1         Chapter-1; Introduction

In this chapter, details of why it is of ultimate importance that the fossil fuel consumption must be limited. An introduction will be presented for the alternate automotive power systems

1.1       Introduction; Importance of alternative fuel in today’s world

Considering there are limited fossil fuels reserves and the fact their high cost attached to production of energy for transportation, the tendency of vehicle industry to switch to other modes of energy is simple inevitable. In recent years, we have witnessed the vehicle industry shifting from typical petrol/diesel power technology to hybrid and electric vehicles. The inclination towards hybrid vehicles seems to be a good solution to the problem at hand as power electronics, embedded power train controller, electric motors and energy storage devices such as ultra capacitors and batteries can play a key role in improving the overall performance and energy efficiency of a vehicle. It is recommended to employ advanced computer modeling and simulation priors to prototyping so manufacturer’s can cope with the challenge of integrating electric components in a drive train configuration. Furthermore, use of simulations and modeling can also reduce the overall cost of design and safety quite significantly. In this paper, we will be discussing how modeling and simulation principles provide a useful platform to achieve efficient and safe design of a hybrid vehicle.

The use of fossil fuels including gas, coal and oil is not jut limited to transportation. Several other industries including power and heating industries largely depend on fossil fuel. Studies have concluded that the growing demand of fossil fuels is considerably higher than the time it takes to convert the stored energy and therefore it is vital to propose and suggest new techniques to switch to other energy sources (Zaroofi, 2008).

Another problem attached to the use of fossil fuel sources is the fact they damage our environment substantially (Jalil, 1997). This might become a serious problem in the near future if other methods of producing energy are not found. Many researchers and scientist have stated in their findings that global warming and air pollution are the two most important environmental issues we will have to face in the future if we continue to rely on fossil fuels.

1.2       Hybrid Vehicles as an Alternative Solution

Considering the environmental and ecological problems highlighted in the previous section and the fact the transportation is an important part of our daily lives, there is a strong need to find a sustainable energy source that results in lower or negligible carbon emissions. As discussed before, use of electric batteries and fuel cells to power vehicles presents an economically viable and environmental friendly solution. With power electronics technology and electric equipment advancing with each passing day, it has become possible to recapture used renewable energy as well as identifying more efficient operating regions for the combustion system of a vehicle (Gao and Emadi, 2007). Furthermore, engine’s idling time can be eliminated completely by using various energy management methods.

The improve technology allows hybrid vehicles to reduce emissions, increase overall efficiency and performance and increase the life cycle of almost all mechanical parts of the vehicle. Taking into account the benefits attached to hybrid vehicles or HV, it will be safe to say that this technology presents a very cost effective and reliable way to reducing carbon emissions and improving fuel economy, performance and comfort to meet customer demands.

1.2.1       Hybrid Vehicle Background

In the early 19^th century, combustion powered vehicles, electric cars and steam powered engines vehicles were all available for buying in the United States but things change substantially with time as fossil fuels like petrol, diesel and gas became readily available at competitive prices. Edson, Westinghouse and Edison were the pioneers in the electric car industry in the United States. (Williamson, 2004). In 1890s and 1900s, it was evident that electric batteries at that time had limited scope and usefulness and therefore manufacturers opted to produce combustion driven vehicles which were an ideal choice for frequent travelers and long journeys

Hybrid cars were first introduced in the Europe in 1901 where a Jenatzy parallel hybrid system (using a 6HP engine and drive and 14 HP generator) was put on display in the Paris Motor Show. A project initiated by Lohner Porsche produced another hybrid vehicle with 21 kW DC Generator and 20 HIP engine in 1903. The car also had an electric motor in each of the front wheels. A collaboration of Mercedes Mixte and Lohner Porsche introduced Mercedes Mixte five to six years later. However, due to the limitations in technology at that time and added weight and cost, the production of hybrid cars soon came to an end.

1.3       Hybrid Vehicles Simulation

Comparing conventional and hybrid vehicles, it will not be wrong to say that the role of electric components such as embedded power train controllers, power electronic converters, super capacitors, energy storage components such as batteries and electric motors and machines is tremendous. The HV design also incorporates the use of modern mechanical parts and internal combustion engine.

When engineers are required to design new hybrid vehicles, they select all the components in the drive train. The components are then controlled and modified in a way that the overall cost affectivity and fuel consumption and reliability and design of the vehicle improves dramatically (Williamson, 2004). However, this is easier said than done as it may take engineers several days or even months to come up with the final design. Furthermore, there is a need to create a simulation environment for each component or part of the train drive to achieve this goal. The simulation of each component usually represents the actual behavior, which proves to be beneficial towards improving design and reducing the cost of vehicle.

The importance of simulation and modeling prior to prototyping and analysis of hybrid vehicles simply cannot be overlooked. The concept becomes even more critical when dealing with novel hybrid power train controllers and configurations. The use of simulation and modeling has long been an important tool for the design of modern industrial systems. Reduction in cost, efficiency in design and an increased life cycle of various components of hybrid vehicles can be achieved by testing energy management systems and configurations with the help of computer simulations. Another advantage attached to computer simulations is the fact it provides a very attractive alternative to performing dangerous, strategically unwanted, complex and expensive tests and studies. The dependence of power train on various control strategies is another concern the computer simulation can take care of.

As the name Hybrid suggests, hybrid vehicles use at least two types of energy sources, which are mainly electric power and combustion or heat energy. The power requirements for auxiliary loads and traction in the vehicle are usually shared by the same sources of energy. Engineers or manufacturers are required to achieve the perfect power sharing management to ensure high class performance. Following are the main components/parts of a hybrid vehicle:

• Transmission
• Control System
• Secondary Energy Converter
• Primary Energy Converter
• Primary energy storage system
• Secondary energy storage system

1.4       Principles/rules of modelling and simulation

For any vehicle type, computer simulation of each component is performed considering the level of details required. User could choose from three modeling categories including quasi state, dynamic and steady state models.

It should be noted that quasi state and steady state models are mainly used to perform long terms analysis over changing drive cycles and they act as a useful tool when high level operational techniques and architectural decisions are required to be made. Although use of quasi state and steady state modeling results in fast computation, the results obtained are far from accurate for dynamic simulation (Zaroofi, 2008).

Dynamic models, in comparison, are mainly used to pay attention to small details such as the lower level comparisons among support subsystem and subsystems design. It is possible to achieve good accuracy in dynamic simulation considering the model mainly relies on differential equation of the components. Studies have revealed that the use of dynamic modeling in essential to be able to achieve accurate design for HV’s as well as finding the power requirements of all components involved. All power electronic devices work with higher switch frequency in hybrid vehicles and thus there is a need to compute the peak rating of these electronic components in the operating process.

Again, the use of dynamic modeling as compared to steady state models is recommended for this purpose. Summarizing, the ratings of components, computation of overall efficiency of the drive train, calculation of conduction can be performed using dynamic modeling which also helps in the estimation of switching losses in power converters. The computer simulation can be performed for various aspects of interest in a hybrid vehicle. Following are the aspects of interest for engineers and manufacturers:

• Modeling for packaging and cost
• Modeling for emission
• Modeling for performance
• Modeling for prediction
• Modeling for optimization and evaluation of the fuel consumption

The more detail are looked into, the more are chances of models becoming sophisticated and complicated. The run time of the simulation can also increase significantly as the model becomes more complicated. It is important to understand the relationship between the run time of the simulation and model details to achieve best results.

1.5       Drive Cycles

The drive cycle command is extremely beneficial as it represent the pattern determined by a scheduled speed. The assumption made for drive cycles is that acceleration during the time step remains constant, which result in speed being a liner function of time. The required mechanical energy, therefore, can be determined as a function of time since the acceleration and speed are known for each point of time. The formula for mechanical energy function of time will be discussed later (Sandberg, 2001). A dynamometer may be used to perform motor way driving cycle. Emissions and the fuel consumption are calculated directly then when dealing with ice driven vehicles. It should be noted that the primary energy are computed from the fuel consumption.

1.6       CVT

CVT, abbreviation for continuously variable transmission is a type of automatic transmissions that ensures improved fuel economy, more power and better driving experience when compared to traditional transmission systems (CVT, 2013).

1.7       MATLAB

MATLAB is mathematical software that is used for visualization and numerical calculations. MATLAB is the obvious choice when programme where working with basic data element matrix and array based data is required.

2         Chapter-2; Diesel and Petrol Engine Performance

In this chapter, a comparison is conducted to analyse the performance of the Diesel and petrol engines. The comparison is completed through the use of European NEDC, American FTP-75 and hard driving US-06 test cycles.

2.1       Petrol Engine Tests

2.1.1       NEDC Drive Cycle;

Following is the Petrol Engine NEDC drive cycle;

                    Figure-1: The mdl of a petrol engine drive in the QSS TB form

The results of the Petrol engines fuel consumption rate for the subject test cycle is given below in the Figure-2

Figure-2: Fuel consumption of petrol engine [liter/100 km]

From the Figure-1 and Figure-2, it is shown that the rate of fuel consumption is highest at the start of engine cycle (time between 0 to 100 seconds), which eventually stabilizes with time. The final and/or lowest fuel consumption rate per 100 km is reached at the time of 1200 seconds, which is 3.6181 liters/100km. 

2.1.2.       FTP-75 DRIVER CYCLE

Following is the petrol engine FTP-75 drive cycle

 Figure-3: The .mdl of a petrol engine drive in the QSS TB form

The results of the Petrol engines fuel consumption rate for the subject test cycle is given below in the Figure-4

Figure-4:    Fuel consumption [liter/100 km]

The Figure-3 and Figure-4 illustrates that the rate of fuel consumption is highest at the start of engine cycle (time between 0 to 60 seconds), which eventually stabilizes with time. The final fuel consumption rate of 4.1521 per 100 km is reached at the time of 180 seconds approximately.

2.1.3.      US-06 DRIVER CYCLE

Following is the petrol engine US- 06 drive cycle

Figure-5: The .mdl of a petrol engine drive in the QSS TB form

The results of the Petrol engines fuel consumption rate for the subject test cycle is given below in the Figure-6

Figure-6: Fuel consumption [liter/100 km]

From the US-06 test cycles illustrated in the figures above, it can be seen that here again the rate of fuel consumption reaches its peak near the start cycle, with time between 0 to 12 seconds, which then stabilizes with passing time. The final fuel consumption rate of 3.9451 for every 100 km is reached at the time of 55 seconds.

2.2       Diesel Engine Tests

Following is the Diesel Engine NEDC drive cycle

2.2.1       DRIVER CYCLE NEDC

Figure -7; The .mdl of a diesel engine drive in the QSS TB

The results of the Diesel engines fuel consumption rate for the NEDC test cycle is given below in the Figure-8;

Figure-8: Fuel consumption [liter/100 km]

From the Figures above, the NEDCS test cycles shows that the rate of fuel consumption reaches its maximum with time between 0 to 150 seconds, which then decreases. The final and lowest fuel consumption rate of 3.5561 for every 100 km is reached at the time of 1200 seconds.

2.2.2      DRIVER CYCELE FTP-75

Similarly, following is the Diesel Engine FTP-75 drive cycle

Figure 9: The .mdl of a diesel engine drive in the QSS TB

In a graphical form, the results of the Diesel engines fuel consumption rate for the FTP-75 test cycle is given below in the Figure-10;

Figure-10: Fuel consumption [liter/100 km]

From the Figure-9 and Figure-10, it is shown that the rate of fuel consumption is highest at the start of engine cycle (time between 0 to 90 seconds), which eventually reduces and stabilizes with time. The final fuel consumption rate per 100 km is reached at the time of 180 seconds approximately, which is 4.2031 liters/100km. 

2.2.3     US 06 Driving Cycle

 The Diesel Engine US 06 drive cycle is given below;

Figure-11: The .mdl of a petrol engine drive in the QSS TB

The results of the Diesel engines fuel consumption rate for the US 06 test cycle in a graphical form is given below in the Figure-12

Figure-12: US 06 Driving Cycle

The two Figures above shows variation of fuel consumption rates in a form cycles. The pattern was calculated for a period of 600 seconds, and a mean/average value of 9.006 fuel consumption rate per 100 km was calculated for the overall test cycle.

2.3       Comparative summary of test cycles

Following is the comparison of the two engine type in tabulated form;

Table-1; Summarized Comparison

Test Cycle	Petrol Engine; Fuel Consumption rate	Diesel Engine;  Fuel Consumption rate
NEDC	3.6181	3.5561
FTP-75	4.510	4.2031
US 06	3.9451	9.006

For an easy presentation, the figure below has been generated to present the difference of the two engine types for each test cycles

Figure-13: Test cycles comparison

From the Figure-13, it can be concluded that both the petrol engine and diesel engine show similar consumption rate for NEDC test cycle, with petrol engine fuel consumption rate of 0.062 lit/100km higher as compared to the diesel engine. Similarly for FTP-75 test cycle, the petrol engine has higher consumption rate, with difference being 0.3069 lit/100km. However for the US 06 test cycles, the difference between petrol engine and diesel engine consumption rates are quite significant, where the diesel engine consumption rate is 5.0609 lit/100km higher than the petrol engine.

3         Chapter-3; Optimized Transmission Design

In this chapter, respective NEDC and FTP-75 test cycle simulation results have been present through the use of optimization tool box function

3.1      Petrol Engine

3.1.1     NEDC DRICE CYCLE

The following figure represents the NEDC drive cycle for petrol engine with CVT Controller through the optimization tool box function;

Figure-14: The .mdl of a petrol engine drive in the QSS TB

The figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-15: Combustion Engine map

Consumption maps: The traditional unit used by the manufacturers to describe the fuel consumption rate is g/kWh since is convenient way to compare the efficiency of engines. This method is quite useful when the engine is producing power, but not when the engine dragging.

3.1.2       FTP-75 DRIVE CYCLE

The FTP -75 drive cycle for petrol engine with CVT Control is as below;

Figure-16: The .mdl of a petrol engine drive in the QSS TB

Similarly, the figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-17: Combustion Engine map

3.2       Diesel Engine

3.2.1       NEDC DRIVE CYCLE

The following figure represents the NEDC drive cycle for diesel engine with CVT Controller and Optimal Transmission Design

Figure-18: The .mdl of a  diesel engine drive in the QSS TB

The figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-19: Combustion Engine map

3.3       Comparative summary of test cycles

Following is the comparison of the two engine types in tabulated form;

Table-2; Summarized Comparison

Test Cycle	Petrol Engine; Fuel Consumption rate	Diesel Engine;  Fuel Consumption rate
NEDC	3.3320	10.050
FTP-75	4.1520	4.2030

For an easy presentation, the figure below has been generated to present the difference of the two engine types for each test cycles

Figure-20; Graphical presentation of results

From the figure and the table above, it can be concluded that both the petrol engine and diesel engine fuel consumption rates have improved due to improved gearing (from comparison of Table 1 and Table 2). For NEDC test cycle, diesel engine fuel consumption rate is 06.718 lit/100km higher than petrol engine. Similarly for FTP-75 test cycle, the diesel engine has higher consumption rate, with difference being 0.0510 lit/100km with compared to petrol engine

4         Chapter-4; Series Hybrid Vehicles

In this chapter, series hybrid vehicle simulation results will be presented and discussed

4.1       Petrol Engine Series Hybrid

4.1.1       NEDC DRIVE CYCLE

The NEDC drive cycle petrol engine is given as below;

Figure-21: The .mdl of a petrol engine drive in the QSS TB

The figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-22: Combustion Engine map

The figure below shows the plot of resulting speed and torque distribution on the electric generator map for the same drive cycle;

Figure-23: Electric generator map

Similarly, the figure below shows the plot of resulting speed and torque distribution on the electric motor map for the same drive cycle;

Figure-24: Electric motor map

Similarly, the following figures represent the battery charge ratio, battery voltage, battery current and battery power simultaneously with respect to time, for the same drive cycle;

Figure-25: Battery statistics

4.1.2       FTP-75 DRIVE CYCLE

Series Hybrid Vehicle Petrol for FTP-75 drive cycle is given below;

Figure-26: The .mdl of a petrol engine drive in the QSS TB

The figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-27: Combustion Engine map

4.1       Diesel Engine Series Hybrid

4.2.1       NEDC DRIVE CYCLE

NEDC drive cycle for the Diesel engine is as below;

Figure-28: The .mdl of a diesel engine drive in the QSS TB

The figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-29: Combustion Engine map

4.2.2.      FTP-75 DRIVE CYCLE

FTP-75 drive cycle for the Diesel engine is as below;

Figure-30: The .mdl of a diesel engine drive in the QSS TB

The figure below shows the plot of resulting speed and torque distribution on the combustion engine map for the same drive cycle;

Figure-31: Combustion Engine map

4.3.       Comparative summary of test cycles

Following is the comparison of the two engine type in tabulated form;

Table-3; Summarized Comparison

Test Cycle	Petrol Engine; Fuel Consumption rate	Diesel Engine;  Fuel Consumption rate
NEDC	1.5590	2.3940
FTP-75	4.5100	3.0110

For an easy presentation, the figure below has been generated to present the difference of the two engine types for each test cycles

Figure-32: Series Hybrid Vehicle Graphical presentation of results

 From the figure and the table above, it can be concluded that both the petrol engine and diesel engine fuel consumption rates have improved through the use of hybrid vehicles. For NEDC test cycle, diesel engine fuel consumption rate is 0.835 lit/100km higher than petrol engine. However, for FTP-75 test cycle, the petrol engine has higher consumption rate, with difference being 1.499 lit/100km with compared to diesel engine

5         Chapter-5; Parallel hybrid vehicle with a 1.8 litre diesel engine

In this chapter, simulation results for parallel hybrid models with a 1.8 liter diesel engine will be presented and discussed

5.1       Parallel Hybrid Vehicle

5.1.1       NEDC DRIVE CYCLE

NEDC Drive cycle for a parallel hybrid vehicle with a 1.8 diesel engine is as below;

Figure-33: The .mdl of a parallel hybrid diesel engine drive in the QSS TB

The fuel consumption rate with respect to time as given in the following figure;

Figure-34: Fuel consumption [liter/100 km]

5.1.2       FTP-75 DRIVE CYCLE

Drive cycle FTP-75 for a parallel hybrid vehicle with a 1.8 diesel engine is as below;

Figure 35: The .mdl of a parallel hybrid diesel engine drive in the QSS TB

The fuel consumption rate with respect to time as given in the following figure;

Figure-36: Fuel consumption [liter/100 km]

5.2       Diesel Engine

5.2.1     NEDC DRIVE CYCLE

NEDC Drive cycle for diesel engine is as below;

Figure-37: The .mdl of a disel engine drive in the QSS TB

The fuel consumption rate with respect to time as given in the following figure;

Figure-38: Fuel consumption [liter/100 km]

5.2.2       FTP-75 DRIVE CYCLE

The FTP-75 cycle for diesel engine is as below;

Figure-39: The .mdl of a diesel engine drive in the QSS TB

The fuel consumption rate with respect to time as given in the following figure;

Figure-40: Fuel consumption [liter/100 km]

5.3.       Comparative summary of test cycles

Following is the comparison of the two engine type in tabulated form;

Table-4; Summarized Comparison Parallel Hybrid Vehicle and diesel engine

Test Cycle	Parallel Hybrid  Diesel Engine; Fuel Consumption rate	Diesel Engine;  Fuel Consumption rate
NEDC	1.8360	3.2480
FTP-75	3.2180	3.8420

For an easy presentation, the figure below has been generated to present the difference of the two engine types for each test cycles

Figure-41; Parallel Hybrid Vehicle and diesel engine presentation of results

From the figure and the table above, it can be concluded that the hybrid vehicles fuel consumption rate are considerably less than of standard 1.8 liters diesel engines. For NEDC test cycle, diesel engine fuel consumption rate is 1.412 lit/100km higher than parallel hybrid vehicle diesel engine. Similarly, for FTP-75 test cycle, diesel engine has higher consumption rate, with difference being 0.624 lit/100km with compared to parallel hybrid vehicle diesel engine.

6         Chapter-6; Conclusion

The project was assigned to compare the performances of the diesel and petrol engine powered cars through the use of MATLAB simulations. A comparison was also conducted for Series hybrid vehicle petrol engines and Series hybrid vehicle diesel engines. Parallel hybrid vehicle 1.8 diesel engine and the 1.8 diesel engine were also compared for fuel consumption performance. Through the simulation results, it was concluded that different test cycles can give different results, however there is not much considerable difference for the petrol powered and diesel powered engines in terms of fuel consumption performance.

Performing simulations also showed that the fuel consumption efficiency also increased with use of improved gearing. Furthermore, the hybrid vehicles fuel consumption for 1.8 liters diesel engines is much more efficient as compared the standard same capacity engine type. Therefore use of the hybrid cars with improved gearing efficiency performs the best, and its further development will play a key role in the vehicle engine technology.

7          References

Blanchard, B. S., (2006). “Systems Engineering and Analysis: Fourth Edition,” Prentice Hall. International Series in Industrial and Systems Engineering.

 

CVT., (2013). “Continuously Variable Transmission”, Available online at: <http://cars.about.com/od/thingsyouneedtoknow/a/CVT.htm> [Retrieved on 14 August 2013]

 

Car reviews, (2013). “ASX Crossover 1.8 DiD 4 2WD Black 5dr”.  Available online at:<http://www.whatcar.com/car-reviews/mitsubishi/asx-crossover/1-8-did-4-2wd-black-5dr/specifications/64834#tabsection2> and <http://www.mitsubishi-cars.co.uk/asx/specifications.aspx?Variant=PB6> [Retrieved on 11 August 2013]

 

Driving cycles, (2013), “ Driving cycles introduction”. Available online at: www.metricmind.com/data/cycles.pdf [Retrieved on 9 August 2013]

 

Gao, W., Mi, C. and Emadi, A., (2007). “Modeling and Simulation of Electric and Hybrid  Vehicles”, Proceedings of the IEEE, Vol. 95-4.

 

Henson, W., (2008). “Optimal battery/ultracapacitor storage combination”, J. Power Sources.

 

Jalil, N., Kheir, N.A.,Salman, M., (1997). ”A Rule -Based energy management Strategy  for a Series Hybrid Vehicle”. Proceeding of American Control Conference, Vol.1.

 

Nelson, R., (2000). “Power requirements for batteries in hybrid electric vehicles”. J. Power Sources 91, 2–26.

 

Sandberg, T., (2001). “Heavy Truck Modeling for Fuel Consumption Simulations and Measurements”.  Available online at: <http:130.236.48.54/en/Publications/Lic/01_LIC_924_TS.pdf> [Retrieved on 14 August 2013]

 

Volkswagen Polo, (2013). “VX Polo1.2 60 S 3dr hatchback petrol”. Available online at: <http://www.buyacar.co.uk/volkswagen_polo_hatchback/car_12_60_s_3dr_16575.jhtml> [Retrieved on 10 August 2013]

 

Williamson, S., Rimmalapudi, C., Emadi A., (2004). “Electrical Modeling of Renewable Energy Sources and Energy Storage Devices”. Journal of Power Electronics, Vol.4, No.2.

 

Zoroofi, S., (2008). “Modeling and Simulation of Vehicular Power Systems”, Master’s Thesis in Electric Power Engineering Chalmers university of technology, Göteborg, Sweden