Boost-Flyback converter

[anhnha]

I am reading about Boost-Flyback converter and this is a bit confusing.
Could you explain the role of D1 and C1 here?
The lecture says that "D1 and C1deliver to the output the energy stored in the transformer leakage inductance Ld." I can't understand what is meant here.
And could you explain why there is Lm there?

 

[schmitt trigger]

Lm is the transformer's primary inductance.

Actually on a flyback, "transformer" is a misnomer. It is actually a coupled inductor, and Lm is its main inductance.

 

[E-design]

There are two popular ways to model the transformer: Coupled inductor or ideal transformer. What is shown is the ideal transformer model.