Lessons from CESA 2012

This second edition of CESA congress has been successful, with a large audience and top experts coming from BMW, PSA, Volkswagen, Bosch, Continental, NXP, Valeo and so many others. Through technical sessions, no less than eight round tables and an attractive exhibition, the congress has kept its promises.
But, what did we learn so far, after such intense discussions ?
First, electrication of the powertrain is really launched. In the future, we should see more mild hybrid, full hybrid and plug in hybrids, and later on pure EVs.
The second point is linked to the first one. Many OEMS and tier 1 suppliers converge on 48 volt, and not only in Germany.
Third, the architecture of the future will be for sure mainly based on Ethenet. It's not the only solution, however, and the automotive industry should find ways to simplify E/E architecture, instead of adding more and more embedded networks.
Fourth, if the connected car is on the way with apps and cloud-based services, nobody knows who will win at the end, between the OEMs, third party players, telecom carriers and giants such as Apple and Google.
Fifth, the automotive industry should work with new partners. The success of Autolib' in Paris, which celebrates its first birthday and which is the largest EV car sharing experience in the world, with nearly 2000 cars running in the streets, is there to show that it's possible to adress customers, even when you're outside of  this business.

Dual voltage power supply system with 48 volts (BMW presentation)

As convened, here is a snapshot of Ottmar Sirch's presentation on 48 volt. This paper is scheduled during CESA 2012.
As an introduction, our expert from BMW reminds that the continuous increase of functionality for comfort, safety, driver assistance and infotainment systems as well as the insertion of innovations raise the requirements. In combination with the electrification of powertrain functions and ancillary units for CO2 reductions these requirements drive today´s vehicle power supply to its limits.

Then, Mr Sirch gives examples : Start-Stop-Function, Brake Energy Recuperation und electrification of mechanical driven systems as well as superpositioning of high power loads. The demand of electric energy and power as well as the cycling of accumulators have increased significantly.

In the future, OEMS will need High Power Recuperation (> 5 kW), Extended Start-Stop-Functions, E-Assist/E-Boost, eTurboCharge, as well as Electrification of ancillary units (electric climate compressor, electrification of chassis control systems) and new functions (front screen heating, electrohydraulic valve control)

As a conclusion, displacing all high power loads and implementation of new high power functions can reduce the requirements to the DC/DC converter and the 12-V-battery significantly.

Ottmar Sirch (BMW) to discuss 48 volt at CESA 2012

CESA speaker

Top expert from BMW, Ottmar Sirch will make a presentation on 48 volt in Paris, during CESA 2012. He's focusing on dual voltage as the responsible for the Predevelopment of Vehicle Electrical Power Supply Systems.
In Munich, the predevelopment projects cover all subjects of electrical power supply in vehicles with combustion engines as well as Hybrid and Electric vehicles.
Mr Sirch came to SIA office in Suresnes, near Paris to share his vision for 48 v, a few days ago.

The presentation has been attended by Gérard Maniez (Freescale), Guy Convenant (Valeo), Uwe Dausch (Valeo), Jean-Yves Stineau (Renault), Oliver Nass (ESG Group), Daniel Benchetrite (Valeo), Gérard Saint-Léger (Renault), Dominique Lenoir (Renault), Franck Briault (PSA Peugeot Citroën), Eric Dequi (PSA Peugeot Citroën), Thierry Seynaeve (ESG Group) and Jean-François Léon (Valeo).

Who is Ottmar Sirch ? 
Since 11 years, he is Project Manager in the Electrics/Electronics Department at the Center of Research and Development. He was responsible for the HVAC Control Electronics of the 1 series and 3 series from 2001 to 2005. In 2005 he took over the responsibility for predevelopment of hybrid vehicle power supply systems for the 1st and 2nd generation. Since 4 years now, he's Project Manager for Predevelopment.

Resume 
Ottmar Sirch received his Dipl.-Ing. Univ. degree in Electrical Engineering at the Technical University of Munich in 1985. During his main study period he focused on semiconductor technologies. He did his Dipl.-Ing. thesis on CMOS Latch-up in 1985. Afterwards he was working 16 years in the semiconductor industry at Siemens Semiconductor Group (from 1999 Infineon Technologies) in several fields and positions (CMOS technology development for VLSI-Logic, Physical Failure Analysis of Integrated Ciruits for Quality and Reliability Strategic and Technical Sales and Marketing for Automotive Semiconductors) He joined BMW Group in 2001.

Other 
Additionally, Ottmar Sirch is chairing the conference “Electrics/Electronics in Hybrid and Electric Vehicles and electrical Energy Management” of Haus der Technik e.V. Essen since 2008.

Next, we will give some details about BMW's vision on 48 v.

Introduction and widening of 48 V voltage system

CESA paper abstract

The maximum power needed for on-board vehicle electrical network has increased continuously, and might overtake the 10kW threshold in the near future (taking into account the energy recovering needs). Standard up to date 14V networks are uncapable of delivering such power needs.

After about 20 years of innovative works concerning the 42V onboard network, this solution was finally abandoned by most of the car manufacturers, substituted by the 48V network. The need to increase the onboard voltage level was initially motivated by the performances enhancement of Lead Acid Batteries systems. Nowadays the CO2 emissions reduction is also expected, thanks to the evolution of battery technologies (as example Li-ion chemistry). This strategy is then justified by increasing needs of electrical power, not compatible with standard 12V networks, as well as by energy recovering needs necessary for CO2 emissions optimization.

This paper will develop the expected scenarios for introduction and widening of the 48V technology in our vehicles, taking into account the 48V standard technical Specification issued from the initiative of the German OEMs, and the VDA help :
 - Define and set up the conditions for succeeding in the introduction of the 48V technology, firstly on Mild-Hybrid powertrain applications. 
- Then extend the 48V voltage as a second onboard network to allow future needs : 
High application rate on hybrid powertrain by 2020 
Optimization of Electrical energy management 
CO2 emissions reduction (48V storage system allowing high recovering performances) 
Potential opportunities of using 48V to supply some high power consumers, like electrical steering, air conditioning compressor, engine cooling fans, heated rear window, …). 

By El Khamis Kadiri and Franck Briault, PSA Peugeot Citroën

48 V, what is so interesting this time?

By Jochen Langheim, STMicroelectronics

Most of us remember the discussion on the 42V in the nineties. There was a lot of excitement around the introduction of a second voltage level for on-board power supply besides 12V in passenger cars. With an ever increasing need for electric power, the fear was to reach too soon the limit of the on board generator to supply power to the devices such as air conditioning, heating or electric steering.
However, 42V didn't succeed, because engineers found ways to limit power consumption, implement intelligent power control, install buffers and Increase the capacity of on board generators to levels sufficient for a long time to supply energy.

What is different today?

There are needs for more power far beyond the present on-board needs of around 5 kW. Start-stop systems already push 12V technology to its limits with some kW. But they are only the beginning of further electrification towards mild hybrids. There, it will need something more powerfull in the range of 10 to 15 kW.

This would mean some 1000 A of current or an equivalent of cables with diameters of 10 to 15 mm. Heavy, costly, difficult to manufacture and install. In addition, each little resistance causes heavy losses according to P = R I²

And this leads to the second aspect, CO2.
Worldwide CO2 reduction and energy efficiency is a growing concern. The European Comission has adopted a very ambitious rule to reduce CO2 emissions. Limits are getting lower and lower and passing these limits will cost penalties, real money.
As an example: 3 g of CO2 above the limit of 120 g cost 45 € per vehicle. Avoiding this penalty can fund a nice efficiency improvement in an electric module leading to power savings of about 200W (or 3 g of CO2). Introduction of all sorts of innovations to reduce CO2 emissions become thus economically viable. Avoiding penalties can finance sophisticated start-stop systems, high efficiency generators, low loss air conditioning, drive train hybridization or... electric vehicles.
Finally, the definition of the 48V system specifies the maximum voltage below 60 V, which is the limit for LOW VOLTAGE, which means non-dangerous operation without specific security measures.

I want to emphasize at this point that the 12V system will not be replaced, but that there will be 2 on-board systems in parallel for 12 and 48 V linked by a DC/DC converter.

With the introduction of the 48V standard, every actor in the market can focus on the optimization of his products. Semiconductor makers can optimise their MOSFET and IGBTs, special connectors, capacitors, passives, etc. They will be able to better take into account the needs for load dump, EMC and automotive quality. Volume effects will lead to productivities that will further decrease the costs for innovation in these areas. Reuse of experience is increased.

What might be the consequence for electric mobility?

Imagine a drive system for a scooter with 48V and 5 to 10 kW. I would expect a nice acceleration for such a two-wheeler. Do you know the number of electric bikes and scooters in China? Tens or even hundreds of millions with 24, 36 or ...48V.
An ICE car with front wheel (conventional) motorisation can easily be equipped with an electric drive train on the rear wheels. Let's say 2 times 15 kW; makes 30 kW. As electric motors show more torque at low speeds, the drive feeling at low speeds can be compared to a car with 100 HP. A relatively easy and economic way to make a hybrid vehicle. Remember the cost advantage in combination with two-wheelers. Consequently one can also realise an electric vehicle with 4 units totalling 60 kW. Such cars are today studied all over the world.
 As a side effect, such a four-wheel drive system in a car can offer electric stability and anti-skid control without extra hardware. Furthermore the use of individual and small motors allows more flexibility in the desiign, which is and will be THE differentiating factor for car sales.

In conclusion, 48 V opens the door to electric driving with plenty of innovation at an affordable price.
48 V can initiate a real revolution!