DC/DC Converters

Products & Services

© Fraunhofer IISB
© Fraunhofer IISB

Insulating DC/DC Converters

We develop all kinds of insulating DC/DC converters for mobile applications. This includes e.g. insulating high voltage (up to 850 V) to low voltage (commonly 14 V, 24 V or 48 V) converters in the power range from 10 W up to approx. 5 kW. With efficiencies of up to 97% and power densities up to 10 kW/dm³, they can be easily integrated into a small car, directly inside the high voltage battery system or the drive inverter. The photo to the right gives a closer look at how by using modern power devices, full digital control techniques, and mechatronic approaches, outstanding power densities and efficiencies are reached.

As with other Fraunhofer IISB vehicle electronics prototypes, insulating DC/DC converters can be developed for plug-and-play installation.

As an example of a fully housed, insulated 5 kW DC/DC DC/DC converter with automotive qualified connectors shows. It could be used within two different voltage ranges for applications in light or heavy trucks and can be controlled via CAN interface. Due to the serial connectable phases on the primary side, the use of automotive qualified Si power semiconductors with 600/650 V blocking voltage is possible to reach a DC-Link voltage up to 800 V.

Non-Insulating DC/DC Converters

© Fraunhofer IISB
© Fraunhofer IISB

Our high voltage, non-insulating, bidirectional converters are mainly used for traction energy management in case of recuperation, boost, the management of different power sources (e.g., fuel cell and battery), and fast charging. The converter covers a power range up to about 600 kW with efficiencies up to 99%.

Combining the converter with drive inverters in terms of system integration is just as possible as an integration into the electrical energy storage. The type of cooling (air, water, or oil) is generally tailored to the specific application. A fully digital control and a CAN-bus inter-face for the communication with a vehicle control unit is standard.  

We make use of the latest Si, SiC, and GaN devices. Our multi-phase concept makes it possible to shift the fundamental frequency of the DC link ripple voltage in the megahertz range, resulting in a considerable reduction of weight and volume of the passive components.

Robust and High-Speed 250 A, 450 V buck / boost DC/DC Converter for universal drive train applications.

Within the latest high power, high voltage DC/DC converter development projects power densities of more than 80 kW per litre are achieved in 850 V high voltage full SiC technology.

We build complete systems for our industrial partners, including high-power and bus connectors. Integrated in a sealed housing, these robust compact devices are used in R&D hybrid cars for evaluating the electric power train.

Efficiencies up to 99% over a wide range of load can be realized via a load-adaptive management of the number of active phases. All converter components including EMI filters, the control electronics, and the fluid cooler are generally included in our power density figures. The high power density and low power to weight ratio of our DC/DC converters make them especially suitable for demanding motor sports (KERS) and aircraft applications.

Key aspects:

  • High efficient compact DC/DC converters
  • Power up to 600 kW, 300 – 1000 A
  • Typical voltage levels 450 / 850 V
  • User specific housing, layout, communication and electrical power specification
  • High Speed control loops for stability and save handling of load dumps
  • Application specific liquid or air cooling techniques