Hybrid electric vehicle
A hybrid electric vehicle is a type of hybrid vehicle that couples a conventional internal combustion engine with one or more electric engines into a combined propulsion system. The presence of the electric powertrain, which has inherently better energy conversion efficiency, is intended to achieve either better fuel economy or better acceleration performance than a conventional vehicle. There is a variety of HEV types and the degree to which each functions as an electric vehicle also varies. The most common form of HEV is hybrid electric passenger cars, although hybrid electric trucks, buses, motorboats, and aircraft also exist.
Modern HEVs use energy recovery technologies such as motor–generator units and regenerative braking to recycle the vehicle's kinetic energy to electric energy via an alternator, which is stored in a battery pack or a supercapacitor. Some varieties of HEV use an internal combustion engine to directly drive an electrical generator, which either recharges the vehicle's batteries or directly powers the electric traction motors; this combination is known as a range extender. Many HEVs reduce idle emissions by temporarily shutting down the combustion engine at idle and restarting it when needed; this is known as a start-stop system. A hybrid-electric system produces less tailpipe emissions than a comparably sized petrol engine vehicle since the hybrid's petrol engine usually has smaller displacement and thus lower fuel consumption than that of a conventional petrol-powered vehicle. If the engine is not used to drive the car directly, it can be geared to run at maximum efficiency, further improving fuel economy.
Ferdinand Porsche developed the Lohner–Porsche in 1901. But hybrid electric vehicles did not become widely available until the release of the Toyota Prius in Japan in 1997, followed by the Honda Insight in 1999. Initially, hybrid seemed unnecessary due to the low cost of petrol. Worldwide increases in the price of petroleum caused many automakers to release hybrids in the late 2000s; they are now perceived as a core segment of the automotive market of the future.
, over 17 million hybrid electric vehicles have been sold worldwide since their inception in 1997. Japan has the world's largest hybrid electric vehicle fleet with 7.5 million hybrids registered as of 2018. Japan also has the world's highest hybrid market penetration with hybrids representing 19.0% of all passenger cars on the road as of 2018, both figures excluding kei cars., the U.S. ranked second with cumulative sales of 5.8 million units since 1999, and, as of 2020, Europe listed third with 3.0 million cars delivered since 2000.
Global sales are led by the Toyota Motor Corporation with more than 15 million Lexus and Toyota hybrids sold as of 2020, followed by Honda Motor Co., Ltd. with cumulative global sales of more than 1.35 million hybrids as of 2014;, worldwide hybrid sales are led by the Toyota Prius liftback, with cumulative sales of 5 million units. The Prius nameplate had sold more than 6 million hybrids up to January 2017. Global Lexus hybrid sales achieved the 1 million unit milestone in March 2016., the conventional Prius is the all-time best-selling hybrid car in both Japan and the U.S., with sales of over 1.8 million in Japan and 1.75 million in the U.S.
Classification
Types of powertrain
Hybrid electric vehicles can be classified according to the way in which power is supplied to the drivetrain:- In parallel hybrids, the ICE and the electric motor are both connected to the mechanical transmission and can simultaneously transmit power to drive the wheels, usually through a conventional transmission. Honda's Integrated Motor Assist system as found in the Insight, Civic, Accord, as well as the GM Belted Alternator/Starter system found in the Chevrolet Malibu hybrids are examples of production parallel hybrids. The internal combustion engine of many parallel hybrids can also act as a generator for supplemental recharging., commercialized parallel hybrids use a full size combustion engine with a single, small electric motor and small battery pack as the electric motor is designed to supplement the main engine, not to be the sole source of motive power from launch. But after 2015 parallel hybrids with over 50 kW are available, enabling electric driving at moderate acceleration. Parallel hybrids are more efficient than comparable non-hybrid vehicles especially during urban stop-and-go conditions where the electric motor is permitted to contribute, and during highway operation.
- In series hybrids, only the electric motor drives the drivetrain, and a smaller ICE works as a generator to power the electric motor or to recharge the batteries. They also usually have a larger battery pack than parallel hybrids, making them more expensive. Once the batteries are low, the small combustion engine can generate power at its optimum settings at all times, making them more efficient in extensive city driving.
- Power-split hybrids have the benefits of a combination of series and parallel characteristics. As a result, they are more efficient overall, because series hybrids tend to be more efficient at lower speeds and parallel tend to be more efficient at high speeds; however, the cost of power-split hybrid is higher than a pure parallel. Examples of power-split hybrid powertrains include 2007 models of Ford, General Motors, Lexus, Nissan, and Toyota.
Type of hybridization
Plug-in hybrids (PHEVs)
A plug-in hybrid electric vehicle, also known as a plug-in hybrid, is a hybrid electric vehicle with rechargeable batteries that can be restored to full charge by connecting a plug to an external electric power source. A PHEV shares the characteristics of both a conventional hybrid electric vehicle, having an electric motor and an internal combustion engine; and of an all-electric vehicle, also having a plug to connect to the electrical grid. PHEVs have a much larger all-electric range as compared to conventional petrol-electric hybrids, and also eliminate the "range anxiety" associated with all-electric vehicles, because the combustion engine works as a backup when the batteries are depleted.Flex-fuel hybrid
In December 2018, Toyota do Brasil announced the development of the world's first commercial hybrid electric car with flex-fuel engine capable of running with electricity and ethanol fuel or petrol. The flexible fuel hybrid technology was developed in partnership with several Brazilian federal universities, and a prototype was tested for six months using a Toyota Prius as development mule. Toyota announced plans to start series production of a flex hybrid electric car for the Brazilian market in the second half of 2019.The twelfth generation of the Corolla line-up was launched in Brazil in September 2019, which included an Altis trim with the first version of a flex-fuel hybrid powered by a 1.8-litre Atkinson engine. By February 2020, sales of the Corolla Altis flex-fuel hybrid represented almost 25% of all Corolla sales in the country.
Energy Management Systems
To take advantage of the emission reduction potential of hybrid electric vehicles, appropriate design of their energy management systems to control the power flow between the engine and the battery is essential.In a conventional vehicle, there is no need for an energy management strategy: the driver decides the instant power delivery using the brake and accelerator pedals and, in manual transmission vehicles, decides which gear is engaged at any time. In a hybrid vehicle, on the other hand, there is an additional decision that must be taken due to its ability to recover energy during braking or driving downhill: how much power is delivered by each of the energy sources on-board of the vehicle. The recovered energy can be stored in the battery and deployed at a later time to assist the prime mover to provide tractive power. This is why all hybrid vehicles include an energy management controller, interposed between the driver and the component controllers. As mentioned, the aim of the energy management system is to determine the optimal power split between the on-board energy sources. The decision regarding what to consider optimal depends on the specific application: in most cases, the strategies tend to minimize the fuel consumption, but optimization objectives could also include the minimization of pollutant emissions, maximization of battery life or—in general—a compromise among all the above goals.
History
Early days
William H. Patton filed a patent application for a petrol-electric hybrid rail-car propulsion system in early 1889, and for a similar hybrid boat propulsion system in mid-1889. He went on to test and market the Patton Motor Car, a gas-electric hybrid system used to drive tram cars and small locomotives. A petrol engine drove a generator that served to charge a lead acid battery in parallel with the traction motors. A conventional series-parallel controller was used for the traction motors. A prototype was built in 1889, an experimental tram car was run in Pullman, Illinois, in 1891, and a production locomotive was sold to a street railway company in Cedar Falls, Iowa, in 1897.In 1896, the Armstrong Phaeton was developed by Harry E. Dey and built by the Armstrong Company of Bridgeport, CT for the Roger Mechanical Carriage Company. Though there were steam, electric, and internal combustion vehicles introduced in the early days, the Armstrong Phaeton was innovative with many firsts. Not only did it have a petrol powered 6.5-litre, two-cylinder engine, but also a dynamo flywheel connected to an onboard battery. The dynamo and regenerative braking were used to charge the battery. Its electric starter was used 16 years before Cadillac's. The dynamo also provided ignition spark and powered the electric lamps. The Phaeton also had the first semi-automatic transmission. The exhaust system was an integrated structural component of the vehicle. The Armstrong Phaeton's motor was too powerful; the torque damaged the carriage wheels repeatedly.
In 1900, while employed at Lohner Coach Factory, Ferdinand Porsche developed the Mixte, a 4WD series-hybrid version of "System Lohner–Porsche" electric carriage that previously appeared in 1900 Paris World Fair. George Fischer sold hybrid buses to England in 1901; Knight Neftal produced a racing hybrid in 1902. Image:Pieper-patent-fig1.gif|thumb|right|Figure 1 of Henri Pieper's 1905 Hybrid Vehicle Patent ApplicationIn 1905, Henri Pieper of Germany/Belgium introduced a hybrid vehicle with an electric motor/generator, batteries, and a small petrol engine. It used the electric motor to charge its batteries at cruise speed and used both motors to accelerate or climb a hill. The Pieper factory was taken over by Impéria, after Pieper died. The 1915 Dual Power, made by the Woods Motor Vehicle electric car maker, had a four-cylinder ICE and an electric motor. Below the electric motor alone drove the vehicle, drawing power from a battery pack, and above this speed the "main" engine cut in to take the car up to its top speed. About 600 were made up to 1918. The Woods hybrid was a commercial failure, proving to be too slow for its price, and too difficult to service. In England, the prototype Lanchester petrol-electric car was made in 1927. It was not a success, but the vehicle is on display in Thinktank, Birmingham Science Museum. The United States Army's 1928 Experimental Motorized Force tested a petrol-electric bus in a truck convoy.
In 1931, Erich Gaichen invented and drove from Altenburg to Berlin a 1/2 horsepower electric car containing features later incorporated into hybrid cars. Its maximum speed was, but it was licensed by the Motor Transport Office, taxed by the German Revenue Department and patented by the German Reichs-Patent Amt. The car battery was re-charged by the motor when the car went downhill. Additional power to charge the battery was provided by a cylinder of compressed air which was re-charged by small air pumps activated by vibrations of the chassis and the brakes and by igniting oxyhydrogen gas. No production beyond the prototype was reported.
During the Second World War, Ferdinand Porsche sought to use his firm's experience in hybrid drivetrain design for powering armoured fighting vehicles for Nazi Germany. A series of designs, starting with the VK 3001, the unsuccessful VK 4501 heavy tank prototype and concluding with the heaviest armoured fighting vehicle ever prototyped, the Panzerkampfwagen Maus of nearly 190 tonnes in weight, were just two examples of a number of planned Wehrmacht "weapons systems", crippled in their development by the then-substandard supplies of electrical-grade copper, required for the electric final drives on Porsche's armoured fighting vehicle powertrain designs.