The reason an inverter is called an "Inverter" is because the challenging part is taking flat, positive DC, and creating negative (inverted) pulses from it. It inverts the positive voltage for the negative part of the sine wave (and keeps it positive for the positive part). If it didn't invert it, it would just be controlling the on/off pulsing of positive DC, which is what a DC controller is "Pulse, Width, Modulation", PWM.
A "VFD" is a "Variable Frequency Drive" which means that it can control, or vary, the frequency (how many times per second) of the switching between positive and inverted pulses. It could switch it many times, or few, or anything in between. A VFD is an inverter that isn't set to a fixed rate.
An inverter is needed from a battery pack because there is only positive voltage that way, and to create AC you need negative parts. If you already had negative parts, you wouldn't need an inverter, because you'd already have a cycling source of voltage that is positive/negative/positive/negative/etc. There's nothing for the inverter to "invert", it's already back and forth being inverted. In this case you may want to use a Transformer to Transform the voltage (which can only be done on AC), but no inverter. A transformer can make the AC voltage higher or lower, but it can't change how fast it's pulsing, the frequency.
So, a VFD presumes you have an AC source, but which needs to have its frequency changed which a transformer can't do. The way it accomplishes this is to take your AC source, then put it through a rectifier to flip the negative parts of the sine wave positive, then puts some capacitors on that to help fill in the gaps to more closely approximate the steady flat positive DC of a battery. Once it has that, it chops it up however fast it wants to and inverts every other pulse to negative so it resembles AC again, but AC at a different frequency.
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So... a VFD has a couple extra components to first convert AC into DC before it uses it. It has to, that's how it works. The electronics won't work on AC, it'll mess them all up and confuse them.
So yes, it will have a DC bus. A bus is just a power rail of Positive and Ground. It will not be hard to find, follow the traces, it will be between the giant capacitors right by the input, after the big black rectifiers. The wires will be gigantic, probably the heaviest traces or wires on the board. It might not be "accessible" in terms of having output terminals, but, it's not going to be some sneaky hidden microscopic wire inside a 16 layer board, it'll be big huge traces, or, likely giant bus bars or cables. It'll be about as hard as finding the front seat on a car "Open the door, in front of the steering wheel, there you've found it."
Ignore the first part of the input, strap your batteries to the DC bus directly, and roll out.
And the 100 hp motor likely is a half ton monster.
Bah, no it won't be.