Die on Heatsink

YASA Ltd is a UK-based company that designs and manufactures a range of novel, power dense, liquid-cooled electric motors and controllers. The company was founded by Dr Tim Woolmer in 2009 to commercialise the unique motor technology that he developed during his DPhil at Oxford University. Today, YASA's revolutionary compact, lightweight and powerful electric motors and controllers enable vehicle hybridization and electrification -- especially when there is limited powertrain space. The very short axial length and high-power density of YASA e-motors make them a particularly effective solution for P2 type hybrid vehicles and range-extending modules as well as for traction.

The electronic controllers for these motors use transistors which must be cooled to remove the semiconductor losses that arise. YASA have a novel, patented, method for mounting several, small standard transistors onto heatsink plates that are immersed in a flow of liquid coolant. This project aims to improve power density and reduce controller weight still further by improving the thermal and transient electrical performance of this technology. The target for this project is to devise a transistor mounting method that will permit a complete 250kW motor controller with a power density of 100kW/l.

To our knowledge, no-one has successfully pushed power density this far in a production product. If successful, the construction method we are proposing will be a world first.