EFFECTIVEE DESIGN AND ANALYSIS OF PEDELEC E-BIKE USING MBD APPROACH

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1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 13, December 2018, pp , Article ID: IJMET_09_13_0599 Available online at aeme.com/ijmet/issues.asp?jtype=ijmet&vtype= =9&IType=13 ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EFFECTIVEE DESIGN AND ANALYSIS OF PEDELEC E-BIKE USING MBD APPROACH Dr. S.Paul Sathiyan Assistant Professor, Department of Electrical and Electronics Engineering, Karunya Institute of Technology and Sciences, Coimbatore - 114, India Daniel Student, Department of Electrical and Electronics Engineering, Karunya Institute of Technology and Sciences, Coimbatore - 114, India C. Benin Pratap Assistant Professor, Department of Electrical and Electronics Engineering, Karunya Institute of Technology and Sciences, Coimbatore - 114, India ABSTRACT Developing country like India should concentrate on having a sustainable nonpolluting alternate means of road transport due to high fuel pricing, and pollution. Two wheelers in India contribute to around 75 % of total vehicle population. E-bikes for short distance transportation could be a better alternative. Tailor made design would be highly beneficial than a predefined model since the cost of E-bike depends solely on the propulsion technology which includes drive and battery system. In order to speed up and arrive at an effective design, Model Based Design (MBD) approach is adopted. In this research work, the propulsion power demand as a function of Grading and Power demand sharing by the rider have been studied with respect to five different bicycle models. Analyses have been carried out by MBD technique using MATLAB / Simulink. Keywords: Two Wheelers, Pollution, Electric Bike, Electric Propulsion. Cite this Article: Dr. S.Paul Sathiyan, Daniel and C. Benin Pratap, Effective Design and Analysis of PEDELEC E-Bike Using MBD Approach, International Journal of Mechanical Engineering and Technology, 9(13), 2018, pp et/issues.asp?jtype=ijmet&vtype=9&itype e=13 IJMET/index.asp 568 editor@iaeme.com

2 Dr. S.Paul Sathiyan, Daniel and C. Benin Pratap 1. INTRODUCTION Larger dependency of two wheelers for day to day living in regions like India creates a positive scope for bicycle industry producing electric propulsion bicycles (E-Bike). Amongst the vehicles on road in India, two wheelers dominate the road upto 75% [1]. By 2020, it is expected that India will become the third largest vehicle market in the world with 34 million units of two wheelers. Due to high urban vehicle population on Indian roads, the average speed has come down to 25 km/hr leading to increase of travel time. In the past century, transportation depended highly on Internal Combustion Engine (ICE) due to ease of use, availability of low-cost fuel. IEA reported in 2009 that road transportation has been the second largest reason for CO2 emission. India dominates the list of cities having highest small particulate measurements in the world (Table 1).According to WHO, 2018, ten out of top 20 cities which are exposed to high air pollution levels are from India[2]. Table 1 Cities of the World with Highest Small Particulate Measurements Country City PM 2.5 (µg/m 3 ) India Kanpur 173 India Faridabad 172 India Varanasi 151 India Gaya 149 India Patna 144 India Delhi 143 India Lucknow 138 India Bamenda 132 India Agra 131 India Muzaffarpur 120 India Srinagar 113 India Gurgaon 113 Considering the two-wheeler demand in India, decreased in the average urban speed and pollution contribution of vehicles, it is predicted that e-bikes shall penetrate by 15 % into twowheeler market in spite of the barriers. According to GoI Industry Study, higher level of incentives ranging from Rs can be given to boost demand. From the literatures, the following parameters have been considered for performance evaluation of Electric s[3]: Speed (Average Speed and Maximum Speed) Travel Range (per Charge) Batteries Power On board Power Supply Torque Hill Climbing Ability Weight Price Regulations governing E-transportation varies from country to country. According to federal law, the maximum speed permitted is 20 mi/hr where as in India it is 25 km/hr. For safety reasons the on-board battery ratings also has limitations which would influence the IJMET/index.asp 569 editor@iaeme.com

3 Effective Design and Analysis of PEDELEC E-Bike Using MBD Approach range of travel as well as the cost of the vehicle. Also, the power rating of the motor should be below 750w for countries under federal jurisdiction whereas in India the power rating of the electric propulsion system is limited to 250w. This restriction in power affects the torque delivered by the propulsion system. Countries have different policies on how the load torque is met. Some countries allow power to be shared between motor and the rider, hence making the e-bike hybrid which is called as Pedelec configuration. There is no regulation on the percentage share of the load torque. Whereas in some countries, the pedaling is not allowed. The entire load torque is to be met by the motor. This leads to higher power rating of the motor and the on-board battery system. The hill climbing of the vehicles are limited to 6% slope.the power demand for different driving cycle like city, hill, distance and speedy bicycle varies it is preferred to have a custom-designed bicycles that are most efficient over a given operating cycle[3]. As a proof of the wide power range, Table 2presents the metric variations for the three different models available with the manufacturer Light Speed [4]. Table 2 Model Comparison of Light Speed E-bike Models PARAMETERS Model 1 Model2 Model 3 Motor a. Type BLDC Hub BLDC Hub BLDC Hub b. Power Rating 250W 250W 250W c. Torque 32 Nm 32 Nm 45 Nm d. Voltage 36 V 36 V 36 V e. Sensor 12 Magnet Dual Hall PAS 12 Magnet Dual Hall PAS 12 Magnet Dual Hall PAS Battery a. Type b. AH Rating c. Charging Cycle d. Charing Current E-Bike General Specifications a. Type b. Model c. Weight d. Wheel Dia e. Maximum Speed f. Distance / Charge Lithium Ion LG/Samsung 10.4 AH A Urban and Off road Dryft 23 kgs m 25 km/hr 50 kms Lithium Ion LG/Samsung 7.8 AH A Urban Glyd 21 kgs m 25 km/hr 35 kms Lithium Ion LG/Samsung 10.4 AH A Off Road Furry 26 kgs m 25 km/hr 45 kms Cost (Rs) 39,999 / - 29,999 / - 59,999 /- The price of the E-bike is predominated by the battery and the propulsion drive system. Further research in both battery and drive technology for their use with E-bikes would certainly benefit electric bicycle market. Keeping in mind the performance, reliability and cost of the product under development, the manufacturers try bringing the product early to the market. In order to aid faster development, Model Based Design (MBD) approach helps in verifying and validating the product during testing under virtual / simulation environment. Right from the early concept design to the final validation and verification testing, this approach covers multidiscipline, functional behavior and cost / performance optimization. The obvious advantages of MBD of a convenient, understandable graphical description of systems, continuous verification and IJMET/index.asp 570 editor@iaeme.com

4 Dr. S.Paul Sathiyan, Daniel and C. Benin Pratap validation at all stages of development as well as its inherent robustness against coding errors have made it a state-of-the-art method in fields such as automotive systems and aerospace and defense[5]. In this research work, the e-bike model is presented along with its dynamic model. The model has been created in MATLAB Simulink and tested under different scenarios and presented in the upcoming section. 3. PEDELEC MODEL AND MBD DEVELOPMENT The basic configuration of pedelec electric bicycle has been presented in Figure 1.The operation of the above configuration is explained below [6]: The controller receives the throttle demand of the rider. Controller senses the torque generated at the pedal and computes the required torque. Controller generates the required control signal for the power electronic converter in accordance to the received throttle demand and the torque available at the pedal. The converter acts as a link between the power source Battery and the electromechanical conversion necessary which is used to transfer / control the power supplied to the motor which in turn controls the speed of the bike. Transmission system is used to couple the power obtained from the motor as well as the rider when pedaling. Wheel speed is monitored in order to maintain the speed in accordance to the government regulations (Maximum Speed < 25 km/hr for India). Controller also monitors the state of charge of the battery to protect the battery from over charging / discharging. Figure 1 Basic Block Diagram of Pedelec Model E-bike Selection of converter used depends on the type of drive motor used. The power demand for the propulsion system is obtained considering various factors which are discussed in the following subsection Longitudinal Dynamic Modelling of Pedelec E-Bike The propulsion power generated (pedal + electric motor) should be sufficient to overcome the longitudinal forces acting against the movement of the vehicle. The total resistive forces IJMET/index.asp 571 editor@iaeme.com

5 Effective Design and Analysis of PEDELEC E-Bike Using MBD Approach acting against the movement of the bike comprises of aerodynamic drag(f d ), rolling resistance (F r ), grading resistance, (F g ) as well as the bearing and mechanical friction, (F b )[6] [8]. The total force required to move the vehicle is given by = acc (1) where M is the total mass of the pedelec (including the rider) and acc is the acceleration of the bike. Hence, the longitudinal dynamics of e-bike can be represented as = + (2) where v is the longitudinal velocity and t is the time. The term F d in (2) is the aerodynamic drag force: =0.5 (+ ) (3) where A d is the reference area of the bicycle-rider system, C d is the aerodynamic drag coefficient, ρ air is the air density. The aerodynamic drag force which acts against the movement of the bike increases with the vehicle velocity as well as the head wind. The values of A d and C d differs for different types of bicycles [9] which is mentioned in Table 3. The term F r is the rolling resistance force which contributes for the forces acting on the front and the rear wheels of the bicycle which is represented as in (4): = ( ) (4) where g is the gravitational acceleration, α is the slope of the road, C rr is the rolling resistance coefficient. Table 3 Parameters Influencing Aerodynamic Force and Rolling Resistance Parameters Utility Sports Road Racing Commuting Ultimate Frontal Area, A d (m 2 ) Drag Coefficient, C D Rolling Resistance Coefficient, C rr Grading resistance force, F g which is a function of the road angle is computed according to (5) as =!"#( ) (5) Bearing and Mechanical friction force, F b is a function of gravity and the total mass on the vehicle, hence it is computed as =$ (5) where, k b is the mechanical friction constant of the bearing (0.005). As torque is the product of the force, acting on the shaft and the shaft lever / wheel radius, the bicycle longitudinal dynamics can be expressed in function of the total driving torque T d,w applied to the rear wheel %, = '( ) (7) where r is the nominal radius of both the bicycle wheels. Introducing the gear ratio ε g and the efficiency η g of the bicycle gearbox IJMET/index.asp 572 editor@iaeme.com

6 Dr. S.Paul Sathiyan, Daniel and C. Benin Pratap * + =, -,. (8) where ω w is the angular velocity of the bicycle wheels, ω p is the pedal angular velocity, T h and T m,p are the human and the motor torque applied to the pedal shaft, respectively. η 0 = 1 -, (9) the torque equilibrium at the motor shaft can be derived % + = ( ) 5 6 (10) where ω m is the motor angular velocity and T m is the torque provided by the electric motor applied to its shaft. The power demand of the motor is computed by considering the gear ratio and torque equilibrium at the motor shaft 7 + = 8(9 : ; 4 )1 - <= (11) 3.2. Design Considerations As per CMVR motorized bicycle with power less than 250W and speed limited below 25km/hr is categorized as vehicle which does not require any driving license. Hence for the design and analysis the following constrains (Table 4) have been considered for analyzing the different types of bicycle mentioned in Table 3. Table 4E-Bike Design Considerations PARAMETERS RANGE Weight 15 Weight of the Rider 75 Maximum Speed* 25 km/hr Motor Power Rating* 250 W Motor Speed 340 RPM Wheel Diameter 26 inches Battery Voltage 36 V Battery AH Rating 7.8 AH 3.3. MATLAB / SIMULINK Model of Computing Power The overall MALTAB/ Simulink MDB model of the Pedelec system is being presented in Figure 2. The resistive forces have been computed initially with various design parameters mentioned in Table 3 and 4. Exploded view of each block has been presented from Figure 3 to 6 which has been developed using the formulae presented from (1) to (11). IJMET/index.asp 573 editor@iaeme.com

7 Effective Design and Analysis of PEDELEC E-Bike Using MBD Approach Figure 2 Overall MBD MATLAB / Simulink Model for Pedelec E- Bike Model Figure 3 Computation of Resistive Forces and Acceleration of the Bike Figure 4 Computation of Aerodynamic Drag Force IJMET/index.asp 574 editor@iaeme.com

8 Dr. S.Paul Sathiyan, Daniel and C. Benin Pratap Figure 5 Computation of Rolling Resistance Force Figure 6Computation of Bearing and Mechanical Frictional Force 4. RESULTS AND DISCUSSION Testing is carried out for the five types of bicycle mentioned in Table 3 according to the following phases mentioned below: Case 1: With Zero Pedal Input Grading angle of Zero Degree Grading angle of One Degree Grading angle of Five Degree. Case 2: With Partial Pedal Input Grading angle of Zero Degree Grading angle of One Degree Grading angle of Five Degree. Under case 1, the entire load torque is met by the electric motor where as in case 2, 50 % of the power is met with by the rider and the rest met by the motor. The parameters mentioned in section 1 (Maximum Speed, Power, Torque, Cost, Hill Climbing ability, Weight) have been considered to examine the performance of the five bicycles. The power backup time of the battery is computed considering the linear operating region of the battery. Table 5 to 8 presents the result obtained for the gradings 0,1 and 5 respectively. The power required for Utility bicycle is around 206 W with a maximum speed of motor restricted to 340 rpm which yields to 25 km/hr speed with a tire of radius m. Where as the back up time is higher for Ultimate model as its power demand is only 54.6W. As the portion of the load torque is met by the rider by pedaling, the power demand of the electric propulsion system reduces depending on the percentage of load sharing. IJMET/index.asp 575 editor@iaeme.com

9 Effective Design and Analysis of PEDELEC E-Bike Using MBD Approach Parameters % of Load Torque met by Rider Table 5Performance of E-Bikes for Zero Degree Grading Utility Sports Road Racing Commuting Ultimate Power, W Acceleration, m/s Torque, Nm Motor Speed, rpm Current, A Backup time, hrs Parameters Table 6Performance of E-Bikes for One Degree Grading Utility Sports Road Racing Commuting Ultimate % of Load Torque met by Rider Power, W Acceleration, m/s Torque, Nm Motor Speed, rpm Current, A Backup time, hrs Parameters Table 6Performance of E-Bikes for Five Degree Grading Utility Sports Road Racing Commuting Ultimate % of Load Torque met by Rider Power, W Acceleration, m/s Torque, Nm Motor Speed, rpm Current, A Backup time, hrs IJMET/index.asp 576 editor@iaeme.com

10 Dr. S.Paul Sathiyan, Daniel and C. Benin Pratap When the grading is increased to one degree, the power for Utility and Sports model exceeds the permitted value of propulsion drive power (250 W), where as for the rest the power demand is less than the permissible limit. Since the current exceeds by 3 Amps the size of the motor also increases which adds to the weight of the vehicle. At 5-degree grading slope, the power demand of all the variant exceeds the permissible limit. Also, the load current in all the variants is high which demands higher on-board power source leading to increase of weight. 5. CONCLUSION Due to the increasing demand of two wheelers and pollution E- bikes would play a vital role in the urban road transportation in India. Since MDB approach in industry provides faster and best possible design of the system, E-Bike is modelled using this approach and the performance is analyzed. It is found thatthe power demand for Ultimate model bicycle is less compared to the rest. For hill climbing task (slope of 5 degrees) using, the power requirement is higher than the permissible power limit prescribed by the government agencies. If 60 % of the torque demand is met by the rider, then the motor power stays below the permissible limit. Out of the five different bicycle models, Ultimate requires very less power for propulsion.in future, this research work is extended to design an optimal drive technology for E-Bikes which in turn reduce the product cost and make it affordable. REFERENCES [1] V. Gulati, National Electric Mobility Mission Plan Department of Heavy Industry, Government of India, Aug [2] D. J. Bhattacharya and S. Tewari, Transformation of on-road automobiles to electric vehicles in India -Regulatory perspectives, KPMG, Mar [3] B. Y. A. Muetze and Y. C. Tan, Electric s, A Performance Evaluation, IEEE Industry Applications Magazine, pp , [4] LightSpeed-Electric--July-2018.pdf.. [5] C. Abagnale, M. Cardone, P. Iodice, S. Strano, M. Terzo, and G. Vorraro, Model-based control for an innovative power-assisted bicycle, vol. 81, pp , [6] W. Du, D. Zhang, and X. Zhao, Dynamic Modelling and Simulation of Electric Ride Comfort, pp , [7] C. Abagnale, M. Cardone, P. Iodice, S. Strano, M. Terzo, and G. Vorraro, Derivation and Validation of a Mathematical Model for a Novel Electric, vol. II, [8] C. Abagnale, M. Cardone, P. Iodice, S. Strano, M. Terzo, and G. Vorraro, A dynamic model for the performance and environmental analysis of an innovative e-bike, Energy Procedia, vol. 81, no. December, pp , [9] D. G. Wilson, Bicycling Science. Cambridge, Massachusetts: MIT Press, IJMET/index.asp 577 editor@iaeme.com