How to parametrize batch GPT variables with spaces in Python?

I have this line:

command = ‘cmd /k “gpt D:\Startup_Voucher\Projetos\Artigo\Export_netcdf4.xml” + -PInput=p_preprocessed + -PBandname=Bandname + -POutput=Output_pathname’
os.system(command)

And nothing happens. The cmd opens, runs, but the output folder is empty