'Introduction' (Energy Engineering, 2016), 'Periodic Control of Power Electronic Converters', Chap. 1, pp. 1-25, DOI: 10.1049/PBPO082E_ch1 IET Digital Library, https://digital-library.theiet.org/;jsessionid=1urld2omu30cj.x-iet-live-01content/books/10.1049/pbpo082e_ch1