Customers who wish to provide some help.
DC power converter whether its input and output electrically isolated, can be divided into non-isolated converter circuit and isolation transformer circuits.

Several switching power supply topology circuit:

Step-Down (Buck) converter,
Step-Up (Boost) converter,
Polarity reversal Buck (Buck-Boost) converter,
Cuk converter single-ended,
Flyback converter,
Push-pull converter
Half-bridge,
Full-bridge converter.