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Introduction to Electric and Hybrid Vehicle - Coggle Diagram
Introduction to Electric and Hybrid Vehicle
Electric Vehicle (EV)
• An electric vehicle (EV) is a vehicle that uses one or more electric motors or traction motors for propulsion
• EVs usually refer to Battery electric vehicles (BEVs) or Hybrid electric vehicles (HEVs) which still use liquid fuels in conjunction with electricity
• Battery electric vehicles (BEVs) and Hybrid electric vehicles (HEVs) use electricity to improve vehicle efficiency
Battery Electric Vehicle (BEV)
• May be powered through a collector system by electricity from off-vehicle sources, or may be self-contained with a battery, solar panels or an electric generator to convert fuel to electricity
• Mainly composed of motor drive system, vehicle energy system, auxiliary system, etc
Hybrid Electric Vehicle (HEV)
• HEV has at least two sources of power for propulsion
Internal Combustion Engine (ICE)
Electric motor
• Can perform at least one of the following functions:
Engine idle stop-start
Electric torque assistance (fill and boost)
Energy recuperation (regenerative braking)
Electric driving
Battery charging (during driving)
Battery charging (from the grid)
Features of HEVs
Engine idle stop/start
Electric torque assistance (fill and boost)
Energy recuperation (regenerative braking)
Electric driving
Battery charging (during driving & from the grid)
Electrification Architecture
Key Components in HEV
Battery
• Function: Stores and supplies electrical energy to power the EV/Hybrid.
• Types:
Lithium-ion (Li-ion): Most common due to high energy density and longevity.
Lithium Iron Phosphate: Commonly used electric vehicle
Nickel-Metal Hydride (NiMH): Used in hybrid vehicles
• Key Considerations:
Capacity (kWh): Determines range.
Voltage: Impacts power output and efficiency.
Charging time: Fast charging vs. slow charging.
Lifespan: Number of charge cycles before degradation.
Thermal management: Prevents overheating and improves longevity.
Motor
• Function: Converts electrical energy into mechanical energy to drive the wheels.
• Types:
Permanent Magnet Synchronous Motor (PMSM): High efficiency, commonly used in EVs.
Induction Motor: No permanent magnets, used in Tesla Model S.
Switched Reluctance Motor (SRM): Simple and rugged but less common.
• Efficiency & Performance:
High efficiency (~90-95%).
Instant torque delivery.
Regenerative braking to recover energy.
Inverter
• Function: Converts DC power from the battery into AC power for the electric motor.
• Key Features:
Controls motor speed and torque.
Enhances energy efficiency by optimizing power conversion.
Enables regenerative braking by converting AC power from the motor back to DC power for the battery.
Battery Management Controller
• Function: Monitors and regulates battery performance to ensure safety and efficiency.
• Key Roles:
Voltage and temperature regulation to prevent overheating and overcharging.
Overcharge and discharge protection to extend battery lifespan.
Balancing individual cell performance for uniform aging and efficiency.
Communication with the vehicle’s control unit for optimal energy usage.
Fault detection and diagnostics for early issue identification.
Control Unit
• Function: Regulates and controls the operation of the electric motor.
• Key Aspects:
Converts driver input (accelerator pedal position) into motor torque control.
Monitors and optimizes motor performance for efficiency and power delivery.
Coordinates with the inverter to ensure smooth acceleration and deceleration.
Manages regenerative braking to recover energy.
Protects against motor overheating and electrical faults.
Charging Unit
•Function: Manages the charging of the EV battery from external sources.
•Types:
Level 1 (120V AC): Slow charging using standard household outlets.
Level 2 (240V AC): Faster charging with dedicated EV chargers.
Level 3 (DC Fast Charging): High-power charging stations reducing charge time to ~30 minutes.
•Considerations:
Charging infrastructure availability.
Onboard chargers vs. external DC fast chargers.
Charging protocols (CCS, CHAdeMO, Tesla Supercharger, etc.).
HEV Configuration
Parallel
Parallel hybrid with one clutch
• Characteristics:
• Layout for mild hybrid
• ICE and motor are independent of each other
• Power flows are parallel and can be added together to get total drive power
• Engine will be running all the time when the vehicle in moving (same speed as the motor)
Positive +
• Conventional drivetrain can be maintained
• Fewer adaptations are needed when converting a conversion system
Negative -
• Pure electric driving is not possible
• Reduce the amount of regeneration as motor be coupled together with engine
Parallel hybrid with two clutch
• Characteristics:
• Extension of the parallel hybrid with one clutch
• Layout for strong hybrid
• Allow for the engine to be disconnected > Pure electric
Positive +
• Increase regenerative braking as engine will be decoupled during deceleration
• Allow engine to start and stop when additional torque is required
Negative -
• Increase the length of the transmission due to addition of clutch
Parallel hybrid with double-clutch transmission
• Characteristics:
• Motor is connected to a sub unit of the transmission instead of engine crankshaft
• Pure electric driving is possible by opening the appropriate transmission clutch
• Allow for both engine and motor to drive in parallel
Positive +
• Overcome the disadvantage of parallel hybrid with double clutch layout
• The gear ratio between engine and transmission can be controlled, allowing designers greater freedom
Negative -
• Sophisticated electronic control, sensor and actuators are necessary
Axle-split parallel hybrid
• Characteristics:
• Motor and engine are completely separated; They are on each axle
• A semi-automatic transmission with start-stop system is needed • Suitable for strong hybrid
• Additional generator is fitted to charge the high-voltage battery (in some cases)
Positive +
• Effectively deliver all-wheel drive when the battery is charged
Series
Series hybrid
• Characteristics:
• Always the strong hybrid (fulfils the requirement)
• A conventional transmission is not needed
• Engine can be optimized to only operate in a set of range of rpm
Positive +
• Starting and stopping the engine has no effect on the vehicle drive, therefore the control systems are less sophisticated
• Packaging advantage – There is no mechanical connection between the engine and the wheel.
• Having a small engine in a pure electric car allows for extension of range and reduces range anxiety
Negative -
• More energy conversion is needed:
• If driven without storage in battery, energy is converted twice Mechanical > Electrical > Mechanical
• If energy is stored in battery, energy is converted three times Mechanical > Electrical > Chemical
Series-parallel hybrid
• Characteristics:
• Extension of series hybrid layout with addition of clutch
• Clutch mechanically connects generator and motor
Positive +
• Eliminates double energy conversion except at certain speed ranges
Negative -
• Loses the packaging advantage of series hybrid due to addition of components
• Requires 2 electric units (generator & motor) compared to parallel hybrid.
Power Split
• Characteristics:
• Combines the advantages of series and parallel layouts but at the expenses of increased mechanical complexity.
• Proportion of the engine power is converted to electric power by alternator and remaining to drive the wheel using motor.
• Electrical path can be used at low power requirement and the mechanical path for higher power requirement
• Is a strong hybrid system
Positive +
• Combine electrical and mechanical power to drive the wheel
• Engine speed can be adjusted independently of the vehicle speed
Negative -
• Increased mechanical complexity
