Mild hybrid

Mild hybrids are essentially conventional fossil-fuel vehicles equipped with a large electric machine (one motor/generator in a parallel configuration) allowing the engine to be turned off whenever the car is coasting, braking, or stopped, yet restart quickly. Mild hybrids may employ regenerative brake and some level of power assist to the ICE, but mild hybrids do not have an exclusive electric-only mode of propulsion.^[1][2]

Since they do not have hybrid powertrains and relatively small electric motors (~20 kW or less) that are unable to propel the vehicle, mild hybrids also don't require the same level of battery power and do not achieve the same levels of fuel economy improvement as compared to full hybrid models. One example is the 2005-07 Chevrolet Silverado, Parallel Hybrid Truck (PHT) a full-size pickup truck with a single 7 kW 3-phase electric motor mounted in the bell-housing between the engine and a conventional 4L60E transmission. Chevrolet was able to get a 10% improvement on the Silverado's city fuel efficiency by shutting down and restarting the engine on demand, and the reduction of parasitic accessory loads. However the PHT had no power assist features or all-electric EV capability, and very limited regenerative braking features.^{[citation needed]}

Compared to a full hybrid vehicle, however, mild hybrids may provide some of the benefits of the application of hybrid technologies, with less of the cost–weight penalty that is incurred by installing a full hybrid series-parallel drivetrain. Fuel savings would generally be lower than expected with use of a full hybrid design, as the design does not facilitate high levels of regenerative braking or necessarily promote the use of smaller, lighter, more efficient internal combustion engines. BMW, however, succeeded in combining regenerative braking with the "start-stop system" which is not a mild hybrid system as do not assist the combustion engine^[3] in their current 1-series model.

General Motors mild hybrids including the Parallel Hybrid Truck (PHT) and numerous cars and SUVs equipped with the BAS Hybrid system, often use a 36–48 volt systems to supply the power needed for the startup motor, as well as a source of power to compensate for the increasing number of electronic accessories on modern vehicles.^[4] GM's Belt alternator starter (BAS) mild hybrid system uses a belt drive to start the internal combustion engine (ICE) through its motor–generator unit (MGU), then once started the engine drives the 14.5 kW motor-generator to charge the batteries. The BAS hybrid system also utilizes regenerative braking to replenish the system's 36 V battery and can provide moderate levels of power assist. According to the EPA, a 2009 Saturn Vue Greenline equipped with the BAS Hybrid system delivers a 27% improvement in combined fuel economy over the non-hybrid version (FWD 4cyl).^[5]

Makes and models

• Chevrolet Silverado Hybrid (2005–2007)^[6]
• Saturn Vue Green Line (BAS Hybrid, 2007–2009)
• Saturn Aura Green Line (BAS Hybrid model 2007-2009)
• Chevrolet Malibu (BAS Hybrid model 2008-2010)
• Mercedes-Benz S400 BlueHybrid^[7]
• BMW ActiveHybrid 7^[7]
• Peugeot 308 e-HDi (from 2011, referred to by the manufacturer as micro-hybrid)

During the 2008 Olympic Games in Beijng in August, Chinese automobile manufacturer Chang'an Motors supplied a number of hybrid-drive cars as taxis for the athletes and spectators. The power electronics for the "mild hybrid" drive was supplied by Infineon.^[8]

Toyota sold a mild hybrid version of the luxurious Toyota Crown beginning in 2002 only for the Japanese domestic market.^[9] Fuel economy was increased when compared with the standard 3.0 V6 petrol unit. Toyota now sells a full hybrid with an electric motor for the new 2008 Toyota Crown.

MINI and BMW have start and stop systems which are not hybrid technology in all of their vehicles sold in Europe running 4 cylinder engines with manual transmissions.

The Smart Fortwo microhybrid sold in Europe, although is not a mild hybrid.

Citroën proposes a stop and start system on its C2 and C3 models.^[10] The concept-car C5 Airscape has an improved version of that, adding regenerative braking and traction assistance functionalities, and ultracapacitors for energy buffering.^[11]

VW brought two mild hybrid concept cars to Shanghai for the Challenge Bibendum.^[12]

See also

• Micro HEV

References

1. ^ http://www.idae.es/index.php/mod.documentos/mem.descarga?file=/documentos_EN_Presentation_of_MOVELE_Project_(Zaragoza_March_2009)_556ea4d8.pdf
2. ^ http://green.autoblog.com/2009/04/30/greenlings-what-is-a-mild-hybrid/
3. ^ BMW EfficientDynamics - Introduction - BMW AG
4. ^ MIT/Industry Consortium on Advanced Automotive Electrical/Electronic Components and Systems
5. ^ http://www.fueleconomy.gov/feg/sbs.htm
6. ^ List of Hybrid Cars
7. ^ ^{a b} Sam Abuelsamid (200-04-03). "What is a mild hybrid?". AutoblogGreen. http://green.autoblog.com/2009/04/30/greenlings-what-is-a-mild-hybrid/. Retrieved 2010-03-22. 
8. ^ "Chinese hybrid car to use Infineon electronics" in EE Times. Retrieved July 22, 2008
9. ^ http://www.marklines.com/en/amreport/rep128_200212.jsp
10. ^ CITROEN - Stop and Start
11. ^ Citroën.com
12. ^ Green Car Congress: VW Brings Diesel Mild-Hybrid Concept to Shanghai