Figure: Fabricated Power Supply PCB, consisting of two
isolated converters mounted on single board.
Designing a Grid-connected PV Inverter System
requires multiple numbers of auxiliary power
supplies for gate drivers, sensors, relays, cooling
fans, DSP, etc. which are meant to be low cost,
simplified, reliable and efficient.
Tradtionally for such application flyback
converters are employed to generate isolated
supply. Flyback topology typically uses
asymmetrical turn’s ratio transformer and an
opto-coupler or a tertiary winding is required for
reference feedback voltage. This makes it a bulky
solution with a high number of component count
subsequently increases BOM cost.
An isolated synchronous buck converter also known as “Flybuck” converter is a solution over this dilemma.This topology is a “synchronous buck” converter with a coupled inductor and a schottky diode for rectifying secondary side output voltage. The number of turns is ideally equal at both primary and secondary winding, connecting an opto-coupler or tertiary winding transformer is not required. As the secondary side output voltage can be regulated by primary side output voltage which results in thti reducon of size, components, and cost.
