Wali Memon                                      walimemon.com   The Electrix                  1988 Homda CRX              ...
Wali Memon                                        walimemon.comEV Fundamentals   Basic   Elements of an EV   Basic   Ele...
Wali Memon                                   walimemon.comBasic Elements of an EV        Motor        Controller       ...
Wali Memon                                                                                         walimemon.comBasic Elem...
Wali Memon                                                                 walimemon.comBasic Elements of an EV           ...
Wali Memon                                                        walimemon.comBasic Elements of an EV                    ...
Wali Memon                                                              walimemon.comBasic Elements of an EV              ...
Wali Memon                                                            walimemon.comBasic Elements of an EV                ...
Wali Memon                                                     walimemon.comBasic Elements of an EV                       ...
Wali Memon                                                            walimemon.comBasic Elements of an EV                ...
Wali Memon                                                  walimemon.comBasic Elements of an EV               Ancillary E...
Wali Memon                                      walimemon.comBasic Electricity Water    Analogy Voltage,    Current, Res...
Wali Memon                                                    walimemon.comBasic Electricity                      Water An...
Wali Memon                                       walimemon.comBasic Electricity            Voltage, Current, Resistance  ...
Wali Memon                                                          walimemon.comBasic Electricity              Voltage, C...
Wali Memon                                                    walimemon.comBasic Electricity              Serial and Paral...
Wali Memon                                                        walimemon.comBasic Electricity               Electrical ...
Wali Memon                                                        walimemon.comBasic Electricity              Electrical P...
Wali Memon                                        walimemon.comEnergy and Power           Basic Physics - Mechanical Forc...
Wali Memon                                           walimemon.comEnergy and Power                Force, Work, Power Newt...
Wali Memon                                            walimemon.comEnergy and Power              Force, Work, Power Newto...
Wali Memon                                                               walimemon.comEnergy and Power                    ...
Wali Memon                                                 walimemon.comEnergy and Power                 Force, Work, Powe...
Wali Memon                                       walimemon.comEnergy and Power               Force, Work, Power Example  ...
Wali Memon                                          walimemon.comEnergy and Power                 Force, Work, Power Exam...
Wali Memon                                                 walimemon.comEnergy and Power                Force, Work, Power...
Wali Memon                                     walimemon.comEnergy and Power              Force, Work, Power Example:   P...
Wali Memon                                                    walimemon.comEnergy and Power              Total Energy and ...
Wali Memon                                                      walimemon.comEnergy and Power               Total Energy a...
Wali Memon                                          walimemon.comEnergy and Power           Total Energy and Peak Power  ...
Wali Memon                                                     walimemon.comEnergy and Power            Total Energy and P...
Wali Memon                                                           walimemon.comEnergy and Power           Total Energy ...
Wali Memon                                                  walimemon.comEnergy and Power         Total Energy and Peak Po...
Wali Memon                                               walimemon.comEnergy and Power           Total Energy and Peak Pow...
Wali Memon                                                      walimemon.comEnergy and PowerRelationship to Electrical En...
Wali Memon                                                      walimemon.comEnergy and Power                            T...
Wali Memon                                                            walimemon.comBatteries, Batteries, Batteries        ...
Wali Memon                                                       walimemon.comBatteries, Batteries, Batteries             ...
Wali Memon                                                 walimemon.comBatteries, Batteries, Batteries                 Le...
Wali Memon                                                        walimemon.comBatteries, Batteries, Batteries            ...
Wali Memon                                           walimemon.comBatteries, Batteries, Batteries               Battery Li...
Wali Memon                                                    walimemon.comBatteries, Batteries, Batteries                ...
Wali Memon                                                    walimemon.comBatteries, Batteries, Batteries                ...
Wali Memon                                                        walimemon.comBatteries, Batteries, Batteries            ...
Wali Memon                                                               walimemon.comBatteries, Batteries, Batteries     ...
Wali Memon                                                                  walimemon.comBatteries, Batteries, Batteries  ...
Wali Memon                        walimemon.com            Thank YouWali Memonwalimemon.com                               ...
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Environmentally Friend Factor of Electric Vehicles

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Electric Vehicles – Are They Environmentally Friendly?

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Environmentally Friend Factor of Electric Vehicles

  1. 1. Wali Memon walimemon.com The Electrix 1988 Homda CRX Restored & converted to electric in 2000 Range 40 km Top speed 130 kphWali Memonwalimemon.com 1
  2. 2. Wali Memon walimemon.comEV Fundamentals  Basic Elements of an EV  Basic Electricity  Energy and Power  Batteries, Batteries, Batteries 2
  3. 3. Wali Memon walimemon.comBasic Elements of an EV  Motor  Controller  Battery Pack  Battery Charger  Ancillary Electronics 3
  4. 4. Wali Memon walimemon.comBasic Elements of an EV Block Diagram Ignition Switch Start + 12 V Battery - Advanced Curtis DC Motor Controller 144 V +ve Main Voltmeter Contactor Battery Pack Ammeter 500 Amp 144 V -ve Current Shunt Accelerator - DC/DC + + Converter - Pot Box 4
  5. 5. Wali Memon walimemon.comBasic Elements of an EV Motor AC Motors  Higher efficiency  No brushes  Complex drive electronics  Generally not suitable for amateur EVs Series Wound DC Motor  Stator and rotor in series  Stator and rotor fields add, so torque goes up as square of current  High starting torque  Simple drive electronics – variable current  Not suitable for regenerative braking  Most popular for amateur EVs 5
  6. 6. Wali Memon walimemon.comBasic Elements of an EV Motor  Shunt Wound DC Motor  Stator and rotor in parallel  Stator winding has high resistance  Torque increases linearly with current  Can be used for regenerative braking  Compond Wound DC Motor  Combination series and shunt wound  Has advantages of both  Complex drive electronics  Permanent Magnet and Brushless DC Motors  Similar performance to shunt wound motors  High efficiency 6
  7. 7. Wali Memon walimemon.comBasic Elements of an EV Series Wound DC Motor Stator and rotor have very low resistance  High current hence high torque at low speeds Motor generates back EMF (voltage) as it speeds up  Higher battery voltage allows more current at higher revs hence increased power Potential motor runaway at low load  Do not apply voltage when not in gear or with clutch disengaged 7
  8. 8. Wali Memon walimemon.comBasic Elements of an EV Controller For Series Wound DC Motor  Modern solid-state variable current motor drive  Very High Power  Up to 150 Volts  Up to 500 Amps  75 Kilowatts  Requires large heat sink with good air flow for cooling 8
  9. 9. Wali Memon walimemon.comBasic Elements of an EV Battery Pack Practical pack voltage - 96 volts to 144 volts Multiple 6, 8, or 12 volt batteries  16 x 6 volts = 96 volts  16 x 8 volts = 128 volts  12 x 12 volts = 144 volts Higher voltage = more cells (2 volts per cell)  144 volts = 72 cells  Range limited by weakest cell 9
  10. 10. Wali Memon walimemon.comBasic Elements of an EV Battery Charger On-board charger Input - 115 or 230 volts AC Single pack charger or individual charger per battery Interlock to prevent starting EV with charger plugged in Battery pack must be vented while charging  explosive hydrogen released 10
  11. 11. Wali Memon walimemon.comBasic Elements of an EV Ancillary Electronics  Battery voltage and current meters  Battery monitoring system  Battery venting and cooling  Battery heater  Car heater  Charger for auxiliary 12 volt battery  Vacuum pump for brakes 11
  12. 12. Wali Memon walimemon.comBasic Electricity Water Analogy Voltage, Current, Resistance (Ohm’s Law) Serial and Parallel Circuits Electrical Power and Energy 12
  13. 13. Wali Memon walimemon.comBasic Electricity Water Analogy Voltage - water pressure Current - water flow Resistance - pipe diameter (smaller diameter equals greater resistance) The higher the water pressure, the greater the water flow The smaller the pipe diameter, the less the water flow 13
  14. 14. Wali Memon walimemon.comBasic Electricity Voltage, Current, Resistance Voltage - Volts (V) Current - Amps (I) Resistance - Ohms (R) Ohm’s Law: V I= R 14
  15. 15. Wali Memon walimemon.comBasic Electricity Voltage, Current, Resistance Current increases as voltage increases and resistance decreases Voltage sometimes referred to as electro-motive force (EMF)  Back EMF was discussed earlier in relation to DC motors 15
  16. 16. Wali Memon walimemon.comBasic Electricity Serial and Parallel Circuits Batteries may be serial or serial/parallel connected Serial connection increases voltage Parallel connection provides more current “Buddy pairs” of batteries are sometimes used with lower capacity batteries to increase range 16
  17. 17. Wali Memon walimemon.comBasic Electricity Electrical Power and Energy Power - watts (W) The instantaneous power is equal to the voltage times the current P=VI Transposing Ohm’s law V = I R Therefore P = I2R This shows that wiring losses square with increasing current 17
  18. 18. Wali Memon walimemon.comBasic Electricity Electrical Power and Energy Energy - joules (J) Energy is power integrated over time (watt/hours) Energy is used to overcome wind and rolling resistance, to accelerate, and to climb hills Assuming a relatively constant battery voltage, the total energy from the battery pack is proportional to the total current drawn  Important when calculating required battery pack capacity 18
  19. 19. Wali Memon walimemon.comEnergy and Power Basic Physics - Mechanical Force, Work, Power Total Energy and Peak Power Relationship to Electrical Energy and Power 19
  20. 20. Wali Memon walimemon.comEnergy and Power Force, Work, Power Newtons First Law: Mass and Inertia An object at rest tends to stay at rest, and an object in motion tends to stay in motion in a straight line at a constant speed 20
  21. 21. Wali Memon walimemon.comEnergy and Power Force, Work, Power Newtons Second Law: Mass and Acceleration F = ma Where F is force, m is mass, and a is acceleration (F and a are vectors). If m is in kg, and a is in m/s2, then F is in newtons 21
  22. 22. Wali Memon walimemon.comEnergy and Power Force, Work, Power Example:What force is required to accelerate a 1200 kg EV from 0 to 100 kph in 30 seconds?Final speed (Vf) 100 kph = 28 m/sTime (t) 30 sMass (m) 1200 kgAcceleration a = v/t = 0.93 m/s2Force F = ma = 1,111 newtons 22
  23. 23. Wali Memon walimemon.comEnergy and Power Force, Work, Power Work Work is the product of the net force and the displacement through which that force is exerted W = Fd F is in newtons, and d is in meters The unit of work is the newton.meter or joule Work is an alternative word for energy 23
  24. 24. Wali Memon walimemon.comEnergy and Power Force, Work, Power Example (force over a distance): F = 50 N D = 60 m W = 3,000 j 24
  25. 25. Wali Memon walimemon.comEnergy and Power Force, Work, Power Example (acceleration over time) m 1,200 kg t 30 s Vf 100 kph = 28 m/s a 0.93 m/s2 F 1,111 N d 417 m W 463 kj 25
  26. 26. Wali Memon walimemon.comEnergy and Power Force, Work, Power Power Power is the work done divided by the time used to do the work P = Fd/t The unit of power is the joule/second or watt (1 kW = 1.34 HP, 1 HP = 746 W) 26
  27. 27. Wali Memon walimemon.comEnergy and Power Force, Work, Power Example: P = 0.5ma2t m 1200 kg Vf 100 kph t 30 s a 0.93 m/s2 P 15.4 kW 27
  28. 28. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power The total energy (or work) is the sum of the energy required to:  Accelerate and climb hills  Overcome rolling and wind resistance 28
  29. 29. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power Example: Our 1,200 kg EV accelerating to 100 kph up a 5% grade hill. Acceleration Force Fa = ma W 1200 kg Vf 100 kph t 30 s a 0.93 m/s2 Fa 1111 N 29
  30. 30. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power Grade Force Fg = W g G (for typical grades) W = vehicle weight in kg g = gravitational force G = Percent grade g 9.8 m/s2 Grade 5 % Fg 588 N 30
  31. 31. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power Rolling Resistance Force Fr = Cr W g cos f Cr = 0.007(1+ (v/30.5)) W = vehicle weight in kg g = gravitational force f = angle of incline Cr 0.0134 f 2.86 degrees (0.05 radians) Fr 120 N 31
  32. 32. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power Aerodynamic Drag Force Fd = (Cd p A V^2)/2 Fd = drag force in Newtons Cd = coefficient of drag p = air density (1.29 kg/m2 @sea level) A = frontal area in sq m Va = average speed in m/s Cd 0.3 P 1.29 kg/m2 A 1.39 sq m Fd 52 N 32
  33. 33. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power Propulsion Force Propulsion Force = acceleration + grade + rolling resistance + aerodynamic drag Fa 1111 N Acceleration 59% Fg 588 N Grade 31% Fr 120 N Rolling Resistance 6% Fd 52 N Aerodynamic Drag 3% Total Propulsion Force 1871 N 33
  34. 34. Wali Memon walimemon.comEnergy and Power Total Energy and Peak Power Total Energy Total Propulsion Force = 1871 N From before, distance = 417 m W = Fd = 779 kj Peak Power P = W/t = 779/30 = 26 kW (35 HP) Note: This would be the power delivered to the wheels! 34
  35. 35. Wali Memon walimemon.comEnergy and PowerRelationship to Electrical Energy and Power Assume efficiency is 80% Total Energy W = 779 kj = 217 wh If V = 144 volts Then Ah = 217/(144 x 0.8) = 1.9 Ah Peak Power P = 26 kW A = 26 x 1000/(144 x 0.8) = 226 Amps 35
  36. 36. Wali Memon walimemon.comEnergy and Power Torque Torque is rotational energy (work) in newton.meters Wheel torque is the applied force in newtons multiplied by the wheel radius Motor torque is the wheel torque divided by the transmission ratio Power is proportional to torque multiplied by RPM P = n.m x 2 π x RPM/60 36
  37. 37. Wali Memon walimemon.comBatteries, Batteries, Batteries Brief Introduction (will be covered in more detail later in course) Lead acid batteries are the most practical for amateur conversions Nickel cadmium are available, but are expensive and have other problems Nickel metal hydride are generally low power and expensive, but could provide good performance Lithium ion provide best performance, but at a high price and are not easily available 37
  38. 38. Wali Memon walimemon.comBatteries, Batteries, Batteries Lead Acid Batteries Most common type is flooded:  Liquid electrolyte - must be kept horizontal  Can tolerate deeper discharge  Can be over-charged to equalize cells  Require periodic topping up with distilled water Gell Cells:  Gelled starved electrolyte  Sealed - can be mounted on sides if required  Lower capacity, lower tolerance to deep discharge  Mustn’t be overcharged 38
  39. 39. Wali Memon walimemon.comBatteries, Batteries, Batteries Lead Acid Batteries Spiral Wound:  A form of absorbent glass mat (AGM) battery where the plates are wound in a spiral  Very rugged and can tolerate high rates of discharge  Not available in very high capacities so sometimes connected as “buddy pairs”  Expensive 39
  40. 40. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Capacity Relationship to Total Energy and Peak Power An earlier example was from an Excel spreadsheet that calculates total energy and peak power required for a typical EV trip scenario From spreadsheet:  For a typical 20 km highway trip in the Electrix:  Total Energy = 3 kwh = 21 Ah  Peak power = 30 kW = 206 A 40
  41. 41. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Limitations Quoted Versus Actual Capacity The nominal capacity of a battery is quoted at the C/20 rate, i.e. the ampere hours delivered if discharged 100% over 20 hours The actual capacity drops exponentially as the discharge rate is increased Peukert’s Law can be used to estimate actual capacity at a given discharge rate 41
  42. 42. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Limitations Peukert’s Law t = H(C/IH)k H is the hour rating that the battery is specified against C is the rated capacity at that discharge rate, in A·h I is the discharge current, in A k is the Peukert constant, (varies between 1.1 and 1.3) t is the discharge time, in hours 42
  43. 43. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Limitations Peukert Calculation Rated battery capacity 130 amp-hours C rate for quoted capacity 20 Hours Discharge rate 75 amps Peukert exponent 1.2 Acceptable depth of discharge (DoD) 60 percent Amp-hours available at discharge rate 48 amp-hours Life at discharge rate to specified DoD 0.64 hours Percentage of rated capacity 37 % 43
  44. 44. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Limitations Operating Temperature Range Batteries are specified at 78O F (26O C) The safe operating range is about 15O to 35O C The optimum operating range is about 20O to 30O C Too low a temperature reduces capacity, increases DoD Too high a temperature decreases life, increases failure rate Batteries are like babies - don’t drop them, don’t let them get too hot or cold, feed and water them, and keep them clean 44
  45. 45. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Limitations The Weakest Link A 144 volt battery pack consists of twelve 12 volt batteries in series This is really seventy-two 2 volt cell in series Which ever cell discharges first determines the capacity of the pack – if you have one weak cell your pack capacity will be reduced Once a cell is fully discharged the other cells are forcing current through it - which can cause futher damage Cell matching must be maintained to prevent premature discharge 45
  46. 46. Wali Memon walimemon.comBatteries, Batteries, Batteries Battery Limitations Cell Matching Insist all batteries in a pack are from the same production batch and have not been sitting around in stock for too long Batteries should be kept at the same temperature  Difficult to do, especially with multiple battery boxes Cells within a battery should remain fairly matched if an equalizing charge is performed regularly Series (bulk) charging can cause batteries to get out of balance Charger per battery ensures all batteries are fully charged 46
  47. 47. Wali Memon walimemon.com Thank YouWali Memonwalimemon.com 47

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