Project "Continuous Power" New Inverter Provides 600 kW Continuous Power with Low Inductance

Related Vendors

Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

Robert Bosch GmbH

FAULHABER Drive Systems

Taiwan Machine Tool & Accessory Builders' Association (TMBA)

Wuxi InfiMotion Technology Co., Ltd.

In a collaborative project between the Fraunhofer Institute IZM, Porsche, and Bosch, the Continuous Power inverter has been designed, which, thanks to the capabilities of SiC transistors and 3D printing, provides 600 kW of continuous power while remaining thermally stable. Is this a technological leap for electromobility?

Electric vehicles would probably be pretty immobile without the backbone of any electric drive system: the inverter. It converts the direct current from the battery into three-phase alternating current (also known as three-phase alternating current) so that the electric motors can be driven. The more powerful the motor is, the more current has to be converted - and the greater the impact of factors such as losses, heat development and form factor. Accordingly, the efficiency with which an inverter works is decisive for the performance of the drive.

The lower the conversion loss, the greater the range of the vehicle. The fast availability of electricity through the inverter has an influence on the driving dynamics of a vehicle, and therefore on the overall driving experience. E-vehicles tend to be quite heavy, which is why it is important to work on the system weight. In short: Electromobility is far from being "fully developed". This can be seen, for example, in the continuous power development of the Fraunhofer Institute for Reliability and Microintegration (IZM) in collaboration with Bosch and Porsche.

Continuous Power for New Standards

The partnership has resulted in the continuous power inverter, which can achieve a continuous output of 600 kW (equivalent to around 815 hp) and a peak output of 720 kW (equivalent to around 979 hp). This continuous output "is not only a good one and a half times as much as is currently usual in a 40-ton truck, it also sets new standards in the segment of electrically powered sports cars", explains the IZM. To make this possible, silicon carbide (SiC) semiconductor technology was used and a new cooling system was designed.

The performance of the continuous power inverter is based on the use of silicon carbide (SiC) transistors, which enable higher temperatures, lower losses and more compact designs compared to conventional silicon components. By embedding the semiconductor modules directly in the circuit board, the leakage inductance has been reduced to 1.1 nanohenries, which promotes more efficient switching and lower heat losses. DC link capacitors with increased power density are also used. The chosen design also supports a compact system layout and facilitates series production.

Innovation From 3D Printing

The cooling system of the continuous power inverter consists of two central components: a 3D-printed copper cooling element and a supplementary water cooling system made of aluminum. Copper was used due to its higher thermal conductivity. Temperature-critical components are connected directly to the cooling system via silver sintered connections.

The water cooling with parallel coolant flow ensures even pressure distribution and a low pressure drop of just 150 millibars at 10 liters per minute. Even under continuous load, the temperature difference between the housing and the coolant remains below 20 Kelvin. The maximum temperature increase at the phase outlet is 41 Kelvin - an indicator of the system's high thermal efficiency.

The components of the continuous power inverter are functionally coordinated with each other and are coordinated by specially developed control software. Thanks to its compact and modular design, the system achieves a power density of 200 kVA per liter, which is two to four times that of current series solutions. The modular design facilitates maintenance and the replacement of individual components, which extends the service life and conserves resources. With the combination of efficient semiconductor technology, sophisticated cooling and high performance, the partners expect the continuous power inverter to play a key role as a technological building block for future electric drive systems. (sb)