The Flag of UruguayThis has quite a jolly Man-in-the-Sun image, probably not suited to that of a would-be controller of the World.
The Flag of the Philippines
The Flag of the Republic of China/Taiwan
The Flag of Japan
The Flag of Antigua/Barbuda
The Flag of KurdistanKurdistan is not currently a sovereign state. Its territory would include parts of Iraq, Syria and Turkey. This flag is interestingly reminiscent of the flag of India.
The Flag of Biafra
The Flag of the Aboriginal People of AustraliaThis flag was created in 1971 by Harold Thomas an Aboriginal artist who sought to create a protest flag that he hoped would unsettle people. The sun and the red earth also seem reminiscent of the landscape of central Australia. The black colour is to represent the Aboriginal people themselves. In 1995 the flag became one of the official flags of Australia. Thomas's intention to unsettle may be why this flag comes close to the one Verne used for Robur.
However, the most 'unsettling' flag bearing a sun symbol must be the flag of the Imperial Japanese Army. The Japanese Imperial Army used the sun flag with rays 1870-1945. The Japanese Navy introduced its own ensign with the sun and rays in 1889 for the Japanese Navy, but with disc off centre and with a different number of rays. It fell into disuse 1947-52 but then was revived as the ensign of the Japanese Navy. This army flag has not come back into use. The self-defence forces of Japan adopted a slightly different model though still referencing the rising sun with rays. The flag of Japan itself is the plain sun disc seen above.
Japanese Naval Ensign
Japanese Imperial Army Standard (1870-1945)
Standard of the Japanese Self-Defence ForcesGiven that the Japanese Imperial Army flag was in use for 16 years before Verne wrote his novel, I imagine he would have avoided his looking too much like the Japanese standard. Saying that, though, his move from red and white to black and gold may have been to distinguish them. I have produced a re-coloured version of the Japanese Imperial Army flag to show how I would envisage it:
Possibly the solution came to me by accident. I came across a segment from the Philippines flag with the sun symbol which features on the 'The Makings of an Illustrados' blog: http://themakingsofanillustrados.wordpress.com/2008/05/28/national-flag-day/
The Philippines flag was first created in 1896 when the islands were under Spanish control. When I copied it across, the white background shown on that site turned to black so it seemed to fit the Robur pattern even better:
Segment of Flag of the Philippines on Black Background - Robur's Flag?This certainly looks like the kind of symbol you would see displayed at the base of some super-villain. No offence meant towards the Philippines.