I am looking to step up the voltage of a 3 phase PM generator which has variable AC output of 200 - 400 Vl-l, and 15 - 30Hz. I am looking for a step up ratio between 1:1.5 and 1:2, and need this transformer to be a commercial device. What i have been finding is that most commercial transformers have defined input voltage and frequencies (i.e. 240/480 V, 60Hz), which is not ideal of course. Does anybody know of commercial devices for this type of application? I have considered back to back VFDs but that seems overly complicated. Thanks in advance.