NCPRE | September Newsletter
Power Electronics Group
Switching over to compact switches

background image 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.

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B. G. Fernandes
Rajesh Farswan

Priya Sinsinwar

Alok Giri