I'm trying to get into a shop that does a lot of VFD's and they want me to do a bit of homework on the topic. Don't like studying systems I don't have my hands in just yet, but I'm up to the task and really wanna get into that shop (lots of interesting work). Now, most of the material I've come across falls into 2 categories:

1) Promo material for beancounters who know nothing about HVAC but they wanna save $$$ - oooh your energy savings will be 60% and it will pay for itself in a few months

2) Techs who already have plenty of VFD experience, so it's more along the lines of why "our" product is better than "their" product - oooh, you can commission one of our units in 36 seconds

I'm stuck in the middle as both categories leave out a lot of information that I could use in understanding the technology and implementation. Is there anything out there for a tech who understands mechanical systems and refrigeration but never worked with VFD's? Thanks in advance