There are tons of books on power electronics and many of them have the same structure. Most of them have their flaws and i think its a good idea to combine some different books for completeness. All of them are basically called "Power electronics" so i wont bother with title
Mohan, Undeland is a classic but somewhat dated.
Daniel Hart i have only skimmed through but seems nice and seems like a book that could be easy to start with.
then there is also M Rashid and Kultanara
These books you can find on libgenhttp://personal.strath.ac.uk/barry.williams/book.htm
This one is fucking massive and very thurogh but also very heavy and not as overlookable as some other in my opinion.https://www.iea.lth.se/kel/2020/Power%20Electronics%202019.pdf
This is a nice short one thats from the Power electronics course in a Swedish university.
Hope this will give you some stuff to start with.