Valeo claims that its Hybrid4All system generates fuel economy benefits of up to 15%

Valeo claims that its Hybrid4All system generates fuel economy benefits of up to 15%

Moving to a 48V architecture in hybrid and electric vehicles offers plenty of promise. It provides about four times the energy recuperation - from regenerative braking - than is available on the traditional 12V system. Calum MacRae takes a closer look at supplier plans and forecasts for 48V.

At the 2013 IAA, a number of prominent suppliers demonstrated their 48V wares. For example, Bosch demonstrated its "Boost Recuperation System" a 48V mild hybrid system featuring an electric motor, with a 48V 0.25kWh lithium-ion battery and DC/DC converter. BRS offers four functions: coasting; start-stop; recuperation and torque boost. The system potentially reduces CO2 emissions by 15% and offers up to 10kW of additional power, a quadrupling of the recuperation and drive performance available with a 12V system.

The supplier Continental demonstrated its 48V EcoDrive innovation vehicle a mild-hybrid that draws on the advanced brake energy regeneration that 48V allows to bring about a half-way house hybrid between existing 12V stop-start or micro hybrids to the 200-400V full hybrids. The concept has a 48V BSG replacing the alternator, a 48V lithium-ion battery and a DC/DC converter as a link to the 12V power supply. The 48V system allows the engine to be switched off more frequently than in 12V micro hybrids and also earlier, to facilitate coasting. What's more, systems such as HVAC, power steering, infotainment etc. can continue to be powered by the 48V systems even when the powertrain is in extended shutdown. According to Jose Avila, head of Continental's powertrain division, "The 48V solution is getting great attention in our industry. The first orders have been received, and production will begin in 2016." At the 2015 CES in Las Vegas the company demonstrated how its eHorizon system, a cloud based dynamic navigation system, could be allied with its 48 Volt Eco Drive to provide the vehicle with the most efficient operating strategies during the drive by using eHorizon to connect with the powertrain controller and instigate the optimal use of sailing, coasting and energy regeneration functions.

Coasting alone has the potential to deliver a 10% fuel economy benefit according to Hella. As hoped by the German OEMs, Hella has the opportunity to showcase its developments with 48V components and systems and has demonstrated its DC/DC converter - a crucial component for controlling energy losses - for the 12V and 48V systems.

Johnson Controls, the world's leading supplier of automotive batteries through brands such as Optima and Varta, showed its first-generation 48V lithium-ion micro hybrid battery at the 2013 IAA. JCI's system involves a 12V starter battery and a 48V lithium-ion battery that enables optimization of energy generation and consumption. According to JCI the system contributes to fuel economy saving of up to 15% and that the system will cost hundreds of dollars as opposed to the thousands of a full-hybrid or tens of thousands of an EV battery.

Acknowledging the future diverse hybrid market - mild, full, PHEVs - Getrag has designed a one-size- fits-all transmission, the 7HDT300, which is based on the 7DCT300. Among the hybrid transmission's additional features are an integrated electric motor with different power levels (i.e. mild 48V, 21kW and PHEV >360V; >110kW) and an intermediate gear set. The transmission allows for several modes including: pure electric; extended sailing; recuperation; boosting; generator mode/load-shift; charge@standstill. Getrag claims that its integrated 48V mild hybrid solution is superior to belt solutions due to it being able to provide more continuous power (13kW versus 2.5-3.5kW) for extended electric driving and more maximum power (21kW versus 12-14kW). All told, Getrag claims a 19-22% fuel economy benefit on the NEDC versus the belt hybrid's 10-12% on NEDC. What's more, changing the stator windings and power connectors means that the 7HDT300 is scaleable as a transmission for PHEVs with 360V.

At the 2014 Paris show, Valeo demonstrated its Hybrid4All 48V architecture based around a compact motor-generator. Valeo claims that the Hybrid4All system generates fuel economy benefits of up to 15%. The system provides up to 15kW of power, delivering instant torque at start up and some compensation for the power loss smaller engines can suffer at start-up, and thus delivering more fuel efficient driving. The system integrates stop-start and regenerative braking and a pure electric drive mode is available at low-speeds. Valeo estimates that the 48V mild hybrid is half as expensive as a full hybrid.

Meanwhile Japanese supplier Denso disclosed at a University of Michigan conference in June 2014 that 48V capable Integrated Starter Generators and batteries were under development for its 48V belt ISG system.

In September 2014, the UK-based technology consultancy Ricardo unveiled its ADEPT 48V hybrid prototype vehicle. Based on a Ford Focus Estate, the ADEPT prototype incorporates a 48V electrical architecture, a SpeedStart 10kW belt integrated starter generator and TIGERS turbine integrated exhaust gas energy recovery system (both switched reluctance machines supplied by Controlled Power Technologies (CPT) - the company which developed the electric supercharger now close to production with Valeo), and an advanced lead carbon battery pack provided by EALABC. With the ADEPT project, the research team aims to demonstrate a powertrain with uncompromised performance and less than 70 g/km CO2 emissions as measured over the European Drive Cycle, but at a projected production cost significantly lower than a comparable full hybrid electric vehicle.

CPT is a prominent technology provider in the movement to 48V hybrids, with its technological base provided by its proprietary switched reluctance motor technology - which is also a feature of the electric supercharger technology it sold to Valeo and has been recently demonstrated in Audi's RS5 TDI prototype. SpeedStart and TIGERS are two 48V ready technologies it has demonstrated both in the Ricardo-managed ADEPT programme and with the LC Super Hybrid prototype that has been developed in conjunction with the European ALABC.

Forecasts

Understandably with a new electrification opportunity there are a broad array of forecasts on mild hybrids available. What is clear, however, is that a form of hybridisation that was thought to be on the wane 3-5 years ago due to slowing sales of Honda's mild hybrids now presents a growth opportunity due to the increasingly likely move to 48V power subnets.

For 2020, Frost & Sullivan has forecast there will be 2 million 48V mild hybrids, while Bosch forecasts a more optimistic 3.5 million. Looking further out, Lux Research has forecast that the 48V market will exceed 7 million vehicles by 2024, with Europe leading the market with 2.6 million. Valeo, meanwhile, looking only at the NAFTA market, sees a 600k mild hybrid market in 2020 increasing to 1.8 million by 2024

Valeo has estimated mild hybrids will account for 3.3% of the NAFTA market in 2020 to 10% by 2024.

just-auto's QUBE service estimates that 48V will have a relatively slow introduction, but that once future emissions legislation takes hold the market will go through very rapid growth and that by 2024 there will be over 3 million 48V mild hybrid light vehicles on the road.

This article was extracted from just-auto/QUBE's engine technologies service: Global light vehicle engine technologies market- forecasts to 2029

See also:

Overview: February 2015 management briefing: 48V mild hybrids (1)

OEM plans: February 2015 management briefing: 48V mild hybrids (2)

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