What is causing these switching transients on a 3 phase motor driver?
wire to loop coupling model and math







simulate this circuit &ndash; Schematic created using CircuitLab

NOTE: this formula [ Vinduce = 2-7 * (Area/Distance) * dI/dT] is conservative; the exact math uses a natural_log to include effects of the two sides of the loop that are at 2 different distances (here 1cm for the near side, and 2cm for the far side). 

WARNING: if you are concerned about this level of Vinduce accuracy, then you have a dangerous system design (IMHO) and need to use serious mitigation methods.