HYBRID ELECTRIC VEHICLE DESIGN AND ANALYSIS

46 CHAPTER 3 HYBRID ELECTRIC VEHICLE DESIGN AND ANALYSIS In a country like India, the usage of two wheelers for daily activities is high. To bring the advancements in these two wheelers, hybrid electric vehicle prototype is being developed. Presently all two-wheeler vehicles are running on internal combustion engine for which the propulsion is derived from petrol fuel. Only small in number the two-wheelers driven with electric motor whose propulsion is derived from electric batteries. The mixture of both is named as hybrid electric vehicle. Generally ICE driven two-wheelers can attain high speed, high torque with trustable attributes in maintenance and replacements. Electric motor driven vehicles can attain comparatively less speed, less torque with feasible maintenance and replacements. ICE can serve more life time comparatively to electric motors. Charging the batteries in electric motor driven vehicles will consume more time and become unavailable for usage in terms of emergency. Though ICE is efficient comparatively to electric motor, as of hardly bearable petrol prices the availability to common man is least in usage. The batteries used in electric vehicles will have a valid life cycle for charging and discharging and has to be replaced after that. The battery cost will be about 25%-35% of actual electric vehicle cost which makes the consumer to think twice before buying these types of vehicles. All these points are justified in the survey conducted on electric scooter which is already explained in deriving the objectives for designing and developing this hybrid electric scooter. 3.1 DRIVETRAIN CONFIGURATIN AND DESIGN Figure 3.1 shows the drivetrain structure in case of parallel hybrid or torque coupled hybrid electric vehicles. Engine controller, motor controller and electric motor are the main components present in this drivetrain arrangement. An advance controller available will be utilized for controlling the engine power and motor speed through accelerator, involving engine and vehicle speed based on throttle position. The vehicle controller communicates with the components through drivetrain algorithm designed for synchronization of the components with each other by

47 processing the signals used for communication. Some of the components rely on component controllers for processing the signals coming from the vehicle controller. By controlling the propulsion sources present in this drivetrain configuration, ICE, electric motor, the torque coupling has to be made controlled in this arrangement. Figure 3.1: Drive train structure of the parallel (torque coupling) hybrid vehicle In this type of drivetrain arrangements, important factors to be considered are Engine power Electric traction motor Energy sources Control strategy of the drive train With the following factors in mind the parallel drive train design is being carried out Satisfying the gradeability, acceleration and maximum speed Overall high efficient hybrid electric vehicle

48 3.2 PARAMETRIC DESIGN OF DRIVETRAIN 3.2.1 ENGINE POWER Based on control strategy and sources, in case of parallel hybrid electric vehicles, the drive train parameters are internal combustion engine, electric motor, energy capacity and gear ratios. Depending on the vehicle performance and need, these parameters has to be selected. Considering flat road and constant speed, the tractive power required in overcoming the road load or road resistance is given by expressions 3.1 and 3.2. Where f r is the rolling resistance coefficient, M is the mass of the vehicle, P e is the engine power, V is speed, ρ a is the air density, A f is the frontal area of the vehicle, C D is the aerodynamic drag coefficient, g is the gravity due to acceleration and i is the percentage road gradient. P e = V 1000η t,e ( f r Mg + 1 2 ρ ac D A f V 2 + Mgi) KW (3.1) P e = V 1000η t,e ( f r Mg + F w + F g ) KW (3.2) The sum of tractive power required for acceleration and tractive power required in overcoming the resistances will form the whole engine tractive power of the vehicle is given by expression 3.3, where δ is the mass factor coefficient. P e = V 1000η t,e ( f r Mg + 1 ρ 2 ac D A f V 2 + Mgi + Mδ dv ) KW (3.3) dt The transmitted torque from the engine, as applied on driven wheels that is the power flow is given by the expression 3.4. T w = i g i 0 η t T P (3.4)

49 Where, T P is the torque output with respect to power flow, i g is the ratio of input rotating speed to output rotating speed, i 0 is the gear ratio with respect to the final drive, η t is the efficiency with respect to power driveline. Figure 3.2: Tractive effort on the driven wheels The tractive effort on the driven wheels as shown in the Figure 3.2 is given by expression 3.5. F t = i gi 0 η t T P r d (3.5) The rotating speed (RPM) of the driven vehicle is given by expressions 3.6 and 3.7. N w = N P i g i 0 (3.6) V = πn m r d 30i g i 0 m/s (3.7) Where N P is the transmission rotating speed (RPM), which will be equal to engine speed in manual transmission vehicles and equal to turbine speed with respect to torque converter in automatic transmission vehicles.

50 For the vehicle propulsion, sufficient power has to be delivered by the engine. During the stop-go conditions, the average power delivered by the engine should be more than the required average load. 3.2.2 ELECTRIC MOTOR POWER DRIVE DESIGN Based on the selected motor, the parameters acceleration, power demand and performance plays major role in vehicle propulsion. The motor acts as supportive propulsion unit during the peak requirements in parallel type of hybrid vehicles. The characteristics of variable speed electric motors are shown in the Figure 3.3. In low-speed region, motor will operate at constant torque, whereas in high-speed region, motor will operate at constant power. This characteristic is represented as the ratio of its maximum speed to its base speed, that is the speed ratio x. This parameter can be used for designing geared propulsion vehicles with electric motor. Figure 3.3: Characteristics of variable speed electric motor performance. Gradeability, cruising time and maximum speed determines the actual vehicle

51 The tractive effort developed by a traction motor on driven wheels and the vehicle speed are given by expressions 3.8 and 3.9. F t = T m i g i 0 η t r d (3.8) V = πn m r d 30i g i 0 (3.9) Where T m and N m are the torque corresponding to motor in N-m and speed in RPM respectively, i g is the gear ratio of transmission, i 0 is the gear ratio of final drive, η t is the efficiency of the whole driveline from the motor to the driven wheels, r d is the radius of the driven wheels. 3.2.3 ENERGY SOURCES The Internal combustion engine uses the petrol fuel as energy source for propulsion and electric traction motor uses rechargeable lead-acid battery power as energy source for propulsion in the design of the hybrid electric vehicle. 3.3 CONTROL STRATEGIES The overall control scheme is as shown in the Figure 3.4. In this drivetrain design, vehicle controller plays major role. The vehicle controller should be compatible with engine alone mode, motor alone mode and hybrid mode of operations. The various operation modes are described in Figure 3.5.

52 Figure 3.4: Schematic arrangement of control scheme Figure 3.5: Various operations modes based on Power demand The operation modes of the drivetrain are explained below Motor alone propelling mode: when the vehicle speed is less than preset value V eb, which is considered to be the bottom line of the vehicle speed below which the engine cannot operate stably, or operated with more fuel consumption and high emissions. The electric motor provides the required

53 propulsion with the engine in idling state. The engine power, electric traction power is given by expressions 3.10 and 3.11. P e = 0 (3.10) P m = P L (3.11) Where P e is the engine power output, P L is the propelling power provided by the driver through the motor controller. Hybrid propelling mode Representing the point A in the graph, both the engine and the motor combine and provide the power to the driven wheels at the same time. In this case the engine operation will be at optimum operation line by controlling the engine accelerator or engine operated throttle. Electric motor provides the remaining power required. The motor power output is given by expression 3.12. P m = P L P e (3.12) Engine alone propelling mode In this mode, the total propulsion of the vehicle relies only on the engine. The traction motor will not be powered or used for propulsion, which can act as generator. Now the motor power is given by expressions 3.13 and 3.14. P m = ( P e P L ) η electric motor (3.13) P e = P L (3.14) The main principle which can be obtained from this control strategy is that, the optimal utilization of engine and electric motor during the drive with relevant vehicle controllers employed in the design.

54 3.4 PERMANENT MAGNET BLDC MOTOR Figure 3.6 shows the control arrangement employed generally for Brushless DC motors. It contains power converter and DSP controller. Figure 3.6: BLDC motor with control configuration The torque and speed of the machine is controlled by maintaining the positions of hall sensors H1, H2 and H3 of the motor rotor. The DSP controller receives the information regarding these rotor sensors and relevantly provides the gating signals to the power converter by turning on and off the specific stator pole winding of the motor. Based on the geometrical mounting of the permanent magnet in the rotor, the BLDC motors are categorized as interior mounted motor and surface mounted motor. This categorization is as shown in the Figure 3.7 (a) and Figure 3.7(b)

55 Figure 3.7: (a): Surface mounted (b): Interior mounted Based on the shape of the EMF waveforms, trapezoidal or sinusoidal the stator windings are categorized in BLDC motors. The trapezoidal-shaped back EMF BLDC motor is designed to develop trapezoidal back EMF waveforms. It has the following ideal characteristics. Rectangular distribution of magnetic flux in the air gap Rectangular current waveform Concentrated stator windings Excitation waveforms take the form of quasisquare current waveforms with two 60 ο electrical intervals of zero current excitation per cycle. These trapezoidal back EMF waveform permits some important significations compared to sinusoidal back EMF machines, stating the resolution requirements for the rotor position sensor are much lower since only six commutation instants are necessary per electric cycle. The Figure 3.8 shows the winding configuration of the trapezoidal back EMF BLDC motor.

56 Figure 3.8: Winding configuration of the trapezoidal back EMF BLDC motor The Figure 3.9(a) shows the equivalent circuit, trapezoidal back EMF and hall sensor signals of the BLDC motor drive. The coils of the stator are positioned in the standard three-phase full-pitch, concentrated arrangement and thus the phase trapezoidal back EMF waveforms are displaced by 120 ο electrical degrees. Current pulse generation is 120 ο on and 60 ο off type, meaning each phase current is flowing for 2/3 of an electrical 360 ο period, Figure 3.9(b).

57 Figure 3.9: (a) Equivalent circuit, (b) Trapezoidal Back EMF and hall sensor signals A sinusoidal shaped back EMF BLDC motor is designed to develop sinusoidal back EMF waveforms. It has the following ideal characteristics Sinusoidal distribution of magnetic flux in the air gap Sinusoidal current waveforms Sinusoidal distribution of stator conductors The fundamental aspect in case of BLDC motor is the back EMF generation in each phase of the stator winding by the rotation of the magnet producing sinusoidal

58 function of the rotor angle. The operation of sinusoidal type of BLDC motor is similar to that of AC synchronous machine operation. The Figure 3.10 shows the winding configuration of sinusoidal EMF BLDC machine. Figure 3.10: The winding configuration of sinusoidal EMF BLDC machine. Speed-Torque analysis is done considering various applications of electric motors. The interaction of current and magnetic field will give rise to torque and the magnetic field is generated by permanent magnets. Magnetic field, source voltage, back EMF and speed of the machine decides the current drawn by the machine. To obtain the torque and speed for a particular load, current has to be controlled. Considering the equivalent circuit for BLDC motor as shown in the Figure 3.11, the analysis can be done. Figure 3.11: Equivalent circuit for BLDC motor

59 The expression for the circuit shown in Figure 3.11 is given by the expressions 3.15 to 3.18. V t = I s R s + L s di s dt +E s (3.15) Where, V t is the power supply voltage, R s is the resistance of the winding, L s is the leakage inductance and E s is the back EMF induced in the winding by the rotating rotor. E s = k E ω r (3.16) T e = k T I s, (3.17) T e = T L + J dω r dt + Bω r (3.18) Where, k E is the back EMF constant, which is associated with the permanent magnets and rotor structure, ω r is the angular velocity of the rotor, k T is the torque constant, T L is the load torque, and B represents the viscous resistance coefficient. Applying Laplace transformation for the above expressions, the transfer function of the BLDC motor driving system is given by expression 3.19. ω r s = k T R s +sl s sj +B +k T k E V t s R s +sl s R s +sl s sj +B +k T k E T L s (3.19) With variable voltage supply, the winding current can be controlled to its maximum by actively controlling the voltage. Thus a maximum torque can be produced as shown in the Figure 3.12

60 Figure 3.12: Torque characteristics 3.4.1 CONTROL OF BLDC MOTOR DRIVES In the case of traction motor applications, by using the accelerator and brake pedals the torque produced by the electric motor can be made to follow the desired torque by the driver commanding the vehicle. The Figure 3.13 shows the torque control scheme for BLDC motor drives. The desired current I is derived from the torque commanded T through torque controller. The current controller and the commutation sequencer receives the desired current I, the position information from the position sensors, the current feedback through current transducers and then produce the gating signals. These obtained gating signals are sent to three-phase inverter to produce the desired phase current to the BLDC machine. Figure 3.13: Torque control scheme for BLDC motor drives

61 The speed control may be required during the cruising applications majorly in case of traction applications. Current feedback is required for high performance applications for achieving torque control methodology. The DC bus current feedback is provided to the machine to protect the machine from overcurrents. The proportional-integral controller or artificial intelligence controller may be used in this methodology. The methodology may be adopted by utilizing peak current control or PWM type current control method as shown in the Figure 3.14. Figure 3.14: Peak current control or PWM type current controls 3.5 DESIGN OF TWO-WHEELER HYBRID ELECTRIC VEHICLE HEV are the vehicles with more than two energy sources are present. The major challenges for HEV design are managing multiple energy sources, highly dependent on driving cycles, battery sizing and battery management. HEV s take the advantages of electric drive to compensate the inherent weakness of ICE, namely avoiding the idling for increasing the fuel efficiency and reduce emission during starting and speeding operations. HEV can meet customer s need and has added value but cost is the major issue. These vehicles are of high cost and certain program should be supported by the specific government for marketing HEVs. The HEVs are classified into two basic kinds- series and parallel. Recently with introduction of some HEVs offering the features of both series and parallel hybrids, the classification has been extended to three kinds- series, parallel and series-parallel. It is interesting to

62 note that some newly introduced HEVs cannot be classified into these three kinds. Hereby final classification involves series, parallel, series-parallel, complex hybrid. With respect to all above said factors, considering any ICE driven two-wheeler vehicle, if the front free wheel is replaced by electric motor in-wheel of hub motor, a parallel Hybrid Electric ICE vehicle can be developed. Here both the wheels of the vehicle will gain individual propulsions. Front wheel will gain propulsion by electric motor with electric batteries as energy source, whereas rear wheel will gain propulsion by ICE with petrol as energy source. The vehicle complete motion will be derived by summing both the propulsions derived. The rear wheel motion is controlled by accelerator whereas the front wheel motion is controlled by motor speed controller similar to accelerator. By synchronizing the propulsions of both the wheels the required total propulsion for the gradient movement in the vehicle can be easily obtained. Consumption of petrol by only ICE driven vehicle for driving through one Km distance can be minimized in this case by moderately operating the ICE accelerator in Sync with electric motor speed controller. Consumption of battery power by electric motor compared to electric vehicle through a distance of one Km will be minimized here as its speed is in sync with ICE propulsion. The arrangement is as shown in the Figure 3.15 and Figure 3.16. Figure 3.15: Concept of two-wheeler parallel configuration

63 Figure 3.16: Concept of two-wheeler parallel Configuration Scooter As the primary need for this work, the chosen test vehicle for the analysis purpose is Kinetic Honda Y2K, made, two-stroke, continuously variable transmission, shown in Figure 3.17, more suitable for testing purpose. Here, the parameters of this two-wheeler ICE operated vehicle that is the technical specifications are shown in table 3.1.

64 Table 3.1: Technical specification of ICE vehicle (Kinetic Honda) considered for design Engine Transmission Engine displacement Maximum power Maximum Torque Wheelbase Ignition Dry Weight Battery Front suspension Rare suspension Front tyre size Rear tyre size Two-Stroke (petrol) Automatic 98cc 7.7bhp@5600rpm (5.74KW) 1.0kgm@5000rpm (9.80665Nm) 1215mm Electronic 99kg 12Volts Bottom link hydraulic damper Unit swing arm/ hydraulic damper 3.50 X 10.4 Pr 3.50 X 10.4 Pr Figure 3.17: Kinetic Honda Y2K, ICE operated Scooter considered for design

65 For obtaining all the result in designing, simulating software MATLAB is used. The Programs written for the obtained results are attached in Appendix. With rolling resistance f r = 0.01, air density ρ a = 1.205kg/m 3, frontal areaa f = 0.7m 2, aerodynamic drag coefficient C D = 0.3, transmission efficiency from engine to drive wheels η t,e = 0.9, and transmission efficiency from motor to drive wheels η t,m = 0.95, it is seen from the engine characteristics obtained for maximum speed of 60Kmph on flat road is as shown in the Figure 3.18, Considering the force required for propelling the vehicle summing with respect to acceleration and for overcoming the road resistances, the engine power for maximum speed of 60Kmph is given also shown in Figure 3.18. Figure 3.18: Engine power required (Blue: power for overcoming only road resistances, Green: overcoming the acceleration criteria along with road resistances) The vehicle considered for the testing purpose took 12 seconds to reach the maximum speed of 60Kmph with only the ICE provided for propulsion. The acceleration curve obtained for the vehicle considered is shown in Figure 3.19.

Power (KW) Speed(Kmph) 66 60 50 40 30 20 10 0 0 2 4 6 8 10 12 time(sec) Figure 3.19: Acceleration curve for the vehicle considered Considering the transmission gear ratio, i g = 1 (As the engine considered is continuously variable transmission type and analyzed for flat road) and final wheel gear ratio i 0 = 0.9, the engine power-speed curve obtained is shown in the Figure 3.20. 3.5 3 2.5 2 1.5 1 0.5 0 0 100 200 300 400 500 600 700 800 Speed (RPM) Figure 3.20: Engine power Vs Speed curve

67 In the design of HEV, the main objective lies with the electric motor are to provide peak power to the drivetrain. It is difficult directly to design the motor power from the acceleration performance of the vehicle, as we have two power sources, we can assume or estimate that, the rolling resistance and aerodynamic drag is handled by the engine and the dynamic load (inertial load in acceleration) is handled by the motor. With this assumption, acceleration is directly related to the output of electric motor, the expression for selection of suitable motor can be given by the expression 3.20. T m i tm η tm r d = δ m M dv dt (3.20) Where, T m is the motor torque, i tm is the gear ratio from the motor to the drive wheel, η tm is the transmission efficiency, r d is the radius in meters corresponding to the driven wheel, δ m is the rotating inertia factor, M is mass in Kg, 3.21. The power rating of the motor suitable can be found by using the expression T m = 30P m πn m (3.21) Where P m is the motor power rating, n m is the motor maximum speed (RPM). The technical specification of the motor is given in table 3.2 Table 3.2 : Rating of the motor considered for the design Type of Motor Hub motor Design of motor BLDC (Brushless DC) Torque 12Nm Speed 300RPM Voltage 60Volts (5 batteries each of 12V, 20Ah) Efficiency 80% Weight 7Kgs

Power Torque 68 The Speed-Torque and Speed-Power characteristics of the motor considered are shown in the Figure 3.21, Figure 3.22 and Figure 3.23. 180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 18 20 Speed Figure 3.21: Speed-Torque Characteristics 250 250 250 250 250 250 250 0 2 4 6 8 10 12 14 16 18 20 Speed Figure 3.22: Speed-Power characteristics

Torque/Power 69 300 250 200 150 100 50 0 0 2 4 6 8 10 12 14 16 18 20 Speed Figure 3.23 : Speed-Torque/Power characteristics (Blue: power, Red: Torque curve) The design concept is developed for driving a scooter with individual wheels of the vehicle separately propelled with different sources. The rear wheel will be coupled to the vehicle as in before driven by ICE, whereas the front wheel is replaced with an electric motor in-wheel hub motor drive driven by five DC batteries. For analysis, the mechanical arrangements with respect to suspension in the front wheel are being altered as per the required design for holding the motor wheel as shown in Figure 3.24 and Figure 3.25. Figure 3.24: Designed vehicle with front wheel as hub motor

70 Figure 3.25: Mechanical arrangement made for fixing the hub motor as front wheel The controller for the motor is being interfaced with the motor speed regulation shown in Figure 3.26. The speed controlling throttle is being interfaced through the motor controller circuit. The motor used here is 60V, 250W, Ampere made hub motor. The controller for the motor is also Ampere made suitable for controlling the specified motor. The throttle or accelerator is an ampere made throttle for speed regulation of the specified motor shown in Figure 3.27. Figure 3.26: motor controller connected to front wheel

71 Figure 3.27: Left hand Throttle / Accelerator used for controlling the speed of the motor The input to the motor is supplied by five Exide made Electra lead-acid batteries each of 12V, 20Ah through controller for testing purpose as shown in Figure 3.28. Figure 3.28: Battery units interconnected and placed on leg guard Two independent propelling sources are being employed for obtaining total propulsion of the vehicle. The overview of the vehicle is shown in Figure 3.29. The

72 right hand side throttle / accelerator in the vehicle handle corresponds to ICE speed control, whereas the left hand side throttle / accelerator in the vehicle corresponds to speed control of electric motor providing the option for the driver to operate the vehicle in engine-alone mode, motor-alone mode and Hybrid mode(combination of engine and motor). When the vehicle will be operated in hybrid mode, engine is used for vehicle propulsion during initial conditions (from the rest) and as the speed of the vehicle increases engine will be maintained at idling or optimal state by maintaining the speed of the motor for vehicle propulsion. Figure 3.29 : overview of the hybrid electric-ice vehicle 3.6 DESIGN OF DRIVING CYCLE As the primary need for this work is to record the data, the method of recording the speed is done through dynamometer provided in the vehicle. For better analysis of the driving conditions and for classifying it, a survey on specific route of test area is conducted where a part of Mysore city is considered. The test vehicle, only in ICE is driven in the test route shown. The route chosen in the test area in Mysore city as shown in the Figure 3.30.

Speed(Kmph) 73 Figure 3.30: Driving Route chosen in the test area (Googlemaps, 2014) The speed in Kmph is recorded in intervals of 10 seconds through the speedometer present in the vehicle. The speed time curve is plotted with the recorded data as shown in the Figure 3.31. 50 45 40 35 30 25 20 15 10 5 0 0 50 100 150 200 250 300 time(sec) Figure 3.31: Speed-Time curve for the derived driving cycle for the test route chosen

Distance(KM) 74 The total distance covered in this trip is 3Km. The time taken for covering this distance is 280 seconds under moderate traffic condition. The obtained speed-time curve is analyzed as quadrilateral type. The parameters obtained from the curve are as follows as shown in table 3.3. Table 3.3: Parameters obtained from the quadrilateral type analysis for the test route derived driving cycle Maximum speed attained at the end of acceleration period Speed at the starting of braking retardation Starting acceleration Braking retardation Coasting retardation Total time of run Total distance Average speed 50kmph 30kmph 6.25kmphps 7.5kmphps 0.07kmphps 280 seconds 3.4km 44Kmph From the obtained average speed, it can be concluded that, the driving cycle comes under Extra Urban Driving Conditions. The distance covered by the vehicle at the rate of time consideration is shown in the Fig 3.32. 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 0 50 100 150 200 250 300 time(sec) Figure 3.32: Distance-time curve for the derived driving cycle in the test route chosen

Tractive force(newtons) 75 As it is estimated that, motor is delivering the force for acceleration and ICE is delivering the force for overcoming the resistances encountered in the road, the tractive effort Vs Speed curve for flat road is as shown in the Figure 3.33., where Red curve indicates the Hybrid operation, Total or combined effort of both motor and ICE for propulsion), Green curve indicates the Motor operation (tractive effort with respect to acceleration), Blue curve indicates the engine operation in overcoming the road load resistances. 180 160 140 120 100 80 60 40 20 0 0 5 10 15 20 25 30 35 40 45 50 Speed(Kmph) Figure 3.33 : Speed-Tractive force curves ( Red: Hybrid operation, Green: Motor operation, Blue: Engine operation) The Time Vs Tractive force curves for the driving cycle are shown in the Figure 3.34 where Red curve indicates the Hybrid operation, Total or combined effort of both motor and ICE for propulsion), Green curve indicates the Motor operation (tractive effort with respect to acceleration), Blue curve indicates the engine operation in overcoming the road load resistances.

Power(KW) Tractive force(newtons) 76 180 160 140 120 100 80 60 40 20 0 0 50 100 150 200 250 300 time(sec) Figure 3.34: Time-Tractive force curves (Red: Hybrid operation, Green: Motor operation, Blue: Engine operation) The power consumption curve for flat road for the derived driving cycle by motor and ICE is as shown in the Figure 3.35. Where Red curve indicates the Hybrid operation, Total or combined power delivered by both motor and ICE for propulsion), Green curve indicates the Motor power delivered (power delivered with respect to acceleration), Blue curve indicates the delivered engine power in overcoming the road load resistances. 3 2.5 2 1.5 1 0.5 0 0 5 10 15 20 25 30 35 40 45 50 Speed(Kmph) Figure 3.35 : Speed-power curves ( Red: Hybrid operation, Green: Motor operation, Blue: Engine operation)

Power(KW) 77 Considering the gradient from one percent to ten percent in the drivetime, estimating the engine is being overcoming the road gradient, the power consumption curve for the drive cycle is as shown in Figure 3.36. Where Red curve indicates the Hybrid operation, Total or combined power delivered by both motor and ICE for propulsion), Green curve indicates the Motor power delivered (power delivered with respect to acceleration), Blue curve indicates the delivered engine power in overcoming the road load resistances. 4 3.5 3 2.5 2 1.5 1 0.5 0 0 5 10 15 20 25 30 35 40 45 50 Speed(Kmph) Figure 3.36 : Speed-power curves ( Red: Hybrid operation, Green: Motor operation, Blue: Engine operation) for road gradient from 1 to 10 percent The Energy curve with the gradient consideration from 1% to 10% in the driving cycle is shown in Figure 3.37. Where Red curve indicates the Hybrid operation (both motor and ICE combined), Blue curve represents engine alone mode, and Green curve represents motor alone mode.

Energy(KWh) Energy(KWh) 78 0.012 0.01 0.008 0.006 0.004 0.002 0 0 50 100 150 200 250 300 time(sec) Figure 3.37 : Energy curves ( Red: Hybrid operation, Green: Motor operation, Blue: Engine operation) for road gradient from 1 to 10 percent The energy consumption by the motor, engine and combined mode is as shown in the Figure 3.38. Where Red curve indicates the Hybrid operation, Total or combined power delivered by both motor and ICE for propulsion), Green curve indicates the Motor power delivered (power delivered with respect to acceleration), Blue curve indicates the delivered engine power in overcoming the road load resistances. 0.012 0.01 0.008 0.006 0.004 0.002 0 0 5 10 15 20 25 30 35 40 45 50 Speed(Kmph) Figure 3.38: Speed- Energy curves ( Red: Hybrid operation, Green: Motor operation, Blue: Engine operation) for road gradient from 1 to 10 percent

79 The time rate of fuel consumption is calculated by expression 3.22. Q fr = P eg e 1000γ f l/ (3.22) Where g e is the specific fuel consumption of the engine in g/kwh, γ f is the mass density of the fuel in Kg/L, The total fuel consumption for a distance S, with constant cruising speed of V is given by expression 3.23. Q fr = P eg e 1000γ f S V litres (3.23) 3.7 RESULTS OF THE DESIGNED HEV TWO-WHEELER FOR THE DERIVED DRIVING CYCLE FROM THE TEST ROUTE MYSORE CITY, INDIA With an average speed of 40Kmph in the derived driving cycle, for flat road, if the vehicle is propelled completely by only ICE (engine provides complete tractive effort, both resistance overcoming and with respect to acceleration), then it should deliver 2.05KW of power for the vehicle propulsion. With constant g e = 250-350 g/kwh, and γ f = 0.737 Kg/ liter, the petrol consumption by the engine in whole driving cycle derived will be approximately 90ml for engine-only mode. By considering the combined operation of both ICE (in overcoming the road resistances) and motor operations (tractive effort with respect to acceleration) for complete propulsion of the vehicle, with an average speed of 40Kmph, with a motor tractive power of 1.52KW and engine tractive power of 0.52KW (1.52KW+0.52KW=2.04KW), the fuel consumption by the engine in the driving cycle derived will be approximately 25ml. About 50% to 70% of the fuel for ICE can be saved in this derived driving cycle of the test route chosen if this type of hybrid ICEelectric vehicle is being designed and followed in driving. The results show that the simulated vehicle components are compatible and support the basic requirements of the driving in selected driving cycle of the test area, Mysore city, Karnataka, India.