasoline powered cars. But as it has two systems to operate one is electric and other is IC engine the operating cost is more than Battery Electric Vehicles and due to presence of IC engine oil change at regular interval is necessary and due to the same reason of presence of IC engine it has higher emission rate than BEVs. [10]

3)       Hybrid Electric Vehicles

Hybrid vehicles have both electrical system and petrol-powered system. Both electrical motor and engine can turn transmission. First vehicle starts using electrical power and then petrol engine cuts off in as load or speed rises. The combination of two systems is controlled by internal computer which ensures optimization of fuel according to driving conditions.

AT it is hybrid system it provides far longer range than BEVs. It is IC Engine system supported by electrical system, so it has less fuel emission than IC engine operated cars. On the other hand, its operation is costly, and it has complex system. But the main disadvantage is that one cannot charge his/her vehicle at home. [7]

VI.  CHARGING LEVELS

When it comes to charging of the electric vehicles there are many options. In plug in hybrid vehicles or BEVs the equipment used for charging the vehicle is called EVSE (Electric Vehicle Service Equipment). EVSE can be a simple cord which converts your household ac power to dc power to charge the batteries or a charging station specifically designed to charge the car. Basically, we can categorize EVSE into three levels: Home Charging or Level 1, Level 2 and DC fast Charging or Level 3. Although Recently Tesla have developed superchargers which exceeds the performance of all three levels of charging.

1. Home Charging (level 1)

This is the simplest form of charging. In this mode we just we plug in your car into standard 120V ac outlet. As we know we need DC source to charge the batteries, we have to convert this AC source into DC which reduces overall efficiency of the system. We can add 40 miles of driving by 8 hours of the charging using this method. [11] So, this method is effective for vehicles with low driving range and charged overnight.

2. Home and Public Charging (level 2)

Level two charging unit has circuit whose voltage level is at 240V. Some homes have this 240V circuit unit because the clothes dryer requires same voltage level. While these type of charging stations are also installed at various public places like grocery stores, Shopping malls etc. You will find more level 2 charging stations nearby you than level 3. This is one of the advantages of this type of plug in charging. Charging time depends on maximum current rate and vehicles acceptance rate. Because when battery level is very low it charges very fast compared to high battery level. With 30-amp circuit we can add 180 miles of driving range in 8 hours. [11]

3. DC Fast Charging (level 3)

In the above methods we charged using AC sources while in this method we use specifically designed DC charging stations to charge the vehicle. There are different types of plugs available for this method. Japanese car maker Nissan have developed CHAdeMO standard. While most Europe and American car developers use CCS system. These two systems are not interchangeable. We can charge 80 % of battery just in 30 minutes.

Tesla’s Superchargers are currently the fastest charger available in the market. They can add 170 miles of driving range in just 30 minutes. [11] Although CHAdeMO and CCS standards are also close to create similar type of charging station. The only disadvantage of this type of charging is that we can not develop it in many places due to cost and power requirements. So you may not find this type of charging stations nearby you.

VII. BATTERY PLACEMENT

Usually battery packs are about 300V and 30KWh. With this battery specifications battery usually weighs between 500 to 1200 lbs which is equivalent to 225 to 550 Kg approximately. Due to this weight of the battery, it highly affects the vehicle’s center of gravity at high speed. In majority of the battery-operated vehicles the battery pack is placed under the sit cabin to obtain precision of center of gravity. Here in Ford Focus we have decided to divide the battery packs in two parts. One will be placed under the rear seats and second portion of the battery will be placed behind the rear seats. [12]

VIII. POWER ELECTRONICS

For any type of Electric vehicle, there are two major parts: Electric Motor and Energy source. Electric Motor is used for propulsion while energy source is used to provide the power to this motor. The Figure below shows the power configurations for any type of electric vehicles.

Figure 5: General Electrical configuration for EVs[13]

In the above figure, double line shows a mechanical link, thick line represents an electrical link while control link is represented by thin line. The arrows show the direction of power flow or communication. Electronic controller will provide the signals to the power converter devices according to the input from brake and accelerator paddle. Power converter will be turned on and off by these signals from controller. The backward power flow shown in the figure is for regenerative braking system. Regenerative braking system is used for energy sources like batteries, capacitors and fuel cells. Energy management unit and electronic controller is used to control the regenerative braking.

There are many different types of electric motors available in the market.  The figure below shows the classification of electric motors. Each of these motors have their own advantages and disadvantages which makes them suitable for different applications. Among these three types of motors have been used widely in electric vehicles: Brushless DC motors, AC induction motor and Ac synchronous motor. These motors have wide speed range and do not have any parts which wears out after certain miles. DC motors were preferred before because we can use batteries to power it directly.  While we need an inverter for an AC motor to work. Although in recent years the development of Power electronics devices like IGBT (Insulated Gate Bipolar transistor) and MOSFET (Metal oxide field effect transistor) has made it possible for us to use AC motor. Recently AC synchronous motor is widely used in electric vehicles because of their high efficiency and less weight. Because of these advantages we will use AC synchronous motor in our electric Vehicle. 

Figure 6: Classification of Electric motors [14]

In our application power converter unit will be an Inverter/converter unit. Inverter/Convert unit is basically an inverter and converter housed in a single unit. An Inverter converts DC (Direct Current) source into AC(Alternating Current) source. While Converter also known as voltage converts changes the Voltage of AC or DC source. There are two types of converter: Step up and Step Down. Step up Converter increases the voltage of the source while step down converter reduces the voltage of the system. In electric Vehicles due to size issues the battery unit has low voltage (Around 300V). While AC motors used for traction have higher Voltage Ratings around 600V. Also, we need lower 12V for light load applications like radio, lighting etc. So, we have to use converter to match the required voltage rating. When Inverter and converter is housed in single unit lot of heat is generated. So, we have to provide a separate cooling system for this unit.

X. SELECTION OF ENERGY STORAGE SYSTEM

Lithium-Ion battery have very high energy density at the same time it has very low maintenance thus it is suitable for many portable electronic devices as well as big electronic applications.  Lithium-iron battery also has very small memory effect and also very less self-discharge. And because of this kind of the characteristics they gaining quiet popularity in Bev’s, aerospace vehicle. Bellow are some reasons why we chose Lithium-iron battery. [15]

    Lithium-ion battery has very high energy density. As some devices needs to operates for longer period of times but at the same time-consuming large amount of power. Thus, having higher energy density is very important characteristic for selection of battery.

    As number of batteries needs to prime as they acquire new fresh charge but lithium-ion doesn’t need for that.

    There are many versions of lithium-ion batteries are available so  they can be used in the particular devices for optimized use.

    One of the main reasons for choosing the lithium-ion battery is that it requires no or very less maintenance.

    Lithium-ion battery has very low self discharge rates.

    It has low material cost because it is available in large amount in nature in compare to other material battery. [16]

XI. SPECIFICATION FOR FORD FOCUS SEDAN S

A. Initial Vehicle Dynamics[17]

B. Modified Vehicle Dynamics

C. Electrical Motor Rating

4. Battery Specifications

XII. CALCULATION FOR BATTERY PACK SIZING

We make the following assumptions about the vehicle:

Required Mile Range: 115 miles

 Total battery energy required =30,000 Wh or 30 kWh

Due to above discussed reasons we have decided to select LiC6 // FePO4 battery cell for our vehicle

A. Battery configuration:

Each cell rating: 3.6 V, 5 Ah

Battery rating: 300 V, 30 kWh Energy

Individual Cell Energy = 3.6 V * 5 Ah = 18 Wh

Therefore, total no. of cells required:

30 kWh/18 Wh = 1666

No. of cells in series: 300 V / 3.6 V = 84

No. of parallel cells: 1666/84 = 20

So final battery configuration can be written as follows: [84S20P]

If we divide the battery packs in two modules, battery pack configurations will be 2[42S10P].

B. Supercapacitor configuration:

We make the following assumptions:

Voltage of single supercapacitor = 2

Voltage of the supercapacitor bank = 50 V

Capacitance of single supercapacitor C = 7200 A.s/V

Total energy of supercapacitor pack = 4 kWh

Calculating using above data:

Total energy in a single supercapacitor = ½ x C x V²

= $\frac{1}{2}$

x 7200/3600 x 2² = 4 Wh

No. of capacitors in series = 50V / 2V = 25

Total no. of capacitors = 4000 Wh/ 4 Wh = 1000

No. of capacitors in parallel = 1000 / 25 = 40

So final supercapacitor configuration can be written as follows: [25S40P]

if we divide in 5 modules, then supercapacitor pack configuration will be 5[5S8P].

C. Bill Of Materials (BOM)

As we know 1 mol electron is equivalent to 26.8 Ah capacity.

Molecular weight of LiC6: M= (6×12 + 7) = 79 g

Molecular weight of FePO4 = (56+31+4×16) =151 g

Ah/g calculation for anode:

Capacity: 26.8/79 = 0.339 Ah/g

Ah/g calculation for cathode:

Capacity: 26.8/151 = 0.177 Ah/g

Ah rating of battery = Wh rating of battery/ Individual Cell Voltage

= 30,000/3.6

= 8333 Ah

Total amount of anode for the battery pack: 8333/0.339 = 24.58 Kg

Total amount of cathode for the battery pack: 8333/0.177 = 47.07 Kg

XIII. COST ANALYSIS

Cost of LI ion battery is the major cost in BEVs. Due to so many researches have been done in recent time the prices have fall largely. Tesla’s battery pack costed around $400/ kWh few years back, but it was reduced to $190/ kWh in 2016 and even reduced to $150/ kWh.

With carmakers buying batteries and renewable energy companies adding stationary storage, the prices drop to lower and lower levels much more quickly.  In last 7 years battery prices have decreased by 70%. The graph shows survey of 51 companies about battery prices.

Figure 7: Reduction of Battery Price Since 2010. [18]

BEVs are cost almost same or even lesser than petrol powered cars and it will be even cheaper by 2030 as the battery prices are expected to reduced even at higher rate and it should be $75/ kWh by then. [19]

Average battery pack cost nowadays is $170/kWh and our battery pack is consisting of 30kWh so it will cost about $5000.

XIV. CONCLUSION

While designing the battery packs we have observed ongoing trend and followed standard procedure to design battery for electric vehicle. When designing battery packs, we have considered various parameters especially for the control system design. In the initial stage of the design we have to assume some of the parameters for the better result.

From the cost analysis it is concluded that over the time battery prices are reducing, which can make battery electric vehicles more economical as compared to conventional IC Engine operated vehicles. So, electrification of any existing vehicles is possible with the efforts in correct direction.

XV. FUTURE SCOPE

This paper discusses the only basic concepts about the electric vehicles.

• Vehicle dynamics can be optimized for better performance and longer lifespan of the vehicle.
• Algorithm can be generated for standard parameters to make design process easier and faster.
• Different type of batteries or motor can be used to observe the behavior of the system.
• Like tesla’s technology, DC motor can be used for gaining more torque and high power.
• This system requires computer aided simulation to better analyze its performance.

REFERENCES