there is an ac mains of about which is rectified to get dc the dc is then inverted to give ac the inverter block is where i want to get my control from( be able to vary the voltage) and then rectify it back to dc. the dc motor rating is 110v and current of 18A.
I'd use a buck converter to vary the voltage and then an h-bridge to control direction. No need to make an actual inverter if you're just going to rectify it to DC again.