
The design goal of the power control/power management subsystem in this application segment is the precision control of a voltage level or levels within a defined topology. The voltage is used to control the timing of events such as: motor start, motor speed, motor sequencing, and motor stop, as required to achieve the operational parameters defined by the target platform design criteria.
Primary design considerations at the subsystem level should include the avoidance of false triggers, system recycling, and the impact on MTBF by voltage surges due to lightning strikes, grid perturbations and insufficient soft start control. This impacts the component level where special attention must be paid to the stability of electromagnetic devices. Here the primary concern is controlling the parasitic values, which reduces the need for compensation components, thus improving overall system stability. Other considerations should include the elimination of transformer manufacturing process variables, that are often deemed acceptable by industry designers and transformer manufacturers.
Another critical factor pertains to MTBF, where most transformer manufacturers look only at a single dielectric strength tests as a means for assuring long term reliability. Bicron's methodology is to characterize Corona (partial discharge) abatement at elevated system voltages, as well as design with overall system BIL requirements in mind.
The nine main types of components that are used in these applications are pulse transformers, gate drive transformers, isolation transformers, and Inductors (also referred to as chokes), switch mode, buck boost, flyback, feed forward and inverter. BIL and / or Corona Free ratings of these devices will have a direct impact on reliability, MTBF, and related system warranties.
Primary Design Considerations Summary
• False Triggers
• System recycling
• MTBF
• Susceptibility to Voltage Surges
• Soft start Control
• Grid Perturbations
• Control of Parasitic Values
• Transformer sub system Stability
• Corona abatement
• BIL
• Design for Manufacturability