Forced Unbalanced Method to Reduce Transient Current Unbalance in Semiconductor Power Switches

Switching power devices, specifically SiC MOSFET, has wider parameter variations (Vth, Rds(on)) due to fabrication process; therefore, when putting several MOSFET dies togther in parallel in a power module, there will be current/power unbalance when they are being used. Several publications have mentioned about using different control techniques to actively reduce the unbalance. However, these controls are usually quite complicated and not so practical in reality. This ID presents an alternative method to passibely reduce the unbalance by designing asymmetrical layout with unipolar coupling.

The main feature and results of the invention:

1.  The forced unbalanced method, which utilizes unbalance layout with unipolar coupling to balance transient currents, is introduced and explained in this ID;

2.  Bipolar coupling configuration is simplified to unipolar coupling by using the forced unbalanced method;

3.  Peak current difference is reduced from 13 A to 2 A

Patent Information:
For Information, Contact:
Li Chen
Licensing Associate
Virginia Tech Intellectual Properties, Inc.
(540) 443-9217
Zichen Miao
Yincan Mao
Khai Ngo
Chi Ming Wang