Hybrid Vehicle
Alternative Energy for Vehicles
Kasetsart University
Engine Losses Fuel Energy 100%
Pumping 4%
Compression Work 5% Exhaust Heat 26%
Cooling Heat 25%
Parasitic 4%
Friction 3% (Water Pump, Alternator)
Engine Output 31%
Engine Operating Points
• For typical ICE cars, engine’s operating points vary based on the driver’s commands.
Energy Losses (ICE Vehicles)
Accessories 3%
(Air Conditioning, Power Steering Pump)
Driving Energy 26%
Engine Output 31%
Drivetrain Friction 2%
Road Resistance and Waste
Aerodynamic
Resistance 7%
Braking 6%
Vehicle Inertia 2% Idling 3%
Driving Energy 26%
Rolling Resistance 8%
Concept of Hybrid Vehicles
• Hybrid electric vehicles are powered by an internal combustion engine and one
or more electric motors, which uses energy stored in batteries.
Parallel/Series Hybrid
• By sharing the load between the engine and the electric motor, there are many
possible energy saving techniques.
Idle start stop
• In idle start-stop system, when the car comes to a stop, the engine stops the spark plug and
fuel. When the driver lifts his foot off the brake, or presses the clutch, the engine
automatically fires up. A car with start-stop system must have a strong starter motor so that it
can quickly ramp up engine rpm. A good battery with enough amperes is also required, in
order to satisfy the car’s entire electrical needs.
Regenerative Braking
• Regenerative braking uses the electric motor to reverse its role and act as a generator,
converting some of the vehicle's kinetic energy back into electrical energy. The electricity
generated is then sent to the battery pack, where it's stored for later use.
• Better Fuel Economy
• Reduce Brake Wear
• Enhance Driving Experience
Power Assist
• Power assist mode refers to a mode of operation where the electric motor provides additional
power to assist the internal combustion engine. This mode allows for better performance and
responsiveness during certain driving conditions.
• The vehicle can operate the internal combustion engine in its more efficient RPM range.
Accessory Electrification
• An electric water pump can operate independently of engine RPM,
providing optimal cooling irrespective of engine speed.
• Electric A/C compressors can operate independently of engine RPM and
can operate in conditions where the engine is turned off.
• Electric power steering (EPS) systems consume energy only when
steering assistance is needed, unlike hydraulic systems that constantly
circulate fluid even when no steering input is provided.
• Electrically driven systems have advantages in terms of efficiency and
functionality and reduce engine parasitic losses.
Atkinson (Miller) Cycle Engine
• Atkinson cycle provides a longer expansion stroke compared to the compression stroke in
the engine's cycle. This differentiation optimizes the engine's thermodynamic efficiency.
However, engine maximum power output is reduced.
• The intake valves remain open for a brief period during the
compression stroke, letting a portion of the air-fuel mixture
escape back into the intake manifold, effectively simulating a
shorter compression stroke.
Degree of Hybridization
• Internal Combustion
• Micro Hybrid
• Mild Hybrid
• Full Hybrid
• Plug-in Hybrid
• Range Extender Electric
• Battery Electric
• Fuel Cell Electric
Hybrid System Component (Toyota)
Hybrid Mode Transition (Honda)
Hybrid Technology
• While hybrids are a step towards cleaner transportation, they are still reliant on fossil fuels to
some extent. Hybrid vehicles are often considered a transitional technology on the path to
fully electric vehicles (EVs).
• Improved fuel economy
• Emission Reduction
• Consumer Familiarity
• Infrastructure Development
• Range Anxiety Mitigation
