When invoking Vivado tools from DOS, you first need to run the file settings64.bat (located in your Xilinx install area e.g. C:\Xilinx\Vivado\2017.3) in order to get your path updated as appropriate. https://www.xilinx.com/support/documentation/sw_manuals/xilinx2017_3/ug975-vivado-quick-reference.pdf