Mild Hybrid Cars: Combining Combustion and Electric Power

Mild hybrid cars represent an innovative blend of traditional internal combustion engines (ICE) and modern electric motors. This technology achieves higher efficiency and reduced emissions without depriving drivers of the performance they demand. In this article, we will delve into the mechanics of how mild hybrids utilize both engine types to enhance driving experience.

Range Extender Mechanism

One approach in the design of mild hybrid vehicles is the use of a range extender. In this configuration, the electric motor takes primary responsibility for powering the car, while the combustion engine engages in a secondary role. When the battery approaches depletion, the ICE kicks in to recharge it. This setup ensures that the vehicle retains its electric driving capability while maintaining a backup source of energy. The ICE becomes a generator, converting fuel into electrical energy to recharge the battery.

Shared Load Through Planetary Gears

An alternative method involves the direct collaboration of the electric motor and the combustion engine via a planetary gear system. Here, both power sources combine their efforts to drive the vehicle, often sharing the output load. This dual-source approach enables each component to operate within its optimal efficiency range. The electric motor excels in low-speed urban driving, while the ICE takes over for high-speed and extended cruising, thus enhancing overall fuel economy.

Internal Combustion Engine: A Power Plant

The internal combustion engine (ICE) functions as a power plant. It plays a vital role in converting the non-moving energy stored in fuel into usable power. This energy, known as power, is essentially the flow of energy and is inherently complex. Nevertheless, the core principle is that this energy must eventually be converted back into a stable, mobile form of energy, such as kinetic energy or potential energy. This concept aligns with the First Law of Thermodynamics, which states that energy cannot be created or destroyed but can only be converted from one form to another.

Battery Electric Vehicle (BEV) and Motor-Generator (MG)

A battery electric vehicle (BEV) operates on a different principle, where the power is primarily stored in the battery rather than generated by an engine. However, the motor-generator (MG) plays a crucial role in the BEV’s system. The MG is part of the transmission system and converts between mechanical and electrical power, rather than dealing with stable energy. Its advantage lies in its bidirectional power conversion capability, which is particularly beneficial for managing both power input and output dynamics.

Hybrid Electric Vehicle (HEV) and Its Complexities

A hybrid electric vehicle (HEV) integrates one or more motor-generators into its transmission system to provide a more sophisticated balance of power. The HEV allows the ICE to produce power at rates that better match the vehicle's needs, either under or over the optimum conditions. Surplus stable energy is stored in the battery during moments of over-production, while the battery supplements the ICE's output during under-production. This mechanism ensures that the ICE operates within its most efficient parameters, thereby enhancing the average efficiency of the vehicle without compromising its total power output.

The exact workings of the HEV's hybrid transmission can vary widely. Some systems may be relatively simple, while others incorporate intricate planetary gear systems and complex power management algorithms. Yet, the core objective remains the same: to improve overall efficiency and performance by optimizing the use of both ICE and electric power.

Understanding the mechanics of mild hybrid cars provides insights into the future of automotive technology. These vehicles promise a smoother transition from traditional to fully electric powertrains, offering drivers the best of both worlds: performance, fuel efficiency, and environmental responsibility.