buck boost

I need to install a 230V, 30A, Single Phase, pressure washer. My available power is 480V / 277V. I thought I'd be able to do it as per figure 1 of the attachment, which is phase 1 and N into a buck-boost. The transformer representative told me I'd have to do it as per figure 2. which is phase 1...

What is the phase to neutral voltage, at the output of the boost transformer, shown in the attached drawing? Thanks