MODELING AND SIMULATION OF A HYBRID ELECTRIC VEHICLE SYSTEM by Eng. Hala Shaban Mohamed Khalil Electronics Research Institute A Thesis Submitted To The Faculty of Engineering at Cairo University In Partial Fulfillment of The Requirements of the Degree of DOCTOR OF PHILOSOPHY In Electrical Power and Machines Engineering FACULTY OF ENGINEERING, CAIRO UNIVERSITY GIZA, EGYPT April 2012 1
MODELING AND SIMULATION OF A HYBRID ELECTRIC VEHICLE SYSTEM By Eng. Hala Shaban Mohamed Khalil Electronics Research Institute A Thesis Submitted To The Faculty of Engineering at Cairo University In Partial Fulfillment of The Requirements of the Degree of DOCTOR OF PHILOSOPHY In Electrical Power and Machines Engineering Under the supervision of Prof. Dr. Mohamed Osama Khalil Electrical Power and Machines Department Faculty of Engineering Cairo University Dr. Sanaa Mohamed Ibrahim Power Electronics and Energy Conversion Department Electronics Research Institute FACULTY OF ENGINEERING, CAIRO UNIVERSITY GIZA, EGYPT April 2012 2
MODELING AND SIMULATION OF A HYBRID ELECTRIC VEHICLE SYSTEM By Eng. Hala Shaban Mohamed Khalil Electronics Research Institute A Thesis Submitted To The Faculty of Engineering at Cairo University In Partial Fulfillment of The Requirements of the Degree of DOCTOR OF PHILOSOPHY In Electrical Power and Machines Engineering Approved by the Examining committee: Prof. Dr. Mohamed Osama Khalil (supervisor) Prof. Dr. Aziza Mahmoud Zaki (member) Prof. Dr. Osama Ahmed Mahgoub (member) FACULTY OF ENGINEERING, CAIRO UNIVERSITY GIZA, EGYPT April 2012. 3
TABLE OF CONTENTS CONTENTS Page TABLE OF CONTENTS. i LIST OF TABLES... v LIST OF FIGURES. vi LIST OF SYMBOLS... xii LIST OF ABBREVIATIONS. xiv ACKNOWLEDGMENT.. xv ABSTRACT. xvi CHAPTER (1): INTRODUCTION 1.1 INTRODUCTION... 1 1.2 HEVs CONFIGURATIONS... 2 1.2.1 Series HEV Configuration... 2 1.2.2 Parallel HEV Configuration. 4 1.2.3 Series Parallel HEV Configuration... 5 1.3 ENERGY STORAGE SYSTEM: BATTERIES 6 1.4 ALTERNATIVE ENERGY SOURCES FOR HEVs.... 7 1.5 OVERVIEW OF ELECTRIC MOTORS FOR HEVs.... 8 1.5.1 Conventional DC Motors. 9 1.5.2 Induction Motors... 9 1.5.3 Switched Reluctance Motors... 10 1.5.4 Permanent magnet synchronous motor... 10 1.6 COMARISON BETWEEN ELECTRIC MOTORS USED IN HEVS... 11 1.7 INTERNAL COMBUSTION ENGINE... 12 1.8 DRIVES AND CONTROL TECHNIQUES IN HEVs. 13 1.9 OVERVIEW ON VEHICLE SIMULATION TOOLS.. 13 1.10 INTELLIGENT CONTROL TECHNIQUES IN HEVS. 15 1.11 THESIS OUTLINE.. 16 CHAPTER (2): FUZZY MODELING of BATTERY STATE of 18 CHARGE in HYBRID ELECTRIC VEHICLE APPLICATIONS 2.1 INTRODUCTION. 18 2.2 BATTERY MONITORING TECHNIQUES.... 18 2.2.1 Specific Gravity... 19 i
2.2.2 Open Circuit Voltage... 19 2.2.3 Coulometric Measurement...... 19 2.3 STATE OF CHARGE (SOC).... 21 2.4 SOC IMPORTANCE. 21 2.5 MODELING OF BATTERY SOC.... 22 2.6 REVIEW OF FUZZY LOGIC... 23 2.7 FUZZY MODELING TECHNIQUES...... 23 2.8 EXPERIMENTAL SYSTEM SETUP AND PROPOSED FUZZY MODEL...... 24 2.9 TEST PROCEDURES.... 25 2.10 RESULTS AND DISCUSSION....... 29 2.11 CONCLUSIONS..... 30 CHAPTER (3): MODELING AND SIMULATION OF DIRECT TORQUE CONTROL OF PERMANENT MAGNET SYNCHRONOUS MOTOR 31 3.1 INTRODUCTION... 31 3.2 MODELING OF PERMANENT MAGNET SYNCHRONOUS MOTOR. 31 3.3 CONTROL TECHNIQUES OF PMSM.... 34 3.3.1 Scalar Control.. 34 3.3.2 Vector Control 35 3.3.3 Direct torque control.... 35 3.4 TORQUE CONTROL STRATEGY OF PMSM... 38 3.5 AMPLITUDE CONTROL OF STATOR FLUX LINKAGE OF PMSM... 38 3.6 CONTROL OF ROTATION OF STATOR FLUX LINKAGE λs... 39 3.7 IMPLEMENTATION OF DTC SYSTEM 40 3.7.1 Hysteresis Controller... 40 3.7.2 Switching Table... 41 3.7.3 Sector Determination... 42 3.7.4 Torque and flux estimation.. 43 3.7.5 Voltage source inverter.... 44 3.8 SIMULATION RESULTS 46 ii
3.9 CONCLUSIONS... 55 CHAPTER (4): FUZZY MODELING AND SIMULATION OF A HYBRID ELECTRIC VEHICLE 57 4.1 INTRODUCTION.. 57 4.2 OVERALL MODEL STRUCTURE... 57 4.3 Speed Command 58 4.4 THROTTLE CONTROL LOGIC... 59 4.5 POWER MANAGEMENT CONTROLLER. 61 4.6 INTERNAL COMBUSION ENGINE....... 64 4.7 ELECTRIC MOTOR..... 67 4.8 BRAKING SYSTEM MODEL..... 67 4.9 VEHICLE DYNAMICS 67 4.9.1 Rolling Resistance Force..... 67 4.9.2 Aero-dynamic drag.. 67 4.9.3 Hill climbing force... 67 4.9.4 Acceleration Force... 68 4.9.5 Total Tractive Effort 68 4.10 TRANSMISSION SYSTEM. 68 4.10.1 Manual Transmission.... 69 4.10.2 Automatic Transmission... 69 4.10.3 Continuously Variable Transmission.... 69 4.11 BATTERY PACK... 70 4.12 SIMULATION RESULTS AND DISCUSSIONS.. 71 4.13 CONCLUSION. 84 CHAPTER (5): EXPERIMENTAL RESULTS. 85 5.1 INTRODUCTION.. 85 5.2 SYSTEM DESCRIPTION... 86 5.3 SYSTEM IMPLEMENTATION 87 5.4 POWER MANAGEMENT CONTROLLER..... 88 5.5 EXPERIMENTAL RESULTS 93 5.6 CONCLUSION. 98 iii
CHAPTER (6): CONCLUSION AND FUTURE WORK 99 6.1 CONCLUSION.. 99 6.2 FUTURE WORK 101 REFERENCES... 102 APPENDICES 109 APPENDIX(1): PMSM specifications- Beckhoff Model AM247L 109 APPENDIX(2): Servo Driver specifications- Beckhoff Model AX2513 110 APPENDIX(3): PC30AT Interfacing Card Specifications... 113 iv
LIST OF TABLES Table Page Table (1.1) parameters of HEV batteries... 7 Table (1.2) Evaluation of motors for HEV... 11 TABLE (2.1): Discharging current versus experimentally measured (BAC) at different temperatures 25 Table (2.2) rules of the mamdani fuzzy model. 27 TABLE (2.3): Actual and modeled BAC at different discharging current and temperatures 29 Table (3-1) switching table for DTC inverter. 42 Table (3-2) Sector Determination... 42 Table (4.1): Manual transmission gear ratio... 69 v
LIST OF FIGURES Figure No. Page Figure (1.1) Drivetrain of an electric vehicle...... 2 Figure (1.2) Configuration of a series hybrid vehicle.. 3 Figure (1.3) Parallel HEV Configuration 5 Figure (1.4) Series-Parallel Hybrid Electric Vehicle... 5 Figure (1.5) Requirements of Electric motor for HEV.. 9 Figure (1.6) fuzzy modeling for output torque of ICE... 15 Figure (2.1) Experimental system setup... 25 Figure (2.2) Discharging current membership functions. 26 Figure (2.3) Temperature membership functions 26 Figure (2.4) BAC membership function... 26 Figure (2.5) Measured BAC at different discharging currents 27 Figure (2.6) Measured BAC at different temperatures 27 Figure (2.7) Measured and modeled BAC at different discharging currents.. 28 Figure (2.8) Measured and modeled BAC at different temperatures... 28 Figure (2.9) Simulink block diagram of SOC estimation..... 28 Figure (2.10) SOC at different discharging currents.. 29 Figure (2.11) Comparison between modeled BAC and actual BAC... 29 Figure (3.1) Simulink block diagram of direct axis current calculation.. 32 Figure (3.2) Simulink block diagram of quadrature axis current calculation... 32 Figure (3.3) Simulink block diagram of motor torque calculation... 33 Figure (3.4) Simulink block diagram of speed and rotor position calculation 33 Figure (3.5) Simulink block diagram of the PMSM 34 Figure (3.6) Control techniques of PMSM..... 34 Figure (3.7) Control of the stator flux linkage 39 Figure (3.8) Basic direct torque control scheme for ac motor drives. 40 Figure (3.9) Simulink block diagram of the hysteresis controller 41 Figure (3.10) Actual value, reference value, and output of the hysteresis controller.. 41 Figure (3.11) Simulink block diagram of sector determination 42 Figure (3.12) Sector number with respect to stator flux position. 43 Figure (3.13) Stator flux estimation... 43 vi
Figure (3.14) Simulink block diagram of modified integrator with a saturable feedback... 44 Figure (3.15) Voltage source inverter... 44 Figure (3.16) Simulink block diagram of the VSI. 45 Figure (3.17) Simulink block diagram of DTC for PMSM. 46 Figure (3.18) Actual motor torque at reference torque=1.5n.m... 46 Figure (3.19) Steady state torque at reference torque=1.5n.m 47 Figure (3.20) Actual motor torque at reference torque=2n.m 47 Figure (3.21) Steady state torque at reference torque=2n.m.. 47 Figure (3.22) Actual motor torque at reference torque=2.5n.m.. 48 Figure (3.23) Steady state torque at reference torque=2.5 N.m... 48 Figure (3.24) Actual motor torque at reference torque=3n.m. 48 Figure (3.25) Steady state torque at reference torque=3 N.m... 49 Figure (3.26) Actual motor torque at reference torque changes from 1.5N.m to 3N.m to 1.5N.m at t=0.2sec. and t=0.3sec. respectively 49 Figure (3.27) Steady state torque at reference torque changes from 1.5N.m to 3N.m to 1.5N.m at t=0.2sec. and t=0.3sec. respectively... 49 Figure (3.28) Actual motor torque at reference torque changes from 1N.m to 2N.m to 3N.m to 2N.m to 1N.m at t=0.2sec., t=0.3sec., t=0.4sec., t=0.5sec respectively... 50 Figure (3.29) Steady state torque at reference torque changes from 1N.m to 2N.m to 3N.m to 2N.m to 1N.m at t=0.2sec., t=0.3sec., t=0.4sec., t=0.5sec respectively.. 50 Figure (3.30) Quadrature axis current component at reference torque changes from 1N.m to 2N.m to 3N.m to 2N.m to 1N.m at t=0.2sec., t=0.3sec., t=0.4sec., t=0.5sec respectively... 51 Figure (3.31) Actual & reference motor torque at reference torque changes from -3N.m to 3N.m 51 Figure (3.32) Steady state actual & reference motor torque at reference value changes from -3N.m to 3N.m.. 51 Figure (3.33) Quadrature axis current component at reference torque changes from -3N.m to 3N.m 52 Figure (3.34) Steady state quadrature axis current component at reference vii
torque changes from -3N.m to 3N.m... 52 Figure (3.35) Actual flux at reference value=0.2wb.. 53 Figure (3.36) Steady state flux at reference value=0.2wb... 53 Figure (3.37) flux trajectory at reference value=0.2wb... 53 Figure (3.38) Stator flux components (y ds,y qs ) 54 Figure (3.39) Stator flux position 54 Figure (3.40) Stator current components in stator reference frame. 54 Figure (3.41) Stator phase voltage... 55 Fig.(3.42) Motor reference and actual speeds at sinusoidal reference speed with amplitude of 200rad/sec in the reversing mode... 55 Figure (4.1) overall model structure.. 57 Figure (4.2) Common driving cycles... 58 Figure (4.3) membership function for the input of the fuzzy logic controller. 59 Figure (4.4) membership function for the throttle percent of the fuzzy logic controller.. 59 Figure (4.5) membership function for the braking percent of the fuzzy logic controller..... 60 Figure (4.6) Throttle Control logic Subsystem... 60 Figure (4.7) throttle percentage of the fuzzy model. (Sec.)...... 60 Figure (4.8) braking percentage of the fuzzy model 61 Figure (4.9) Operating schedule of HEV. 61 Figure (4.10) Simulink block diagram of power management controller.. 62 Figure (4.11) Electric motor operation subsystem... 63 Figure (4.12) Internal combustion engine operation subsystem... 63 Figure (4.13) Required motor torque subsystem 64 Figure (4.14) Required ICE torque subsystem 64 Figure (4.15) the membership function of the input for WOT... 65 Figure (4.16) the membership function of the output for WOT.. 65 Figure (4.17) the output of fuzzy model for WOT... 65 Figure (4.18) Simulink block diagram of the engine model. 66 Figure (4.19) Simulink diagram of simulated braking subsystem 66 Figure (4.20) the forces acting on a vehicle moving along a slope.. 67 Figure (4.21) Simulink block diagram of simulated vehicle dynamics... 68 viii
Figure (4.22) Simulink diagram of the simulated transmission system... 70 Figure (4.23-a) Vehicle speed at reference speed = 35 km/h. 71 Figure (4.23-b) Motor operation mode at reference speed = 35 km/h..... 72 Figure (4.23-c) ICE operation mode at reference speed = 35 km/h 72 Figure (4.23-d) Vehicle reference torque at reference speed = 35 km/h 72 Figure (4.23-e) Motor reference torque at reference speed = 35 km/h. 73 Figure (4.23-f) Motor actual torque at reference speed = 35 km/h.. 73 Figure (4.23-g) Throttle percent at reference speed = 35 km/h... 73 Figure (4.23-h) ICE output torque at reference speed = 35 km/h 74 Figure (4.24-a) Vehicle speed at reference speed = 60 km/h.... 74 Figure (4.24-b) Motor operation mode at reference speed = 60 km/h.... 75 Figure (4.24-c) ICE operation mode at reference speed = 60 km/h. 75 Figure (4.24-d) Vehicle reference torque at reference speed = 60 km/h..... 75 Figure (4.24-e) Motor reference torque at reference speed = 60 km/h. 76 Figure (4.24-f) Motor actual torque at reference speed = 60km/h.. 76 Figure (4.24-g) Throttle percent at reference speed = 60 km/h... 76 Figure (4.24-h) ICE output torque at reference speed = 60 km/h. 77 Figure (4.25-a) Vehicle speed at step change in speed from 30 km/h to 70km/h... 77 Figure (4.25-b) Motor operation mode at step change in speed from 30 km/h to 70km/h.. 78 Figure (4.25-c) ICE operation mode at step change in speed from 30 km/h to 70km/h. 78 Figure (4.25-d) Vehicle reference torque at step change in speed from 30 km/h to 70km/h. 78 Figure (4.25-e) Motor reference torque at step change in speed from 30 km/h to 70km/h. 79 Figure (4.25-f) Motor actual torque at step change in speed from 30 km/h to 70km/h.. 79 Figure (4.25-g) Throttle percent at step change in speed from 30 km/h to 70km/h.. 79 Figure (4.25-h) ICE output torque at step change in speed from 30 km/h to 70km/h. 80 ix
Figure (4.26-a) Vehicle speed response at trapezoidal speed profile. 80 Figure (4.26-b) Motor operation mode at trapezoidal speed profile.. 81 Figure (4.26-c) ICE operation mode at trapezoidal speed profile.. 81 Figure (4.26-d) Vehicle reference torque at trapezoidal speed profile... 81 Figure (4.26-e) Motor reference torque at trapezoidal speed profile. 82 Figure (4.26-f) Motor actual torque at trapezoidal speed profile... 82 Figure (4.26-h) ICE output torque at trapezoidal speed profile... 82 Figure (4.26-j) Braking percent at trapezoidal speed profile.. 83 Figure (4.27) Vehicle speed response at high-way driving cycle.... 83 Figure (4.28) Reference and actual speed response at C-driving cycle...... 83 Figure (5.1) System Components and Lab Set-up...... 85 Figure (5.2) Experimental system setup.... 86 Figure (5.3) Connection diagram of the servo amplifier [Beckhoff]. 87 Figure (5.4) SOC fuzzy modeling system.... 88 Figure (5.5) Flow chart of experimental work executed in the Lab.... 89 Figure (5.6) Flow Chart of EM Control Logic.... 89 Figure (5.7) Flow Chart of ICE Control Logic. 90 Figure (5.8) Flow Chart of motor reference torque calculation... 91 Figure (5.9a) Estimated SOC using fuzzy logic.. 92 Figure (5.9b) EM operation mode... 92 Figure (5.9c) ICE operation mode 92 Figure (5.10) Control signals for motor Driver with buffering circuit. 93 Figure (5.11) Actual Speed of the PMSM at reference speed 1500 rpm.... 94 Figure (5.12) Reference and actual speeds of the PMSM at 300 rpm. 94 Figure (5.13) Reference and actual speed response when the reference speed changes 95 from 500rpm to -500rpm. Figure (5.13-b) Motor actual speed response and motor current when the reference speed changes from 500rpm to -500rpm 95 Figure (5.14) Reference and actual speed response when the reference speed changes from 1000rpm to -1000rpm. 95 Figure (5.15) Reference and actual current signals at 0.5A (corresponding to 0.7N.m). 96 x
Figure (5.16) Reference and actual current signals at 1A (corresponding to 1.4N.m). 96 Figure (5.17) Actual motor speed response when the analogue signal is set to 1V (450rpm) 97 Figure (5.18) actual motor speed response when the analogue signal is set to 1.5V (675rpm) 97 Figure (5.19) actual motor speed response when the analogue signal is set to 2V (900rpm) 97 Figure (5.20) actual motor speed response when the analogue signal is set to 5V (1750rpm).. 98 xi
LIST OF SYMBOLS A: vehicle frontal area (m 2 ). B: friction coefficient. SOC: state of charge. C a : battery available capacity (Ah). C d : drag coefficient. F rr : rolling resistance force (N). F ad : Aero-dynamic drag force. F hc : hill climbing force (N). F la: acceleration force (N). F te : total tractive effort (N). g: gravational acceleration (9.8 m/sec 2 ). i: discharging current in Amps (ampere). i d : direct axis current (ampere). i q : quadrature axis current (ampere). J: motor moment of inertia (kg.m 2 ). L d : direct axis stator inductance (H). L q : quadrature axis stator inductance (H). m: vehicle mass (kg). N t : gear ratio of the transmission. N tf : total final gear ratio. p: differential factor. P: number of pole pairs. R: stator resistance. S a, S b, and S c : status of the three switches a,b,c. t: time in sec. μ rr : coefficient of rolling resistance. V oc : steady-state open circuit voltage (volts). V d : direct axis stator voltage (volts). V q : quadrature axis stator voltage (volts). V a, V b, and V c ; stator voltages in abc reference frame (volts). V dc : DC link voltage (volts). xii
v: vehicle speed in kilometers per hour.. ω e : rotor electrical angular speed (rad/sec.). ω e : motor electrical speed (rad/sec.). ω r : motor mechanical speed (rad/sec.). ω ICE : internal combustion engine speed (rad/sec.). λ d : direct axis flux linkage(wb.). λ q : quadrature axis flux linkage(wb.). λ m : flux of the permanent magnet (Wb.). λ s : stator flux vector (Wb.). δ: load angle (radians). Θ: stator flux position sector (radians). ρ: density of the air (kgm -3 ). xiii
LIST OF ABBREVIATIONS ADVISOR: Advanced vehicle simulator. ANN: Artificial neural network. BAC: Battery available capacity. BRC: Battery residual capacity. DAC: Digital to analogue converter. DAS: Data acquisition system. DC: Direct current. DTC: Direct torque control. DTDTC: Discrete time direct torque control. DSVM: Discrete space vector modulation. EM: Electric motor. ESS: Energy storage system. EV: Electric vehicle. FOC: Field oriented control. GUI: Graphical user interface. HEV: Hybrid electric vehicle. ICE: Internal combustion engine. PHEV: Parallel hybrid electric vehicle. PI: Proportional integral. PMSM: Permanent magnet synchronous motor. PWM: Pulse width modulation. SOC: State of charge. VSI: Voltage source inverter. WOT: Wide-open throttle. xiv
ACKNOWLEDGMENT I am very grateful with my deep thanks to my supervisor at Cairo university, Faculty of Engineering, Prof. Dr. Mohamed Osama Khalil for his kind supervision and encouragement throughout this work. I am very grateful with my deep thanks to my supervisor at Electronics Research Institute Assistant Prof. Sanaa Mohamed Ibrahim for her kind supervision, useful comments, and several discussions. Also my deep thanks to Prof. Dr. Sayed Wahsh, Dr. Ahmed Ali Mansour and Dr. Khaled Nagdy for their valuable help. Also my deep thanks to Electronics Research Institute for its financial support and the staff of power electronics and energy conversion department in Electronics Research Institute. xv
ABSTRACT The exhaust emissions of the conventional internal combustion engine (ICE) vehicles are the major source of pollution that causes the greenhouse effect leading to global warming. The pollution problem is enlarged due to the increasing the number of automobiles on the road every year. The large number of automobiles has caused serious problems for the environment, human life air pollution and the rapid depletion of the petroleum resources. Electric vehicles (EVs) would seem to be the solution to most of these pollution and fuel consumption problems. Electric Vehicles (EVs) are vehicles that are powered by an electric motor instead of an internal combustion engine. EVs have many advantages over the ICE vehicles such; The propulsion system in EV is simpler than that in ICE vehicles, which contain hundreds of moving parts. EVs are more efficient than ICE vehicles, because the efficiency of the electric motor is higher than that of ICE. Regenerative braking is the most significant advantage of EV over ICE vehicle. The major drawbacks of EVs and limit its acceptance are their limited range and high charging time. In order to overcome these drawbacks, hybrid electric vehicles (HEVs) are used. A hybrid drive train combines two modes of propulsion to achieve results that are un-producible with a single drive train. The HEVs employ an ICE and an electric motor (EM). The HEV combines the features of both EVs and ICE vehicles. Many different configurations of HEVs are possible such as series, parallel, and series parallel hybrids. This thesis presents a detailed model for each part in the HEV system concerning on the electrical part (electric battery system and electric motor drive). The battery system is modeled in details using fuzzy logic model. The data used in the model has been collected experimentally. Fuzzy model has been used to calculate the battery available capacity (BAC) and battery state of charge (SOC) based on discharging current and temperature. A good SOC calculator provides the following advantages for EVs; Longer battery life, better battery performance, improved power system reliability, reduced electrical requirements, improved fuel economy, prefailure warning of the battery pack, and decreased warranty costs. This work handled a detailed model of the permanent magnet synchronous motor (PMSM) using direct torque control (DTC) as a driving technique in such applications. xvi
A complete simulation model of HEV including electrical and mechanical parts has been presented. The simulation results have been obtained at different operation modes according to the power management controller and at different driving cycles. A laboratory scaled model for the experimental system has been constructed, including the implementation of power management controller and DTC driving system for PMSM. In addition, SOC estimation using fuzzy model has been presented. Borland C has been used as a programming tool in this work. The experimental results and remarks have been recorded and analyzed. xvii