ISO 21780 set to make life a little easier for 48-volt system suppliers
In recent weeks European Automotive manufacturers’ emissions reduction plans have been dealt a body blow by a series of unexpected events, including the revelation last month that the amount of carbon dioxide produced by new cars rose last year - reversing at least seven years of steady declines of GHGs in many countries.
What is more, the rise in vehicle-related CO2 emissions is set to get much worse this year, according to Peter Fuss, a partner at consultancy EY. A 0.4 gram increase last year, raising the average to 118.5 grams per kilometer for new cars sold in the EU, highlights the challenge for manufacturers in meeting the 2021 target of 95 grams per kilometer on average. Yet relying on diesel to help is no longer an option, according to the EU’s industrial-policy chief.
In a May 24 interview European Commissioner Elzbieta Bienkowska claimed: “Diesel cars are finished,” continuing, “I think in several years they will completely disappear. This is the technology of the past.”
This is not what the auto industry wanted to hear: With Dieter Zetsche, chief executive officer of Mercedes-Benz maker, Daimler responding: “It’s safe to say our original premises and plans to meet fleet emissions goals are good for the bin.” Zetsche referring to the company’s widely held belief that diesel powered vehicles would remain an integral part of the emissions strategy up until at least 2030.
Highly reliant on retaining a strong mix of diesel powered vehicles, that emit up to 15 percent less Green House Gases (GHG) than gasoline derivatives, manufacturers who, up until now, were on track to meet the 2020/ 2021 emissions targets are now in danger of failing to comply. Non-compliance could expose them to projected fines of 4.5 billion euros ($5.3 billion), according to a study by PA Consulting.
With diesel power in passenger vehicles seemingly set to expire sooner than expected manufacturers are scrambling for cost effective, relatively simple, alternatives to meet upcoming fleet emissions regulations.
Fortunately there is a fix that not only meets the costing of a diesel derivative, but is also relatively quick and easy to implement – the 48V Mild Hybrid Electric Vehicle (MHEV).
Image Source: Autoblog
A dominant 48V electrification strategy requires standards
In future 48V will not only support MHEV systems such as energy regeneration and torque boost - with the 12V system rapidly running out of power, the uprated powernet will enable new comfort features such as ride-control, and eventually, automated driving systems.
Image Source: Magna
According to the VDA (German Association of the Automotive Industry), around four million vehicles will be fitted with 48V subsidiary electrical systems in 2020. By 2026, this figure will rise to some ten million vehicles, or roughly one in every ten vehicles worldwide.
However, many challenges in the development of 48V systems need to be addressed before the widespread adoption of the technology. Issues such as the expansion of the definitions regarding 48V systems, standardization and the setting of global standards, as well as specific areas of concern such as arcing and fusing, all need to be resolved before the technology can be deemed safe and efficient.
Currently, standards tend to cover high voltage systems or the traditional 12 and 24-volt systems, however this leaves a lot up to the interpretation by industry stake-holders involved in the testing and verification of 48V systems.
Existing standards don’t directly address the 48V powernet
An example of this is ISO 7637 which specifies test methods and procedures to ensure the compatibility of the “conducted electrical transients of equipment installed on passenger cars and commercial vehicles fitted with 12V or 24V electrical systems.”
While the standard describes bench tests for both the injection and measurement of transients, and is applicable to all types of road vehicles independent of the propulsion system (e.g. spark ignition or diesel engine, electric motor), it is generic and does not address specific issues regarding electrical requirements and testing applicable to 48V.
Introducing the 48V powernet requires a complete change in the architecture of the vehicle. Since the voltage is four times higher, the current must and/or can be reduced in order to keep the power unchanged. On the other hand, the higher electrical energy places additional loads on components such as fuses and relays, thereby increasing the risk of arcing.
Moreover, as the technology is refined and adapted to meet manufacturers’ changing requirements 48V electrification is expected to go through several changes in the coming years.
For instance: Looking at the relays and safety fuses, the first phase will involve electrification of the mechanical components, but the architecture will remain the same. Electronic relays and electronic fuses will simply replace mechanical relays and fuses.
Later, possibly between 2020 and 2030, a transition to connected smart junction boxes and smart fuse boxes could occur which would take full advantage of all the benefits that electrification can bring by revisiting the architecture to optimize the wire harness size, align it with the source capabilities and be ready for an autonomous car with a full safe and fault tolerant architecture.
Confronted by these radicle changes and unique requirements the industry needs dedicated 48V standards that suppliers, OEMs and regulators can turn to for guidance as the technology evolves.
ISO/CD 21780 addresses 48-volt system requirements and testing
Current specifications for 48V exist in the form of LV148/VDA320, however, a wider worldwide standard encompassing inputs and requirements from various regions and OEMs will enable accelerated development and acceptance of systems and components in 48V automotive structures.
Moreover, suppliers of components and sub-systems will have a global unambiguous standard to work to. This is extremely important to save development time and costs, as well as guaranteeing a well-tested, defect free product is ready for series production.
To achieve these goals the ISO has tasked the ISO/TC 22/SC 32 Technical Committee with developing such a unique 48V specification: Presently the process rests at 30.60 with the voting/ comment period having closed on 31st May 2018.
While little detail is available as to the content of the upcoming standard, when compiling the 48V-specific standard the group will no doubt consider known issues such as fusing/arcing of 48V systems under high-power loads, along with the necessity to use electric power distributors to monitor current paths electronically (in addition to the deployment of safety fuses) so that even creeping short circuits can be detected and switched off in the event of a fault.
In addition, testing must ensure that the separation of both the 48-volt and 12-volt systems is maintained at all times.
A 12/48-volt short circuit would cause considerable damage to all 12-volt control units. As a result, arcing and loss of ground are among the top issues currently posing challenges in the 12/48V dual power supply system for automotive suppliers, and therefore would likely be included in any test standards.
ISO 21780 will make suppliers’ lives easier as 48V systems roll out
Without globally accepted standards for 48V electrical systems and the unique testing of these, suppliers are currently applying best in class practices adopted from other industry norms and standards that do not necessarily cover 48V specific requirements.
A single, unified, global standard holds several benefits for suppliers:
- Conformance to a single global standard builds customer confidence that products are safe and reliable
- Suppliers will be able to meet regulatory requirements, at a lower cost
- A global standard will cut costs for suppliers developing solutions for international markets
- A single standard makes it easier for suppliers to access global markets
- Testing time and costs will be reduced
Although the ISO 21780 standard is only due to be finalized in 2019 it will play a significant role in cutting supplier costs and optimizing efficiencies as the 48V powernet stamps its dominance on vehicle electrification leading up to 2030.
- Elisabeth Behrmann; Bloomberg; Europe’s Rising Car Emissions Box BMW, Daimler Into Tight Corner; May 2018; https://www.bloomberg.com/news/articles/2018-06-01/europe-s-rising-car-emissions-box-bmw-daimler-into-tight-corner
- International Organization for Standardization; ISO/CD 21780; Road vehicles - Supply voltage of 48 V - Electrical requirement and tests; May 2018; https://www.iso.org/standard/71607.html
- Deres Eshete; ON Semiconductors; Automotive 48V Power Supply, finally a reality?; September 2017; http://www.onsemi.com/PowerSolutions/blog.do?method=post¶m1=automotive-48v-power-supply