A2Z Consulting

Stray inductance of commutation loops in snubberless Medium Voltage VFDs and high power converters should be as low as possible. Excessive stray inductance will cause overvoltage on power semiconductors followed by increased turn off losses and increased heating.
Stray inductance of commutation loops depends mainly on the layout of power components, their specifications and the design of busbars connecting between them. Therefore it is important to design the busbars with the lowest stray inductance values. As the geometry of these busbars is typically very complex, their inductance cannot be estimated using available analytical calculation methods. Hence, numerical methods are commonly used for the stray inductance analysis. 
In this project, low-inductive busbars connecting between power components in the phase module of Medium Voltage VFD were analyzed. The analysis was done using 3D electromagnetic finite element simulation. The stray inductance of commutation loops was estimated and the design of busbars was optimized to achieve the minimum values of stray inductance.