1. Research projects that have won Ig Nobel Prizes are real, serious scientific work.
2. Research projects that have ever won Ig Nobel Prizes are real, serious scientific work.
(Does #1 mean #2? What is the meaning of 'have won'? Does 'have won' mean 'experience in the past?)
3. Research projects that won Ig Nobel Prizes are real, serious scientific work.
(What about this sentence? Only 'won', the past tense' is used. What is the difference between #3 and #1?)
The present perfect tense as in "have won" indicates an action that has taken place in the past and continues into the present. Sentences #1 and #2 mean the same thing, yes. (You also need a comma after "serious"!)
The simple past tense (in #3) indicates an action that happened in the past and has not occurred again. In that sentence, I'd also change the main verb to "were."