This presentation deals with the basic architecture of electric vehicle and mathematical modelling of battery systems and its charging scenarios.

1. Electrical
Vehicle(EV)
Modelling for
Smart Grid
Prepared By:
Srikanth Reddy K
Renewable Energy-NIT Jaipur
(srikanthkonda.eee@gmail.com)
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2. Vehicle Architectures
 HEV
 EV
 PHEV
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3. General Nature and Engg. Fields of HEV[1]
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4. System level diagram of HEV[1]
The HEV’s can be of two types:
1.HEV with battery systems
2.HEV without battery systems
In HEV the ICE will drive the electric generator which in turn supplies the electric motor. The advantage is that
the ICE can be run at an optimal speed to achieve the best possible efficiency.
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5. HEV Architectures[1]
Series HEV Parallel HEV
Series-Parallel
HEV
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6. System level diagram of EV[1]
WHY EV?
High overall efficiency: The ICE itself has an efficiency of 30-37% and by the time the power arrives at wheels it
will become 5-10% where as in EV the efficiency of motor , inverter& battery are above 90% individually, by the
time power arrives at wheels it would be in the order of 70%.
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7. System level architecture of PHEV[1]
This allows the battery to be charged from external utility grid and also discharge back to it.
Since the battery is charged from utility ,vehicle can have a larger battery than that of HEV which is fuel economic.
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8. Marketed models of HEV’s[1]
Toyota Pirus HEV Honda Civic Hybrid
Ford escape
hybrid
The chrisler
Aspen Hybrid
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9. Battery Equivalent electric circuit models
 There are many electrical equivalent models that were developed for different types
of batteries, some of them were are discussed here:
 This is the simplest model for battery in which a single voltage source and an
internal resistance is considered.
 The drawback is that the internal resistance is different for charging and
discharging conditions. Therefore the model is modified.
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10. Larmine and lowry model equations[1]
1)Terminal voltage is given by
𝑽𝒕 = 𝑽𝒐𝒄 − 𝑰𝒃 𝑹𝒊𝒏𝒕
Where,
𝑉𝑡 = terminal voltage
𝑉𝑜𝑐 =open circuit voltage which is a function of SOC and temperature
𝐼𝑏 = battery discharge current
𝑅𝑖𝑛𝑡 =Internal resistance
2)The open circuit voltage is given by
𝑽𝒐𝒄 = 𝑬𝒐 +
𝑹 𝑻
𝑭
𝒍𝒏
𝑺𝑶𝑪
𝟏 − 𝑺𝑶𝑪
Where,
𝐸𝑜 = standard (nominal voltage) potential of battery
𝑅 = Ideal gas constant
T= absolute temperature
F = Faraday constant
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11. Modified battery models[1]:
 This model includes separate charge and discharge resistances and two diodes associated with them
such that either of them comes into picture in charging and discharging conditions.
 For a required amount of power(Preq) the battery current is given by:
𝑰𝒃 =
𝑽𝒐𝒄 − (𝑽𝒐𝒄 𝟐− 𝟒(𝑹 × 𝑷𝒓𝒆𝒒))
𝟐𝑹
Where,
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12. Models with capacitance[1]
 Again a capacitance is added to indicate the diffusion of electrolyte and its resultant transients
RC model
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13. Factors effecting Battery performance
1. Discharge Rate/C-rate:
 The C rate is given by discharge current(A) divided by capacity of the battery(Ah).
 For example if a 100Ah battery is discharged at 10A then Cr=0.1,if discharged at 5A then Cr=0.05.
 The discharge rate effects the battery life(Number of cycles of use),the available energy for discharge and
voltage.
 The lower the discharge rate, more the available energy is. This is called as Rate Capacity Effect and the
estimation of the effect can be calculated by Peukert’s Law[1].
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14. Peukert’s law
 The peukert’s equation relates the available capacity of the battery to the discharge rate for a constant discharge
current.
 Since the discharge current is variable in most of the cases the peukert’s method is modified to adapt it to
variable discharge current.
 Ibatt*t = C
 If capacity(C1) at any discharge rate(Ibatt1) is given then the capacity(C2) at any discharge rate(Ibatt2) can be
found by the equation given by:
 𝑪𝟐 = 𝑪𝟏(𝑰𝒃𝒂𝒕𝒕𝟏/𝑰𝒃𝒂𝒕𝒕𝟐) 𝒏−𝟏
 If the discharge current is varying consider constant current for a particular time interval(∆𝑡) then change in
SOC is given by:
 ∆𝑺𝑶𝑪 =
𝑰𝒃𝒂𝒕𝒌
𝑪𝟏
𝑰𝒃𝒂𝒕𝒕𝒌
𝑰𝒃𝒂𝒕𝒕𝟏
𝒏−𝟏
∆𝒕
 𝑺𝑶𝑪 𝒕𝒌 = 𝑺𝑶𝑪(𝒕 𝒌−𝟏) ± ∆𝑺𝑶𝑪
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15. 2. Temperature:
 Temperature effects the batteries chemical reactions and there by the energy available in the battery.
 The battery’s available energy is lower at lower temperatures due to high portion of the activation
polarisation losses and available capacity will increase as the temperature increases however the
battery life may degrade under high temperatures.
 The empirical relation of the temperature effect for the given battery can be estimated by using the
equation derived from curve fitting method.
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16. SOC determination:
Coulomb counting method[2]:
Where,
θ= SOC remaining
θ o=Initial SOC
δ (I)=Current loss coefficient (typically 0.9 to 1)
Ibatt =Battery discharge current
CN= Nominal battery capacity
There are many other models/ Algorithms proposed to estimate the SOC[2],[3],[4].
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17. Battery charging control
The charging control is very important as per the efficiency and life of battery is concerned.
Some of the battery charging control methods are given as follows:
1.Passive charging: In this method the battery is directly connected to DC link. It is the worst method
and may cause serious damage to battery with the current spikes and voltage fluctuations.
2.Constant Voltage(CV) charging: In this the charge voltage is maintained slightly above the battery
voltage irrespective of SOC. This suffers from disadvantage of Current spike when battery charged at
low SOC.
3.Constant Current(CC) charging: In this the charging current is kept constant. The advantage is that
the charging current remains constant and below the safe limit of battery which will improve battery
performance and life. Disadvantage is that towards the end of charge deposits may form at the
electrodes and cause to shorting of battery.
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18. CC-CV charging control method:
 CC-CV charging method is the widely used method of charging.
 This method eliminates the problems such as current spike and short circuiting associated with CV
and CC methods respectively.
 Compared to CC charging the charging time as well as is more.
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19. Pulsed charging method:
 It is the most advance and fast charging method.
 The charging current is applied in pulses. So this is often called as PWM charging.
 When the SOC is low the pulse duration is high.
 As the SOC tends towards 100% the pulse width reduces and becomes zero at 100% SOC.
 This method has an advantage of charge normalization during the rest/relaxation period between two pulses
which improves the efficiency(by reducing concentration polarization losses) and life of battery.
[3]
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20. Regenerative charging
 In this we recover kinetic energy at time of breaking
 For this the torque is reversed thus reversing the power. It is done by revering the
voltage of drive.
 Recovery power depend on the how and where you drive.
Factors to be taken care of :
 Safety
 Performance
 Limitations
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21. V/F and Voltage control of Induction drives
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22. V2G
MODELING
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24. Requirements for V2G
 Storage element
 Semiconductor devices
 Inverter
 Chopper
 Control circuitry
 Communication system
 Internal
 External
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25. One type of Circuitry
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26. Control strategy of V2G[1]
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27. Applicable standard for V2G
 IEEE for Power and Energy
 P2030 for smart grid infrastructure
 P1547 physical and electrical interconnection b/w utility and distribution
 Society of Automotive and Engineers(SAE)
 J2293 communications b/w PEV and EV supply equipment for DC energy
 J1772 electrical connection b/w PEV and EV supply equipment
 J2847 communications for PEV interactions
 J2836 use cases for PEV interactions
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28.  Underwriters Laboratories (UL)
 2202 Electrical vehicle charging system
 2231-1and-2 Personal protection system for EV supply system
 2251 Plugs, Receptacles and couplers for EV
 2580 batteries for use in EV
 458A power converters/Inverters for Electric Land Vehicle
 2594 EV supply equipment
Applicable standard for V2G (Cntd.)
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30. References
1. Hybrid Electric Vehicles: Chris Mi, Abul Masrur, Weily publications.
2. http://www.teslamotors.com/blog/magic-tesla-roadster-regenerative-braking
3. Design of Duty-Varied Voltage Pulse Charger for Improving Li-Ion Battery-Charging Response, Liang-Rui
Chen, Member, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 56, NO. 2, FEBRUARY
2009.
4. A critical review of using the Peukert equation for determining the remaining capacity of lead-acid and
lithium-ion batteries Dennis Doerffel , Suleiman Abu Sharkh, science direct.
5. A New Online State-of-Charge Estimation and Monitoring System for Sealed Lead–Acid Batteries in
Telecommunication Power Supplies Koray Kutluay, Yigit Çadırcı, Yakup S. Özkazanç, Member, IEEE, and
Isik Çadırcı, Member, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 52, NO. 5,
OCTOBER 2005.
6. State-of-Charge Determination From EMF Voltage Estimation: Using Impedance, Terminal Voltage, and
Current for Lead-Acid and Lithium-Ion Batteries Martin Coleman, Chi Kwan Lee, Chunbo Zhu, and William
Gerard Hurley, Fellow, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL. 54, NO. 5,
OCTOBER 2007.
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31. THANK YOU
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