Transformers in the transportation segment are utilized in power control/power management subsystems for rail, hybrid and 42 volt automotive, electric carts, and marine applications. Gate drive transformers and pulse transformers are utilized to initiate or terminate a drive voltage. They also represent a mission critical function as the transformer is the last voltage control interface into the application.
      Similar to other applications there is the potential for system damage related to voltage surges and dynamic loading in grid environments with high saturation Electromagnetic device design in this environment present a significant challenge to the designer in that off-the-shelf standard cores and bobbin sets are not well suited for the stringent voltage control requirements in transportation applications. Typically, transformer parasitics (coupling capacitance and leakage inductance) and isolation requirements (creepage and clearance) are underestimated by designers.
      The results are varying yields as manufacturability variances associated with inter-winding adhesive tapes, margin tapes, sleeving and lead dressing are multiplied by tolerance stacking that originated with a poor selection of cores and bobbins. The result is a reliance on operator workmanship which is often outside the coverage of written documentation. Many designers have fallen prey to this problem due to a lack of experience, or they do not have the proper design tools. The utilization of Finite Element Analysis and Spice Circuit Simulations allows us to refine core and bobbin geometry beyond standard practices and increase overall manufacturability.
      Another critical factor in system design pertains to MTBF. Many transformer manufacturers use a single dielectric strength test as a means for assuring long term reliability. This is a flawed approach best remedied by Corona (partial discharge) abatement for elevated system voltages, along with designing with an overall system BIL rating in mind. It should be noted that BIL and/or Corona Free ratings of these devices will have a direct impact on reliability, MTBF, and related warranties.
     Other transformers within the overall design are switch mode, feed forward, flyback, inverter, buck boost and isolation/step up/step down.

Primary Design Considerations Summary:
• Drive voltage control and repeatability
• EMI/noise suppression
• Energy storage  
• Power efficiency,
• Vibration and shock.
• HiPOT
• BIL