Evaluating Component Substitution Costs in High-Density Power Electronics
Evaluating power component substitutions requires amortizing NRE and re-qualification expenses against true volume savings while accounting for parasitic and thermal shifts.
Planar Transformer Leakage Inductance
Meaning
Magnetic component parameters define the unwanted inductive energy stored between the primary and secondary windings of a transformer built directly on a circuit board. For high-frequency power supplies, planar transformer leakage inductance determines the level of voltage spikes generated during switching transitions. This parameter must be kept low to prevent damage to the semiconductor switches.
Energy Storage
Uncoupled magnetic flux stores energy that cannot be transferred to the secondary side. This energy caused by planar transformer leakage inductance must be dissipated in snubber circuits. This dissipation results in lower overall converter efficiency and increased thermal load.
Voltage Spike
High spikes of voltage require the use of semiconductor switches with higher voltage ratings. When planar transformer leakage inductance is minimized, lower-voltage transistors can be used safely. This change reduces the cost and improves the efficiency of the power converter.
Board Layout
Controlling the thickness and spacing of the board layers is necessary to optimizing this magnetic coupling. Production contracts for planar transformers require tight tolerances on the board fabrication process to control planar transformer leakage inductance. This precision increases the manufacturing cost of the circuit board but eliminates the need for expensive external components.
This balance must be managed to achieve the most cost-effective manufacturing strategy for high-volume products.