A mild hybrid engine, also known as a power-assist hybrid or MHEV (Mild Hybrid Electric Vehicle), is a type of hybrid vehicle that incorporates an electric motor and a small battery into a conventional combustion engine setup. Unlike full hybrids or plug-in hybrids, mild hybrids cannot drive solely on electric power. Instead, they use the electric components to assist the internal combustion engine, primarily during acceleration and cruising, thereby improving fuel efficiency.

The key components of a mild hybrid system typically include:

• Electric Motor/Generator: A mild hybrid vehicle has an integrated starter-generator (ISG) or belt-driven starter-generator (BSG) that assists the engine. This motor is capable of starting the engine, providing additional power during acceleration, and recovering energy during braking.
• Battery Pack: Mild hybrids use a small battery pack, usually with a capacity ranging from 0.2 kWh to 0.5 kWh. This battery is designed to store energy captured during deceleration and braking, which is then used to power the electric motor during acceleration or to run ancillary systems when the engine is off.
• Engine Start-Stop Functionality: Mild hybrids often feature engine start-stop technology. The electric motor restarts the engine quickly and smoothly when needed, reducing unnecessary idling and improving fuel efficiency, especially in city driving conditions.
• Regenerative Braking: When the vehicle decelerates or brakes, the electric motor operates in reverse, acting as a generator to convert kinetic energy into electrical energy. This energy is then stored in the battery for later use, reducing the load on the engine and improving overall efficiency.

Benefits of Mild Hybrid Engines

• Improved Fuel Efficiency: By assisting the combustion engine during acceleration and utilizing regenerative braking, mild hybrids can achieve better fuel economy compared to conventional vehicles.
• Reduced Emissions: Mild hybrids produce fewer tailpipe emissions due to the optimized operation of the internal combustion engine and the use of electric power during certain driving conditions.
• Enhanced Performance: The electric motor can provide instant torque, improving the vehicle's responsiveness and acceleration.
• Cost-Effectiveness: Mild hybrid systems are generally less complex and more affordable than full hybrid or electric drivetrains, making them a practical choice for automakers looking to meet efficiency regulations without significant cost increases.

Mild hybrid engines represent a stepping stone towards more sustainable transportation solutions. By integrating electric power with conventional engines, automakers can deliver tangible improvements in fuel efficiency and emissions reduction without requiring drivers to switch to fully electric vehicles. As technology continues to evolve, mild hybrid systems are expected to play a significant role in the transition towards greener and more efficient mobility.