EE512 Electric Vehicle
2015-11-25 13:56:44 0 举报AI智能生成
Electric Vehicle
作者其他创作
大纲/内容
EV infrasturcture基础设施
Infrastructure issues
availability of charging stations
Convenience of payment for charging
standardization of EV batteries and charging
regulation of clean and safe charging
support from training and promotion
impacts on power utilities
charging current levels
Normal charging current@15A, 6hrs
Medium charging current@30-60A, a few hrs
Fast charging current@150-400A, short time
Domestic and public charging
Domestic Charging
Houses with private garage uses indoor socket outlet
Car parks install outdoor socket outlet
Public charging station
Public fast charging stations
35kW, large current
have communication between charging module and EV battery monitor
7 wires include +, -, GND, pilot wire and 3-wired communication channel
Public Battery Swapping Stations
Move and Charge Zone
Charge the vehicle on road
The System is embedded on the surface of roadway
2 types
conductive
inductive
payment system
Charge for both parking and recharging separately
Charge for recharging only, with free parking
Charge for parking only, With free recharging
One-line charge for both parking and rechargging
Impact on Power System
Positively
the batteries can be charged at off-peak period so that the overall power demand can be levelled and the utilization can be improved
Negatively
The chargers are non-linear devices generate harmonic contamination污染
Harmomic Impact
harmonic currents and voltages can deteriorate conventional measure devices
Harmonic currents can damage capacitor banks
Harmoic current flows can affect neutral conductor(overload) and LG voltage
Causing excessive heat problems in transformer
Influence the protection devices from false alarm or tripping
Harmonic Compensation补偿
use new battery chargers with minimum harmonic contamination
In the system level, use filter
battery charging at peak period creats additional demand burden
Current Demand Impact
overload the system
affect the capital cost of power system
Increase running cost of power system
Current demand Coordination
Distributive Coordination
Centralized coordination
Auxillary Units
EV Auxilaries
Battery temp. sensor
Battery voltage sensor
Battery current sensor
Battery charging control
Lighting control
Temp. control
Propulsion controller
SOC, state of charge
Range predication
Speedometer&odometer
Text display
Barke pedal
Accelerator pedal
Control selection
Power-up switch
Accelerometer
Speed sensor
Motor temp. sensor
Convertor temp. sensor
Ambient
Battery Chargers
Controlled Voltage
Controlled Current
Controlled Voltage&Current
Temperature
Temperature rise speed dT/dt
Battery Management System
Air conditioner
Electric Power Steering
Regenerative Barking
Energy Source
Energy and Battery Capacity
Cut off Voltage: the point during the discharge of the battery, when it experience a sudden voltage drop
Coulometric capacity: The current capacity of the battery(AH)
Depth of Discharge: the percentage of discharge of battery, from fully charged(100%) to the cut off voltage(0%)
State of discharge: Ratio of present capacity over fully charge capacity
Life cycle: the number of charge and discharge cycles of a battery, usually quoted in relation of the DOD
Lead Acid Batteries
VRLA
Nickel Based Batteries
Ni-Cd
Ni-Zn
Ni-MH
Metal Air Batteries
Zn/Air
Al/Air
Sodium Batteries
Na/S
Na/NiCl2
Lithium Batteries
Li-Polymer
Li-Ion
Battery Technologies Comparison
Fuel Cells
Ultra Capacitors
Flywheels
Electric Vehicle Developments
What is an EV
Past, Present and Future of EV
Engineering Philosophy of EV
Historical Developments
Modern EV Developments
Electric Propulsion推进
EV considerations
three factors
driver expectation
vehicle constraint
energy source
Concept of EV Motors
Special considerations for EV motors
1. offer the maxium torque that 4 to 5 times of rated torque for acceleration
2. Achieve 4 to 5 times the base speed for cruising
3.Designedd according to the vehicle driving profiles and drivers' habits
4. High power density and good efficiency map
5. High controllability, high steady-state accuracy and good dynamic performance
6. Harsh operating conditions
compared with industrial motor
1. twice rated torque for overload operation
2. twice the base speed for constant-power operation
3. based on a typical working mode
4. Need a compromise ammong power density, efficiency and cost with the efficiency optimized at a rated operating point
5. only special purpose industrial motor need
6. generally located in fixed places
Key issues on system technology
Single or multiple motor technology
Fixed or multiple gear transmission
Gear or Gearless
System voltage
Integration
Classification of EV motors
Commutator
Self-excited
Series
Shunt
Separately-excited
Field-excited
PM excited
Cons
Not reliable
Need to change brush
Cannot pass high current
EMI
Limited power output(field weaking)
Commutatorless
Induction
Wound-rotor
Squirrel cage
Pros
No magnet, Low cost
High power
No brush
Cons
Non-peak torque at low speed
complicated control
Synchronous
Wound-rotor
PM rotor
Reluctance
PM burshless DC
PROS
Coil outside, easy cooling
No commutator, reliable
High power density
CONS
Dteact rotor angle
Complicated control
Magnet is expensive
Switched reluctancce
Pros
No magnet, cheap
No temperature problem
Reliable
Cons
Difficult to control
PM hybrid
PV power electronics
Switching Devices
Criteria
Ratings
Voltage rating is based on battery nominal V, max Vcharging, and max Vregeneration
Irate depends on motor peak power and number of power devices
Switching frequency, e.g. 20kHz
EMI limiation
Filter size
Power losses
Base/gate driverability
Dynamic characteristics
Ruggedness
Maturity and cost
Power Convertors
4-quadrant DC chopper
3-phase full-bridge voltage-fed inverter
Soft switching(compared with hard switching)
Switching loss almost ZERO
Overall efficiency possibly HIGHER
Heat-sinking requirement possibly LOWER
Hardware count MORE
Overall power density possibly HIGHER
EMI problem LOW
dv/dt Problem LOW
modulation scheme LIMITED
maturity DEVELOPING
Cost HIGHER
Electric Vehicle Systems
EV configurations
Fixed and Variable Gearings
Single and Multiple Motor Drives
In-Wheel Drives
EV Parameters
Electric Motors for EV
DC Motor Drives
AC Drives
Induction Motor Drives
Permanent Magnet Motor Drives
Switched Reluctance Motor Drives
Hybrid Electric Vehicles
HEV configurations
Series hybrid
Parallel hybrid
series-parallel hybrid
complex hybrid
Power Flow Control
Goals
Maximum fuel economy
Minimum emissions
minimum system cost
good driving performance
Key control stragegies for Power flow control
Optmal ICE operation point
Optimal ICE operation line
Optimal ICE operating region
Minimum ICE dynamics
Minimum ICE speed
Minimum ICE turn-on time
Proper battery capacity
Safety battery voltage
Relative distribution
Geographical policy
Example of HEV System Performancces
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