InMove

The Insulated Gate Bipolar Transistor (IGBT) is the most important semiconductor power device for applications in the medium power range for voltages > 400 V. To improve its efficiency in terms of switching and conduction behavior, Fraunhofer ISIT focuses on the development of ultra-thin field-stop IGBTs. Another aspect is the adaptation to advanced assembly techniques.

As part of the joint project InMOVE, technologies for a drive concept for modular distributed electric drives with high speed and, therefore, high power density on the part of the electric motor were researched. The prerequisite for realizing such drive modules is a very compact design of the power electronics components to be integrated.

Goals & challenges

• Distribution of the drive power of the electric vehicle drive to several compact electric drive modules
• Scalable electric drive power
• Variable drive architecture using the same components
• Electric drive modules consisting of a slim, high-speed electric motor with integrated inverter
• Reduction in the development costs of the electric drive components
• Very compact design of the power electronics components
• Pursuit of power electronics technologies in an overall mechatronic approach

The solution

Based on the system simulations for the modular inverter to be developed, the requirements for 1200 V / 200 A trench field-stop IGBTs were defined. The IGBTs should be able to be operated at 13.5 kHz and with the lowest possible switching losses up to Tj,max = 175°C.

System model of the drive inverter

• Implementation of the thermal behavior of the half-bridge module using a Foster network
• Permissible component temperature at maximum load: TJ,max = 175°C
• Service life: driving cycle 8875 s
• Temperature strokes: min 2°C, max 60°C
• Estimated service life (number of cycles until failure): Driving distance of 450,000 km
• With Danfoss Bond Buffers 10-15 times longer service life
• Improvement in overall efficiency and overall performance thanks to IGBTs from Fraunhofer ISIT and Vishay

Chip layout, mask set and special processes

• Metallization of the front side of the chip with an electroless Ni/Au layer
• Application of carrier processes for backside processing of thin silicon (50 µm to 150 µm)
• Backside processing by implantation and laser annealing (l =515 nm)
• Metallization of the chip backside with Ti/Ni/Ag

Find more information directly on the Fraunhofer ISIT website:

https://www..isit.fraunhofer.de/en/power-electronic/advanced-power-transistors/AutomotivePowerInverts.html

https://www.atem-inmove.de/en.html

Paper:

https://ieeexplore.ieee.org/document/8402830