Introduction
My objective is to convert AC to DC and do it in such a manner that the output is isolated.
All power supplies contain a network of energy storage inductors and capacitors as well as power handling transistors and rectifiers. The particular configuration is referred to as power supply topology.
There are about a dozen widely used power supply topology:
- Buck
- Boost
- Flyback
- Cuk
- Sepic
- DCM Flyback
- DCM 2-switch Flyback
- Single Switch Forward
- 2-switch Forward
- Active Clamp Forward
- Half-bridge
- Push-Pull
- Full Bridge
- Phase Shifted Full Bridge
- LLC Half Bridge
Well executed trivial design is better than poorly executed “fancy” one
For our power supply design we’ll be using a isolated flyback topology as it is the simplest one to implement.
Design
These 7 points have to be considered while designing a flyback power supply:
- AC to DC conversion
- EMI Noise filtering
- Transformer
- PWM Controller / Convertor
- Snubber Circuit
- Secondary Filtering
- Feedback Circuit
AC to DC Conversion
A simple full bridge rectifier and filtering capacitor (electrolytic capacitor would do just fine)
For finding the ideal capacitance for the power supply we can:
