Electromobility

Driving on with SiC and GaN

High-efficiency, light-weight electromobility with DC/DC converters using WBG semiconductors.

According to market research by Bloomberg, the energy demand of electric vehicles will increase from 6 TWh in 2016 to 1,800 TWh by 2040. That illustrates the crucial importance of energy-efficient systems in the sector. In fact, many power circuits and components in electrified vehicles can be made significantly more efficient by using gallium nitride (GaN) and silicon carbide (SiC). After Tesla introduced SiC-based power electronics for its main inverters in 2018, the automotive sector is increasingly becoming the driving application area for SiC components. More and more Tier 1 suppliers and car manufacturers are using SiC technology in their products.

Longer range for electric vehicles

Modern hybrid and fully electric vehicles benefit especially from GaN and SiC components. In view of the relatively low energy density of today's battery systems, the energy consumption of all electrical systems installed in the vehicle must be minimised in order to achieve an acceptable range. Conventional silicon-based power electronics generally achieve an efficiency of between 85 and 95%, meaning that on average around 10% of electrical energy is lost as heat during each power conversion. This is where wide band gap (WBG) semiconductors, with their higher efficiency, can significantly improve the overall efficiency of the system. They also take up less space and - a particularly crucial factor for the maximised efficiency of electric vehicles - are lighter in weight. Improving the efficiency of an electric vehicle by one percent will increase its range by more than one percent. And range is one of the key criteria for electric powered vehicles to gain wider acceptance.

More efficient, smaller in size

The core component in this is the traction DC/DC converter. It converts energy between different energy storage devices, battery chargers (AC chargers, fast DC chargers), drive converters and range extenders. Power electronics cores based on SiC and GaN achieve the highest power densities and lightest weights of DC/DC converters. They allow many times the switching frequency of silicon components, and achieve much higher efficiency. The high switching frequency enables passive components to be made much smaller, resulting in a record power density of up to 143 kW/dm³.

Today's electric drives are generally operated at 400 V or 800 V. IGBT converters have mainly been used to date, but in the 800 V operating voltage range they are increasingly being replaced by SiC components.

GaN technology is mainly used in DC/DC converters for on-board power supply. The converters lower the high voltage of the vehicle batteries to the voltage of the on-board power supply network. GaN technology increases efficiency and reduces size, especially in the 48 V bus systems which are increasingly being used. Overall system cost is also reduced. Using WBG transistors in the automotive industry, for example, can reduce total product costs by up to 20% compared to conventional silicon technology.

Lower cost at charging stations

The use of WBG power electronics does not end with the on-board systems of an electrified vehicle. SiC and GaN components also enable higher efficiency in the charging infrastructure. Power Innovation, a company based in Achim, Germany, uses SiC transistors in its power converters for electromobility charging stations for example. They are used for the voltage range up to 1,000 V DC - previously a classic application area for IGBTs. SiC allows the use of significantly higher switching frequencies of over 100 kHz. As a result, the chargers are much smaller, and the size of inductive components is also reduced. Their efficiency is also significantly higher than with IGBT solutions. And last but not least, the smaller inductive components have also helped to cut costs.