Lessons learned in China over the past decade can help as the European Union pushes truck and bus electrification

Since 10 years the Chinese government is pushing the vehicle electrification with specific focus on the rolling stock in their mega-cities. This success story still continues after it reaches e.g. 99% of the global electric bus stock end of 2017, i.e. close to 400 000 units. 

Recently, in summer 2019 the European Parliament has established binding regulations that truck and other heavy commercial vehicle manufacturers will have to reduce CO2 emissions from new heavy commercial vehicles by an average of 15% from 2025 compared to 2019, and by 30% from 2030. Furthermore emission-free and low-emission vehicles will be credited by 2024, with a factor of 2 applying to fully electric vehicles. By 2025, manufacturers must also ensure that zero-emission or low-emission vehicles account for at least two per cent of all new vehicles sold.

To expedite further within two years all EU Member States will be obliged to take emission free commercial vehicles in public vehicle procurement contracts into regard. As an example, Germany must procure at least 38.5% emission-free vehicles for public orders of light commercial vehicles. For heavy commercial vehicles, the figure is 10% (from 2026: 15%) and for buses it is 45% (from 2026: 65%).

Semikron, a leading supplier of power electronics equipment, has been providing products for vehicle electrification for more than 25 years. Starting with material handling applications  (such as forklifts) in the 1990s, Semikron has since equipped more than 1.5 million vehicles  for material handling and beyond 200,000 passenger cars with power electronic products. Semikron also contributes significantly to the electrification of Chinese city buses where Semikron has shipped more than 50,000 traction inverters from the SKAI2HV product family.  Since 2013 these SKAI2HV inverters accumulate field operating hours, meanwhile exceeding 1 billion operation hours in total. The resulting field data underline the fundamental advantages of solder free assemblies of power semiconductors as they are incorporated in SKAI2HV inverters. The lack of solder joints in the SKAI2HV power semiconductor assembly enables the product to fulfil the challenging requirements for load power cycling, which is a direct consequence of the continuously ongoing accelerations and decelerations in city bus drive cycles. 

Since end of 2018 the 2nd edition of the automotive functional safety standard ISO26262 applies also to development programs of commercial vehicles with a gross weight of more than 3.5 ton. The manufacturers of electrified commercial vehicles have analysed their vehicle hazards and risks for potential failures which are not acceptable to happen during lifetime. In order to mitigate those risks the suppliers of key components, e.g. the traction inverter, are now – depending on the chosen vehicle safety concept - often requested to add certain safety requirements into their product specifications. Semikron has prepared itself for these extended requirements and is now jointly customizing their SKAI products in accordance with their customer´s individual safety goals. Consequently Semikron certifies it´s quality management system and software development process in accordance to IATF16949 and Automotive Spice, respectively. All process items of the Automotive Spice standard fully coincide with the ISO26262 development process steps.  

Since product launch of the SKAI2HV product family it has been available on different integration levels, just to align it with customer´s needs.  These integration levels comprise variants with gate driver interface, which offers direct control of power semiconductor switching signals. Additionally, variants with CAN-bus interface are available. The required motor control software for the latter is offered by Semikron but might also be customer proprietary.

Semikron will contribute that the European vehicle decarbonisation program will become a success story as it is proud on its contribution to the Chinese vehicle electrification program since 2013. The additional challenges introduced by the new ISO26262:2018 will be covered based on the proven-in-use SKAI products.