Types of Hybrid Electric Vehicle and the Recent Trends in the HEV Market

Types of Hybrid Electric Vehicles and the Recent Trends in the HEV Market

With the increasing demand for environment-friendly and better fuel economy vehicles, automotive companies are focusing more on electric vehicles and hybrid electric vehicles. These vehicles are powered by a battery and/or internal combustion engines to improve vehicle performance, fuel economy, emissions, safety, and comfort.

Here, we will be discussing the hybrid electric vehicle (HEV) and its various types. The first hybrid car was built in the year 1899 by Ferdinand Porsche and the car used a gasoline engine to supply power to an electric motor. We already know HEV consists of an ICE (Internal Combustion Engine) along with an electric propulsion system (which makes use of electrical power to accelerate a propellant by various electrical or magnetic means).

HEVs can be classified based on various parameters such as architecture, degree of hybridization, energy storage system, etc. Here we will classify the HEV based on the Degree of Hybridisation. This depends on the amount of power supplied by the IC engine and the electric motor. Mathematically, the degree of hybridization is defined as the ratio of the power developed by the electric motor to the total power consumed by the vehicle.

Degree of hybridization = [Motor Power/(Motor Power + Engine Power)]*100

Based on the degree of hybridization, the HEV is classified into three different types.

These include:

• Micro HEV
• Mild HEV
• Pure HEV
  

MICRO HEV

A micro-hybrid vehicle uses a "start-stop system". The Start-Stop system is based on the simple principle of not burning the fuel when it is not required. While driving, the system automatically detects instances when the vehicle is idle & stops the engine thereby, conserving fuel. Thus it helps in attaining better fuel efficiency & reducing running costs. Here regenerative braking technology helps to stop a combustion machine when the vehicle pulls to a stop, and to restart it when the driver accelerates. Energy stored in an auxiliary battery is used to quickly start a vehicle at the traffic signal. It is the lowest level of vehicle hybridisation. In India, a common example of a micro-hybrid is the Mahindra Scorpio. Here is how the car actually functions in such a scenario:

The global micro-hybrid vehicles market can be segmented on the basis of battery type into lead acid batteries, lithium-ion batteries, and others. Based on battery capacity the global market can be segregated into 12-V Micro-Hybrid, 48-V Micro Hybrid, and others. It can be further classified geographically into North America, Europe, Asia Pacific, South America and the Middle East, and Africa. Some of the major players operating in the global micro-hybrid vehicles market include Audi AG, General Motors Company, BMW AG, Toyota Motor Corporation, Daimler AG, Fuji Motor Corp, Hyundai Motor Company, Fiat Automobiles S.p.A., Jaguar Land Rover, Nissan, Mahindra & Mahindra, Porsche Ag, and Mazda Motor Corporation among others.

MILD HEV

Mild Hybrids/ power-assist hybrids/battery-assisted hybrid vehicles have IC engines generally equipped with a motor or generator in a parallel hybrid configuration (here IC engine and electric motor are configured in parallel and more than one conversion device delivers propulsion power to the wheels) and allows the engine to be turned off whenever the car is coasting, braking, or has to be stopped but restarts quickly. A mild hybrid uses a smaller battery and a motor-generator that can both create electricity and help boost the gas engine’s output.

It employs a technique called regenerative braking (regenerative braking is the conversion of the vehicle's kinetic energy into chemical energy stored in the battery, where it can be used later to drive the vehicle) for charging the battery. Many automakers have started using 48V mild hybrids as a standard feature in their vehicle models. With the increasing production of 48V and above voltage mild hybrid models from automakers, the growth rate of mild hybrid vehicles in the global market is likely to grow positively during the forecast period. Although, these vehicles generally cost less but provide less fuel economy.

Toyota sold a mild hybrid version of the luxurious Toyota Crown in 2002 only for the Japanese domestic market. MINI and BMW have start and stop, and some with regenerative braking, in all of their vehicles sold in Europe that run on 4-cylinder engines with manual transmissions. Citroen proposes a stop and starts system on its C2 and C3 models. The CONCEPT-car C5 Airscape has an improved version of that, adding regenerative braking and traction assistance functionalities, and ultracapacitors for energy buffering. In 2004, VW brought two mild hybrid concept cars to Shanghai for the Challenge Bibendum. Suzuki has also announced the Suzuki Baleno with integrated SHVS technology on a new car platform.

FULL HEV

A full or Strong hybrid, is a vehicle that can run either only on a combustion engine or only on an electric motor or a combination of both. A large, high-capacity battery pack is needed for battery-only operation. Larger batteries and more powerful electric motors can power the vehicle for short distances and at low speeds. These vehicles cost more than mild hybrids but provide better fuel economy benefits. These vehicles have a split power path allowing greater flexibility in the drivetrain by interconverting mechanical and electrical power, at some cost in complexity. It has improved fuel consumption and reduced emissions. The arrangement of its electric motor, engine, and battery system is such that the vehicle can drive using electricity at low speeds.

If more power is needed, the engine kicks in and allows the vehicle to operate with twice as much power. The vehicle's accessories, such as the a/c, windows, and radio are all powered using the battery. This system allows for more fuel consumption under certain circumstances. Ford's hybrid system, Toyota's Hybrid Synergy Drive and General Motors/Chrysler's Two-Mode Hybrid technologies are full hybrid systems.

Differences Between the Various Types of HEV