does anybody have schematic of dc drives for 40hp motors?

Answer 1

Some high-current (up to 158 amp; see circuit #6) designs are given in the ref. You may have to search further, to get the combination of voltage and current capability you want (you didn't specify these), but you may be able to substitute power mosfets or profets with the needed ratings in the circuits shown. Note that these are just the driver circuits. They need a pulse-width modulation PWM) input to operate over a variable speed range.