A heat pipe assembly includes walls having porous wick linings, an insulating layer coupled with at least one of the walls, and an interior chamber sealed by the walls. The linings hold a liquid phase of a working fluid in the interior chamber. The insulating layer is directly against a conductive component of an electromagnetic power conversion device such that heat from the conductive component vaporizes the working fluid in the porous wick lining of the at least one wall and the working fluid condenses at or within the porous wick lining of at least one other wall to cool the conductive component of the electromagnetic power conversion device. The assembly can be placed in direct contact with the device while the device is operating and/or experiencing time-varying magnetic fields that cause the device to operate.