The electro-mobility market has taken off, the global electric vehicle stock – this comprises on-road battery electric and plug-in hybrid vehicles – exceeded three million units during 2017 and in the same year for the first time the one million sales per year milestone has been passed.

According to McKinsey Norway has already reached the critical mass on the way to entire electric vehicle adoption, also China and Sweden show a clear disruptive trend towards electro-mobility. These countries joined also the 30@30 Campaign: target for them is to reach a minimum of 30% sales share with electrified vehicles until 2030.

As a part of this trend towards road traffic electrification also the commercial vehicle market has started to electrify. The city-bus segment has taken the lead especially pushed by strategic incentive public programs in China: the OECD/IEA has reported a global stock figure of 385000 electrified busses, thereof est. 382500 (99%) units in the People’s Republic of China.

Fig. 1: SKAI2HV with cable gland interface

Compared to passenger cars delivery trucks or city-buses face much higher frequency of start and stop, accelerate and decelerate activities during their daily usage. This significantly increases the requirements for the power cycling capabilities of the electric power train. Especially the traction inverter with its incorporated power semiconductors needs to be designed to sustain 60000 and more operating hours during life.

SEMIKRON, one of the leading suppliers of power electronic equipment, provides products for vehicle electrification since more than 25 years. Starting with material handling applications (e.g. forklifts) in the 90ies Semikron meanwhile equipped more than 1.5 million vehicles for material handling, more than 53000 city-buses and beyond 200000 passenger cars with power electronic products.

It has brought it´s experience into the SKAI2HV converter design (Fig 1), which is dedicated to application in electric powertrains of commercial vehicles.  SKAI2HV incorporates sintered power semiconductor dice, which enable the inverter to withstand the required mission profiles of medium or heavy-duty vehicles. SKAI2HV converters are available with cable gland interface or high power connectors, respectively (Fig 2).  Continuous motor current is available up to 350Arms depending on conditions. The maximum battery voltage can be selected up to 800Vdc.

Fig. 2: SKAI2HV with power-connector interface

Since production start in 2013 tens of thousands of commercial vehicles, especially city-buses, have been electrified by usage of a SKAI2HV converter variant. These units accumulated more than 800 million of field operating hours since then. With the assumption of a typical city-bus driving profile of 10km/hour meanwhile electrified commercial vehicles with implemented SKAI2HV accumulated a mileage in the range of 8 billion kilometres.

At the recent IAA show in Hannover some well-known manufacturers have presented electrified commercial vehicles using SKAI2HV as traction converter. The power range of those vehicles varies between 80kW und 300kW.